Depressed contractile response to exercise in diabetic patients in the absence of cardiovascular disease: relationship to adrenergic cardiac dysinnervation.

We investigated the presence of subclinical left ventricular dysfunction by determining left ventricular diastolic filling at rest and the left ventricular ejection fraction (LVEF) response to exercise with radionuclide angiography. The subjects were 40 patients with non-insulin-dependent diabetes who showed no evidence of cardiovascular disease based on clinical findings, electrocardiography and 201T1 perfusion scintigraphy. We also used 123I-metaiodobenzylguanidine (123I-MIBG) scintigraphy to investigate whether subclinical left ventricular abnormalities were related to adrenergic cardiac dysinnervation. The change on LVEF in response to exercise (delta LVEF) was < 5% in 1 of 20 normal controls and in 22 of 40 diabetic patients (P < 0.01). The peak filling rate was within normal limits in all controls but was abnormal (< 2.3 EDV s-1) in 5 of 40 patients (P = N.S.). Of the clinical and scintigraphic variables that correlated significantly with delta LVEF, the heart-to-mediastinum 123I-MIBG uptake ratio on the late planar images was the most important and independent predictor. Nearly half of the patients with non-insulin-dependent diabetes without apparent cardiovascular disease exhibited a depressed LVEF response to exercise. This subnormal response was significantly associated with diminished myocardial 123I-MIBG uptake, suggesting a causal relationship.