Echocardiographic Myocardial Scar Burden Predicts Response to Cardiac Resynchronization Therapy in Ischemic Heart Failure

Background: Because echocardiography is routinely applied for left ventricle (LV) evaluation before cardiac resynchronization therapy (CRT), it is important to know whether echocardiographic assessment of myocardial scar burden may also help to predict CRT response in patients with drug-refractory systolic heart failure of ischemic origin. Methods: Seventy-one patients with ischemic heart failure who underwent CRT were retrospectively analyzed. The number of LV scar segments was evaluated in each patient, defining transmural scar as an end-diastolic wall thickness ≤ 5 mm associated with increased acoustic reflectance. CRT response was defined by LV end-systolic volume decrease by at least 10% after 6 months of treatment. The role of pacing site with respect to scar location was also assessed. Results: Thirty-nine patients (55%) were responders and 32 patients (45%) were nonresponders to CRT. At baseline, responders had a lower number of scar segments (1.7 ± 1.6 vs 3.5 ± 2.5, P = .001). The number of scar segments was significantly associated with CRT response and correlated significantly with end-systolic volume variation (r = 0.57, P = .0001). The presence of 3 or more scar segments allowed the identification of nonresponders with a sensitivity of 62% and specificity of 71%. In responders, the pacing stimulus was more frequently delivered remote from scar segments, whereas in nonresponders it was more often delivered over the scar segments. Conclusion: Echocardiographic evaluation of transmural scar burden predicts CRT response after 6 months of treatment and should be performed in all candidates for CRT with ischemic heart failure before biventricular pacemaker implantation. © 2009 American Society of Echocardiography.