In the Literature: March 2010

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.

Dabigatran Is Not Inferior to Warfarin in Atrial Fibrillation

Clinical question: Is dabigatran, an oral thrombin inhibitor, an effective and safe alternative to warfarin in patients with atrial fibrillation?

Background: Warfarin reduces the risk of stroke among patients with atrial fibrillation (AF) but requires frequent laboratory monitoring. Dabigatran is an oral direct thrombin inhibitor given in fixed dosages without laboratory monitoring.

Study design: Randomized, multicenter, open-label, noninferiority trial.

Setting: 951 clinical centers in 44 countries.

Synopsis: More than 18,000 patients 65 and older with AF and at least one stroke risk factor were enrolled. The average CHADS2 score was 2.1. Patients were randomized to receive fixed doses of dabigatran (110 mg or 150 mg, twice daily) or warfarin adjusted to an INR of 2.0-3.0. The primary outcomes were a) stroke or systemic embolism and b) major hemorrhage. Median followup was two years.

The annual rates of stroke or systemic embolism for both doses of dabigatran were noninferior to warfarin (P<0.001); higher-dose dabigatran was statistically superior to warfarin (relative risk (RR)=0.66, P<0.001). The annual rate of major hemorrhage was lowest in the lower-dose dabigatran group (RR=0.80, P=0.003 compared with warfarin); the higher-dose dabigatran and warfarin groups had equivalent rates of major bleeding. No increased risk of liver function abnormalities was noted.

Bottom line: Dabigatran appears to be an effective and safe alternative to warfarin in AF patients. If the drug were to be FDA-approved, appropriate patient selection and cost will need to be established.

Citation: Connolly SJ, Ezekowitz MD, Yusuf S, et al. Dabigatran versus warfarin in patients with atrial fibrillation. N Engl J Med. 2009;361(12):1139-1151.