Clinical question: Does cardiac resynchronization therapy (CRT) with biventricular pacing decrease cardiac events in patients with reduced ejection fraction (EF) and wide QRS complex but only mild cardiac symptoms?
Background: In patients with severely reduced EF, implantable cardioverter defibrillators (ICDs) have been shown to improve survival. Meanwhile, CRT decreases heart-failure-related hospitalizations for patients with advanced heart-failure symptoms, EF less than 35%, and intraventricular conduction delay. It is not as clear whether patients with less-severe symptoms benefit from CRT.
Study design: Randomized, controlled trial.
Setting: 110 medical centers in the U.S., Canada, and Europe.
Synopsis: This Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT) study randomly assigned 1,820 adults with EF less than 30%, New York Health Association Class I or II congestive heart failure, and in sinus rhythm with QRS greater than 130 msec to receive ICD with CRT or ICD alone. The primary endpoint was all-cause mortality or nonfatal heart-failure events. Average followup was 2.4 years.
A 34% reduction in the primary endpoint was found in the ICD-CRT group when compared with the ICD-only group, primarily due to a 41% reduction in heart-failure events. In a subgroup analysis, women and patients with QRS greater than 150 msec experienced particular benefit. Echocardiography one year after device implantation demonstrated significant reductions in left ventricular end-systolic and end-diastolic volume, and a significant increase in EF with ICD-CRT versus ICD-only (P<0.001).
Bottom line: Compared with ICD alone, CRT in combination with ICD prevented heart-failure events in relatively asymptomatic heart-failure patients with low EF and prolonged QRS.
Citation: Moss AJ, Hall WJ, Cannom DS, et al. Cardiac-resynchronization therapy for the prevention of heart-failure events. N Engl J Med. 2009;361(14):1329-1338.
