Diabetics With Autonomic Neuropathy Have Decreased Myocardial Perfusion Reserve

Type 1 diabetics with autonomic neuropathy exhibit decreased myocardial perfusion reserve capacity when challenged with a vasodilator.

This finding may be related to the increased mortality seen in these patients, according to investigators from the Departments of Endocrinology, Magnetic Resonance and Cardiology at Hvidovre University Hospital in Copenhagen, Denmark.

The investigators studied nine type 1 diabetics with autonomic neuropathy, 10 type 1 diabetics without autonomic neuropathy and 10 healthy controls. Dynamic contrast-enhanced magnetic resonance perfusion imaging was performed at baseline and after challenge with the vasodilator Dipyridamole.

Baseline myocardial perfusion index was similar among the three study groups.

During Dipyridamole vasodilation, myocardial perfusion index was 131.1 ± 13.0 milliliters/100 grams/minute in the autonomic neuropathy group. This was significantly lower than the non-autonomic neuropathy and control groups, whose myocardial perfusion indices were 177.3 ± 8.6 and 197.2 ± 8.9 milliliters/100 grams/minute, respectively.

Patients in the autonomic neuropathy group showed a significant drop in blood pressure during the vasodilator challenge, while blood pressure remained unchanged in the non-autonomic neuropathy patients and control subjects.

Blood pressure changes in response to Dipyridamole were significantly correlated with myocardial perfusion reserve index.

These findings suggest a pathophysiological substrate for the increased mortality observed in type 1 diabetic patients with autonomic neuropathy, according to the investigators. Possible underlying mechanisms for these observations include defective myocardial sympathetic vasodilation and a lack of ability to maintain blood pressure during vasodilation.

Diabetes 2002; 51(11): 3306-3310.