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(Circulation. 2007;115:204-212.)
© 2007 American Heart Association, Inc.
Heart Failure |
From the Department of Medicine, University of Colorado Health Sciences Center (J.L., M.R.B.), and Womens Health Research Center (J.L.), Denver, Colo; Thomas Jefferson Medical College (A.M.F.), Philadelphia, Pa; University of Southern California (Keck School of Medicine) (L.A.S.), Los Angeles; Milton Hershey Medical Center, Penn State School of Medicine (J.B.), Hershey, Pa; Washington DC Veterans Administration (S.S., P.C.), Washington, DC; Wayne State School of Medicine (J.K.G.), Detroit, Mich; Minneapolis Veterans Administration (I.A.), Minneapolis, Minn; San Diego Cardiac Center (B.J.), San Diego, Calif; University of California (T.M.), San Francisco; Cardiovascular Associates and St Mary and Elizabeth Hospital (D.M.), Louisville, Ky; and Boston Scientific (P.Y., E.G., F.E.), St. Paul, Minn.
Correspondence to Dr JoAnn Lindenfeld, Division of Cardiology, University of Colorado Health Sciences Center, 4200 E. Ninth Ave, B-130, Denver, CO 80262. E-mail joann.lindenfeld{at}uchsc.edu
Received April 7, 2006; accepted October 11, 2006.
| Abstract |
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Methods and Results The COMPANION trial randomized 1520 patients with NYHA class III and IV HF to optimal medical therapy, CRT, or CRT-D. In the class IV patients (n=217), the primary end point of time to death or hospitalization for any cause was significantly improved by both CRT (hazard ratio [HR], 0.64; 95% CI, 0.43 to 0.94; P=0.02) and CRT-D (HR, 0.62; 95% CI, 0.42 to 0.90; P=0.01). Time to all-cause death and HF hospitalization was also significantly improved in both CRT (HR, 0.57; 95% CI, 0.37 to 0.87; P=0.01) and CRT-D (HR, 0.49; 95% CI, 0.32 to 0.75; P=0.001) Time to all-cause death trended to an improvement in both CRT (HR, 0.67; 95% CI, 0.41 to 1.10; P=0.11) and CRT-D (HR, 0.63; 95% CI, 0.39 to 1.03; P=0.06). Time to sudden death appeared to be significantly reduced in the CRT-D group (HR, 0.27; 95% CI, 0.08 to 0.90; P=0.03). There was a nonsignificant reduction in time to HF deaths for both CRT (HR, 0.68; 95% CI, 0.34 to 1.37; P=0.28) and CRT-D (HR, 0.79; 95% CI, 0.41 to 1.52; P=0.48).
Conclusions CRT and CRT-D significantly improve time to all-cause mortality and hospitalizations in NYHA class IV patients, with a trend for improved mortality. These devices should be considered in ambulatory NYHA class IV HF patients similar to those enrolled in COMPANION.
Key Words: defibrillation heart failure pacemakers survival
| Introduction |
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Editorial p 161
Clinical Perspective p 212
| Methods |
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0.35, and a hospitalization for the treatment of HF or the equivalent in the 12 months preceding enrollment.8 Exclusion criteria included expectation of a heart transplantation in the subsequent 6 months, medically refractory atrial arrhythmias, unexplained syncope, myocardial infarction within 60 days, surgically uncorrected primary valvular heart disease, coronary artery intervention (catheter or surgical) within 60 days, progressive or unstable angina, and life expectancy <6 months for non-HF conditions.8 In addition, no patient could have a scheduled or unscheduled admission for HF or intravenous inotropic or vasoactive therapy in excess of 4 hours in the previous month.8 The steering committee, clinical endpoints committee, and sponsor were blinded to treatment assignments. Physicians, patients, independent statisticians, and members of the data-management group and the data and safety monitoring board were not blinded to treatment assignments. Enrolled patients were randomly assigned in a 1:2:2 ratio to treatment with OPT, CRT, or CRT-D. Randomization was stratified by clinical site and ß-blocker use, but not by NYHA class. All patients were taking diuretics (unless not needed), angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (unless not tolerated), ß-blockers (unless not tolerated), and spironolactone (unless not tolerated). Successful implantation of CRT or CRT-D was defined as successful implantation of all leads.
Once randomized, patients received CRT with implantation of a biventricular pacemaker (Contak TR model 1241, Guidant, Indianapolis, Ind) or a CRT-defibrillator (Contak CD model 1823, Guidant) with the use of commercially available leads for right atrial pacing and right ventricular pacing or for pacing with defibrillation (Endotak models 0125, 0154, and 0155, Guidant). Implantation techniques were described elsewhere.3
The primary end point of the present study, as well as the main trial, was a composite of death from any cause and hospitalization from any cause analyzed from the time of randomization to the time of first event. Unscheduled administration of intravenous vasoactive or inotropic agents for >4 hours in the emergency department was counted as a hospitalization. The implant hospitalization was not included in the primary end point. All-cause mortality was a secondary end point. An additional end point of interest was death from any cause or hospitalization for heart failure. Components of the primary end point were adjudicated by a blinded 7-member endpoints committee. Sudden death was defined as observed or unobserved sudden death in the absence of progressive HF. This category included patients who experienced sudden cardiac death and survived in a postresuscitative course but never regained consciousness and did not leave the hospital. HF death was defined as progressively worsening HF manifested by increased symptoms that required increases in medications, which included intravenous medications. HF hospitalization was defined as a hospitalization for the treatment of HF that required increases in medications, which included intravenous medications.
Statistical Analyses
All analyses were performed according to intention to treat. Comparisons between baseline characteristics were conducted by ANOVA for continuous variables and a
2 test for categorical variables. Hazard ratios (HRs) and associated probability values were calculated based on time to first event with a Cox proportional hazard model. All hazard ratios are unadjusted except where indicated. Hazard ratios were adjusted with stepwise selection (entry 0.30, stay 0.05) and included the following baseline variables: treatment, systolic blood pressure, diastolic blood pressure, heart rate, LVEF, QRS, NYHA class, ischemic status, diabetes status, left bundle-branch block, right bundle-branch block, atrial fibrillation, renal disease, hypertension, peripheral vascular disease, body mass index, age, gender, and medication (ß-blocker, angiotensin converting-enzyme or angiotensin receptor blocker, digoxin, diuretic). A log(-log) plot was used for each survival analysis to validate the proportionality assumption. To analyze the end points of mortality and hospitalization, data on patients who withdrew before reaching an end point, who were not known to have died and for whom complete postwithdrawal information on hospitalization could not be obtained, were censored at the time of elective hospitalization for device implantation or on the date of the last contact. For the NYHA class IV patients, some were censored before the end of the present study. That is, for the primary end point of all-cause death or hospitalization, 6 (11%), 0 (0%), and 0 (0%) of the OPT, CRT, and CRT-D patients, respectively, were censored; for the mortality end points, 2 (4%), 0 (0%), and 5 (6%) of the OPT, CRT, and CRT-D patients were censored. Survival curves were plotted based on the Kaplan-Meier method. Two-year rates for mode of death adjusted for follow-up time were calculated based on life table survival estimates from SAS softwares LIFETEST procedure. Continuous functional capacity variables were tested with a Wilcoxon 2-sample test. NYHA class change was evaluated with the Mantel-Haenszel
2 for NYHA class change and implant success by the Fisher exact test. For the functional capacity end points (6-minute walk, quality of life, NYHA class), CRT and CRT-D were combined in the original protocol design because there was no expectation that CRT-D would influence exercise capacity in a manner dissimilar to CRT. The duration of implant hospitalization days was based on the sum of all implants (ie, some patients had >1 attempt or successful implant) and tested with a Wilcoxon 2-sample test. All probability values are 2-sided.
The authors had full access to the data and take full responsibility for the integrity of the data. All authors have read and agreed to the manuscript as written.
| Results |
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Table 2 presents the baseline characteristics of the NYHA class IV patients by treatment group. There were no significant differences by treatment group in any of the baseline demographics.
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Efficacy of Device Therapy
For NYHA class IV patients, the median duration of follow-up for the primary end point was 7.2 months for OPT, 14.2 months for CRT, and 14.1 month for CRT-D. Figure 1 demonstrates the primary, secondary and additional end point of the study in NYHA class IV subjects. The primary end point of time to death or hospitalization for any cause was significantly prolonged by both CRT (HR, 0.64; P=0.02) and by CRT-D (HR, 0.62; P=0.01) compared with optimal medical therapy (OPT). Despite favorable trends, time to death from any cause was not significantly different when CRT (HR, 0.67; P=0.11) or CRT-D (HR, 0.63; P=0.06) was compared with OPT. Time to mortality or HF hospitalization was significantly improved by both CRT (HR, 0.57; P=0.01) and CRT-D (HR, 0.49; P=0.001) compared with OPT. Analysis of time to HF death or HF hospitalization demonstrated a significant benefit of CRT-D (CRT-D versus OPT: HR, 0.58; P=0.03). There was a strong trend for a benefit of CRT versus OPT in time to HF death or HF hospitalization (CRT versus OPT: HR, 0.64; P=0.07). CRT did not differ from CRT-D for any of these endpoints.
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Figure 2 depicts the time to sudden death and time to HF death in each of the 3 treatment groups of NYHA class IV patients. The time to sudden death was significantly prolonged by CRT-D compared with OPT (HR, 0.27; P=0.03). The time to sudden death was not affected by CRT compared with OPT (HR, 0.81; P=0.64). The time to HF death was not significantly altered by either CRT (HR, 0.68; P=0.28) or CRT-D (HR, 0.79; P=0.48) compared with OPT. CRT was not significantly different from CRT-D for either time to sudden death or HF death.
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Although baseline covariates were not significantly different among the 3 treatment groups, an analysis adjusted for covariates was performed for all the end points. The adjusted analysis differed from the unadjusted analysis in only 1 comparison, which became significant in the adjusted analysis: time to all-cause death in CRT versus OPT (HR, 0.58; 95% CI, 0.35 to 0.96; P=0.04). The proportionality assumption appeared to be met in all analyses except the sudden death and the HF death analyses.
At 1 year in the NYHA class IV patients, 44% of OPT patients died, compared with 36% of CRT and 30% of CRT-D patients. Table 3 shows mode of death over 2 years, adjusted for follow-up time: 62% of OPT subjects died compared with 45% of CRT and 55% of CRT-D subjects. Total mortality, HF mortality, and sudden cardiac death, as expected, were higher in NYHA class IV subjects than in class III subjects: 29%, 26%, and 41% of NYHA class IV OPT, CRT, and CRT-D patients died of HF over 2 years, but time to HF death was not significantly different (Figure 2B). In the OPT, CRT, and CRT-D groups, 25%, 16%, and 9% of NYHA class IV patients died of sudden cardiac death. Time to sudden death was prolonged by CRT-D compared with OPT, but CRT and CRT-D were not significantly different (Figure 2A). In OPT patients, HF was the cause of death in 48% and 39% of all deaths in the NYHA class IV and III subjects respectively. Also in OPT patients, sudden death accounted for 28% and 22% of all deaths in the NYHA class IV and III groups, respectively.
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By the time of the 1-month visit, 67% of NYHA class IV CRT-D and CRT patients improved at least 1 NYHA class, compared with only 31% of OPT patients. Of those patients who improved, there was a significant treatment benefit with regard to mortality (CRT-D versus OPT: HR, 0.43; P
0.01; CRT versus OPT: HR, 0.41; P=0.02). No mortality benefit was seen in those who did not improve in NYHA class status by 1 month.
Table 4 shows the baseline to 6-month changes in 6-minute walk, quality of life, and NYHA class for combined CRT-D/CRT versus OPT patients. The 6-minute walk test did not improve significantly when CRT/CRT-D was compared with OPT, but there were only 12 patients in the OPT group. However, quality-of-life score and percent of patients who improved at least 1 NYHA class improved significantly in the CRT/CRT-D patients compared with OPT.
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No NYHA class IV patients died during the implantation hospitalization. The duration of implantation hospitalization did not differ between NYHA class IV and III patients, both of whom averaged
4 days. Implantation success rates by NYHA class and treatment group are shown in Table 5. Success rates were slightly higher in NYHA class III subjects compared with class IV subjects in the CRT patients (88% versus 83%, respectively), and significantly higher in the CRT-D patients (92% versus 84%, P=0.04, respectively).
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Adverse Events
Overall, 40% (n=87) of NYHA class IV patients had a severe adverse event within 1 year of randomization compared with 21% (n=275) of NYHA class III patients (P<0.0001). For NYHA class III patients, the percent of patients with a severe adverse event was consistent across all 3 treatment arms; however, for NYHA class IV patients, the percent varied across OPT, CRT, and CRT-D arms (47%, 43%, and 33%, respectively; all P<0.015).
Crossovers
There were 19 patients (35%) in the OPT class IV group that "crossed over" to device therapy during the course of the study. Seven (9%) of the CRT and 4 (5%) of CRT-D class IV patients crossed over. In class III, the crossovers were 37%, 11%, and 3% for OPT, CRT, and CRT-D, respectively. There were no significant differences in crossovers between NYHA class III and IV.
| Discussion |
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Only a few trials of CRT have included patients with NYHA class IV HF.1,5,7 The number of NYHA class IV patients was <200 in all these trials and only 1 other trial randomized patients before device implantation was attempted.5 None of the trials have reported NYHA class IV patients separately, although 1 trial of CRT alone reported no significant difference in outcomes between class III and IV patients.5 There were only 50 NYHA class IV subjects, however, and wide confidence intervals.
Progressive HF was the cause of death in 39% of class III OPT patients and 48% of class IV OPT patients in the present study at 2 years. This compares to 26% and 56% of deaths caused by progressive HF in NYHA class III and IV in Metoprolol Controlled-Release Randomized Intervention Trial in Heart Failure (MERIT-HF).9 It is likely that progressive HF was a more common cause of death in NYHA class III patients in COMPANION than in MERIT-HF because of the requirement for a HF hospitalization in the preceding 12 months in COMPANION, which led to a more advanced degree of HF in COMPANION class III patients versus those in MERIT-HF.
None of the large trials of prophylactic implantable cardiac defibrillators alone have included patients with NYHA class IV HF.1014 Our data demonstrate that CRT-D decreases sudden death (P=0.03) in class IV patients. Similar to the entire cohort data, CRT-D improved sudden death, although there was no significant difference between CRT and CRT-D.3 Salutary effects of CRT-D on all-cause or HF hospitalizations as measured in the combined end points, which include mortality, was similar to results with CRT alone.
Although COMPANION NYHA class IV subjects were ambulatory at the time of randomization, they clearly had severe HF. Our NYHA class IV OPT subjects were very comparable to subjects in other studies with ambulatory but advanced HF (Table 6). LVEF was 21% in the present study, which was equivalent to the LVEF of the NYHA class IV subjects in the Beta-Blocker Evaluation of Survival Trial (BEST) and Carvedilol Prospective Randomized Cumulative Survival Trial (COPERNICUS), a trial of carvedilol in subjects with advanced HF.15,16 COMPANION class IV subjects had a systolic blood pressure of 110 mm Hg, lower than the 123 mm Hg in COPERNICUS and 117 mm Hg in the NYHA class IV subjects in BEST.15,16 Indeed, the 1-year mortality of 44% in the NYHA class IV OPT group was exceeded only by the 1-year mortality of 62% for patients in the Flolan International Randomized Survival Trial (FIRST) and the 1-year mortality of 51% and 76% of noninotrope- and inotrope-dependent patients in the Randomized Evaluation of Mechanical Assistance in Treatment of Chronic Heart Failure (REMATCH).17,18 Thus, COMPANION NYHA class IV patients were more ill than patients in previous studies of NYHA class IV ambulatory patients, but slightly less ill and perhaps more stable than patients in FIRST, more than half of whom required intravenous inotropes, or those in the noninotrope group of REMATCHNYHA class IV patients who were felt to need cardiac transplantation but had an absolute contraindication. It is important to recognize that the class IV patients in COMPANION were ambulatory outpatients who had had at least 1 HF hospitalization or equivalent in the 12 months prior to randomization. They could not be enrolled, however, if they had had a hospitalization for HF or intravenous inotropic or vasoactive therapy in excess of 4 hours in the 30 days before randomization. They also did not have a recent coronary intervention, refractory atrial arrhythmias, or a recent myocardial infarction.
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To date, it has been uncertain whether patients with NYHA class IV CHF benefit from either CRT or CRT-D. Arguments have been made that a procedure in these very ill patients may destabilize the HF and thus cause prolonged hospitalization and increased mortality. Furthermore, it has been argued that implantable cardioverter-defibrillator therapy may not be warranted as these patients primarily die of progressive HF. However, the absolute number of lives saved and hospitalizations prevented were much greater than in a less-ill population. Our data argue strongly that CRT devices can be employed with an excellent risk-benefit ratio in class IV HF patients who did not require a hospitalization for HF in the preceding month. Furthermore, our data demonstrate that an implantable cardioverter-defibrillator added to CRT may benefit class IV patients in that it may produce the same incremental reduction in sudden death noted in the entire COMPANION cohort.19 Thus, CRT and CRT-D are both beneficial in altering mortality and morbidity in this very ill population of NYHA class IV patients.
Limitations
The present study was not stratified by NYHA class, but the treatment groups were similar in all baseline demographics. A proportionality assumption was violated in the time to sudden death and time to HF death analyses. The present study is limited by the retrospective nature of the evaluation. The present study, however, is the only evaluation of CRT or CRT-D in NYHA class IV patients alone and is the largest group yet studied.
| Acknowledgments |
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Dr Lindenfeld has received speaking honoraria and consulting fees from Boston Scientific and Medtronic, as well as consulting fees from St. Jude. Dr Feldman is a consultant to Boston Scientific. Dr Saxon has received consultant fees and research support from Boston Scientific and Medtronic. Dr Boehmer has received consulting fees from Boston Scientific and research funding from Boston Scientific and Medtronic. Dr Ghali has received research funding from Guidant. Dr Anand has received consulting fees and research funds from Boston Scientific. Dr Steinberg has received speaking honoraria, consulting fees, and research support from Boston Scientific; speaking honoraria and research support from Medtronic; and research support from St. Jude. Dr Jaski has received speaking honoraria and consulting fees from Boston Scientific. Dr DeMarco is a consultant for Boston Scientific. P. Yong, E. Galle, and F. Ecklund are employees of Boston Scientific. Dr Bristow has received consulting fees from Boston Scientific. Drs Carson and Singh report no conflicts.
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