I-123 MIBG scintigraphy can classify coronary spastic angina patients from chest pain syndrome patients

Objectives Cardiac sympathetic nerve activity and coronary endothelial cell function (ECF) were reported to be disturbed in patients with coronary spastic angina (CSA). Our aim is to evaluate the usefulness of cardiac sympathetic nerve activity estimated by MIBG scintigraphy and ECF estimated by flow-mediated dilation (FMD).

Methods We compared consecutive 60 patients (M/F=24/36, age=69±8 y.o) who had rest chest pain and suspected of CSA with 10 age matched controls without heart disease (M/F=4/6, age=66±7y.o). All patients undertook coronary angiography, acetylcholine loading test, FMD and MIBG scintigraphy. Controls undertook FMD and MIBG scintigraphy. On acetylcholine loading test, acetylcholine was injected into RCA (25, 50μg), then LCA (50, 100μg). Spasm was defined as subtotal or total occlusion. Cardiac sympathetic nerve activity was estimated using the summed defect score (TDS, DS:0=normal to 4=defect) and heart/mediasitinum activity ratio (H/M) of delayed MIBG scintigraphy.

Results All patients had no significant stenosis. Spasm was induced in 39 patients, who were diagnosed as CSA, and not induced in 21 patients, who were considered as chest pain syndrome (CPS). There were no significant differences in background and in FMD between CSA and CPS patients (4.0±2.3% vs 4.2±1.8% p=0.8), but FMDs of both patients groups were significantly lower than 5.6±0.8% of controls (p<0.05). While TDS of CSA, CPS patients and controls were 13.2±17.2, 5.1±6.7 and 0.7±0.8, respectively. TDS of both patients groups were significantly higher than controls (p<0.05). Moreover TDS of CSA was significantly higher than CPS patients (p=0.04). H/M ratio of CSA, CPS patients and controls were 2.0±0.4, 2.2±0.2 and 2.5±2.2, respectively. H/M ratio of both patients groups were significantly lower than controls (p<0.01), moreover H/M ratio of CSA was significantly lower than CPS patients (p=0.03).

Conclusions MIBG scintigraphy can classify CSA patients from chest pain syndrome patients with no significant coronary stenosis, but with endothelial cell dysfunction