Prognostic benefits of heart rate reduction in cardiovascular disease

Abstract

Increased heart rate is associated with high blood pressure and metabolic disturbances that lead to hypertension, atherosclerosis and increased cardiovascular morbidity and mortality. In this respect, elevated heart rate can be considered a marker of risk. Whole body temperature and energy needs are controlled by heart activity, and the ‘language’ employed by the heart could be considered its rate, which, via the intensity and frequency of shear stress, it uses to regulate endothelial function and vascular tone. A close link between body temperature, metabolism and heart rate has been observed, and so heart rate may determine metabolic demand and ‘control’ the duration of life. In mammals, the calculated number of heart beats in a lifetime is remarkably constant, despite a 40-fold difference in life expectancy. According to this view, a reduction in heart rate would increase life expectancy also in humans. The heart produces and utilizes approximately 30 kg adenosine triphosphate each day, and slowing its rate by 10 beats/min would result in a saving of about 5 kg in a day. Considering that heart rate is a major determinant of oxygen consumption and metabolic demand, heart rate reduction would be expected to diminish cardiac workload. Clinical studies with beta-blockers have already shown a reduction in mortality and improvement in outcome as a result of reduction heart rate.