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(Circulation. 2008;117:2608-2616.)
© 2008 American Heart Association, Inc.
Heart Failure |
From the Lindner Clinical Trial Center, The Ohio Heart and Vascular Center, and The Christ Hospital, Cincinnati, Ohio (E.S.C.); Emory University–Crawford Long Hospital, Atlanta, Ga (A.R.L., J.-P.S., J.M.); Ospedale Policlinico San Matteo, Pavia, Italy (L.T., S.G.); Imperial College London and Hammersmith Hospital, London, UK (P.N.); Ohio State University Heart Center, Columbus (W.T.A.); University Hospital, Rennes, France (C.L.); Leiden University Medical Center, Leiden, the Netherlands (J.J.B.); Prince of Wales Hospital, Hong Kong, China (C.-M.Y.); University of Pittsburgh, Pittsburgh, Pa (J.G.); University of Pennsylvania Medical Center, Philadelphia (M.S.J.S.); University Hospital Gent, Gent, Belgium (J.D.S.); and Sentara Norfolk General Hospital, Norfolk, Va (J.M.).
Correspondence to Eugene Chung, The Christ Hospital, Ohio Heart and Vascular Center, and the Lindner Clinical Trial Center, Cincinnati, OH 45219. E-mail chunge{at}ohioheart.org
Received October 24, 2007; accepted February 27, 2008.
| Abstract |
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Methods and Results— Fifty-three centers in Europe, Hong Kong, and the United States enrolled 498 patients with standard CRT indications (New York Heart Association class III or IV heart failure, left ventricular ejection fraction
35%, QRS
130 ms, stable medical regimen). Twelve echocardiographic parameters of dyssynchrony, based on both conventional and tissue Doppler–based methods, were evaluated after site training in acquisition methods and blinded core laboratory analysis. Indicators of positive CRT response were improved clinical composite score and
15% reduction in left ventricular end-systolic volume at 6 months. Clinical composite score was improved in 69% of 426 patients, whereas left ventricular end-systolic volume decreased
15% in 56% of 286 patients with paired data. The ability of the 12 echocardiographic parameters to predict clinical composite score response varied widely, with sensitivity ranging from 6% to 74% and specificity ranging from 35% to 91%; for predicting left ventricular end-systolic volume response, sensitivity ranged from 9% to 77% and specificity from 31% to 93%. For all the parameters, the area under the receiver-operating characteristics curve for positive clinical or volume response to CRT was
0.62. There was large variability in the analysis of the dyssynchrony parameters.
Conclusion— Given the modest sensitivity and specificity in this multicenter setting despite training and central analysis, no single echocardiographic measure of dyssynchrony may be recommended to improve patient selection for CRT beyond current guidelines. Efforts aimed at reducing variability arising from technical and interpretative factors may improve the predictive power of these echocardiographic parameters in a broad clinical setting.
Key Words: dyssynchrony echocardiography echocardiography, Doppler heart failure pacemakers
| Introduction |
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Editorial p 2573 Clinical Perspective p 2616
Recently, several echocardiographic measures of mechanical dyssynchrony have identified responders to CRT before device implantation. Ventricular dyssynchrony has been measured with traditional echocardiographic techniques,10 tissue Doppler imaging (TDI), and other methods.11–18 A few of these parameters have demonstrated the ability to distinguish CRT responders from nonresponders with a high degree of accuracy in multiple small single-center studies. To date, however, no multicenter study has examined the potential of echocardiography to assist in determining patients most likely to respond to CRT. Here, we present the results of Predictors of Response to CRT (PROSPECT), a prospective, multicenter, nonrandomized study designed to evaluate selected, predefined baseline echocardiographic parameters for their ability to predict clinical and echocardiographic response to CRT.
| Methods |
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Study Population
Patients with heart failure symptoms referred for CRT according to the current guidelines for the treatment of chronic heart failure were evaluated for enrollment. Patients were included according to the following criteria: left ventricular ejection fraction (LVEF)
35% as assessed by the investigator, NYHA functional status III or IV, and QRS duration
130 ms. Medical therapy, unless contraindicated, was to include an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker for at least 1 month before enrollment and a β-blocker started at least 3 months before and unchanged for at least 1 month before enrollment. Patients were enrolled across 53 centers in the United States, Europe, and Hong Kong between March 2004 and December 2005. All centers collected data at preimplant baseline assessment; at the time of implantation; immediately after implantation; at 1, 3, and 6 months after implantation; and every 6 months until study closure. Any Medtronic market–released CRT device with or without implantable cardioverter-defibrillator (ICD) functionality could be used in the study.
Echocardiographic Measures of Ventricular Dyssynchrony
The PROSPECT Steering Committee selected 12 echocardiographic parameters identified from published and unpublished literature as possible predictors of a positive response to CRT.10,11,13–18 Details of each parameter are presented in Table 1.
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Echocardiography Core Laboratories
The recording of a baseline echocardiogram was performed according to study protocol and sent to either a US or European core laboratory. The core laboratories used echocardiographic equipment from 1 of 3 manufacturers: General Electric (GE, Milwaukee, Wis), Philips (Andover, Mass), and Siemens (Malvern, Pa). Echocardiogram data obtained on GE machines (37%) were analyzed with GE Echopac software on a standalone workstation V4.0.4 or a GE Vivid 7 ultrasound system running version 3.2.6. Data obtained on Philips (50%) used Sonos 5500, 7500, or IE33, and TDI data were analyzed beginning with Philips QLAB version 2.0 and progressively updated throughout the study to version 4.1. TDI data on Siemens (12%) were analyzed with Tomtec Research Arena software version 1.0. In addition, 6 baseline echocardiograms (1%) were obtained with Aloka ProSound 5500.
The US core laboratory in Atlanta, Ga (Emory University–Crawford Long Hospital), processed all studies from the United States and Hong Kong. For studies from Europe, the core laboratory in Pavia, Italy (Policlinico San Matteo), analyzed all standard 2-dimensional measurements and TDI analysis of studies recorded on machines from GE. The core laboratory in London, UK (Hammersmith Hospital), performed TDI analysis of echocardiograms recorded on machines manufactured by Philips and Siemens.
Training and Quality Control
At all centers, training on the echocardiogram protocol, data acquisition, and storage was completed by means of a written manual and video presentation. In addition, each center was required to obtain accreditation from the echocardiography core laboratory in its region by providing high-quality images before enrolling any study subjects. Furthermore, any subsequent studies judged to be of insufficient quality by the core laboratory were censored and not included in the analysis.
A team of echocardiologists (see the Appendix in the online Data Supplement) assisted in the creation and review of an echocardiographic measurement manual that was followed by the core laboratories to ensure consistent measurement of images. This document was reviewed and approved by the PROSPECT Steering Committee, which was made up of heart failure specialists, echocardiologists, and electrophysiologists (see the Appendix). In addition, an independent echocardiographic review committee (see the Appendix) reviewed the core laboratory data and predictor calculations before statistical analysis. The echocardiographic review committee provided support and expert review during visits to each of the core laboratories.
Repeatability and Reproducibility of Measurements
Variability was evaluated with measurements selected to represent the major echocardiographic methodology categories: 2-dimensional study, M-mode, pulsed Doppler, and TDI based. Intraoperator variability was assessed within each core laboratory with 10 baseline recordings. Measurement of each echocardiographic recording was conducted 3 times (on days 1, 2, and 7). For each patient, left ventricular end-systolic volume (LVESV; study end point), septal-posterior wall motion delay (SPWMD), the SD of time to peak systolic velocity of 12 segments of the left ventricular wall at the basal and medial levels (Ts-SD; used for power calculations), left ventricular preejection interval (measured in MIRACLE and MIRACLE ICD), and maximal time to peak systolic velocity difference of 6 segments at the basal level (Ts-peak) were measured.
Interobserver variability was measured between core laboratories with the same echocardiographic parameters (LVESV, SPWMD, Ts-SD, left ventricular preejection interval, Ts-peak). For this assessment, a total of 12 recordings were exchanged by the US and Italian core laboratories; the US and UK core laboratories exchanged 20 echocardiograms.
Definition of Response to CRT
Response to CRT was evaluated through the use of 2 separately analyzed primary outcomes at 6 months: heart failure CCS and relative change in LVESV. The CCS describes patients regardless of vital status at 6 months and includes both objective and subjective measures of clinical status. A patients CCS was classified as one of the following: worsened (the patient died or was hospitalized for or associated with worsening heart failure, demonstrated worsening in NYHA class at last observation carried forward, had moderate or marked worsening of patient global assessment score at last observation carried forward, or permanently discontinued CRT because of or associated with worsening heart failure), improved (the patient had not worsened as defined above and demonstrated improvement in NYHA class at last observation carried forward or had moderate or marked improvement in patient global assessment score at last observation carried forward), or unchanged (the patient was neither improved nor worsened).9 An independent end point committee (see the Appendix) adjudicated all hospitalizations and CRT discontinuations for heart failure relatedness. A positive response to CRT was defined in the case of CCS as a designation of "improved" and with LVESV as a reduction of
15% at 6 months compared with baseline (paired LVESV measurements). A reduction in LVESV of
15% has been used in previous trials10,11 and was used in this study as an objective measure of cardiac function.
Statistical Methods
Prespecified cutoff values for each echocardiographic measure were determined from both published and unpublished data, and each parameter was tested against the response outcomes (CCS and LVESV). When predictive cutoff values did not appear in the literature, the cutoff was defined as the median value (Table 1). The proportions of patients with a positive response to CRT above and below the specified cutoff values were compared by Fishers exact test. No adjustment for conducting multiple statistical tests was made. Receiver-operating characteristics curves were generated, and areas under the curve are reported as a measure of the ability to predict positive response at any cutoff value.
For the analysis of intraobserver and interoperator echocardiographic variability, we calculated an adjusted coefficient of variation (CV), defined as the ratio of the SD and the mean of absolute readings for each echocardiographic parameter. Agreement of binary echocardiographic predictors was assessed with Cohens
coefficients.
Finally, to further characterize the relationship between echocardiographic measures and the 2 primary outcomes, retrospective analyses of the following subgroups were performed: core laboratory–measured LVEF
35%, left ventricular end-diastolic diameter
65 mm, and ischemic and nonischemic origin of heart failure.
The authors had full access to and take full responsibility for the integrity of the data. All authors have read and agree to the manuscript as written.
| Results |
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Echocardiographic Data
Variability analyses of echocardiographic measures are shown in Table 3. Intraobserver reproducibility was similar in the 3 core laboratories, with low variability for LVESV and left ventricular preejection interval (CV, 3.8% and 3.7%, respectively), moderate variability for Ts-SD and Ts-peak (CV, 11.4% and 15.8%), and high variability for SPWMD (CV, 24.3%). Interobserver variability was higher for each parameter than intraobserver variability, with high variability for Ts-peak, Ts-SD, and SPWMD (CV, 31.9%, 33.7%, and 72.1%, respectively).
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TDI data obtained with the Siemens machines were excluded from analysis because of suboptimal data quality as determined by the core laboratories.
CCS End Point
Overall, based on the CCS, 69% of patients improved, 15% remained unchanged, and 16% worsened (Figure 2). Fourteen patients (3%) died and 45 patients (11%) were hospitalized for worsening heart failure during the 6-month follow-up. Table 4 summarizes the ability of each evaluated echocardiographic parameter to predict clinical response as measured by the CCS. Three of the 5 non-TDI parameters and 1 of the 7 TDI-based methods (Ts onset basal) demonstrated modest, statistically significant value in predicting a higher rate of CCS response for those reaching the cutoff value. In receiver-operating characteristics analyses (Table 5), among the published TDI methods, the SD of time to peak velocity of 12 segments achieves an area under the curve of 0.60 (P=0.03) for the ability to predict improved CCS.
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LVESV as an End Point
The 286 patients with available paired LVESV measurements showed a relative LVESV reduction of 19.7±27.3% (mean±SD) at 6 months. One hundred sixty-one patients (56.3%) had a reduction of
15%, meeting the prespecified definition of improvement, and 26 patients (9.1%) had an increase of at least 15% in LVESV (Figure 2). The predictive ability of each echocardiographic parameter for LVESV reduction is shown in Table 4. All 4 of the non-TDI methods and 1 of the TDI-based tests (time difference between lateral and septal peak systolic wall velocity) demonstrated a significantly higher level of response among those meeting the cutoff criterion.
Based on the receiver-operating characteristics analysis, the time difference between lateral and septal peak systolic wall velocity achieved an area under the curve of 0.61 (P=0.01) for the ability to predict LVESV reduction of
15%.
Subgroup Analyses
There were no statistically significant differences in CCS or LVESV responses between patients in the United States and those outside the United States (65.2% and 73.4%, respectively, P=0.07 for CCS; and 54.2% and 58.3%, respectively, P=0.55 for LVESV). The CCS response rate was higher among nonischemic patients compared with those with ischemic origin (75% versus 64%, respectively; P=0.01); also, the LVESV response rate tended to be higher in the nonischemic group compared with the ischemic group (63% versus 50%, respectively; P=0.03).
Although the center reported that mean LVEF was 23.6±7% in PROSPECT, the core laboratory–measured mean LVEF was 29.3±10%; 20.2% of subjects had a core laboratory–measured LVEF >35%. Nonetheless, in the subgroups defined by core laboratory–measured LVEF
35% (n=340, 79.8%) or left ventricular end-diastolic diameter
65 mm (n=265, 62.2%), there were no substantial differences in the predictive power of the echocardiographic parameters compared with all subjects (data not shown).
| Discussion |
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Given the background of numerous smaller, single-center studies demonstrating a strong correlation between echocardiographic measures of mechanical dyssynchrony and clinical response to CRT,11–18 the results of PROSPECT are somewhat surprising. There may be several explanations for this discrepancy.
We observed relatively low yield and high variability for the TDI measures. Specifically, the percent of individual parameters deemed interpretable by the core laboratories ranged between 61% and 95% for the routine non-TDI methods and between 37% and 82% for TDI-based tests. Although TDI measurements, performed in a laboratory with special expertise, may be effective in predicting outcomes to CRT, current technology, degree of training standards, and analytic methods do not allow its incorporation in a generalized setting and may currently represent a significant limitation for the widespread use of TDI methods. The use of different echocardiographic platforms and equipment to collect and analyze images may have exacerbated variability in measurements. However, in this study evaluating methods across a wide spectrum of locations and medical practices, we sought to include the major vendors of these technologies. There also appear to be differing practice styles between the United States and Europe with regard to patient selection for CRT, with a tendency toward use of CRT earlier in the disease process in the United States, which may have added to the variability in patient selection characteristics. Note, however, that distance walked in 6 minutes was 246 m on average in US patients versus 308 m in European patients. It also has been suggested that longitudinal dyssynchrony may be subject to higher variability and may correlate less well with ventricular functional recovery after CRT than 2-dimensional strain techniques that evaluate radial dyssynchrony.20 Other potentially interesting methods for further study are novel echocardiographic techniques, including 2-dimensional strain imaging (speckle tracking approach),21 3-dimensional echocardiography,22 anatomic M-mode imaging,23 and magnetic resonance imaging.24
Were the cutoff points for the echocardiographic measurements appropriately selected? The values selected for PROSPECT, although based on published reports when available, were developed in observational single-center studies and may need to be refined when the methodology is translated to the larger community. Do the end points reflect clinically relevant outcomes, and are they robust enough to be accurately predicted by echocardiographic methods? The 2 primary end points were selected to measure clinically relevant outcomes in heart failure patients with a validated tool (CCS) and to assess cardiac structural response (reverse remodeling). The CCS has been used in heart failure clinical trials with success1,7 and consists of easily measured components (survival, hospitalization, NYHA class, patient global assessment) with stringent criteria for improved status. Nonetheless, given that patients enrolled in clinical trials generally improve even in the absence of therapy, it is possible that CCS changes may not be due to events that bear any relationship to echocardiographic measures. Therefore, a measure of cardiac structural change also was incorporated. The reverse remodeling end point (LVESV reduction
15%) has been used more specifically in studies evaluating echocardiographic predictors,10,11 and there was general consensus among the steering committee that 15% reduction in LVESV was a robust and clinically relevant outcome measure. The ideal end point to assess response to CRT is currently unclear, and it has been noted that a discrepancy exists between clinical and echocardiographic responses (a reduction in LVESV), with a greater rate of clinical response compared with echocardiographic response.25
The PROSPECT patient population may be somewhat different from those studied for the published echocardiographic parameters, partly accounting for the discrepancy with previously reported results. Indeed, as measured by the core laboratory, 20.2% had LVEF >35% and 37.8% had left ventricular end-diastolic diameter <65 mm, suggesting that perhaps the severity of illness in PROSPECT, a study conducted in the course of clinical practice, was not congruent with previously studied patients in the setting of clinical trials. Nonetheless, the average 6-minute walk distance in PROSPECT was 274±122 m compared with 298±92 m in MIRACLE1 and 243±122 m in MIRACLE ICD.7 More specifically, in 2 TDI methodology studies,11,15 baseline 6-minute walk distances were
248 and 320 m, respectively. Furthermore, extensive subgroup analyses looking at those with the lowest LVEF, greatest left ventricular diameter, and ischemic or nonischemic origin do not demonstrate substantial difference in the predictive ability of the echocardiographic parameters. Still, additional studies focusing on patients with LVEF
35% and left ventricular end-diastolic diameter
65 mm should be performed.
It is possible that mechanisms other than attenuation of systolic dyssynchrony per se underlie the benefits seen with CRT. Chronically, the existence of an abnormally high regional wall stress such as with an infarcted zone may lead to progressive left ventricular dilation.26 Prinzen and colleagues27 have shown that ventricular pacing significantly reduces wall stress and workload by causing the region near the pacing site to contract early in the cycle against a lower ventricular pressure and at a reduced preload. Therefore, the preexcited region does less external work and develops less stress; in a chronic setting, this phenomenon may have favorable effects on the failing heart.
Finally, determining the patients most likely to respond before CRT requires an assessment of factors other than echocardiography-measured dyssynchrony. For example, limited venous anatomy may introduce a mismatch between left ventricular lead position and latest activation site28 that is likely to lead to a variation of CRT response that is unrelated to echocardiographic parameters. In a multicenter setting, this factor is even more difficult to control. In addition, extensive left ventricular scar tissue attenuates clinical and structural response rates to CRT despite the presence of cardiac dyssynchrony and could be a potential confounder of results in ischemic patients.29 Therefore, integration of cardiac dyssynchrony and magnetic resonance imaging evaluation for the presence, location, and size of the scar in patients with ischemic cardiomyopathy may be a useful modality in patient selection for CRT.30,31 In this regard, the interplay between heart failure origin, end-point selection, and echocardiographic parameters should be noted in future study design.
The major limitation of this study is the observational, nonrandomized design. The main purpose of this study was to assess predictive abilities of the echocardiographic parameters, not to test whether the use of these parameters has a clinical impact. If echocardiographic parameters can be identified in a multicenter setting that improve significantly on the current implantation criteria, further randomized studies testing such parameters would be warranted. The relatively high levels of both interobserver and intraobserver variability noted in this multicenter study impair our ability to conclusively assess the potential predictive capabilities of the echocardiographic parameters in an ideal setting. Therefore, the introduction of variability in image acquisition and analysis currently represents a major limitation to translating expert, single-center experience to widespread use.
| Conclusions |
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| Acknowledgments |
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Medtronic Inc provided funding for this study and manufactured the CRT system used in this research.
Disclosures
Drs Abraham, Bax, Chung, Gorcsan, Nihoyannopoulos, St. John Sutton, Tavazzi, and Yu have served as consultants to and received research grants from Medtronic. Drs De Sutter, Ghio, Leclercq, Leon, Murillo, Nihoyannopoulos and Sun have received honoraria from or consulted for Medtronic.
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| Footnotes |
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The online Data Supplement, which consists of an Appendix, can be found with this article at http://circ.ahajournals.org/cgi/content/full/ CIRCULATIONAHA.107.743120/DC1.
Clinical trial registration information—URL: http://www.clinicaltrials.gov. Unique identifier: NCT00253357.
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O. Oyenuga, H. Hara, H. Tanaka, H.-N. Kim, E. C. Adelstein, S. Saba, and J. Gorcsan III Usefulness of Echocardiographic Dyssynchrony in Patients With Borderline QRS Duration to Assist With Selection for Cardiac Resynchronization Therapy J. Am. Coll. Cardiol. Img., February 1, 2010; 3(2): 132 - 140. [Abstract] [Full Text] [PDF] |
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T. P. Abraham and N. T. Olsen QRS Width and Mechanical Dyssynchrony for Selection of Patients for Cardiac Resynchronization Therapy: One Can't Do Without the Other J. Am. Coll. Cardiol. Img., February 1, 2010; 3(2): 141 - 143. [Full Text] [PDF] |
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A. C.T. Ng, D. T. Tran, C. Allman, J. Vidaic, and D. Y. Leung Prognostic implications of left ventricular dyssynchrony early after non-ST elevation myocardial infarction without congestive heart failure Eur. Heart J., February 1, 2010; 31(3): 298 - 308. [Abstract] [Full Text] [PDF] |
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I. E. van Geldorp, K. Vernooy, T. Delhaas, M. H. Prins, H. J. Crijns, F. W. Prinzen, and B. Dijkman Beneficial effects of biventricular pacing in chronically right ventricular paced patients with mild cardiomyopathy Europace, February 1, 2010; 12(2): 223 - 229. [Abstract] [Full Text] [PDF] |
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G. V. Ramani, P. A. Uber, and M. R. Mehra Chronic Heart Failure: Contemporary Diagnosis and Management Mayo Clin. Proc., February 1, 2010; 85(2): 180 - 195. [Abstract] [Full Text] [PDF] |
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A Bhan, S Kapetanakis, and M J Monaghan Three-dimensional echocardiography Heart, January 15, 2010; 96(2): 153 - 163. [Abstract] [Full Text] [PDF] |
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M. Bertini, V. Delgado, D. W. den Uijl, G. Nucifora, A. C.T. Ng, R. J. van Bommel, C. J. W. Borleffs, G. Boriani, M. J. Schalij, and J. J. Bax Prediction of Cardiac Resynchronization Therapy Response: Value of Calibrated Integrated Backscatter Imaging Circ Cardiovasc Imaging, January 1, 2010; 3(1): 86 - 93. [Abstract] [Full Text] [PDF] |
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J. E. Sanderson Reply. J. Am. Coll. Cardiol., December 1, 2009; 54(23): 2204 - 2204. [Full Text] [PDF] |
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D. Schaber Clarification and Correction About the Design and Implementation of the PROSPECT Trial. J. Am. Coll. Cardiol., December 1, 2009; 54(23): 2203 - 2204. [Full Text] [PDF] |
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S. Lafitte, P. Reant, A. Zaroui, E. Donal, A. Mignot, H. Bougted, H. Belghiti, P. Bordachar, A. Deplagne, J. Chabaneix, et al. Validation of an echocardiographic multiparametric strategy to increase responders patients after cardiac resynchronization: a multicentre study Eur. Heart J., December 1, 2009; 30(23): 2880 - 2887. [Abstract] [Full Text] [PDF] |
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J. Stirrup, A. Maenhout, K. Wechalekar, and C. Anagnostopoulos Radionuclide imaging in ischaemic heart failure Br. Med. Bull., December 1, 2009; 92(1): 43 - 59. [Abstract] [Full Text] [PDF] |
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M. Santaularia-Tomas and T. P. Abraham Criteria predicting response to CRT: is more better? Eur. Heart J., December 1, 2009; 30(23): 2835 - 2837. [Full Text] [PDF] |
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Q. Ciampi, B. Petruzziello, M. D. Porta, S. Caputo, V. Manganiello, C. Astarita, and B. Villari Effect of intraventricular dyssynchrony on diastolic function and exercise tolerance in patients with heart failure Eur J Echocardiogr, December 1, 2009; 10(8): 907 - 913. [Abstract] [Full Text] [PDF] |
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R. Vatasescu, A. Berruezo, L. Mont, D. Tamborero, M. Sitges, E. Silva, J. M. Tolosana, B. Vidal, D. Andreu, and J. Brugada Midterm 'super-response' to cardiac resynchronization therapy by biventricular pacing with fusion: insights from electro-anatomical mapping Europace, December 1, 2009; 11(12): 1675 - 1682. [Abstract] [Full Text] [PDF] |
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D. E. Thomas, R. Wheeler, Z. R. Yousef, and N. D. Masani The role of echocardiography in guiding management in dilated cardiomyopathy Eur J Echocardiogr, December 1, 2009; 10(8): iii15 - iii21. [Abstract] [Full Text] [PDF] |
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N. A. Marsan, L. F Tops, P. Nihoyannopoulos, E. R Holman, and J. J Bax Real-time three dimensional echocardiography: current and future clinical applications Heart, November 15, 2009; 95(22): 1881 - 1890. [Full Text] [PDF] |
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E Liodakis, O A. Sharef, D Dawson, and P Nihoyannopoulos The use of real-time three-dimensional echocardiography for assessing mechanical synchronicity Heart, November 15, 2009; 95(22): 1865 - 1871. [Abstract] [Full Text] [PDF] |
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P. W.X. Foley, B. Stegemann, K. Ng, S. Ramachandran, A. Proudler, M. P. Frenneaux, L. L. Ng, and F. Leyva Growth differentiation factor-15 predicts mortality and morbidity after cardiac resynchronization therapy Eur. Heart J., November 2, 2009; 30(22): 2749 - 2757. [Abstract] [Full Text] [PDF] |
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J. Solis, D. McCarty, R. A. Levine, M. D. Handschumacher, L. Fernandez-Friera, A. Chen-Tournoux, L. Mont, B. Vidal, J. P. Singh, J. Brugada, et al. Mechanism of Decrease in Mitral Regurgitation After Cardiac Resynchronization Therapy: Optimization of the Force-Balance Relationship Circ Cardiovasc Imaging, November 1, 2009; 2(6): 444 - 450. [Abstract] [Full Text] [PDF] |
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K. Muellerleile, L. Baholli, M. Groth, A. A. Barmeyer, K. Koopmann, R. Ventura, R. Koester, G. Adam, S. Willems, and G. K. Lund Interventricular Mechanical Dyssynchrony: Quantification with Velocity-encoded MR Imaging Radiology, November 1, 2009; 253(2): 364 - 371. [Abstract] [Full Text] [PDF] |
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M. Bertini, V. Delgado, J. J. Bax, and N. R.L. Van de Veire Why, how and when do we need to optimize the setting of cardiac resynchronization therapy? Europace, November 1, 2009; 11(suppl_5): v46 - v57. [Abstract] [Full Text] [PDF] |
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C. Leclercq Problems and troubleshooting in regular follow-up of patients with cardiac resynchronization therapy Europace, November 1, 2009; 11(suppl_5): v66 - v71. [Abstract] [Full Text] [PDF] |
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N. R. Van de Veire, V. Delgado, J. D. Schuijf, E. E. van der Wall, M. J. Schalij, and J. J. Bax The role of non-invasive imaging in patient selection Europace, November 1, 2009; 11(suppl_5): v32 - v39. [Abstract] [Full Text] [PDF] |
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P. W.X. Foley, F. Leyva, and M. P. Frenneaux What is treatment success in cardiac resynchronization therapy? Europace, November 1, 2009; 11(suppl_5): v58 - v65. [Abstract] [Full Text] [PDF] |
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L. K. Williams, S. Ellery, K. Patel, F. Leyva, R. A. Bleasdale, T. T. Phan, B. Stegemann, V. Paul, P. Steendijk, and M. Frenneaux Short-Term Hemodynamic Effects of Cardiac Resynchronization Therapy in Patients With Heart Failure, a Narrow QRS Duration, and No Dyssynchrony Circulation, October 27, 2009; 120(17): 1687 - 1694. [Abstract] [Full Text] [PDF] |
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T. D. Karamitsos, J. M. Francis, S. Myerson, J. B. Selvanayagam, and S. Neubauer The Role of Cardiovascular Magnetic Resonance Imaging in Heart Failure J. Am. Coll. Cardiol., October 6, 2009; 54(15): 1407 - 1424. [Abstract] [Full Text] [PDF] |
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J. Holzmeister Time to RethinQ PROSPECT? Eur. Heart J., October 2, 2009; 30(20): 2436 - 2437. [Full Text] [PDF] |
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R. J. van Bommel, J. J. Bax, W. T. Abraham, E. S. Chung, L. A. Pires, L. Tavazzi, P. J. Zimetbaum, B. Gerritse, N. Kristiansen, and S. Ghio Characteristics of heart failure patients associated with good and poor response to cardiac resynchronization therapy: a PROSPECT (Predictors of Response to CRT) sub-analysis Eur. Heart J., October 2, 2009; 30(20): 2470 - 2477. [Abstract] [Full Text] [PDF] |
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K. Dickstein, N. Bogale, S. Priori, A. Auricchio, J. G. Cleland, A. Gitt, T. Limbourg, C. Linde, D. J. van Veldhuisen, J. Brugada, et al. The European cardiac resynchronization therapy survey Eur. Heart J., October 2, 2009; 30(20): 2450 - 2460. [Abstract] [Full Text] [PDF] |
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N. A. Marsan, J. J.M. Westenberg, C. Ypenburg, R. J. van Bommel, S. Roes, V. Delgado, L. F. Tops, R. J. van der Geest, E. Boersma, A. de Roos, et al. Magnetic resonance imaging and response to cardiac resynchronization therapy: relative merits of left ventricular dyssynchrony and scar tissue Eur. Heart J., October 1, 2009; 30(19): 2360 - 2367. [Abstract] [Full Text] [PDF] |
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M. Jessup MADIT-CRT -- Breathtaking or Time to Catch Our Breath? N. Engl. J. Med., October 1, 2009; 361(14): 1394 - 1396. [Full Text] [PDF] |
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F Leyva, P W X Foley, B Stegemann, J A Ward, L L Ng, M P Frenneaux, F Regoli, R E A Smith, and A Auricchio Development and validation of a clinical index to predict survival after cardiac resynchronisation therapy Heart, October 1, 2009; 95(19): 1619 - 1625. [Abstract] [Full Text] [PDF] |
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H. R. Bonakdar, M. V. Jorat, A. F. Fazelifar, A. Alizadeh, N. Givtaj, N. Sameie, A. Sadeghpour, and M. Haghjoo Prediction of response to cardiac resynchronization therapy using simple electrocardiographic and echocardiographic tools Europace, October 1, 2009; 11(10): 1330 - 1337. [Abstract] [Full Text] [PDF] |
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M. Bertini, N. A. Marsan, V. Delgado, R. J. van Bommel, G. Nucifora, C. J. W. Borleffs, G. Boriani, M. Biffi, E. R. Holman, E. E. van der Wall, et al. Effects of cardiac resynchronization therapy on left ventricular twist. J. Am. Coll. Cardiol., September 29, 2009; 54(14): 1317 - 1325. [Abstract] [Full Text] [PDF] |
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A. K. Rutz, R. Manka, S. Kozerke, S. Roas, P. Boesiger, and J. Schwitter Left ventricular dyssynchrony in patients with left bundle branch block and patients after myocardial infarction: integration of mechanics and viability by cardiac magnetic resonance Eur. Heart J., September 1, 2009; 30(17): 2117 - 2127. [Abstract] [Full Text] [PDF] |
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B. W.L. De Boeck, A. J. Teske, M. Meine, G. E. Leenders, M. J. Cramer, F. W. Prinzen, and P. A. Doevendans Septal rebound stretch reflects the functional substrate to cardiac resynchronization therapy and predicts volumetric and neurohormonal response Eur J Heart Fail, September 1, 2009; 11(9): 863 - 871. [Abstract] [Full Text] [PDF] |
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M. Tomaske, O. A. Breithardt, and U. Bauersfeld Preserved cardiac synchrony and function with single-site left ventricular epicardial pacing during mid-term follow-up in paediatric patients Europace, September 1, 2009; 11(9): 1168 - 1176. [Abstract] [Full Text] [PDF] |
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L. F. Tops, M. J. Schalij, and J. J. Bax The effects of right ventricular apical pacing on ventricular function and dyssynchrony implications for therapy. J. Am. Coll. Cardiol., August 25, 2009; 54(9): 764 - 776. [Abstract] [Full Text] [PDF] |
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G. M. Marcus, E. Keung, and M. M. Scheinman The year in review of clinical cardiac electrophysiology. J. Am. Coll. Cardiol., August 25, 2009; 54(9): 777 - 787. [Full Text] [PDF] |
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M. Biffi, C. Moschini, M. Bertini, D. Saporito, M. Ziacchi, I. Diemberger, C. Valzania, G. Domenichini, E. Cervi, C. Martignani, et al. Phrenic Stimulation: A Challenge for Cardiac Resynchronization Therapy Circ Arrhythm Electrophysiol, August 1, 2009; 2(4): 402 - 410. [Abstract] [Full Text] [PDF] |
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D. E. Thomas, Z. R. Yousef, and A. G. Fraser A critical comparison of echocardiographic measurements used for optimizing cardiac resynchronization therapy: stroke distance is best Eur J Heart Fail, August 1, 2009; 11(8): 779 - 788. [Abstract] [Full Text] [PDF] |
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M. Schmidt, H. Rittger, H. Marschang, A.-M. Sinha, M. Daccarett, J. Brachmann, M. Block, and O. A. Breithardt Left ventricular dyssynchrony from right ventricular pacing depends on intraventricular conduction pattern in intrinsic rhythm Eur J Echocardiogr, August 1, 2009; 10(6): 776 - 783. [Abstract] [Full Text] [PDF] |
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C. Sonne, L. Sugeng, M. Takeuchi, L. Weinert, R. Childers, N. Watanabe, K. Yoshida, V. Mor-Avi, and R. M. Lang Real-Time 3-Dimensional Echocardiographic Assessment of Left Ventricular Dyssynchrony: Pitfalls in Patients With Dilated Cardiomyopathy J. Am. Coll. Cardiol. Img., July 1, 2009; 2(7): 802 - 812. [Abstract] [Full Text] [PDF] |
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R. J. Gibbons and P. Chareonthaitawee Establishing the Prognostic Value of Rb-82 PET Myocardial Perfusion Imaging: A Step in the Right Direction J. Am. Coll. Cardiol. Img., July 1, 2009; 2(7): 855 - 857. [Full Text] [PDF] |
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R. Gervais, C. Leclercq, A. Shankar, S. Jacobs, H. Eiskjaer, A. Johannessen, N. Freemantle, J. G.F. Cleland, L. Tavazzi, C. Daubert, et al. Surface electrocardiogram to predict outcome in candidates for cardiac resynchronization therapy: a sub-analysis of the CARE-HF trial Eur J Heart Fail, July 1, 2009; 11(7): 699 - 705. [Abstract] [Full Text] [PDF] |
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G. Boriani, M. Bertini, I. Diemberger, M. Biffi, and C. Martignani The QRS interval in patients treated with resynchronization therapy: which value? Eur J Heart Fail, July 1, 2009; 11(7): 635 - 637. [Full Text] [PDF] |
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Q Zhang, R J van Bommel, J W-H Fung, J Y-S Chan, G B Bleeker, C Ypenburg, G Yip, Y-j Liang, M J Schalij, J J Bax, et al. Tissue Doppler velocity is superior to strain imaging in predicting long-term cardiovascular events after cardiac resynchronisation therapy Heart, July 1, 2009; 95(13): 1085 - 1090. [Abstract] [Full Text] [PDF] |
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T. H. Marwick and J. Narula The Growth and Growth of Cardiac Ultrasound for the Evaluation of Myocardial Function J. Am. Coll. Cardiol. Img., June 1, 2009; 2(6): 790 - 792. [Full Text] [PDF] |
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J. Janousek Cardiac resynchronisation in congenital heart disease Heart, June 1, 2009; 95(11): 940 - 947. [Full Text] [PDF] |
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J. J. Bax and J. Gorcsan III Echocardiography and noninvasive imaging in cardiac resynchronization therapy: results of the PROSPECT (Predictors of Response to Cardiac Resynchronization Therapy) study in perspective. J. Am. Coll. Cardiol., May 26, 2009; 53(21): 1933 - 1943. [Full Text] [PDF] |
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N. M. Hawkins, M. C. Petrie, M. I. Burgess, and J. J.V. McMurray Selecting patients for cardiac resynchronization therapy: the fallacy of echocardiographic dyssynchrony. J. Am. Coll. Cardiol., May 26, 2009; 53(21): 1944 - 1959. [Abstract] [Full Text] [PDF] |
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J. E. Sanderson Echocardiography for cardiac resynchronization therapy selection: fatally flawed or misjudged? J. Am. Coll. Cardiol., May 26, 2009; 53(21): 1960 - 1964. [Abstract] [Full Text] [PDF] |
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S. J. Buss, P. M. Humpert, R. Bekeredjian, S. E. Hardt, C. Zugck, D. Schellberg, A. Bauer, A. Filusch, H. Kuecherer, H. A. Katus, et al. Echocardiographic phase imaging to predict reverse remodeling after cardiac resynchronization therapy. J. Am. Coll. Cardiol. Img., May 1, 2009; 2(5): 535 - 543. [Abstract] [Full Text] [PDF] |
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O. A. Breithardt Echocardiographic patient selection for cardiac resynchronization therapy betting on a dead horse? J. Am. Coll. Cardiol. Img., May 1, 2009; 2(5): 544 - 547. [Full Text] [PDF] |
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L. Mertens and M. K. Friedberg Selecting pacing sites in children with complete heart block: is it time to avoid the right ventricular free wall? Eur. Heart J., May 1, 2009; 30(9): 1033 - 1034. [Full Text] [PDF] |
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S. Ghio, N. Freemantle, L. Scelsi, A. Serio, G. Magrini, M. Pasotti, A. Shankar, J. G.F. Cleland, and L. Tavazzi Long-term left ventricular reverse remodelling with cardiac resynchronization therapy: results from the CARE-HF trial Eur J Heart Fail, May 1, 2009; 11(5): 480 - 488. [Abstract] [Full Text] [PDF] |
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Q. Ciampi, L. Pratali, R. Citro, M. Piacenti, B. Villari, and E. Picano Identification of responders to cardiac resynchronization therapy by contractile reserve during stress echocardiography Eur J Heart Fail, May 1, 2009; 11(5): 489 - 496. [Abstract] [Full Text] [PDF] |
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F. Z. Khan, M. S. Virdee, S. P. Fynn, and D. P. Dutka Left ventricular lead placement in cardiac resynchronization therapy: where and how? Europace, May 1, 2009; 11(5): 554 - 561. [Abstract] [Full Text] [PDF] |
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A. E. Weyman The year in echocardiography. J. Am. Coll. Cardiol., April 28, 2009; 53(17): 1558 - 1567. [Full Text] [PDF] |
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R. M Cubbon and K. K A Witte Cardiac resynchronisation therapy for chronic heart failure and conduction delay BMJ, April 28, 2009; 338(apr28_2): b1265 - b1265. [Full Text] |
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J. Coromilas Physician Credentials and ICD Implantation: Certified "Electricians" Best Deal With Electrical Problems JAMA, April 22, 2009; 301(16): 1713 - 1714. [Full Text] [PDF] |
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C. Parsai, B. Bijnens, G. R. Sutherland, A. Baltabaeva, P. Claus, M. Marciniak, V. Paul, M. Scheffer, E. Donal, G. Derumeaux, et al. Toward understanding response to cardiac resynchronization therapy: left ventricular dyssynchrony is only one of multiple mechanisms Eur. Heart J., April 2, 2009; 30(8): 940 - 949. [Abstract] [Full Text] [PDF] |
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C. Parsai, A. Baltabaeva, L. Anderson, M. Chaparro, B. Bijnens, and G. R. Sutherland Low-dose dobutamine stress echo to quantify the degree of remodelling after cardiac resynchronization therapy Eur. Heart J., April 2, 2009; 30(8): 950 - 958. [Abstract] [Full Text] [PDF] |
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J.-U. Voigt, T.-M. Schneider, S. Korder, M. Szulik, E. Gurel, W. G. Daniel, F. Rademakers, and F. A. Flachskampf Apical transverse motion as surrogate parameter to determine regional left ventricular function inhomogeneities: a new, integrative approach to left ventricular asynchrony assessment Eur. Heart J., April 2, 2009; 30(8): 959 - 968. [Abstract] [Full Text] [PDF] |
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J.-U. Voigt Rocking will tell it Eur. Heart J., April 2, 2009; 30(8): 885 - 886. [Full Text] [PDF] |
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K. P. Phillips, Z. B. Popovic, P. Lim, J. E. Meulet, C. D. Barrett, L. D. Biase, D. Agler, J. D. Thomas, and R. A. Grimm Opposing Wall Mechanics Are Significantly Influenced by Longitudinal Cardiac Rotation in the Assessment of Ventricular Dyssynchrony J. Am. Coll. Cardiol. Img., April 1, 2009; 2(4): 379 - 386. [Abstract] [Full Text] [PDF] |
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J. K. Oh and C. Miyazaki Rock 'n Roll Ventricle of the Dyssynchronous Heart: Clinical Significance of Rocking Motion in Selection of Patient for Cardiac Resynchronization Therapy J. Am. Coll. Cardiol. Img., April 1, 2009; 2(4): 387 - 389. [Full Text] [PDF] |
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T. Abraham, D. Kass, G. Tonti, G. F. Tomassoni, W. T. Abraham, J. J. Bax, and T. H. Marwick Imaging Cardiac Resynchronization Therapy J. Am. Coll. Cardiol. Img., April 1, 2009; 2(4): 486 - 497. [Abstract] [Full Text] [PDF] |
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L. F. Tops and J. J. Bax The Year in Imaging Related to Electrophysiology J. Am. Coll. Cardiol. Img., April 1, 2009; 2(4): 498 - 510. [Full Text] [PDF] |
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D. Mele, T. Toselli, F. Capasso, G. Stabile, M. Piacenti, M. Piepoli, S. Giatti, C. Klersy, L. Sallusti, and R. Ferrari Comparison of myocardial deformation and velocity dyssynchrony for identification of responders to cardiac resynchronization therapy Eur J Heart Fail, April 1, 2009; 11(4): 391 - 399. [Abstract] [Full Text] [PDF] |
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