Tachycardia: an important determinant of coronary risk in hypertension.

Heart rate and blood pressure are highly correlated and in large population studies, individuals with high blood pressure tend to have high heart rates. Fast heart rate precedes the development of high blood pressure and serves as an early indicator of coronary heart disease. Not only does the heart rate predict coronary mortality, but also the non-cardiovascular mortality and is, therefore, an overall predictor of longevity. In the Tecumseh Blood Pressure study, we have seen that 37% of all patients with borderline hypertension have the 'hyperkinetic hypertension state', which consists of elevated cardiac output, high heart rate, high sympathetic tone, and decreased parasympathetic tone. In this population, evidence of high heart rate exists in these individuals as children, and persists through early adulthood. This suggests that tachycardia is a reliable marker of high sympathetic tone. High sympathetic tone might be the mechanism whereby heart rate is associated with high insulin, insulin resistance, dyslipidemia, high hematocrit and excess weight. These mechanisms are discussed in details in this review. Tachycardia is a strong risk factor for sudden death and arrythmia. Heart rate, as one of the prime determinants of cardiac work, may contribute to greater cardiac strain. Animal studies have shown that a higher heart rate may be associated with a greater development of atherosclerotic plaque in coronary vasculature. Therefore, heart rate elevation is not merely a sign of underlying pathology, but it may also cause further damage that leads to increased mortality. In the treatment of hypertension, reducing heart rate by pharmacologic and non-pharmacologic measures may have a greater effect on coronary mortality than blood pressure reduction alone.