Letter by Shanmugam et al Regarding Article, “Primary Results From the SmartDelay Determined AV Optimization: A Comparison to Other AV Delay Methods Used in Cardiac Resynchronization Therapy (SMART-AV) Trial: A Randomized Trial Comparing Empirical, Echocardiography-Guided, and Algorithmic Atrioventricular Delay Programming in Cardiac Resynchronization Therapy”

Abstract

To the Editor: We read with great interest the recent article by Ellenbogen et al,1 who compare atrioventricular optimization (AVOpt) in cardiac resynchronization therapy (CRT) with a fixed atrioventricular (AV) delay. Using improvement in left ventricular end-systolic volume (LVESV) at 6 months as the primary end point, the authors conclude that the routine use of AV optimization is no longer warranted. We believe that the study was underpowered to detect the additional response to AVOpt. In the sample size calculation the authors assumed a standard deviation of 60 mL and an expected response to CRT of a 30-mL reduction in LVESV. They then assumed a …