Why does atherosclerosis not directly affect diastolic blood pressure?

Why Diastolic Blood Pressure Is Not Directly Affected by Atherosclerosis

Atherosclerosis primarily affects systolic blood pressure rather than diastolic blood pressure because atherosclerosis impacts arterial stiffness and compliance, which predominantly influences systolic pressure while diastolic pressure is more dependent on peripheral vascular resistance and cardiac function. 1

Pathophysiological Mechanism

Atherosclerosis affects blood pressure components differently due to their distinct physiological determinants:

Systolic Blood Pressure (SBP)

• Directly impacted by arterial stiffness and reduced arterial compliance caused by atherosclerotic changes
• Increases as arteries lose elasticity due to plaque buildup
• Shows consistent association with increased cardiovascular disease (CVD) risk even after adjustment for diastolic blood pressure 1

Diastolic Blood Pressure (DBP)

• More dependent on peripheral vascular resistance and cardiac function than on large artery stiffness
• Not consistently associated with CVD risk after adjustment for systolic blood pressure 1
• Less affected by atherosclerotic changes in large arteries

Evidence from Clinical and Animal Studies

Multiple lines of evidence support this differential relationship:

• In the American Heart Association scientific statement, studies demonstrated that systolic blood pressure, not diastolic, correlates with atherosclerosis development in mouse models 1
• When antihypertensive medications (hydralazine) reduced blood pressure in experimental models, atherosclerosis was not attenuated, suggesting the relationship is not simply pressure-dependent 1
• The Kuopio Ischaemic Heart Disease Risk Factor Study found that systolic hypertension, but not diastolic hypertension, was associated with increased prevalence of both early and advanced atherosclerotic lesions in carotid arteries 2

Clinical Implications

This differential impact has important clinical implications:

• Systolic blood pressure should be the primary focus for cardiovascular risk assessment related to atherosclerosis 1
• In epidemiological studies, a 20 mmHg higher SBP is associated with a doubling in the risk of death from stroke, heart disease, or other vascular disease 1
• When evaluating blood pressure components, SBP has been prioritized in clinical guidelines because of its robust evidence base in both observational studies and clinical trials 1

Important Caveats

• While atherosclerosis may not directly affect diastolic blood pressure, both components remain important clinical parameters
• In younger individuals with elevated diastolic pressure, different pathophysiological mechanisms may be at play
• The stimulus for hypertension appears to be a major determinant of atherosclerosis rather than elevated pressure itself 1
• Patients with combined systolic-diastolic hypertension have higher cardiovascular risk than those with isolated systolic hypertension 3

Understanding this relationship helps explain why isolated systolic hypertension becomes more common with advancing age as atherosclerosis progresses, while diastolic pressure often remains normal or even decreases in older adults with significant atherosclerotic disease.