CardioExchange Archive

Approximately 40% of cardiac resynchronization therapy (CRT) devices are implanted in patients with QRS intervals below 150 msecs, but a meta-analysis published in Archives in Internal Medicine finds that these patients may not benefit from the device.

Ilke Sipahi and colleagues performed a meta-analysis that included five CRT clinical trials (COMPANION, CARE-HF, REVERSE, MADIT-CRT, RAFT) with designs that enabled them to examine the effect of QRS duration on outcome. Although patients with severely prolonged QRS had a 40% reduction in risk associated with CRT therapy (CI 0.53-0.67, p<0.001), no benefit at all was observed in the patients with only moderately prolonged QRS. The same finding was observed in patients with class 1 and 2 heart failure as in patients with class 3 and 4 heart failure. The presence or absence of an ICD did not alter the pattern.

The authors point out that between one third and one half of patients who receive CRT don’t benefit from the therapy and then suggest “that a predominant reason for CRT non-response is a suboptimal patient selection criterion for QRS duration.” They recommend an individual patient level analysis of current trials to more precisely identify which patients enjoy the benefits of CRT.

“It may now be unethical…”

In an accompanying commentary, Lynne Warner Stevenson addresses the issue of subgroup analysis, agreeing that skepticism is warranted in trials with negative findings, but asking: “What about those with positive results?” In this instance, she argues, “the results of this meta-analysis are robust enough to anchor a growing suspicion that the patients with QRS in the 120- to 150- millisecond range do not improve after CRT. The trials are remarkably congruent, regardless of clinical class or etiology.” She then writes:

To continue to perform this procedure when benefit is unlikely will undermine enthusiasm for a remarkably effective therapy in appropriate patients. It may have been optimistic to recommend and reward this procedure in patients for whom there was no evidence of benefit; it may now be unethical to recommend and reward this procedure in patients for whom we now have evidence of no benefit.