Cardiac sympathetic denervationmodulates the sympathoexcitatoryresponse to acute myocardial ischemia

Objectives This study was designed to elucidate the influence of cardiac sympathetic denervation on the sympathoexcitatory response to acute myocardial ischemia during balloon coronary occlusion (BCO) in humans. Background Alterations of cardiac sympathetic nerve function could modulate sympathetic reflexes originating from the ischemic area. Methods In 23 patients with angina pectoris, we quantified the baseline cardiac sympathetic denervation of the ischemia-related area by iodine-123 metaiodobenzylguanidine (123I-MIBG), and transient changes in sympathetic activity during BCO by wavelet analysis of RR interval variability. Results Balloon coronary occlusion resulted in a transient augmentation of low-frequency (LF: 0.04 to 0.14 Hz) spectral components of RR interval variability in 4 of 12 patients with cardiac denervation and in 8 of 11 patients without denervation (p < 0.01 by the chi-square test). Consequently, the increase in LF components was significantly less during BCO in patients with cardiac denervation (34%) than in those without denervation (273%) (interaction: p < 0.05). In seven patients with severe ischemia provoked by a fall of ≥10% in the left ventricular ejection fraction, LF components increased by 506% during BCO, regardless of the condition of cardiac denervation. In contrast, in patients with mild ischemia provoked by a fall of <10% in the ejection fraction, changes of LF components during BCO were significantly less in patients with denervation than in those without denervation (84 vs. 344%, p < 0.05). Conclusions These findings suggest that if the provoked ischemia is not severe, cardiac sympathetic denervation could prevent ischemia-induced sympathoexcitation.