The role of impaired sympathetic nerve function in enhancing coronary vasoconstriction in patients with hypertrophic cardiomyopathy.

Coronary vasospasm and diminished coronary blood flow reserve have often been reported in patients with hypertrophic cardiomyopathy (HCM). However, the mechanism of coronary spasm in HCM is unknown. Thus, coronary endothelial function and sympathetic nerve function in 11 patients with HCM and 11 control patients matched for age and sex were examined. The diameter of the left anterior descending coronary artery was assessed by quantitative coronary angiography, and the change in coronary blood flow was estimated using an intracoronary Doppler flow wire. To assess myocardial sympathetic nerve function, metaiodobenzylguanidine images - 15 min and 180 min after the injection of (123)I-metaiodoben-zylguanidine at a dosage of 111 MBq - were obtained, and the heart to mediastinum (H/M) count ratio and the washout rate (WR) were calculated. The H/M ratio was significantly lower in patients with HCM (2.1+/-0.3) than in control patients (2.6+/-0.4) (P<0.01). In addition, the WR was higher in patients with HCM (35+/-6%) than in control patients (28+/-3%) (P<0.01). The HCM subjects with coronary spasm had lower H/M ratios and higher WRs than HCM subjects without coronary spasm (P<0.05, respectively). In conclusion, impaired sympathetic nerve function may be associated with coronary vasospasm and diminished coronary blood flow reserve in HCM.