Antihypertensive therapy in the prevention of stroke: what, when and for whom?

It is clear that antihypertensive regimens based on a low dose thiazide diuretic are effective for the primary prevention of stroke, particularly in older patients. In patients with diabetes mellitus who are at a higher risk of stroke, low dose thiazide diuretics and ACE inhibitors are of benefit. In those with isolated systolic hypertension, long-acting dihydropyridine calcium antagonists, in addition tolow dose thiazide diuretics, have also been shown to significantly reduce stroke risk. However, to attain sufficient lowering of blood pressure (BP) to most effectively reduce the risk of stroke (i.e. to levels of 140-150/80-85 mm Hg or lower and perhaps to <140/<80 mm Hg in patients with diabetes mellitus) combination therapy will be required. Immediately following stroke BP tends to fall spontaneously and therapy is probably not required in the great majority of patients during the first few days poststroke. If treatment is required shortly after this period, agents with a slow and gentle onset of action appear to be preferable; some preliminary data suggest that ACE inhibitors, despite lowering systemic BP, have no significant effect on cerebral blood flow. However, there is little clinical outcome data to clearly define the role of antihypertensive treatment in the early poststroke period. Whether existing antihypertensive therapy should be continued following stroke is also unclear, but such decisions may be influenced by factors such as the actual BP level, other indications for treatment (e.g. angina pectoris or cardiac failure) or the presence of dysphagia. There is more evidence to suggest that, some weeks to months following stroke (particularly a minor stroke), lower rather than higher BP is favourable, and better control of high BP with therapy reduces stroke recurrence.