Abstract 2511: Utility of three-dimensional echocardiography in assessing and predicting response to Cardiac Resynchronization Therapy
Objective: To assess the use of three-dimensional echocardiography (3DE) in the evaluation of immediate and long term effects of Cardiac Resynchronization Therapy (CRT).
Methods: 3DE were performed in patients before, within 24 hours of and 6 –12 months after CRT. Left ventricular (LV) global, segmental volumes and ejection fraction (EF) were obtained. Synchronicity Index (SI) was calculated as the standard deviation of time to minimum volume in 16 LV segments corrected by heart rate. Functional class by NYHA and 3DE acquisition time was recorded. Immediate responders were defined as > 6% increase of EF within 24hrs of CRT. Long term responders required > 15% reduction of LV end-systolic volume with > 1 NYHA Class improvement by 6 –12 months.
Results: 46 patients were enrolled (24 ischemic; age 66+/-12). Within 24 hours of CRT, LVEF improved from 25% to 29%, this was correlated with a decrease of SI from 0.125 to 0.088 (correlation coefficient = -0.72, P < 0.05). Baseline SI > 0.10 had a positive predictive value (PPV) of 68% and negative predictive value (NPV) of 92% of immediate responders. At 6 –12 months visit, 3 patients died or received cardiac transplantation. 31 patients had repeat 3DE. LVEF improved from baseline of 25% to 34% (P < 0.05). 15/19 patients with baseline SI of > 10 were long term responders (PPV = 76%). None of the 12 patients with baseline SI ≤10 responded (NPV = 100%). All immediate and long term responders had reduction of SI of > 0.05 (sensitivity 100%, specificity 75%). 1 patient had inadequate 3DE for analysis. Average technical acquisition time for each 3DE was less than 2 minutes.
Conclusion: In our initial experience using 3DE in assessment of CRT. We found:
3DE was a practical tool in assessing dynamic LV changes with CRT
Synchronicity index improvement by 3DE significantly correlated with LVEF increase.
Reduction of SI > 0.05 was highly sensitive in predicting immediate and long term response
None of our patients with baseline SI ≤ 10 responded to CRT by 6 –12 months (NPV = 100%)
Baseline SI of > 0.10 had 68% and 76% positive predictive value for immediate and long term response respectively.