What does it mean if systolic blood pressure (SBP) is significantly higher than diastolic blood pressure (DBP)?

Isolated Systolic Hypertension: Causes and Clinical Significance

Significantly higher systolic blood pressure (SBP) compared to diastolic blood pressure (DBP) typically indicates isolated systolic hypertension, which is the predominant form of hypertension in older adults and carries significant cardiovascular risk. 1

Understanding Blood Pressure Components and Age-Related Changes

• Both SBP and DBP increase linearly up to the fifth or sixth decade of life, after which DBP gradually decreases while SBP continues to rise, leading to isolated systolic hypertension in many older adults 1
• This pattern is due to increased arterial stiffness that occurs with aging, resulting in reduced vascular compliance of large arteries 2
• By age 60, isolated systolic hypertension becomes the most common form of hypertension, affecting more than half of Americans over age 65 1
• In the Framingham Heart Study, SBP alone correctly classified BP stage in 94% of adults over 60 years old, while DBP alone correctly classified only 66% 1

Clinical Significance and Cardiovascular Risk

• A widened pulse pressure (difference between SBP and DBP) is an independent marker of cardiovascular risk 2
• Each increase in SBP of 20 mmHg doubles the risk of fatal coronary events 1
• Isolated systolic hypertension is associated with increased risk of:
  • Fatal and nonfatal stroke 1
  • Cardiovascular events 1
  • Death 1
• The risk of cardiovascular disease increases in a log-linear fashion from SBP levels <115 mmHg to >180 mmHg 1

Diagnosis and Classification

• Isolated systolic hypertension is typically defined as SBP ≥140 mmHg with DBP <90 mmHg 3
• According to current guidelines, BP categories are:
  • Normal: <120/<80 mmHg
  • Elevated: 120-129/<80 mmHg
  • Stage 1 hypertension: 130-139/80-89 mmHg
  • Stage 2 hypertension: ≥140/≥90 mmHg 1
• Proper measurement technique is essential, including measuring BP over 2-3 respiratory cycles at end-exhalation 4

Treatment Considerations

• Treatment of isolated systolic hypertension has been shown to reduce cardiovascular events and mortality 1, 5
• For adults ≥65 years with isolated systolic hypertension, a SBP treatment goal of less than 130 mmHg is recommended for ambulatory community-dwelling adults 1
• For older adults with high comorbidity burden and limited life expectancy, treatment decisions should consider risk/benefit assessment, patient preference, and a team-based approach 1
• Effective medications for isolated systolic hypertension include:
  • Diuretics
  • Calcium channel blockers
  • Angiotensin II inhibitors 5
• Beta-blockers appear to be less effective as monotherapy for isolated systolic hypertension 5, 6
• Combination therapy is frequently required to achieve target SBP 5, 6

Common Pitfalls to Avoid

• Focusing solely on diastolic pressure in older adults, when systolic pressure is the more important risk factor after age 60 1
• Withholding treatment based on age alone - evidence shows benefit of treatment even in patients over 80 years 1
• Concerns about "brittle hypertension" in the elderly leading to inadequate drug titration and poor BP control 1
• Failing to monitor for orthostatic hypotension, which is more common in older adults and can lead to falls 1
• Not considering pulse pressure as an independent risk factor, especially in older adults 2

Special Considerations

• Randomized controlled trials have demonstrated that improved BP control does not exacerbate orthostatic hypotension and has no adverse impact on risk of injurious falls in community-dwelling older persons 1
• BP-lowering therapy is one of the few interventions shown to reduce mortality risk in frail older individuals 1
• For most patients with isolated systolic hypertension, combination therapy with two or more drugs is often needed to achieve optimal BP control 1