Cardiac-Resynchronization Therapy for Mild-to-Moderate Heart Failure

Abstract
Background
Cardiac-resynchronization therapy (CRT) benefits patients with left ventricular systolic
dysfunction and a wide QRS complex. Most of these patients are candidates
for an implantable cardioverter–defibrillator (ICD). We evaluated whether adding
CRT to an ICD and optimal medical therapy might reduce mortality and morbidity
among such patients.
Methods
We randomly assigned patients with New York Heart Association (NYHA) class II or
III heart failure, a left ventricular ejection fraction of 30% or less, and an intrinsic
QRS duration of 120 msec or more or a paced QRS duration of 200 msec or more
to receive either an ICD alone or an ICD plus CRT. The primary outcome was death
from any cause or hospitalization for heart failure.
Results
We followed 1798 patients for a mean of 40 months. The primary outcome occurred
in 297 of 894 patients (33.2%) in the ICD–CRT group and 364 of 904 patients
(40.3%) in the ICD group (hazard ratio in the ICD–CRT group, 0.75; 95% confidence
interval [CI], 0.64 to 0.87; P<0.001). In the ICD–CRT group, 186 patients died,
as compared with 236 in the ICD group (hazard ratio, 0.75; 95% CI, 0.62 to 0.91;
P = 0.003), and 174 patients were hospitalized for heart failure, as compared with
236 in the ICD group (hazard ratio, 0.68; 95% CI, 0.56 to 0.83; P<0.001). However,
at 30 days after device implantation, adverse events had occurred in 124 patients in
the ICD-CRT group, as compared with 58 in the ICD group (P<0.001).
Conclusions
Among patients with NYHA class II or III heart failure, a wide QRS complex, and
left ventricular systolic dysfunction, the addition of CRT to an ICD reduced rates of
death and hospitalization for heart failure. This improvement was accompanied by
more adverse events. (Funded by the Canadian Institutes of Health Research and
Medtronic of Canada; ClinicalTrials.gov number, NCT00251251.)
The New England Journal of Medicine
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