Echocardiography Is Not Useful Before Cardiac Resynchronization Therapy if QRS Duration Is Available

Several multicenter prospective randomized trials have shown that cardiac resynchronization therapy (CRT) improves functional capacity and quality of life in ≈70% of symptomatic heart failure (HF) patients.1 A smaller proportion of these selected patients shows a >5% increase in left ventricular (LV) ejection fraction and a >15% reduction of LV end-systolic volume, indicating reverse remodeling of the LV.2 Finally, CRT reduces morbidity and mortality rates by ≈30% to 40%.3 These data are comparable to those of established pharmacological therapies for HF, including angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, β-blockers, and aldosterone antagonists. Of note, CRT is indicated in HF patients who remained symptomatic despite medical therapy; thus, they could be considered nonresponders to medical therapy. However, the precise proportion of nonresponders to medical therapy has not yet been quantified. Response by Abraham and Abraham see p 70 Notwithstanding CRT being a very efficacious and cost-effective treatment, several efforts have been made to reduce the number of nonresponder patients. The issue of patients not responding to CRT is rather complex. There is lack of agreement on the definition of nonresponder (volumetric, functional, or exercise response), the cause of CRT nonresponse is likely multifactorial, and some patients may be too sick to show a meaningful and measurable benefit (“beyond repair”). Currently, we do not know which factors are predicting response to therapy and the relative weight of each of these factors. Therefore, the proportion of patients who are not amenable to CRT remains undefined. Among the factors predicting response to CRT, the presence of mechanical dyssynchrony has been indicated to play a determinant role.4–7 The putative lack of responsiveness to CRT in the absence of mechanical dyssynchrony, together with evidence that mechanical dyssynchrony may exist even when QRS duration is within the normal range, has encouraged investigators to …