Can 123 I-MIBG cardiac scintigraphy predict functional recovery in heart failure after cardiac resynchronization?

Abstract

Background: Cardiac heart failure patients may benefit from cardiac resynchronization, but around 30% do not respond. Several parameters have been studied to evaluate possible positive predictive factors. Aim: To evaluate if baseline 123 I-MIBG cardiac scintigraphy parameters can predict functional capacity modification after cardiac resynchronization (CRT), assessed by cardiopulmonary testing, in patients (P) with chronic heart failure (CHF). Methods: We prospectively assessed 49 consecutive CHF P referred to CRT, mean age 68±14 (34-82 years old), 68% male, LVEF<35%; 28% ischemic cardiomyopathy P and 72% nonischemic cardiomyopathy P; 37% diabetic P; 43% P class III and 57%≤ class II (NYHA). All patients underwent, before CRT and 6 months post-CRT, echocardiogram for left ventricular ejection fraction (LVEF), cardiopulmonary testing, CPT, for peak oxygen consumption (VO2p), and 123 I-MIBG cardiac scintigraphy, for early heart-mediastinum rate (HMR), late HMR and washout (WO). Results: Our preliminary results showed, mean LVEF 27±8%; VO2p mean value 14.8±5.5 ml/kg/min. Regarding 123 I-MIBG scintigraphy parameters, we found early HMR mean value 1.5±0.17 (75% P with early HMR < 1.6); late HMR mean value 1.4+/0.16, (94% P with late HMR<1.6); washout (WO) mean value 41±27. VO2 change after CRT at 6 months was positive in 68% of the P (mean variation +4.3+/2.7 ml/kg/min), group A, and negative in 32% of the P (mean variation -3.4+/2.3), group B. There was a very significant difference between VO2 variation in group A and B (p 1.6 (100%) had a positive VO2 variation (group A); P with baseline early HMR <1.6, had negative VO2 variation in 60% (group B) and positive in 40% (group A).Considering early HMR<1.5, 88% P had negative VO2 variation (group B). No significant differences were found in the late HMR, WO and LVEF. Conclusion: In this heart failure patients group, ischemic and nonischemic, baseline MIBG early heart-mediastinum rate was predictive of functional capacity modification: early HMR superior to 1.6 was always associated to VO2 increase after CRT (100% P); contrarly, early HMR inferior to 1.5 was mostly associated to VO2 decrease (88% P).