ALTERATION OF CORONARY PERFUSION RESERVE IN HYPERTENSIVE PATIENTS WITH DIABETES

This investigation was performed to determine whether diabetes mellitu s has an additive effect on diminishing coronary perfusion reserve ind ex in hypertensive patients. Coronary perfusion reserve index, thalliu m lung uptake, the electrocardiogram and haemodynamic parameters were evaluated by exercise thallium myocardial perfusion scintigraphy. In 1 8% of hypertensive and 13% of diabetic-hypertensive patients there was evidence of left ventricular hypertrophy on electrocardiogram. The ma ximum heart rate achieved in hypertensive, diabetic and diabetic-hyper tensive patients was significantly lower (P < 0.05) than in control pa tients. 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 n umber of diabetic patients (53%) did not achieve the exercise rate pre ssure product of > 26 000 when compared with control (27%), hypertensi ve (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 com parison 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 cor onary perfusion reserve index in patients with hypertension and theref ore many account for the increased cardiovascular morbidity in these p atients.