Journal of Nuclear Cardiology Abstracts $33 Volume 4, Number 1, Part 2 Monday afternoon, April 7, 1997 26.6 123I.MIBG HEART TO MEDIASTINUM RATIO (HIM) IN ARRHYTHMOGENIC VENTRICULAR DYSPLASIA CARDIOMYOPATHY (AVD/C) DIAGNOSIS. S. Severi*, R. Bettini, E. Lorenzi*, A. Bertoldi, M. Camerani*. Nuclear Medicine* and Cardiology-S.Chiara Hospital-Trente-Itaty. The 123I-MIBG allows the landmarking of the Sympatetic Nervous System of the heart. In AVD/C patients (pts) the detection with 123I MIBG SPET is based on the presence in the left ventricle of regional defects. We tested if the association of the H/M ratio to SPET can improve the test's ability, MATERIALS AND METHQD$: we studied 5 controls and 37 pts with hyperkinetic ventricular arrhythraias, apparently normal heart and high performance, suspected to have AVD/C by invasive and not invasive Cardiological study and by Nuclear Medicine protocol comprehensive of a perfusory rest SPET and a rest (4 hours) 123I-MIBG SPET. The 123I-MIBG scan also included a planar anterior image of 1000 Kcounts to evaluate the H/M ratio between two kind of heart ROIs (ROIldrawn in the anterolateral wall-ROI2 in the projection of the all heart) and the mediastinal Rot located near the pulmonar apex. RESULTS: after the eardiological examination 16 pt. had no cardiomyopathy, 21 AVD/C (concealed forms) while the 5 controls were negative. The mean ROll and ROI2 H/M ratio of the controls showed a statistically significative difference (9<0.002) between the mean value of the AVD/C pt while this difference is not present respect the group of pt. with no cardiomyopathy. CONCLUSIONS: As demonstrated in our praevious papers the 123I-MIBG SPET scintigraphy is a necessary modality for mapping, in AVD/C, the left ventricle symphatefic nervous system involvement, The H/M ratio study gives an important information about the global sympatetic activity of the heart that may be useful to improve the test's accuracy of the test independently from extension and localization of the regional defect. 26.8 DOBUTAMINE-INDUCED AUGMENTATION OF LEFT VENTRICULAR EJECTION FRACTION AS AN ASSES SMENT OF INOTROPIC RESERVE IN PATIENTS W1TH IDIOPATHIC DILATEDCARDIOMYOPATHY Tarlk M. Ramahi, Mark A. Saari, Elizabeth Hsia, Forrester A. Lee, Barry L. Zaret, Yale University School of Medicine. New Haven, CT, USA. Patients with chronic heart failure (CHF) have a decreased inotropic response to intra-eoronary dobutamine infusion. In order to explore the role of dobutamine-indueed augmentation of LVEF as a measure of IR in patients with idiopathic dilated cardiomyopathy (DCM), 30 such patients with stable CHF (mean LVEF 25% + SD 8, range 11-38%) on standard medical therapy underwent intravenous dobutamine infusion at a dose of 10 t.tgm/kg/min, and equilibrium radionuelide ventrieulography (ERNA) was used to determine LVEF after 10 minutes of infusion. A wide variation was detected in the increase in LVEF (range 2-23 points, mean 12 ± SD 7). There was a weak linear correlation between the increment in LVEF (ALVEF) and resting LVEF (r=0.44, p <0.03) and resting RVEF (r=0A4, p <0.04). No linear relation eoutd be discerned between ALVEF and peak exercise oxygen consumption (mVO2). Of these patients, 17 underwent quantitative ERNA. In this group, mean increase in heart rate was 21 (+ SD 18). No linear relation could be discerned between ALVEF and resting HR, SBP, DBP, MBP, ehange in HR, SBP, DBP, MBP, nor in ERNA-estimated stroke volume and systemic vascular resistance. An inverse linear relation was detected between ALVEF and left ventrieular and diastolic volume (r=0.6, p<0.03). Conclusion: Patients with DCM and stable CHF exhibit a wide range of dobutamine-indueed augmentation of LVEF weakly proportional to ventricular function but not related to measures of afterload nor exercise capacity. This method of inotropie reserve assessment may have an independent prognostic role. 26.7 IMPAIRMENT OF LEFT VENTRICULAR ADRENERGIC INNERVATION IN PATIENTS LISTED FOR HEART TRANSPLANTATION ..D. Agostini, G. Babatasi*, A. Belin**, P. Scanu**, M. Massetti*, Y. Darlas, G. Grollier**, JC Potter**, A. Khayat*, G. Bouvard. Departments of Nuclear Medicine, Cardiac Surgery,-*, Cardiology**, Caen, France. The purpose of the study was to assess the sympathetic activity in patients with cardiac heart failure listed for heart transplantation (HTx). 123I-metaiodobenzylguanidine (MIBG) scintigraphy has recently evolved as a nonivasive method for the in vivo evaluation of sympathetic activity by measuring postganglionic prcsynaptic noradrenergic uptake. A consecutive series of 65 patients from 1991 to 1996 (52+10 yrs, 52 men, 13 women) with ischemic (n=33), idiopathic (n=32) cardiomyopathy, and left ventricular (LV) dysfunction entered the study. All patients underwent right and left catetberization, coronary angiography, radionuclide LVEF and planar MIBG scintigraphy. They were listed on clinical (NHYA funtional class III-IV, 32 (Ill) and 11 (IV)), cardiac-thoracic enlargment on xray-chest (>0.55, 0.58+0.08)) and reduction of left LVEF (<25%, 22+5%). Ten normal volunteers (44+_12 yrs) were also studied and served as control group. Cardiac MIBG function was assessed as the heart to medisatinum (H/M) activity ratio measured on the chest anterior view image acquired on gamma- camera, obtained after intravenous injection of 185 MBq of 123I- MIBG. Data from patients with congestive heart failure showed a significant reduction of cardiac MIBG uptake, when compared with control group (H/M : 104+20% vs 230+21%, p<0.003). Conclusion: These results indicate that cardiac adrenergic innervation is dramatically impaired in patients listed for HTx. 26.9 Correlation Between Cardiac '~1- meta- iodobenzyl guanidine Imaging and Neurohormonal Activation in Patients with Congestive Heart Failure K. IUCHI, K. USUDA, T. NAKABAYASHI, T. ISHIKAWA Department of Internal Medicine, Toyama Prefectural Hospital, Toyama, Japan We studied the correlation between cardiac '231 meta- iodobenzytguanidine (MIBG) imaging and neuro- hormonal factors in 28 patients with congestive heart failure. The initial and delayed MIGB images were obtained 30 and 180 min after MIBG injection, and the ratio of heart/mediastinum (E-H/M and D-H/M) and washout rates (WR) were calculated. Plasma norepi- nephrine (Nor), renin activity (PRA) and aldosterone (Aid) were measured as neurohormonal factors. Results: E-H/M D-H/M WR E-H/M D-H/M WR PRA r=-0.343 -0.340 0.521' Nor r=-0.4037 -0.387t 0.2]5 Aid r=-O.302 -0. 351 O.577* ~ p <0. 005, ~. p <0. 05 Conclusions : The clearance of MIBG from myocardium (WR) may be regulated by renin-aldosterone system in patients with congestive heart failure. The correlation with plasma norepinephrine and MIBG kinetics may be weak.