Abstract 3582: Extent of Viability to Predict Response to Cardiac Resynchronization Therapy
Introduction: At present, 20–30% of patients do not respond to cardiac resynchronization therapy (CRT). Non-response to CRT may be explained by the presence of scar tissue and consequently less viable myocardium.
Hypothesis: We hypothesized that a substantial amount of viable myocardium is needed for improvement in LV function, and that the extent of viability may be useful for prediction of clinical response to CRT.
Methods: Sixty-one consecutive patients with advanced heart failure, left ventricular ejection fraction (LVEF) <35%, QRS duration >120 ms and chronic coronary artery disease were included. All patients underwent nuclear imaging with F18-fluordeoxyglucose SPECT before implantation to determine the extent of viability (number of viable segments in a 17-segment model). Clinical and echocardio-graphic parameters were assessed at baseline and after 6 months of follow-up.
Results: The number of normal, viable segments ranged from 2 to 17 (mean 10±4). The extent of viability before implant was directly related to an increase in LVEF after 6 months of CRT. Furthermore, the extent of viability was significantly larger in responders (n=38, 12±3 vs. non-responders n=3, 7±3 viable segments, P<0.01). ROC curve analysis (Figure⇓) demonstrated that in the presence of ≥11 viable segments, a sensitivity of 74% with a specificity of 87% were obtained to predict clinical response to CRT.
Conclusions: In patients with ischemic heart failure, the presence of myocardial viability is directly related to response to CRT. Using a cut-off value of ≥11 viable segments on nuclear imaging, the extent of viability could be used to predict response.