Abnormal autonomic function in diabetic and nondiabetic patients after first acute myocardial infarction.

We performed autonomic function testing in 68 patients, 34 with diabetes mellitus (group A) and 34 without (group B), at 72 h after a first acute myocardial infarction (MI) to determine the prevalence of autonomic dysfunction in these patients. Heart rate (HR) variation during 6 breaths/min obtained from mean of longest RR interval during expiration(E)/mean of shortest RR interval during inspiration (I) (E:I ratio), immediate HR response to standing = RR at 30th beat/RR at 15th beat (30:15 ratio) and postural fall of blood pressure were evaluated. In group A, 25 (78 percent) of 32 patients had an abnormal expiration-inspiration ratio compared with 28 (85 percent) of 33 in group B. Twenty-six (76 percent) patients in group A and 16 (47 percent) in group B had an abnormal 30:15 ratio. Abnormal postural fall of blood pressure was seen in 16 (47 percent) patients in group A compared with ten (29 percent) in group B. During follow-up, four women in group A with an initial autonomic dysfunction died, and in group B, three patients with a normal autonomic function died. Thus, autonomic dysfunction does not seem to contribute to the high mortality among diabetics after an acute MI.