The physiological determinants and risk correlations of elevated heart rate

A number of studies have. shown that fast heart rate is associated with hig h blood pressure and metabolic disturbances, and that it is a strong precur sor of hypertension, atherosclerosis, and cardiovascular events. Subjects w ith tachycardia often also exhibit increased plasma insulin, overweight, an d higher hematocrit. These relationships have been observed also in the eld erly and among hypertensive individuals and have held true after controllin g for smoking, alcohol intake, and physical activity habits. In three diffe rent populations studied with a mixture analysis we demonstrated that the h eart rate-blood pressure association was mostly explained by a subpopulatio n of subjects with high heart rates who had higher levels of blood pressure , total cholesterol, triglycerides, postload glucose, and plasma insulin. T he clustering of these risk factors may explain why cardiovascular morbidit y is higher in individuals with fast heart rates. Sympathetic overactivity seems to be responsible for both the increase in heart rate and blood press ure, and for the metabolic abnormalities. In addition to being a marker of sympathetic overactivity, tachycardia seems to have a direct action in the induction of risk. Studies in cholesterol-fed monkeys have shown that the r eduction of heart rate could retard the development of coronary atheroscler osis. Furthermore, fast heart rate increases the pulsatile nature of the ar terial blood now and increases arterial wall stress. Antihypertensive drugs that lower the heart rate seem to have a good potential for prolonging lif e expectancy in humans. (C) 1999 American Journal of Hypertension, Ltd.