Myocardial sympathetic innervation in patients with chronic coronary artery disease: is reduction in coronary flow reserve correlated with sympathetic denervation?

PURPOSE: Higher sensitivity of sympathetic nerves to ischaemia in comparison with myocytes has been observed and has been claimed to contribute to poor prognosis in patients with coronary artery disease (CAD). The aim of this study was to evaluate the dependency of myocardial sympathetic innervation on restrictions in coronary flow reserve (CFR).

METHODS: We analysed 27 non-diabetic patients with advanced CAD. We determined quantitative myocardial blood flow using (13)N-ammonia PET, myocardial viability with (18)F-FDG PET and cardiac innervation with (11)C-HED PET. Scarred segments were excluded from analysis. We investigated the relationship between regional HED retention, blood flow and CFR.

RESULTS: There was no correlation between rest perfusion and HED retention within a flow range from approximately 30 to 120 ml/(100 ml x min). A slight correlation was observed between stress perfusion values and HED retention (p<0.001), and between CFR and HED retention (p<0.001).

CONCLUSION: In non-diabetic CAD patients, HED retention in vital myocardium does not correlate with myocardial rest perfusion over a large flow range. The observed relation between HED retention and CFR indicates that sympathetic innervation can be preserved even when there is major impairment of myocardial blood supply. Most probably the occurrence of denervation depends not only on reductions in CFR, but also on the duration and severity of resulting ischaemic episodes.