European Society of Cardiology guidelines recommend the use of cardiac resynchronization therapy (CRT) in patients with symptomatic heart failure (HF) and QRS durations >120 ms 1,2 (Table 1). However, 2 recent meta-analyses by Sipahi et al 6 and Stavrakis et al 7 challenged these recommendations. Both studies found that patients with QRS durations between 120 and 150 ms do not benefit from CRT.
Response by Sipahi and Fang on p 435This is a very important conclusion, from both the clinical and financial standpoints. If the conclusions of these meta-analyses are correct, the guidelines should be revised, and the cutoff for QRS duration indicating the need for CRT should be changed from 120 to 150 ms. From the reimbursement standpoint, these analyses would suggest that the cost of CRT devices implanted in patients with QRS durations shorter than 150 ms should not be covered by insurers. Indeed, the authors of the second metaanalysis state that "the decision to routinely recommend CRT for patients with QRS <150 ms may not be justified." Although not in such categorical terms, some societies are already embracing this idea. In fact, in their recently published update, the Heart Failure Society of America, citing one of the abovementioned meta-analyses, 6 definitely recommends CRT only for patients with QRS durations >150 ms (and not because of right bundle-branch block), with severe left ventricular (LV) systolic dysfunction and persistent New York Heart Association (NYHA) functional class II-III symptoms, despite optimal medical therapy. According to the same update, CRT may still be considered for patients with QRS intervals between 120 and 150 ms and severe left ventricular dysfunction who have persistent symptoms on medical treatment. 5 However, the wording "may be considered" reflects the lowest possible strength of recommendation. Despite the high quality of both meta-analyses, as well as of the individual trials included in them, we doubt that such a conclusion is justified.CRT is a unique therapy for patients with HF and prolonged QRS duration. Not only does it induce reverse LV remodeling, it also improves functional status and increases longevity in these patients. 8,9 Unlike any other therapy with the exception of ventricular assist devices, CRT interrupts the progression of the disease and reverses the natural course of HF, 9 even in minimally symptomatic or asymptomatic patients with complete left bundle-branch block (LBBB) and systolic dysfunction. In just 1 year of therapy, LV end-systolic and end-diastolic volume decreases and ejection fraction increases in most patients, especially those with nonischemic cardiomyopathy. There is also a subset of super-responders in whom biventricular pacing leads to restoration of cardiac geometry and (Circ Arrhythm Electrophysiol. 2013;6:429-435.)