How does hypertension contribute to the development of cerebrovascular accident (CVA) or stroke?

From the Guidelines

Hypertension causes stroke because it damages blood vessels over time, making them more prone to rupture or blockage, and managing it through medications and lifestyle changes can significantly reduce stroke risk. When blood pressure is consistently high, it exerts excessive force against artery walls, causing them to thicken and become less flexible (atherosclerosis) 1. This narrowing restricts blood flow to the brain and increases the risk of clots forming. Additionally, weakened blood vessels may burst under pressure, leading to hemorrhagic stroke. The brain is particularly vulnerable to these effects because its blood vessels are delicate and essential for delivering oxygen and nutrients to brain tissue.

The relationship between blood pressure and stroke is continuous, with each 10-mm Hg increase in blood pressure increasing the risk of stroke by 30% to 45% 1. Conversely, antihypertensive therapy reduces the risk of stroke, with a meta-analysis of more than 40 trials and >188,000 patients finding a 33% decreased risk of stroke for each 10-mm Hg reduction in systolic blood pressure to 115/75 mm Hg 1.

Some key points to consider in managing hypertension to reduce stroke risk include:

• Using medications like ACE inhibitors (such as lisinopril 10-40mg daily), ARBs (like losartan 25-100mg daily), calcium channel blockers (amlodipine 2.5-10mg daily), or diuretics (hydrochlorothiazide 12.5-25mg daily) 1
• Implementing lifestyle changes including reducing sodium intake, regular exercise, maintaining healthy weight, limiting alcohol, and avoiding smoking
• Aiming for consistent blood pressure control below 130/80 mmHg for most adults, as even modest reductions in blood pressure can decrease stroke risk by 30-40% 1.

It's also important to note that the type of therapy appears less important than the response, and that antihypertensive therapy has been shown to reduce the risk of recurrent stroke by 24% in a systematic review of 7 randomized trials 1. Overall, managing hypertension is crucial in reducing the risk of stroke, and a combination of medications and lifestyle changes can be effective in achieving this goal.

From the FDA Drug Label

Elevated systolic or diastolic pressure causes increased cardiovascular risk, and the absolute risk increase per mmHg is greater at higher blood pressures, so that even modest reductions of severe hypertension can provide substantial benefit The largest and most consistent cardiovascular outcome benefit has been a reduction in the risk of stroke, but reductions in myocardial infarction and cardiovascular mortality also have been seen regularly Hypertension causes stroke because elevated systolic or diastolic pressure increases cardiovascular risk.

• The absolute risk increase per mmHg is greater at higher blood pressures.
• Modest reductions of severe hypertension can provide substantial benefit in reducing the risk of stroke. 2 3

From the Research

Hypertension and Stroke

Hypertension is a major risk factor for stroke, and its management is crucial in preventing stroke and its recurrence 4, 5. The relationship between hypertension and stroke is complex, and high blood pressure can lead to various types of stroke, including ischemic stroke, intracerebral hemorrhage, and aneurysmal subarachnoid hemorrhage 5.

Mechanisms of Stroke in Hypertension

Some key mechanisms by which hypertension causes stroke include:

• Atheromatous deposits blocking or narrowing brain arteries, predisposing to local clot formation 6
• Damage to cerebral arterioles and brain tissue due to atheroma and its ischemic consequences 6
• High blood pressure increasing the risk of bleeding into the brain once a break in an arteriolar wall has occurred 6
• Pressure- or ischemia-induced arteriolar spasm, which can be prevented by induced hypotension 6

Management of Hypertension to Prevent Stroke

Effective management of hypertension is essential in preventing stroke, and various antihypertensive agents have been shown to reduce stroke risk 7, 5. Some key points to consider include:

• Lowering blood pressure to reduce the risk of stroke 4, 6, 5
• Using calcium channel blockers, which have been shown to decrease the incidence of stroke compared to placebo and other antihypertensive agents 7
• Managing blood pressure in the acute phase of stroke, which remains a topic of controversy 4, 8
• Targeting optimal blood pressure goals to prevent stroke, which requires further research 8