Hypertension & Stroke

Hypertension is the most prevalent and powerful modifiable risk factor for stroke, irrespective of geographic region and ethnic group. Persons with hypertension are about 3 or 4 times more likely to have a stroke. Whereas diastolic BP was once thought to be the most important predictor of stroke, the relationship between stroke and hypertension may be stronger for systolic than for diastolic BP. The association between BP and stroke risk seems to occur on a continuum rather than as a threshold effect. Major strokes have been reported among persons with only “borderline” or “mild” hypertension, and both persons classified as “hypertensive” as well as “normotensive” could have the benefit of BP lowering. Therefore, although the highest BP levels predict the highest relative risk of stroke, the conceptual pendulum has swung in the direction of the continuum of absolute BP levels and somewhat away from the construct of “hypertension” per se. Furthermore, as discussed below, recent evidence points to the fact that mediators of hypertension, such as Ang II, may influence stroke risk independently of Blood pressure elevation.

Hypertension (high blood pressure) remains the single most important modifiable risk factor for stroke, and the impact of hypertension and nine other risk factors together account for 90% of all strokes. Stroke is a leading cause of death and disability, particularly in low-income and middle-income countries. The two major types of stroke include ischaemic stroke (caused by blood clots), which accounts for 85% of strokes, and haemorrhagic stroke (bleeding in the brain), which accounts for 15% of strokes. Prevention of stroke is a major public health priority, but needs to be based on a clear understanding of the key preventable causes of stroke.