IMPACT OF EXERCISE REHABILITATION ON CARDIAC NEURONAL FUNCTION IN HEART-FAILURE - AN I-123 METAIODOBENZYLGUANIDINE SCINTIGRAPHY STUDY

Exercise training can induce important haemodynamic and metabolic adap tations in patients with chronic heart failure due to severe left vent ricular dysfunction. This study examined the impact of exercise rehabi litation on cardiac neuronal function using iodine-123 metaiodobenzylg uanidine (MIBG) scintigraphy. Fourteen patients (11 men, 3 women; mean age 38 years; range: 36-66 years) with stable chronic heart failure o f NYHA class II-III and an initial resting radionuclide left ventricul ar ejection fraction (LVEF) <50% were enrolled in the study. Patients underwent progressive, supervised endurance training (treadmill test, Bruce protocol) during a 6-month period (60 sessions, 3 sessions per w eek) at a cardiac rehabilitation referral centre in order to measure e xercise parameters. Planar I-123-MIBG scintigraphy provided measuremen ts of cardiac neuronal uptake (heart-mediastinum ratio activity, 4 h a fter intravenous injection of 185 MBq of MIBG). Radionuclide LVEF was also assessed at the outset and after 6 months of exercise training. W orkload (801+/-428 vs 1229+/-245 kpm.min(-1), P = 0.001), exercise dur ation (504+/-190 vs 649+/-125 s, P = 0.02), and myocardial MIBG uptake (135%+/-19% vs 156%+/-25%, P = 0.02) increased significantly after re habilitation. However, LVEF did not change significantly (23%+/-9% vs 21%+/-10%, p = NS). It is concluded that exercise rehabilitation induc es improvement of cardiac neuronal function without having negative ef fects on cardiac contractility in patients with stable chronic heart f ailure.