Association Between Blunted Heart Rate Response to Dipyridamole and Myocardial Ischemia in Diabetic Patients as Compared With Nondiabetic Patients

Background: Blunted heart rate response (BHR) during dipyridamole stress testing has been reported to be related to higher cardiac death. This study was performed to assess the association between BHR and perfusion abnormalities in diabetic patients undergoing dipyridamole stress ECG-gated myocardial perfusion imaging (MPI) as compared with nondiabetic patients. Methods: A total of 2172 subjects (1602 women and 570 men) at a mean age of 61 ± 11 years who were referred for MPI to our department were studied. The subjects were divided into 2 groups on the basis of the presence or absence of diabetes mellitus (849 diabetic vs 1323 nondiabetic subjects). Results: Dipyridamole-related BHR was noted in 471 (67.7%) patients, demonstrating a significantly higher incidence in the diabetic patients than in the nondiabetic subjects (P < 0.05). Both basal systolic and peak systolic blood pressures were significantly higher in the patients with diabetes mellitus (P < 0.05). However, no significant difference was noted in the number of segments with perfusion abnormalities in patients with BHR as compared with the subjects with a normal hemodynamic response, neither in the diabetic nor in the nondiabetic subjects. Conclusions: The results of our study suggest that the presence of myocardial perfusion abnormalities and left ventricular dysfunction is not related to abnormal heart rate response during dipyridamole stress testing, neither in diabetic nor in nondiabetic subjects. The incidence of BHR to dipyridamole is significantly higher in diabetic patients, however.