Abstract 3578: MIBG Scintigraphy as a Potent Method for Identifying Responders Receiving CRT
Background and Purpose: Several studies have shown that cardiac resynchronization therapy (CRT) reduces morbidity and rehospitalization in patients with severe heart failure. However, not all patients respond to CRT and the accurate factors to determine the responder for this novel therapy remains unknown. It is well known that impaired sympathetic nerve activity of the myocardium coexists with severe left ventricular (LV) in severe heart failure. By using 123I-MIBG scintigram, severity of impaired sympathetic nerve activity of the myocardium can be evaluated. So we aimed to evaluate the baseline parameters that may affect the outcome of CRT in severe heart failure patients.
Methods: We studied 34 consecutive patients with severe heart failure (NYHA class III/IV, BNP 744+/−670) and LV dysfunction (LVEF 26+/−6%) who underwent CRT at our institute. First, we performed standard echocardiography to determine the left ventricular (LV) end-diastolic volume before performing CRT. During follow up period (1 month to 6months), LV end-diastolic volume was revaluated. Then patients were classified as responders (n=14) of CRT if the LV end-diastolic volume was reduced >10% compared with baseline volumes, and others as nonresponders (n=20). We compared the following baseline parameters between the two groups: QRS width, BNP, LVEF, LV end-diastolic volume, LV end-systolic volume, SPWMD, IVMD, and Heart Mediastinal activity ratio (H/M) at early phase and delayed phase and washout rate on 123I-MIBG-scintigram. Results: Although QRS width, BNP, LVEF, LV end-diastolic volume, LV end-systolic volume, SPWMD, IVMD, and washout rate on 123I-MIBG-scintigram at baseline showed no significant differences among the two groups, H/M (early phase, delayed phase) on 123I-MIBG-scintigram of responders at baseline showed significantly greater value than that of nonresponders (2.13+/−0.38 vs. 1.79+/−0.36 p=0.02, 1.86+/−0.45 vs. 1.53+/−0.45 p=0.05 respectively).
Conclusion: Preserved sympathetic nerve activity of the myocardium in severe heart failure may be one of the potent key factor to have a better outcome after CRT.