Nigel Gupta

Longitudinal study of implantable cardioverter-defibrillators: methods and clinical characteristics of patients receiving implantable cardioverter-defibrillators for primary prevention in contemporary practice

Background—Implantable cardioverter-defibrillators (ICDs) are increasingly used for primary prevention after randomized, controlled trials demonstrating that they reduce the risk of death in patients with left ventricular systolic dysfunction. The extent to which the clinical characteristics and long-term outcomes of unselected, community-based patients with left ventricular systolic dysfunction undergoing primary prevention ICD implantation in a real-world setting compare with those enrolled in the randomized, controlled trials is not well characterized. This study is being conducted to address these questions. Methods and Results—The study cohort includes consecutive patients undergoing primary prevention ICD placement between January 1, 2006 and December 31, 2009 in 7 health plans. Baseline clinical characteristics were acquired from the National Cardiovascular Data Registry ICD Registry. Longitudinal data collection is underway, and will include hospitalization, mortality, and resource use from standardized health plan data archives. Data regarding ICD therapies will be obtained through chart abstraction and adjudicated by a panel of experts in device therapy. Compared with the populations of primary prevention ICD therapy randomized, controlled trials, the cohort (n=2621) is on average significantly older (by 2.5–6.5 years), more often female, more often from racial and ethnic minority groups, and has a higher burden of coexisting conditions. The cohort is similar, however, to a national population undergoing primary prevention ICD placement. Conclusions—Patients undergoing primary prevention ICD implantation in this study differ from those enrolled in the randomized, controlled trials that established the efficacy of ICDs. Understanding a broad range of health outcomes, including ICD therapies, will provide patients, clinicians, and policy makers with contemporary data to inform decision-making.

Age and Sex Differences in Long‐Term Outcomes Following Implantable Cardioverter‐Defibrillator Placement in Contemporary Clinical Practice: Findings From the Cardiovascular Research Network

Background Patient sex and age may influence rates of death after receiving an implantable cardioverter-defibrillator for primary prevention. Differences in outcomes other than mortality and whether these differences vary by heart failure symptoms, etiology, and left ventricular ejection fraction are not well characterized. Methods and Results We studied 2954 patients with left ventricular ejection fraction ≤0.35 undergoing first-time implantable cardioverter-defibrillator for primary prevention within the Cardiovascular Research Network; 769 patients (26%) were women, and 2827 (62%) were aged >65 years. In a median follow-up of 2.4 years, outcome rates per 1000 patient-years were 109 for death, 438 for hospitalization, and 111 for heart failure hospitalizations. Procedure-related complications occurred in 8.36%. In multivariable models, women had significantly lower risks of death (hazard ratio 0.67, 95% CI 0.56 to 0.80) and heart failure hospitalization (hazard ratio 0.82, 95% CI 0.68 to 0.98) and higher risks for complications (hazard ratio 1.38, 95% CI 1.01 to 1.90) than men; patients aged >65 years had higher risks of death (hazard ratio 1.55, 95% CI 1.30 to 1.86) and heart failure hospitalization (hazard ratio 1.25, 95% CI 1.05 to 1.49) than younger patients. Age and sex differences were generally consistent in strata according to symptoms, etiology, and severity of left ventricular systolic dysfunction, except the higher risk of complications in women, which differed by New York Heart Association classification (P=0.03 for sex–New York Heart Association interaction), and the risk of heart failure hospitalization in older patients, which differed by etiology of heart failure (P=0.05 for age–etiology interaction). Conclusions The burden of adverse outcomes after receipt of an implantable cardioverter-defibrillator for primary prevention is substantial and varies according to patient age and sex. These differences in outcome generally do not vary according to baseline heart failure characteristics.

Multi‐Center, Community‐Based Cardiac Implantable Electronic Devices Registry: Population, Device Utilization, and Outcomes

Background The purpose of this study is to describe key elements, clinical outcomes, and potential uses of the Kaiser Permanente–Cardiac Device Registry. Methods and Results This is a cohort study of implantable cardioverter defibrillators (ICD), pacemakers (PM), and cardiac resynchronization therapy (CRT) devices implanted between January 1, 2007 and December 31, 2013 by ≈400 physicians in 6 US geographical regions. Registry data variables, including patient characteristics, comorbidities, indication for procedures, complications, and revisions, were captured using the healthcare systems electronic medical record. Outcomes were identified using electronic screening algorithms and adjudicated via chart review. There were 11 924 ICDs, 33 519 PMs, 4472 CRTs, and 66 067 leads registered. A higher proportion of devices were implanted in males: 75.1% (ICD), 55.0% (PM), and 66.7% (CRT), with mean patient age 63.2 years (ICD), 75.2 (PM), and 67.2 (CRT). The 30‐day postoperative incidence of tamponade, hematoma, and pneumothorax were ≤0.3% (ICD), ≤0.6% (PM), and ≤0.4% (CRT). Device failures requiring revision occurred at a rate of 2.17% for ICDs, 0.85% for PMs, and 4.93% for CRTs, per 100 patient observation years. Superficial infection rates were <0.03% for all devices; deep infection rates were 0.6% (ICD), 0.5% (PM), and 1.0% (CRT). Results were used to monitor vendor‐specific variations and were systematically shared with individual regions to address potential variations in outcomes, utilization, and to assist with the management of device recalls. Conclusions The Kaiser Permanente–Cardiac Device Registry is a robust tool to monitor postprocedural patient outcomes and postmarket surveillance of implants and potentially change practice patterns.

Contemporary Procedural Complications, Hospitalizations, and Emergency Visits After Catheter Ablation for Atrial Fibrillation

Contemporary data on complications and resource utilization after atrial fibrillation (AF) ablation are limited. We evaluated rates and risk factors for procedural complication, rehospitalization, and emergency department visits after AF ablation. We identified all adult patients who underwent isolated AF ablation between 2010 and June 2014 in 2 large integrated health-care delivery systems and evaluated rates of acute inpatient complication, 30-day, and 1-year readmission and emergency evaluation. We used multivariable logistic regression to identify predictors of procedural complications, 30-day readmission, or 30-day emergency department evaluation. In 811 AF ablation patients, procedural complications occurred in 2.5% of patients, 9.7% of patients were rehospitalized within 30 days, and 19.1% of patients had an emergency visit within 30 days. At 1 year after AF ablation, 28.9% of patients were readmitted, with 18% of patients readmitted for AF or atrial flutter. At 1 year, 44.5% of patients were seen in an emergency department, with 37.1% related to AF or atrial flutter. Vascular complications and perforation or tamponade were the most common complications, and Hispanic ethnicity, mitral or aortic valvular disease, and diabetes mellitus were the strongest risk factors for adverse outcomes at 30 days after AF ablation. Contemporary rates of acute complication and 1-year readmission after AF ablation have markedly decreased compared with previous community-based studies.

Device Therapies Among Patients Receiving Primary Prevention Implantable Cardioverter‐Defibrillators in the Cardiovascular Research Network

Background Primary prevention implantable cardioverter‐defibrillators (ICDs) reduce mortality in selected patients with left ventricular systolic dysfunction by delivering therapies (antitachycardia pacing or shocks) to terminate potentially lethal arrhythmias; inappropriate therapies also occur. We assessed device therapies among adults receiving primary prevention ICDs in 7 healthcare systems. Methods and Results We linked medical record data, adjudicated device therapies, and the National Cardiovascular Data Registry ICD Registry. Survival analysis evaluated therapy probability and predictors after ICD implant from 2006 to 2009, with attention to Centers for Medicare and Medicaid Services Coverage With Evidence Development subgroups: left ventricular ejection fraction, 31% to 35%; nonischemic cardiomyopathy <9 months’ duration; and New York Heart Association class IV heart failure with cardiac resynchronization therapy defibrillator. Among 2540 patients, 35% were <65 years old, 26% were women, and 59% were white. During 27 (median) months, 738 (29%) received ≥1 therapy. Three‐year therapy risk was 36% (appropriate, 24%; inappropriate, 12%). Appropriate therapy was more common in men (adjusted hazard ratio [HR], 1.84; 95% confidence interval [CI], 1.43–2.35). Inappropriate therapy was more common in patients with atrial fibrillation (adjusted HR, 2.20; 95% CI, 1.68–2.87), but less common among patients ≥65 years old versus younger (adjusted HR, 0.72; 95% CI, 0.54–0.95) and in recent implants (eg, in 2009 versus 2006; adjusted HR, 0.66; 95% CI, 0.46–0.95). In Centers for Medicare and Medicaid Services Coverage With Evidence Development analysis, inappropriate therapy was less common with cardiac resynchronization therapy defibrillator versus single chamber (adjusted HR, 0.55; 95% CI, 0.36–0.84); therapy risk did not otherwise differ for Centers for Medicare and Medicaid Services Coverage With Evidence Development subgroups. Conclusions In this community cohort of primary prevention patients receiving ICD, therapy delivery varied across demographic and clinical characteristics, but did not differ meaningfully for Centers for Medicare and Medicaid Services Coverage With Evidence Development subgroups.

Association of Burden of Atrial Fibrillation With Risk of Ischemic Stroke in Adults With Paroxysmal Atrial Fibrillation: The KP-RHYTHM Study

Importance Atrial fibrillation is a potent risk factor for stroke, but whether the burden of atrial fibrillation in patients with paroxysmal atrial fibrillation independently influences the risk of thromboembolism remains controversial. Objective To determine if the burden of atrial fibrillation characterized using noninvasive, continuous ambulatory monitoring is associated with the risk of ischemic stroke or arterial thromboembolism in adults with paroxysmal atrial fibrillation. Design, Setting, and Participants This retrospective cohort study conducted from October 2011 and October 2016 at 2 large integrated health care delivery systems used an extended continuous cardiac monitoring system to identify adults who were found to have paroxysmal atrial fibrillation on 14-day continuous ambulatory electrocardiographic monitoring. Exposures The burden of atrial fibrillation was defined as the percentage of analyzable wear time in atrial fibrillation or flutter during the up to 14-day monitoring period. Main Outcomes and Measures Ischemic stroke and other arterial thromboembolic events occurring while patients were not taking anticoagulation were identified through November 2016 using electronic medical records and were validated by manual review. We evaluated the association of the burden of atrial fibrillation with thromboembolism while not taking anticoagulation after adjusting for the Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) or CHA2DS2-VASc stroke risk scores. Results Among 1965 adults with paroxysmal atrial fibrillation, the mean (SD) age was 69 (11.8) years, 880 (45%) were women, 496 (25%) were persons of color, the median ATRIA stroke risk score was 4 (interquartile range [IQR], 2-7), and the median CHA2DS2-VASc score was 3 (IQR, 1-4). The median burden of atrial fibrillation was 4.4% (IQR ,1.1%-17.23%). Patients with a higher burden of atrial fibrillation were less likely to be women or of Hispanic ethnicity, but had more prior cardioversion attempts compared with those who had a lower burden. After adjusting for either ATRIA or CHA2DS2-VASc stroke risk scores, the highest tertile of atrial fibrillation burden (≥11.4%) was associated with a more than 3-fold higher adjusted rate of thromboembolism while not taking anticoagulants (adjusted hazard ratios, 3.13 [95% CI, 1.50-6.56] and 3.16 [95% CI, 1.51-6.62], respectively) compared with the combined lower 2 tertiles of atrial fibrillation burden. Results were consistent across demographic and clinical subgroups. Conclusions and Relevance A greater burden of atrial fibrillation is associated with a higher risk of ischemic stroke independent of known stroke risk factors in adults with paroxysmal atrial fibrillation.

Severe Intraventricular Diastolic Gradient Due to Hypertrophic Cardiomyopathy and Systolic Left Ventricular Midcavitary Obstruction

A 50-year-old man presented with exertional chest pain and dyspnea. Cardiac auscultation revealed an S4 gallop and a faint, high-pitched, decrescendo diastolic murmur along the left sternal border. Rest/stress myocardial perfusion imaging showed a fixed, severe defect at the apex. An echocardiogram revealed severe left ventricular hypertrophy with systolic midcavitary obstruction and apical aneurysmal formation but without evidence of mural thrombus (Fig. 1). Doppler findings are shown in Figures 2 and 3. Coronary angiography showed no obstructive lesions. The patient subsequently developed ventricular tachycardia and received an implantable defibrillator. Hypertrophic cardiomyopathy (HCM) commonly manifests systolic midcavitary obstruction, but infrequently leads to sufficient pressure build up in the apex as to result in thinning and outward bulging. In this case, it also resulted in a perfusion defect on radionuclide scintigraphy simulating an infarction.1 During early diastole, a turbulent retrograde jet directed toward the mitral valve plane was detected (Fig. 2). Spectral Doppler (Fig. 3) revealed a truncated systolic envelope

INTEGRATING THE ELECTRONIC HEALTH RECORD WITH A CARDIAC DEVICE REGISTRY ENHANCES OUTCOMES MEASURES

A Cardiac Device Registry1 was developed by a communitybased, integrated healthcare system to: • Identify and track patients with implantable cardioverterdefibrillator (ICD) and pacemaker (PM) and lead implants • Respond immediately to identify patients involved during recalls/advisories • Provide an active surveillance system for unexpected or harmful events • Monitor trends in device performance and safety • Produce data to support best clinical practices • Provide a framework for research The purpose of this study was to describe the registered cohort of this registry and incidence of surgical outcomes associated with these procedures.