Abstract 2814: Dyssynchrony Transthoraccic Echocardiogram As A Predictor Of Response To Cardiac Resynchronization.
Introduction: Present indications for the use of cardiac resynchronization therapy (CRT) include advanced CHF, ejection fraction (EF) < 35%, and QRS duration > 120 msec despite stable maximal medical therapy. Several randomized studies, however, have shown that up to 30% of patients do not respond to CRT, and current criteria do not identify non-responders. We retrospectively studied patients who underwent dyssynchrony echocardiography (DE) prior to implantation of a CRT device to test DE as a predictor of response to CRT, using mortality, EF/left ventricular (LV) remodeling, and change in BNP as parameters.
Methods: Baseline characteristics were taken from chart review. All patients met established criteria for CRT and had BNP levels drawn before and after device implantation; these BNP levels were drawn during periods of clinical stability and were drawn in close proximity to initiation of CRT. Follow-up routine echocardiography was performed at ~ 6 months post-CRT. Dyssynchrony was defined by currently accepted criteria: septal-posterior wall delay > 130 msec; tissue Doppler criteria, including time-to-peak systolic velocity > 60 msec, time-to-onset of systolic contraction > 65 msec, or 12-segment time-to-peak systolic velocity standard deviation > 31 msec; or interventricular mechanical delay > 40 msec.
Results: Of 500+ consecutively screened patients, 95 were eligible for study; DE was positive in 69 patients. Overall mortality was 31% among those without dyssynchrony and 11% in the dyssynchrony group (p=0.026). Dyssynchrony patients had decreased BNP levels post-CRT (501 to 387 pg/dL, p = 0.020) while BNP rose in those patients without dyssynchrony (466 to 819pg/dL, p = 0.025). EF was unchanged in patients without dyssynchrony (22% to 21%, p=NS) but increased in the dyssynchrony group (20% to 25%, p= 0.001), along with a statistically significant decrease in LV systolic and diastolic dimensions. Multivariable analysis identified dyssynchrony and statin use as significant predictors of survival post-CRT.
Conclusions: Echocardiographic evidence of dyssynchrony pre-CRT predicts improvement in BNP, increase in EF and LV remodeling parameters post-CRT. CRT is also associated with reduced mortality in patients with dyssynchrony on pre-CRT DE.