Abstract :
Numerous epidemiologic studies have emphasized that the risk of cardiovascular events increases as blood pressure increases, even within what is usually regarded as the normal range of blood pressure. However, since the risk of events seems to rise more sharply at blood pressure levels of mmHg and above, clinical hypertension tends to be diagnosed at this point. Theoretically, the goal of treatment should be to reduce blood pressure to mmHg or below. This simple concept has been confounded by recent evidence indicating that for older patients the risk of cardiovascular events may actually be inversely related to the diastolic pressure, probably because low diastolic values are probably indicative of advanced arterial stiffening and the presence of vascular pathologic changes. Perhaps related to this phenomenon is concern that aggressive treatment of hypertension in elderly patients that drives their diastolic blood pressures below 85 mmHg might exaggerate the risk of coronary events rather than provide protection. This seems to be a problem in patients known to have preexisting coronary disease. However, the Systolic Hypertension in the Elderly Program (SHEP), in which isolated systolic hypertension was treated aggressively and caused many patients to experience very low diastolic values, there was no evidence for excess coronary events; indeed, a trend in the reverse direction was claimed. It is possible that variability in blood pressure during the day may be as important as absolute values in predicting events. There is evidence that fluctuations in blood pressure can acutely produce myocardial ischemia, especially in patients with underlying coronary disease. Moreover, drug therapy in elderly patients, even when not successful in reducing their hypertension, seems to provide useful protection against events. This could possibly be explained by an ability of the drugs to dampen blood pressure fluctuations even when measurements obtained clinically do not change. Another consideration in deciding on the treatment of high blood pressure is the circadian pattern. Blood pressure rises sharply during the early morning hours, the time of day at which there is a heightened incidence of coronary and cerebrovascular events. Thus, is could be argued that a primary goal of therapy is to provide blood pressure protection during those critical morning hours, and it may not be necessary--or potentially may even be harmful--to have excessive antihypertensive actions at other times. Clinical trials with drugs commonly used in the treatment of hypertension, both in hypertensive and non-hypertensive clinical conditions, have shown that the more modern agents such as ACE inhibitors can have cardiovascular preventative effects. Although these direct vascular actions potentially are of value in reducing coronary and other endpoints in hypertensive patients, the weight of evidence suggests that effective blood pressure reduction remains an important strategy in protecting hypertensive patients.
