Abstract
Frequent right ventricular (RV) pacing can cause and exacerbate heart failure. Cardiac resynchronization therapy (CRT) has been shown to be associated with improved outcomes among patients with reduced left ventricular ejection fraction who need frequent RV pacing, but the patterns of use of CRT vs dual chamber (DC) devices and the associated outcomes among these patients in clinical practice is not known. To assess outcomes, variability in use of device type, and trends in use of device type over time among patients undergoing implantable cardioverter defibrillator (ICD) implantation who were likely to require frequent RV pacing but who did not have a class I indication for CRT. This retrospective cohort study used the National Cardiovascular Data Registry (NCDR) ICD Registry. A total of 3100 Medicare beneficiaries undergoing first-time implantation of CRT defibrillator (CRT-D) or DC-ICD from 2010 to 2016 who had a class I or II guideline ventricular bradycardia pacing indication but not a class I indication for CRT were included. Data were analyzed from August 2018 to October 2019. Implantation of a CRT-D or DC-ICD. All-cause mortality, heart failure hospitalization, and complications were ascertained from Medicare claims data. Multivariable Cox proportional hazards models and Fine-Gray models were used to evaluate 1-year mortality and heart failure hospitalization, respectively. Multivariable logistic regression was used to evaluate 30-day and 90-day complications. All models accounted for clustering. The median odds ratio (MOR) was used to assess variability and represents the odds that a randomly selected patient receiving CRT-D at a hospital with high implant rates would receive CRT-D if they had been treated at a hospital with low CRT-D implant rates. A total of 3100 individuals were included. The mean (SD) age was 76.3 (6.4) years, and 2500 (80.6%) were men. The 1698 patients (54.7%) receiving CRT-D were more likely than those receiving DC-ICD to have third-degree atrioventricular block (828 [48.8%] vs 432 [30.8%]; P < .001), nonischemic cardiomyopathy (508 [29.9%] vs 255 [18.2%]; P < .001), and prior heart failure hospitalizations (703 [41.4%] vs 421 [30.0%]; P < .001). Following adjustment, CRT-D was associated with lower 1-year mortality (hazard ratio [HR], 0.70; 95% CI, 0.57-0.87; P = .001) and heart failure hospitalization (subdistribution HR, 0.77; 95% CI, 0.61-0.97; P = .02) and no difference in complications compared with DC-ICD. Hospital variation in use of CRT was present (MOR, 2.00), and the use of CRT in this cohort was higher over time (654 of 1351 [48.4%] in 2010 vs 362 of 594 [60.9%] in 2016; P < .001). In this cohort study of older patients in contemporary practice undergoing ICD implantation with a bradycardia pacing indication but without a class I indication for CRT, CRT-D was associated with better outcomes compared with DC devices. Variability in use of device type was observed, and the rate of CRT implantation increased over time.
Highlights
Frequent right ventricular (RV) pacing may be deleterious, given that it results in electrical dyssynchrony, can exacerbate symptoms of heart failure, and is associated with incident atrial fibrillation.[1,2] Cardiac resynchronization therapy (CRT) improves morbidity and mortality among patients with low left ventricular ejection fraction (LVEF) and electrical dyssynchrony.[3]
The 1698 patients (54.7%) receiving CRT defibrillator (CRT-D) were more likely than those receiving dual chamber (DC)-implantable cardioverter defibrillator (ICD) to have third-degree atrioventricular block (828 [48.8%] vs 432 [30.8%]; P < .001), nonischemic cardiomyopathy (508 [29.9%] vs 255 [18.2%]; P < .001), and prior heart failure hospitalizations (703 [41.4%] vs 421 [30.0%]; P < .001)
CRT-D was associated with lower 1-year mortality and heart failure hospitalization and no difference in complications compared with DC-ICD
Summary
Frequent right ventricular (RV) pacing may be deleterious, given that it results in electrical dyssynchrony, can exacerbate symptoms of heart failure, and is associated with incident atrial fibrillation.[1,2] Cardiac resynchronization therapy (CRT) improves morbidity and mortality among patients with low left ventricular ejection fraction (LVEF) and electrical dyssynchrony.[3]. The Biventricular Pacing for Atrioventicular Block and Systolic Dysfunction (BLOCK-HF) randomized clinical trial evaluated the use of CRT in a broader group of patients with reduced left ventricular systolic function with frequent anticipated ventricular pacing and found a lower incidence of a combined end point of time to death from any cause, heart failure visit, or increase in the left ventricular end-systolic volume index among patients randomized to CRT compared with patients receiving a traditional DC system.[4] While the results of this trial were published in 2013, it took until 2018 for an update and change in guidelines. The extent of practice variation and, importantly, outcomes among real-world patients with anticipated frequent ventricular pacing during this time frame is unknown
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