Alteration of coronary perfusion reserve in hypertensive patients with diabetes.

This investigation was performed to determine whether diabetes mellitus has an additive effect on diminishing coronary perfusion reserve index in hypertensive patients. Coronary perfusion reserve index, thallium lung uptake, the electrocardiogram and haemodynamic parameters were evaluated by exercise thallium myocardial perfusion scintigraphy. In 18% of hypertensive and 13% of diabetic-hypertensive patients there was evidence of left ventricular hypertrophy on electrocardiogram. The maximum heart rate achieved in hypertensive, diabetic and diabetic-hypertensive patients was significantly lower (P < 0.05) than in control patients. The maximum SBP achieved in hypertensive (210 +/- 40 mmHg) and diabetic-hypertensive patients (216 +/- 36 mmHg) was higher (P < 0.05) than in control patients (186 +/- 32 mmHg). A significantly higher number of diabetic patients (53%) did not achieve the exercise rate pressure product of > 26,000 when compared with control (27%), hypertensive (24%) and diabetic-hypertensive (30%) patients. Coronary perfusion reserve index in hypertensive patients decreased significantly (P < 0.05) when compared with control (no hypertension, no diabetes) patients (1.67 +/- .14 vs. 1.79 +/- .17). Coronary vasodilatory reserve index was also reduced significantly (P < 0.05) in diabetic patients in comparison with controls (1.66 +/- .17 vs. 1.79 +/- .17), and was further reduced in diabetic-hypertensive patients when compared with control patients (1.63 +/- .13 vs. 1.79 +/- .17). Thallium uptake in the lung quantified as thallium lung to heart ratio were comparable in all four groups. The results suggest that diabetes mellitus diminishes the coronary perfusion reserve index in patients with hypertension and therefore many account for the increased cardiovascular morbidity in these patients.