Isolated systolic hypertension in older patients.

Pathophysiologic changes and risks associated with isolated systolic hypertension (ISH) are described, findings of clinical trials pertaining to ISH are summarized, and recommendations for management are provided. ISH is the most frequent type of hypertension in patients over 65 years of age and is associated with increased cardiovascular and cerebrovascular morbidity and mortality. Decreased arterial compliance, increased peripheral vascular resistance, changes in cardiac output, decreases in plasma renin activity, and reduced beta-adrenergic function are all possible mechanism contributing to hypertension in older patients. Environmental factors that may contribute to hypertension in this population include diet, exercise, and salt sensitivity. Currently, the Systolic Hypertension in the Elderly Program (SHEP) is the only study that has evaluated the efficacy of treating ISH. The risk of stroke was lowered in patients who received low doses of the diuretic chlorthalidone, which was well tolerated with minimal adverse effects. Thiazide diuretics, beta-blockers, angiotensin-converting-enzyme inhibitors, calcium antagonists, and isosorbide dinitrate have been shown to lower systolic blood pressure (SBP) in patients with ISH. Because the SHEP study is the only trial to document a decrease in morbidity, diuretics are considered firstline therapy for patients with a SBP of > or = 160 mm Hg. In older patients, it is prudent to initiate antihypertensive therapy at lower doses with a more gradual increase in dosage. The SHEP trial demonstrated a significant reduction in morbidity with a trend toward decreased mortality when patients with ISH received pharmacologic treatment. More studies are necessary to determine whether other antihypertensive agents will have similar effects on mortality in patients with ISH.