High blood pressure is a major modifiable risk factor for all clinical manifestations of coronary artery disease (CAD). In people without known cardiovascular disease, the lowest systolic (down to 90–114 mmHg) and the lowest diastolic (down to 60–74 mmHg) pressures are associated with the lowest risk for developing CAD. Although diastolic blood pressure is the strongest predictor of CAD in younger and middle-aged people, this relationship becomes inverted and pulse pressure shows the strongest direct relationship with CAD in people above 60 years of age.
Pathophysiological mechanisms of blood pressure as a risk factor for CAD are complex and include the influence of blood pressure as a physical force on the development of the atherosclerotic plaque, and the relationship between pulsatile hemodynamics/arterial stiffness and coronary perfusion. Treatment of arterial hypertension has been proven to prevent coronary events in patients without clinical CAD. In patients with established CAD, the effect of blood pressure lowering per se is beneficial, probably more than specific drugs or drug classes. The important exceptions are beta blockers (BBs), which are superior to all other drug classes for use after a recent myocardial infarction. Blood pressure targets in patients with established CAD have created controversy in the light of the so-called J-curve phenomenon, which describes an increase in coronary events at lower diastolic blood pressures. One explanation for this observation is that perfusion of the left ventricle occurs predominantly during diastole, and that coronary autoregulation may be exhausted with low diastolic blood pressure in the setting of left ventricular hypertrophy and atherosclerotic narrowing of the epicardial coronaries. The worst situation is a high systolic blood pressure in the presence of a low diastolic blood pressure, both a hallmark of increased aortic stiffness. However, the lowering of systolic blood pressure is clearly beneficial in this setting, even at the price of further lowering diastolic pressure. Primary blood pressure goal in patients with established CAD is below 140/90 mmHg. Recent studies suggest that a lower systolic blood pressure may be appropriate, whereas caution is advised with diastolic blood pressure below 60 mmHg.