Myocardial damages in systemic sclerosis detected by gated myocardial perfusion SPECT and sympathetic imaging.

BACKGROUND Cardiac involvement is an important factor for the appropriate management of systemic sclerosis (SSc). The possibility for detecting early myocardial damage was investigated using (99m)Tc methoxyisobutylisonitrile (MIBI) gated perfusion single photon emission computed tomography (SPECT) and (123)I metaiodobenzylguanidine (MIBG) sympathetic imaging. METHODS AND RESULTS Twenty-three patients with SSc and 14 control subjects were studied. The severity of SSc was defined by disease type and semi-quantitative skin thickness scores. A myocardial perfusion study was performed using (99m)Tc MIBI exercise--rest study, and systolic and diastolic parameters were calculated from the volume curve of the gated SPECT. (123)I MIBG was evaluated by segmental defects, a heart-to-mediastinum ratio and washout rate (WR). No significant exercise-induced ischemia was observed and the left ventricular ejection fraction was within normal range in patients with SSc. However, diastolic function calculated by time to peak filling (TPF) in the early diastole was significantly prolonged in SSc compared with the control group (184+/-35 ms, 160+/-25 ms, p=0.030) and more rapid MIBG WR from the myocardium (18.2+/-7.0% vs 11.1+/-4.3%, p=0.0015). Compared with the control group, the severe group with either diffuse SSc or a skin thickness score >or=10 had more prolonged TPF/RR interval than the less severe group. Both diastolic and sympathetic abnormalities were observed in 7 (30%) patients, and 1 abnormality in 17 (74%) patients with SSc. CONCLUSIONS In patients with SSc, either diastolic dysfunction or sympathetic derangement, or both were observed even without induced ischemia and normal ventricular contractility. Based on these subclinical early findings, further follow-up studies are recommended.