Abstract 17309: The Reduction in Radial Strain Delay Index Predicts Remodelling Response to CRT
Background Correcting mechanical dyssynchrony is proposed as one of the major mechanisms of benefit from CRT. Very early and late segmental contraction may not fully contribute to end-systolic function. Echocardiographic dyssynchrony measures as predictive parameters of CRT response have been disappointing. We evaluated a novel radial strain delay index (RSDI) to quantify reserve of wasted contraction, caused by dyssynchrony and segments of low amplitude strain or scar, prior to CRT implantation and gain of contractility following CRT and relate our findings to response.
Methods 50 heart failure patients referred for CRT (NYHA III, QRS 146±19ms, EF 22%±6.5, ischaemic aetiology 60%) were studied with baseline echocardiograpy, prior to implantation, and at 6 months follow-up. RSDI was calculated using speckle tracking radial strain as the sum of the difference between peak and end-systolic strain (%) across 12 (basal and mid) LV segments. Response to CRT was defined as >15% reduction in end systolic volume (ESV).
Results 50% of patients were classified as CRT responders. RSDI did not correlate with QRS duration (r=0.14). CRT responders had a greater baseline RSDI than non-responders (median 74% vs. 21.7% p<0.001). Reduction in RSDI correlated with reverse remodeling (15% reduction in ESV), r=0.43,p=0.03. In CRT responders the decrease in RSDI was more marked than in non-responders (33% reduction vs. 8% reduction p<0.001). In CRT non-responders no significant change in RSDI was observed between baseline and follow up studies (median 24.7% vs. 27.7% p=0.1)
Conclusion RSDI may provide a valuable tool for understanding the mechanism of CRT response. Recruitment of wasted energy appears to be related to LV remodelling after CRT. Evaluation in a larger population of patients is required.
- © 2012 by American Heart Association, Inc.