March 30th, 2014
MADIT-CRT Long-Term Follow-Up Shows Survival Benefit with CRT-D
MADIT-CRT was an influential trial that showed a reduction in heart failure complications — but not mortality — when cardiac resynchronization therapy (CRT) was added to an implantable defibrillator in patients with mild heart failure who also had left bundle-branch block (LBBB). Patients in the trial were followed for 2.4 years, raising questions about the long-term effects of CRT. Now, a second look at 854 patients who participated in a follow-up study suggests that over the long term, CRT may save lives in this population.
Overall, there was a highly significant 41% reduction in death (P=0.001) associated with CRT therapy in the large subgroup of patients with LBBB. The mortality rate was different after 1 year and remained significant throughout follow-up. At 7 years, the mortality rate was 29% in the control group versus 18% in the CRT group. There was an even bigger difference in nonfatal heart failure events (P<0.001). The benefits were remarkably consistent across a broad range of subgroups.
However, the group of MADIT-CRT patients who did not have LBBB showed no reduction in either mortality or heart failure events associated with CRT. The authors wrote that this “lack of benefit of CRT in patients without left bundle-branch block was consistent, regardless of the QRS duration or ECG morphologic findings with respect to right bundle-branch block and an intraventricular conduction delay. Thus, at present, our data do not support early intervention with CRT in any subset of this population.”
In an accompanying editorial, Jeffrey Goldberger writes that the results should serve “as a strong impetus to pursue CRT in patients with mild heart failure with reduced ejection fraction and left bundle-branch block.”
Arthur Moss, responding in CardioExchange to a question from John Ryan, said the 2013 heart failure guidelines, which recommend CRT for non-LBBB patients with a QRS duration of >150 msec, needs to be revised.
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