Hypertension Medication and Stroke

 

High blood pressure (hypertension) is the strongest risk factor associated with stroke. Despite improved control of blood pressure during the past few decades, a considerable proportion of patients failed to achieve target blood pressure levels. In a population survey of over 9900 adults, 24% had high blood pressure but 30% of them were unaware of their diagnosis.  Although the majority of these surveyed individuals were taking prescribed medications, only a quarter of the at-risk population achieved adequate blood pressure control.[1] 

 

Stroke risk rises in direct proportion to uncontrolled high blood pressure.[2]  The risk of stroke is more strongly associated with high systolic blood pressure (the top number) than with high diastolic blood pressure (the bottom number).[3] Still, both numbers matter and both impact your risk of having a cardiac event such as a heart attack or stroke. [4]  In a cohort study approximately 27% of incident ischemic strokes and 57% of hemorrhagic strokes were attributed to uncontrolled blood pressure.[5] Ischemic strokes are caused by narrowed vessels; hemorrhagic strokes are caused by weakened vessels bleeding into the brain. One study showed that when patients 60 years and older with high systolic blood pressure (the top number) were treated with drugs to lower their blood pressure, the total occurrences of stroke went down by 36% over 5 years.[6]   

 

Although systolic blood pressure elevation has a greater effect on stroke, both systolic and diastolic high blood pressure independently influence the occurrence of adverse cardiovascular events, such as heart attack, and stroke.[4]

 

There are a number of possible causes of uncontrolled blood pressure even when the person is being treated with blood-pressure lowering drugs. They include:

  • Treatment-resistant hypertension

  • Lack of access to medical care

  • Suboptimal treatment by physician

  • Patients who don’t take their medications

The latter two causes have been identified as the most important barriers to hypertension control. Other studies have shown that overall patient survival increases when systolic blood pressure in men is less than 134 mm Hg and less than 149 mm Hg in women and diastolic blood pressure is less than 95.[7] 

 

These studies show that many strokes may be prevented by achieving adequate control of blood pressure. In general, that means blood pressure below 140/90 in men and women.

 

[1] Burt VL, Whelton P, Roccella EJ, et al. Prevalence of hypertension in the US adult population: results from the Third National Health and Nutrition Examination Survey, 1988-1991. Hypertension 1995;25:305-313.

[2] Du X, Cruickshank K, McNamee R, et al. Case-control study of stroke and the quality of hypertension control in north west England. BMJ 1997;314:272-276.

[3] Al-Roomi K, Heller RF, Holland T, et al. The importance of hypertension in the aetiology of infarctive and hemorrhagic stroke: The Lower Hunter Stroke Study. Med J Aust. 1992;157:452-455.

[4] Flint AC, Conell C, Ren X, et al. Effect of systolic and diastolic blood pressure on cardiovascular outcomes.  N Engl J Med 2019;381:243-51.

[5] Klungel OH, Kaplan RC, Heckbert SR, et al. Control of blood pressure and risk of stroke among pharmacologically treated hypertensive patients. Stroke 2000;31:420-424.

[6] SHEP Cooperative Research Group. Prevention of stroke by antihypertensive drug treatment in older persons with isolated systolic hypertension: final results of the Systolic Hypertension in the Elderly Program (SHEP). JAMA 1991;265:3255-3264.

[7] Bulpitt CJ, Palmer AJ, Fletcher AE, et al. Optimal blood pressure control in treated hypertensive patients:  report from the Department of Health Hypertension Care Computing Project (DHCCP). Circulation 1994;90:225-233.

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