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Previous Volume 357:2461-2471 December 13, 2007 Number 24 Next

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ABSTRACT

Background Indications for cardiac-resynchronization therapy (CRT) in patients with heart failure include a prolonged QRS interval (120 msec), in addition to other functional criteria. Some patients with narrow QRS complexes have echocardiographic evidence of left ventricular mechanical dyssynchrony and may also benefit from CRT.

Methods We enrolled 172 patients who had a standard indication for an implantable cardioverter–defibrillator. Patients received the CRT device and were randomly assigned to the CRT group or to a control group (no CRT) for 6 months. The primary end point was the proportion of patients with an increase in peak oxygen consumption of at least 1.0 ml per kilogram of body weight per minute during cardiopulmonary exercise testing at 6 months.

Results At 6 months, the CRT group and the control group did not differ significantly in the proportion of patients with the primary end point (46% and 41%, respectively). In a prespecified subgroup with a QRS interval of 120 msec or more, the peak oxygen consumption increased in the CRT group (P=0.02), but it was unchanged in a subgroup with a QRS interval of less than 120 msec (P=0.45). There were 24 heart-failure events requiring intravenous therapy in 14 patients in the CRT group (16.1%) and 41 events in 19 patients in the control group (22.3%), but the difference was not significant.

Conclusions CRT did not improve peak oxygen consumption in patients with moderate-to-severe heart failure, providing evidence that patients with heart failure and narrow QRS intervals may not benefit from CRT. (ClinicalTrials.gov number, NCT00132977 [ClinicalTrials.gov] .)

Source Information

From the University of Chicago, Chicago (J.F.B.); the Cleveland Clinic Foundation, Cleveland (R.A.G., P.J.T.); Methodist Hospital, Houston (S.F.N.); St. Thomas Hospital, Nashville (J.H.B.); Arkansas Heart Hospital, Little Rock (S.L.B.); St. Francis Hospital, Roslyn, NY (S.M.G.); and St. John Hospital and Medical Center, Detroit (L.A.P.).

This article (10.1056/NEJMoa0706695) was published at www.nejm.org on November 6, 2007.

Address reprint requests to Dr. Beshai at the University of Chicago Medical Center, 5758 S. Maryland Ave., MC 9024, Chicago, Il 60637, or at jbeshai{at}medicine.bsd.uchicago.edu.

Full Text of this Article

Related Letters:

Cardiac-Resynchronization Therapy
Daubert C., Leclercq C., Miljoen H., Paelinck B. P., Vrints C. J., Beshai J. F., Grimm R. A., Nagueh S. F.
Extract | Full Text | PDF  
N Engl J Med 2008; 358:1865-1866, Apr 24, 2008. Correspondence

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