Abstract 15046: Apical Rocking Predicts Response to Cardiac Resynchronization Therapy - A Novel Application of Rotational Strain Analysis

Abstract

Introduction One third of patients who receive cardiac resynchronization therapy (CRT) in accordance with current guidelines fail to benefit from this therapy. A threshold level of contractile function in the dyssynchronously activated walls exists below which CRT cannot be expected to provide benefit. We propose a novel and simple echocardiographic technique that simultaneously assesses dyssynchrony and contractile function.

Hypothesis We hypothesized that left ventricular (LV) apical rocking assessed by rotational strain analysis (RSA) in the apical 4 chamber view (4CH) predicts response to CRT by identifying both dyssynchrony and preservation of contractile function of the opposing dyssynchronous walls.

Methods A cohort of 35 consecutive patients underwent assessment of apical rocking prior to CRT in the apical 4-chamber window (4CH) by RSA. Correlation between apical rocking and changes in LV ejection fraction (LVEF), LV end-systolic dimension (LVESD), and New York Heart Association functional class (NYHAFC) were made. We used RSA to assess angular displacement of the apex around a centroid defined by the arc formed by the apex in the 4CH. Apical rocking which consists of an initial counterclockwise rotation of the apex followed by a delayed clockwise rotation in the 4CH, is a direct consequence of the altered electrical activation sequence of the LV in LBBB, and is seen only when both dyssynchrony and preservation of contractile function in the dyssynchronously activated opposing walls are present. Clockwise rotation of the apex (CR) correlates with contractile function of the posterolateral wall and demonstrates a potential for increasing LV stroke volume as a result of CRT.

Results Pre-CRT apical rocking was present in 77% and was associated with improvement in LVESD (p=0.031) and NYHAFC (p=0.037) with a trend towards improved LVEF (p=0.089), post-CRT. The sensitivity for prediction of improvement was 87.5%, 85.2% and 88.9%, respectively. There was a significant correlation of CR pre-CRT with LVEF post-CRT (r=0.41; p=0.016) and of CR pre-CRT with LVESD post-CRT (r=0.38; p=0.027).

Conclusion Apical rocking and CR measured by RSA are sensitive predictors of response to CRT in patients meeting existing criteria for this therapy.