CRT use may be associated with better outcomes among older patients undergoing ICD implantation with a bradycardia pacing indication but without a class I indication for CRT, according to a study published Jan. 26 in JAMA Network Open.

Using data from ACC's ICD Registry, Ryan T. Borne, MD, FACC, et al., examined trends, variability and outcomes in the use of CRT-D and dual-chamber ICD devices between 2010 and 2016 in 3,100 Medicare beneficiaries with a class I or II guideline ventricular bradycardia pacing indication who did not have a CRT class I indication based on left ventricular ejection fraction (LVEF). The researchers looked at all-cause mortality, heart failure (HF) hospitalization and device-related complications.

According to the results, the mean age of patients was 76.3 years, and 80.6% were men. At baseline, 69.9% (2,167) patients had ischemic heart disease, 40.6% (1,260) had third-degree atrioventricular block and 31.1% (965) had second-degree atrioventricular block. The average LVEF was 31.2%. Overall, 1,698 patients (54.8%) underwent CRT-D and 45.2% (1,402) underwent dual-chamber ICD implantation. Patients receiving dual-chamber ICDs were more likely to be women, have higher average LVEF, have a history of ventricular tachycardia and have shorter QRS duration, while those undergoing CRT-D implantation were more likely to have third-degree atrioventricular block, nonischemic cardiomyopathy, a primary prevention indication, prior HF hospitalization, more advanced NYHA class, and a right bundle branch block or a left bundle branch block.

After adjustment, CRT-D implantation was associated with lower one-year mortality (Hazard Ratio [HR]: 0.70; 95% Confidence Interval [CI]: 0.57-0.87; p=.001) and HF hospitalization (subdistribution HR: 0.77; 95% CI: 0.61-0.97; p=.02). There was no difference in complications among patients undergoing CRT-D implantation vs. dual-chamber ICD implantation. The use of CRT-D increased throughout the study period, accounting for 48.4% of implantations in 2010 and 60.9% in 2016.

The researchers conclude that CRT use was associated with better outcomes, including lower mortality and HF hospitalization, among patients undergoing ICD implantation with bradycardia pacing indication but without a class I CRT indication. Going forward, randomized and real-world investigations are needed to confirm the findings and potentially expand CRT use among patients with normal LVEF who require frequent right ventricular pacing.

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Prevention, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure

Keywords: Bundle-Branch Block, Stroke Volume, Atrioventricular Block, Bradycardia, Ventricular Function, Left, Medicare, Arrhythmias, Cardiac, Heart Failure, Tachycardia, Ventricular, Heart Ventricles, Cardiomyopathies, Hospitalization, Myocardial Ischemia, Registries, Primary Prevention, National Cardiovascular Data Registries, ICD Registry

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