LOW BLOOD-PRESSURE LEVELS AND SIGNS OF MYOCARDIAL-ISCHEMIA - IMPORTANCE OF LEFT-VENTRICULAR HYPERTROPHY

To clarify a possible relationship between the level of BP and signs of myocardial ischaemia, two groups of treated hypertensive patients with (n = 12) and without (n = 18) increased left ventricular mass defined by echocardiography were investigated with 24h ambulatory BP and ECG monitoring. It was found that hypertensive patients with increased left ventricular mass had the following. (1) Higher systolic BP, heart rate (HR) and SBP x HR product during the night indicating a higher ventricular work load than hypertensives without increased LVM in this period. (2) This increased left ventricular work load during the night was concomittant with a lower DBP consistent with a lower perfusion pressure of the left ventricular myocardium. (3) Significantly depressed ST segment levels throughout the 24 hours with a significant positive correlation between BP and the level of the ST segment indicating increased ischaemic metabolic changes within the myocardium the lower the BP. (4) A higher ratio between the systolic SBP x HR product and DBP during sleep than in hypertensives without increased left ventricular mass, further corroborating that low DBP during the night might cause ischaemia through an imbalance between left ventricular work load and coronary perfusion pressure. We conclude that low BPs in hypertensive patients with increased left ventricular mass seem to induce ischaemia of the left ventricle. These findings provide a possible mechanism for the increased risk of ischaemic heart disease in hypertensive patients with low achieved BP.