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Cardiac Resynchronization in Patients with Mild Heart Failure: Equal Benefit for All?

March 30, 2014

Cardiac Resynchronization in Patients with Mild Heart Failure: Equal Benefit for All?

  1. Mark S. Link, MD

In an extended follow-up of MADIT- CRT patients, CRT reduced mortality in patients with left bundle-branch block, but not in those without it.

  1. Mark S. Link, MD

Cardiac resynchronization therapy (CRT) has been demonstrated to improve quality-of-life measures, heart failure (HF) admissions, and left ventricular ejection fraction (LVEF). However, most trials have not had sufficient power or follow-up duration to examine effects on mortality. In the MADIT-CRT trial, CRT reduced rates of a composite endpoint of HF events and death at about 2 years of follow-up. The MADIT-CRT investigators now report longer-term follow-up results.

Post-trial follow-up continued for a median 5.6 years in 1691 patients; a smaller group of 854 was followed longer. At 7 years, rates of death from any cause in patients with left bundle-branch block (LBBB) were 18% in recipients of CRT and 29% in those treated with standard implantable cardioverter defibrillators (hazard ratio, 0.59; 95% confidence interval, 0.43–0.80; P<0.001). The mortality curves continued to diverge as follow-up time lengthened. No similar mortality benefit was observed in patients without LBBB.

Comment

These findings demonstrate that the benefits of cardiac resynchronization pacing are probably limited to patients with left bundle-branch block. Whether other subsets of patients receive some benefit is still not completely clear; for example, the number of patients with extremely wide QRS interval and right bundle-branch block in CRT trials is relatively small, rendering any findings in this subset inconclusive. These findings support the benefit of CRT in mild HF but do not warrant any change in guideline recommendations for now.

  • Disclosures for Mark S. Link, MD at time of publication Editorial boards UpToDate Leadership positions in professional societies American Heart Association (Chair, Core 4; Scientific Sessions)

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