The Effect of Intermittent Atrial Tachyarrhythmia on Heart Failure or Death in CRT-D Versus ICD Patients: A MADIT-CRT Substudy

Study Questions:

Do intermittent atrial tachyarrhythmias (IATs), defined as atrial fibrillation (AF), atrial flutter, or paroxysmal supraventricular tachycardia, compromise the effects of cardiac resynchronization therapy (CRT)?


This was a post-hoc analysis of 1,264 patients (mean age 64 years) with an ejection fraction ≤30% and left bundle branch block (LBBB), who received an implantable cardioverter-defibrillator with (n = 757) or without (n = 507) CRT. The primary endpoint was a composite of all-cause mortality and nonfatal heart failure events.


The primary endpoint was reached in 24% of patients during 3.4 years of follow-up. Eleven percent of patients had a history of IATs. In the ICD + CRT group, the incidence of the primary endpoint was similar in patients who did and did not have a history of IAT. CRT reduced the risk of the primary endpoint by approximately 50% in patients with and without a history of IAT. CRT also reduced the risk of the primary endpoint to a similar degree in patients who did (hazard ratio [HR], 0.47) and did not (HR, 0.39) develop IAT during the study period.


The beneficial effects of CRT in patients with cardiomyopathy and an LBBB are not attenuated by a history of IAT or by IATs that occur after device implantation.


CRT previously has been shown to be less effective in patients with persistent AF. This study has shown that intermittent IAT (most often paroxysmal AF) does not compromise the effects of CRT. However, an interaction between CRT and AF probably depends on the AF burden, which was not analyzed in this study.

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

Keywords: Death, Heart Failure, Bundle-Branch Block, Atrial Flutter, Cardiac Resynchronization Therapy, Tachycardia

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