Management of Isolated Systolic Hypertension

Isolated systolic hypertension (ISH) [systolic blood pressure (SBP) > or = l60mm Hg with diastolic blood pressure (DBP) <90mm Hg] is the commonest form of hypertension in the elderly, and accounts for about 60% of all hypertensive conditions in the population aged over 65 years. It is associated with a significantly increased risk of cardiovascular and cerebrovascular morbidity and mortality. The landmark Systolic Hypertension in the Elderly Program (SHEP) study, published in 1991, has shown that lowering the SBP in elderly patients with ISH results in a significant reduction in cardiovascular events. These results have had a major impact on clinical practice in hypertension. On theoretical grounds, considering the pathophysiological mechanisms of ISH in the elderly, any drug which lowers total peripheral resistance and/or arterial stiffness should reduce SBP effectively in these patients. This effect has been observed in outcome studies and short term clinical trials using a variety of drugs from the 4 major antihypertensive classes: diuretics, beta(1)-blockers, calcium channel antagonists and ACE inhibitors. Other drugs, including alpha antagonists, may also be effective. In general, there is compelling evidence to support active treatment of any individual with an SBP > or = 160mm Hg. As in essential hypertension, the maximum benefit is gained by aggressive treatment of those individuals at highest risk because of coexisting cardiovascular risk factors. In these people, an SBP of 140 to 159mm Hg should be considered to be an indication for active management. Initial management should be by manipulation of lifestyle factors such as bodyweight, salt and alcohol intake and aerobic exercise. Drug therapy, generally well tolerated in low doses, should be considered if SBP remains > or = 160mm Hg, or > or = 140mm Hg in the presence of multiple risk factors. The choice of initial drug therapy should be influenced by the particular clinical situation. If there are no coexisting contraindications or co-indications for particular drugs, it is reasonable to begin treatment with a low dose of a thiazide-like diuretic, as used in the SHEP study. However, in short term treatment trials calcium channel antagonists and ACE inhibitors have been shown to lower SBP effectively and can be used in the appropriate clinical context. Beta-blockers appear to be less effective as monotherapy in ISH. Combination therapy is frequently required and can be effective and well tolerated if carefully chosen.