Myocardial sympathetic innervation in patients with symptomatic coronary artery disease: follow-up after 1 year with neurostimulation.
UNLABELLED
In both diabetic and nondiabetic patients, there is a loose correlation between coronary flow reserve (CFR) and sympathetic innervation in viable myocardial segments. The loose correlation implies that sympathetic innervation may be preserved even with major impairment of myocardial blood supply. In some patients, denervation is due to repetitive episodes of ischemia in areas with severely reduced CFR. We investigated the long-term effect of reduced CFR on myocardial sympathetic innervation in diabetic and nondiabetic patients with spinal cord stimulation.


METHODS
We analyzed 23 patients (10 diabetic and 13 nondiabetic) with coronary artery disease and without known cardiac autonomic neuropathy. At baseline, we determined quantitative myocardial blood flow using (13)N-ammonia PET, myocardial viability using (18)F-FDG PET, and cardiac innervation using (11)C-hydroxyephedrine (HED) PET. At the 1-y follow-up we measured CFR and (11)C-HED retention. During follow-up, no cardiac intervention was performed and no myocardial infarction occurred. In all patients, spinal cord stimulation was performed for relief of angina.


RESULTS
There was no significant difference in segmental (11)C-HED retention between baseline and follow-up in the whole patient group. In diabetic patients, as well as in segments with severely reduced CFR (<1.5), (11)C-HED retention showed a small but significant decrease (P<0.05). Linear regression of segmental (11)C-HED retention between baseline and follow-up was high (r(2)=0.81), confirming good reproducibility of the investigation on the one hand and little change in regional sympathetic innervation on the other hand.


CONCLUSION
In patients with stable chronic coronary artery disease, sympathetic innervation of the myocardium is almost unchanged in both diabetic and nondiabetic patients in a 1-y follow-up. In myocardial segments with severely altered blood supply, a small but significant decrease in (11)C-HED retention most probably reflects ischemic neuronal damage. The prognostic relevance of sympathetic denervation in viable myocardium still has to be determined.