Coronary vasodilator capacity and exercise-induced myocardial ischemia are related to the pulsatile component of blood pressure in patients with essential hypertension.

Abstract

High pulsatile load is associated with structural alterations of the heart and arteries, which may cause changes in the coronary circulation and predispose to myocardial ischemia. This study was designed to investigate the relationships of coronary vasodilator capacity and exercise-induced myocardial ischemia to pulsatile and steady components of office blood pressure. Eighty-two untreated, middle-aged hypertensive patients without coronary artery stenosis and 23 normotensive volunteers, underwent exercise electrocardiogram test and standard and transesophageal echocardiography to assess the occurrence of myocardial ischemia, left ventricular (LV) mass and geometry, total arterial compliance and coronary vasodilator capacity. In the hypertensive population, minimum coronary resistance (MCR) was significantly higher (P < 0.01) in the top as compared to all three lower pulse pressure (PP) quartiles (1.10 +/- 0.19, 1.21 +/- 0.23, 1.20 +/- 0.26 and 1.43 +/- 0.26 mmHg s/cm). An additional increase in MCR also occurred in the top quartile of systolic blood pressure (SBP), but not across quartiles of mean blood pressure. In regression analysis, MCR increased with PP, SBP and LV wall thickness and decreased with total arterial compliance. As compared to hypertensive patients with a negative exercise test for myocardial ischemia (n = 30), those with a positive test (n = 20) had higher MCR (1.12 +/- 0.22 versus 1.39 +/- 0.29 mmHg s/cm, P < 0.01) and lower total arterial compliance (96 +/- 22 versus 81 +/- 16%, P < 0.01). In untreated middle-aged hypertensive patients, coronary vasodilator capacity declines with increasing office PP and SBP. A decreased arterial compliance and increased LV wall thickness appear to be major alterations underlying this relationship. Exercise-induced myocardial ischemia is associated with higher MCR and lower arterial compliance.