Circulation: Clinical Summaries
Original Research Put Into Perspective for the Practicing Clinician
- Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia Incorporating a “Superior” Slow Pathway: A Distinct Supraventricular Tachyarrhythmia
- Association of Hospital and Physician Characteristics and Care Processes With Racial Disparities in Procedural Outcomes Among Contemporary Patients Undergoing Coronary Artery Bypass Grafting Surgery
- Frequency and Predictors of Internal Mammary Artery Graft Failure and Subsequent Clinical Outcomes: Insights From the Project of Ex-vivo Vein Graft Engineering via Transfection (PREVENT) IV Trial
- Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Risk Score in Young Adults Predicts Coronary Artery and Abdominal Aorta Calcium in Middle Age: The CARDIA Study
- Physical Activity and Risk of Coronary Heart Disease and Stroke in Older Adults: The Cardiovascular Health Study
- Study of Cardiovascular Health Outcomes in the Era of Claims Data: The Cardiovascular Health Study
- Extracorporeal Cardiopulmonary Resuscitation (E-CPR) During Pediatric In-Hospital Cardiopulmonary Arrest Is Associated With Improved Survival to Discharge: A Report from the American Heart Association’s Get With The Guidelines–Resuscitation (GWTG-R) Registry
- Endothelial β-Catenin Signaling Is Required for Maintaining Adult Blood–Brain Barrier Integrity and Central Nervous System Homeostasis
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Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia Incorporating a “Superior” Slow Pathway: A Distinct Supraventricular Tachyarrhythmia
The usual arrhythmogenic substrate of atrioventricular nodal reentrant tachycardia (AVNRT) is a slow pathway (SP) that can be ablated in the posterior or mid septum. We identified 8 patients with a rare, superior (sup-) type of fast-slow (F/S-) AVNRT incorporating a sup-SP located near the His bundle. Programmed ventricular stimulation induced retrograde conduction over the sup-SP with an earliest atrial activation near the His bundle, a mean shortest stimulus-atrial interval of 378±119 milliseconds, and decremental properties in all patients. sup-F/S-AVNRT was characterized by a long-RP interval; a retrograde atrial activation sequence during tachycardia identical to that during retrograde conduction over a sup-SP during ventricular pacing; ventriculoatrial dissociation during ventricular overdrive pacing of the tachycardia or atrioventricular block occurring during tachycardia, excluding atrioventricular reentrant tachycardia; termination of the tachycardia by ATP; and a V-A-V activation sequence immediately after ventricular induction or entrainment of the tachycardia, including dual atrial responses. Elimination or modification of retrograde conduction over the sup-SP by ablation near the right perinodal region or from the noncoronary cusp of Valsalva eliminated and confirmed the diagnosis of AVNRT in 4 patients each. sup-F/S-AVNRT is a distinct supraventricular tachycardia, incorporating an SP above the Koch triangle as the retrograde limb, that can be eliminated by radiofrequency ablation. Its formal inclusion in the differential diagnosis of long-RP tachycardia should be reflected in a corresponding adaptation of the ablation therapy for refractory AVNRT. See p 114.
Association of Hospital and Physician Characteristics and Care Processes With Racial Disparities in Procedural Outcomes Among Contemporary Patients Undergoing Coronary Artery Bypass Grafting Surgery
The degree to which clinician, hospital, and care factors account for differences in outcome between black and white patients undergoing coronary artery bypass graft (CABG) surgery is not known. We evaluated procedural outcomes in 11 697 blacks and 136 362 whites undergoing isolated CABG at 663 Society of Thoracic Surgery Adult Cardiac Surgery Database participating sites adjusted for patients’ clinical and socioeconomic features, hospital and surgeon effects, and care processes. We found that blacks were more likely to be treated at hospitals with higher risk-adjusted operative mortality. Unadjusted in-hospital mortality and major morbidity rates were higher in blacks than whites (1.8% versus 2.5%, P<0.0001) and (13.6% versus 19.4%, P<0.0001), respectively. These racial differences in outcomes narrowed but still persisted after adjusting for surgeon, hospital, and care processes in addition to patient and socioeconomic factors (odds ratio, 1.17; 95% confidence interval, 1.00–1.36 and odds ratio, 1.26; 95% confidence interval, 1.19–1.34, respectively). Our data suggest that black race remained an independent predictor of outcomes even after accounting for measured baseline confounding factors, including hospital and surgeon characteristics, calling for more research to understand the reasons for these differences and to evaluate measures to reduce this race-related disparity in CABG outcomes. See p 124.
Frequency and Predictors of Internal Mammary Artery Graft Failure and Subsequent Clinical Outcomes: Insights From the Project of Ex-vivo Vein Graft Engineering via Transfection (PREVENT) IV Trial
In this study, the frequency, predictors, and impact of internal mammary artery (IMA) graft failure were evaluated in patients undergoing coronary artery bypass grafting. Using data from the Project of Ex-vivo Vein Graft Engineering via Transfection (PREVENT) IV trial, we identified 1539 participants with IMA–left anterior descending (LAD) graft and protocol angiography at 12 to 18 months after the index procedure. Our main findings included that IMA graft failure (defined as ≥75% stenosis) occurred in 132 participants (8.6%) at angiographic follow-up. Independent predictors of IMA graft failure were low-grade LAD stenosis, additional bypass graft to the diagonal branch, and not having diabetes mellitus. LAD stenosis and additional diagonal graft, but not diabetes mellitus, remained predictive of IMA graft failure in an alternative model that included IMA failure or death before angiography as the outcome. IMA failure was associated with a significantly higher incidence of subsequent acute (within 14 days of angiography) clinical events, mostly as a result of a higher rate of repeat revascularization. This study represents the first robust assessment of IMA graft failure and long-term clinical outcomes in a large cohort of patients undergoing coronary artery bypass grafting surgery with systematic angiographic follow-up, regardless of symptom status. Our study raises concerns about the performance of coronary artery bypass grafting with the use of IMA in the treatment of native vessels with only mild or moderate stenosis, as well as the use of an additional bypass graft to the diagonal branch. Thus, it confirms findings from smaller studies that have suggested that the severity of LAD stenosis and competitive flow are of key importance for patency of the IMA-LAD graft, which is thought to be responsible for the survival benefit observed in clinical studies that compared coronary artery bypass grafting with multivessel percutaneous coronary intervention or medical therapy. See p 131.
Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Risk Score in Young Adults Predicts Coronary Artery and Abdominal Aorta Calcium in Middle Age: The CARDIA Study
Clinically silent, atherosclerosis begins at a young age. Cardiovascular risk factors measured in youth and young adulthood predict future subclinical atherosclerosis. Risk scores derived from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study, where atherosclerosis was directly measured postmortem in the coronary artery and abdominal aorta and correlated with cardiovascular risk factors, was calculated for Coronary Artery Risk Development in Young Adults (CARDIA) study participants with risk factors measured at 18 to 30 years of age and at intervals thereafter. This score predicted both coronary artery and abdominal aorta calcification 25 years later, at 43 to 55 years of age; in fact, risk measured early in the CARDIA study predicted future atherosclerosis as well as or better than risk measured at the time of the coronary artery or abdominal aorta calcium assessment. These data confirm the hypothesis that atherosclerosis evolves over decades, and the presence of higher risk at a young age is ominous. We also analyzed the impact of change in risk over the 25 years; and, reassuringly, lowering risk lowered future likelihood of future subclinical atherosclerosis, conversely, increasing risk had adverse consequences. Furthermore, these data suggest that the reason coronary artery calcium improves future risk prediction is that it functions as a measure of chronic risk exposure, adding information to risk measured at the time of the scan. See p 139.
Physical Activity and Risk of Coronary Heart Disease and Stroke in Older Adults: The Cardiovascular Health Study
One in every 3 adults in the United States has ≥1 type of cardiovascular disease (CVD); of these, about half are >60 years of age. National guidelines suggest that older adults engage in regular physical activity (PA) to reduce CVD, but surprisingly few studies have evaluated this relationship. Most previous studies were conducted in middle-aged participants, typically averaging 45 to 60 years of age. A small number of studies included individuals with average ages exceeding 65 years, and few data were available for individuals aged ≥75 years. We investigated whether usual PA, assessed by walking pace, distance, and overall walking score, leisure-time activity, and exercise intensity, was associated with the incidence of coronary heart disease, stroke, and CVD, among older adults with an average age of 72.5 years at baseline. After multivariable adjustment for major CVD risk factors, greater PA was inversely associated with coronary heart disease, stroke, and total CVD, even in those ≥75 years. These findings provide evidence supporting PA recommendations, in particular walking, as a way to reduce the incidence of coronary heart disease, stroke, and CVD among older adults. Our findings for walking distance and pace are especially important given that walking is the most common type of PA later in life; increasing either pace or distance seems to provide benefits. These results support the need for clinicians and policy makers to focus on regular PA as a way to maintain and promote cardiovascular health in older adults. See p 147.
Study of Cardiovascular Health Outcomes in the Era of Claims Data: The Cardiovascular Health Study
In both observational studies and clinical trials, cardiovascular disease event rates vary for a number of biological and methodological reasons. Increasingly, the diagnostic codes from administrative claims data are being used to measure clinical outcomes. The quality of claims data varies according to the condition, and many cardiovascular events are coded with a moderate degree of accuracy. The approach of defining events on the basis of claims data influences the results. Methods that minimize misclassification such as the use of specific diagnostic codes in the primary diagnosis position also tend to underestimate event rates. Methods that use broad diagnostic codes in any position tend to capture not only genuine outcomes of interest but also nonevents that fail to meet standard criteria. Levels of risk factor associations with the outcome may not be reliable guides to the amount of misclassification. Observed event rates are directly related to the intensity of surveillance. When data from active-surveillance studies are used, for instance, to create risk-prediction algorithms, they also generate higher levels of predicted absolute risk than studies that rely on passive surveillance or self-report. Although events data collection activities should be appropriate to the purpose of the study, the achieved or observed event rates in both observational studies and clinical trials can also serve as an important quality-control measure of study conduct. See p 156.
Extracorporeal Cardiopulmonary Resuscitation (E-CPR) During Pediatric In-Hospital Cardiopulmonary Arrest Is Associated With Improved Survival to Discharge: A Report from the American Heart Association’s Get With The Guidelines–Resuscitation (GWTG-R) Registry
Cardiopulmonary resuscitation (CPR) modalities that include the use of extracorporeal membrane oxygenation (E-CPR) have been shown to improve survival for cardiac arrest in select populations of pediatric cardiac arrest patients. However, to further refine resuscitation practices across the spectrum of pediatric patient populations, a better understanding of the differences in outcomes between conventional CPR and E-CPR is required. Our study of 3756 pediatric patients from all illness categories undergoing ≥10 minutes of conventional CPR after in-hospital cardiac arrest found that survival to hospital discharge was 40% in E-CPR recipients compared with 27% for patients receiving continued conventional CPR. This Get With the Guidelines–Resuscitation registry analysis also evaluated neurological outcomes after in-hospital cardiac arrest and found higher levels of neurological function for patients who received E-CPR. Our study evaluated patients with differing reasons for arrest and found that E-CPR improved survival and neurological outcomes for all patients regardless of cause. Furthermore, this study demonstrated improved survival and favorable neurological outcome even after exclusion of the surgical cardiac patient population. This analysis adds to previous studies that have found E-CPR to be an effective rescue therapy and expands this benefit to nonsurgical cardiac patients and noncardiac patients. This study will serve to encourage the use of E-CPR as a rescue strategy after failed conventional CPR and provides information for investigators eager to expand our understanding of extracorporeal support in resuscitation. See p 165.
Endothelial β-Catenin Signaling Is Required for Maintaining Adult Blood–Brain Barrier Integrity and Central Nervous System Homeostasis
Blood–brain barrier (BBB) dysfunction has been implicated in a variety of central nervous system diseases such as Alzheimer disease, epilepsy, multiple sclerosis, and stroke. However, little is known about the molecular mechanisms responsible for integrity of the adult BBB. In this study, we provide the first genetic evidence that BBB disruption secondary to loss of endothelial β-catenin induces cerebral hemorrhage, seizures, and death after seizure activity in adult mice. We have delineated the requisite role of β-catenin signaling in maintaining the restrictive nature of BBB and transcriptional regulation of the specific tight junction proteins claudin-1 and -3. Our results also provide evidence of the clear association of intracerebral hemorrhage with reduced nuclear β-catenin and claudin-1 expression in endothelial cells from patients with hemorrhagic stroke. Our data suggest that BBB dysfunction secondary to defective endothelial β-catenin transcription activity is a key pathogenic factor in hemorrhagic stroke, central nervous system inflammation, and seizure. Thus, the development of means of activation of β-catenin transcription activity in brain endothelial cells to enhance the BBB integrity is a potential novel strategy for treatment of these central nervous system diseases. See p 177.
- © 2015 American Heart Association, Inc.
- Study of Cardiovascular Health Outcomes in the Era of Claims Data: The Cardiovascular Health Study
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