NO DIFFERENCE IN CARDIAC INNERVATION OF DIABETIC-PATIENTS WITH PAINFUL AND ASYMPTOMATIC CORONARY-ARTERY DISEASE

OBJECTIVE - To test the hypothesis that diabetic autonomic neuropathy interfering with sensory impulses from the heart by sympathetic denerv ation is the major cause of the high prevalence of asymptomatic corona ry artery disease (CAD) in diabetic patients. RESEARCH DESIGN AND METH ODS - We evaluated cardiac sympathetic innervation in a population-bas ed group of 10 asymptomatic diabetic patients with angiographically pr oven CAD and in an age- and sex-matched group of 10 diabetic patients with symptomatic CAD using [I-123]metaiodobenzylguanide (MIBG) scintig raphy. Exercise electrocardiography and myocardial perfusion imaging b y Tl-201 were used to detect myocardial ischemia, and standard cardiov ascular tests were used to diagnose autonomic nervous dysfunction. RES ULTS - Thallium scintigraphy revealed perfusion defects in all 10 symp tomatic patients and in 9 of the asymptomatic patients. MIBG accumulat ion defects were found in all cases with painless and with painful dis ease. In the asymptomatic group, the denervation area exceeded the isc hemic area in six cases and areas with total MIBG accumulation defects were seen in four cases. In one case, the MIBG defect was not in the ischemic region. In the symptomatic group, the denervation area exceed ed the area of the ischemic region in all cases and areas of total den ervation were seen in six cases. The autonomic nervous function tests were abnormal in two asymptomatic and three symptomatic patients with CAD. CONCLUSIONS - Cardiac sympathetic denervation is common in both p atients with painful CAD and patients with asymptomatic CAD regardless of diabetic autonomic neuropathy. This finding supports the view that sympathetic innervation of the heart is highly sensitive to ischemia and this profound effect of ischemia masks the potential effects of au tonomic neuropathy on sympathetic innervation. Mechanisms leading to t he lack of ischemic pain in diabetic patients with CAD are complex and are not solely explained by autonomic neuropathy.