Is diastolic blood pressure less important than systolic blood pressure?

Systolic vs. Diastolic Blood Pressure: Relative Importance

Both systolic and diastolic blood pressure are important, but systolic blood pressure is generally a stronger predictor of cardiovascular risk, especially in individuals over 55 years of age.

Comparative Importance by Evidence

Systolic Blood Pressure

• Systolic blood pressure increases progressively with age and is the most common form of hypertension in aging populations 1
• In most epidemiological studies comparing readings of systolic and diastolic blood pressure, systolic blood pressure has been a better predictor of cardiovascular risk 1, 2
• Isolated systolic hypertension predicts risk better than isolated diastolic hypertension 1
• The European Society of Cardiology (ESC) and European Society of Hypertension (ESH) guidelines recognize that in elderly individuals, cardiovascular risk is directly proportional to systolic blood pressure 3

Diastolic Blood Pressure

• Diastolic blood pressure remains clinically significant, particularly in younger and middle-aged patients 4
• For patients with coronary artery disease, maintaining diastolic BP ≥70 mmHg is important to ensure adequate coronary perfusion 5
• Very low diastolic blood pressure (<60 mmHg) has been associated with increased risk of cardiovascular events, particularly in patients with treated systolic blood pressure <130 mmHg 6

Age-Related Considerations

• Under 55 years of age: Both systolic and diastolic blood pressures are independently and similarly predictive of stroke and coronary mortality 3
• Over 55 years of age: The predictive value of pulse pressure (systolic minus diastolic) increases, particularly in patients with cardiovascular risk factors 3
• In elderly individuals, for any given systolic level, cardiovascular outcomes are inversely proportional to diastolic blood pressure 3

Clinical Implications

Blood Pressure Measurement

• Blood pressure should be measured in standardized conditions, preferably using validated devices 3
• Systolic and diastolic pressures vary in different parts of the arterial tree - systolic pressure increases in more distal arteries while diastolic pressure decreases 3
• When a patient's systolic and diastolic blood pressures fall into different categories, the higher category should apply for risk assessment and treatment decisions 3

Treatment Considerations

• Treatment decisions should be based primarily on systolic blood pressure, which has been the main criterion in randomized controlled trials 3
• For patients with isolated systolic hypertension and low diastolic BP, treatment should balance the benefits of lowering systolic BP against risks of further reducing diastolic BP 5
• The optimal diastolic BP range appears to be 70-80 mmHg, particularly in patients with treated systolic blood pressure <130 mmHg 6

Pitfalls to Avoid

• Don't ignore low diastolic pressure: Overaggressive reduction in diastolic pressure may lead to increased coronary events in patients with established ischemic heart disease 5
• Don't focus exclusively on diastolic BP: The traditional focus on diastolic blood pressure as the primary target of antihypertensive therapy is outdated 1
• Don't overlook pulse pressure: In elderly patients with systolic hypertension, a high pulse pressure is a marker of increased large artery stiffness and advanced organ damage 3

Bottom Line

While both components of blood pressure are clinically significant, systolic blood pressure should be the primary target for cardiovascular risk assessment and antihypertensive therapy, especially in older adults. However, excessively low diastolic blood pressure (<60-70 mmHg) should be avoided, particularly in patients with coronary artery disease.