Effect of quinapril on the attenuated heart rate recovery of type 2 diabetic subjects without known coronary artery disease

BACKGROUND: Heart rate (HR) recovery at 1 min is a measure of the vagal reactivation that occurs after cessation of exercise. Despite ample evidence about the association of attenuated HR recovery with increased mortality, pharmacologic modification of this predictor has not been shown. On the other hand, angiotensin-converting enzyme (ACE) inhibitors are known to have vagomimetic activity. HYPOTHESIS: We hypothesized that ACE inhibition would increase HR recovery in a group of subjects known to have reduced HR recovery, namely diabetics. METHODS: Maximal treadmill exercise stress test was performed in 31 type 2 diabetic and 31 nondiabetic male subjects with similar age, body mass index, and hypertensive status. None of the subjects had known heart disease or evidence of myocardial ischemia during the test. The diabetic subjects, after 2 weeks of treatment with quinapril, underwent a second exercise test. A third test was performed 2 to 3 weeks after cessation of quinapril treatment. RESULTS: At baseline, despite similar exercise capacity, the diabetics had a lower HR recovery at 1 min than nondiabetics (25 +/- 8 vs. 31 +/- 8 beats/min, p < 0.01). Quinapril significantly increased HR recovery at 1 min in diabetics (25 +/- 8 beats/min at baseline vs. 28 +/- 8 beats/min with quinapril vs. 25 +/- 7 beats/min off-therapy, p < 0.01 by analysis of variance). CONCLUSIONS: The attenuated HR recovery of type 2 diabetics can be improved by quinapril. Whether the improvement in HR recovery with ACE inhibition can lead to decreased mortality is currently unknown.