Abstract 12574: Relationship between Baseline Dyssynchrony, Contractile Function and Primary Outcome in MADIT-CRT
Background: Despite benefits of cardiac resynchronization therapy (CRT) in patients (pts) with severe and less symptomatic heart failure (HF), approximately 30% do not respond fully to treatment. We hypothesized that a combined assessment of LV dyssynchrony and contractility by 2D-speckle tracking imaging (2D-STI) would identify pts who would most benefit from CRT.
Methods: We studied 1077 pts in NYHA class I/II, EF less than or equal 30% and QRS greater than or equal 130ms enrolled in MADIT-CRT with sufficient echocardiographic image quality (ICD, n= 416; CRT, n = 661). Using apical 4- and 2-chamber views, dyssynchrony was defined as the standard deviation of time to peak transverse strain out of 12 segments and contractile function was determined by averaging longitudinal strain out of 12 segments. We assessed the treatment effect on the primary outcome of death or HF based on degree of dyssynchrony and contractile function individually and the combination of both. Pts were divided into 4 groups based on median of dyssynchrony (low 180ms) and strain (worse >-8.7%, better <-8.7%).
Results: Treatment benefit improves as dyssynchrony and strain increase. With a total of 213 primary outcome events, pts with better contractile function and greater dyssynchrony showed greatest benefit from CRT (HR 0.33; CI 0.12–0.85) compared with patients in the 3 other groups (p for interaction <0.05; Figure). The measures of dyssynchrony and strain were of greater value in pts with ischemic than non-ischemic heart disease and were independent of QRS width, baseline ejection fraction, and other clinical variables.
Conclusions: Both mechanical dyssynchrony and contractile function are important determinants of CRT benefit and these assessments may help identify which patients would derive greater benefit from CRT.
- © 2010 by American Heart Association, Inc.