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 dysfuncti on by determining left ventricular diastolic filling at rest and the l eft ventricular ejection fraction (LVEF) response to exercise with rad io-nuclide angiography. The subjects were 40 patients with non-insulin -dependent diabetes who showed no evidence of cardiovascular disease b ased on clinical findings, electrocardiography and Tl-201 perfusion sc intigraphy. We also used I-123-metaiodobenzylguanidine (I-123-MIBG) sc intigraphy to investigate whether subclinical left ventricular abnorma lities were related to adrenergic cardiac dysinnervation. The change i n LVEF in response to exercise (Delta LVEF) was <5% in I 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 E DV s(-1)) in 5 of 40 patients (P=N.S.). Of the clinical and scintigrap hic variables that correlated significantly with Delta LVEF, the heart -to-mediastinum I-123-MIBG uptake ratio on the late planar images was the most important and independent predictor. Nearly half of the patie nts with non-insulin-dependent diabetes without apparent cardiovascula r disease exhibited a depressed LVEF response to exercise. This subnor mal response was significantly associated with diminished myocardial I -123-MIBG uptake, suggesting a causal relationship.