From the Guidelines
The primary difference between diastolic and systolic blood pressure is that systolic pressure represents the force of blood against artery walls when the heart beats, while diastolic pressure measures the pressure between beats when the heart is resting. Blood pressure is measured using two numbers: systolic and diastolic, with systolic being the top number and diastolic being the bottom number, typically written as systolic over diastolic, like 120/80 mmHg 1.
Key Differences
- Systolic pressure is the force of blood against artery walls when the heart beats
- Diastolic pressure measures the pressure between beats when the heart is resting
- Elevated blood pressure is defined as a systolic blood pressure 120–129 mmHg and a diastolic blood pressure <80 mmHg, while hypertension is defined as a systolic blood pressure ≥130 mmHg or a diastolic blood pressure ≥80 mmHg 1
Clinical Significance
Understanding the difference between systolic and diastolic pressures is crucial for interpreting blood pressure readings and managing cardiovascular health, as hypertension is a major risk factor for ASCVD, heart failure, and microvascular complications 1.
Management
Numerous studies have shown that antihypertensive therapy reduces ASCVD events, heart failure, and microvascular complications, highlighting the importance of accurate blood pressure measurement and management 1.
From the Research
Difference between Diastolic and Systolic Blood Pressure
- Diastolic blood pressure is the pressure in the arteries when the heart is resting between beats, while systolic blood pressure is the pressure in the arteries when the heart beats 2, 3.
- Systolic blood pressure increases progressively with age, and in aging societies, elevated systolic pressure is the most common form of hypertension 2.
- Diastolic blood pressure, on the other hand, has traditionally been considered the most important component of blood pressure and the primary target of antihypertensive therapy 2.
- However, research has shown that systolic blood pressure is a better predictor of risk, and isolated systolic hypertension predicts risk better than isolated diastolic hypertension 2, 3.
Importance of Systolic and Diastolic Blood Pressure
- Systolic blood pressure is the overall best predictor of future cardiovascular risk for the entire hypertensive population 4.
- Diastolic blood pressure is important in predicting cardiovascular risk, especially when considered in relation to simultaneous levels of systolic blood pressure 4.
- The ratio of diastolic and systolic arterial pressure is associated with pulse pressure, which is a potentially independent risk factor for cardiovascular disease 5.
Clinical Implications
- Systolic blood pressure appears to play a greater role in the determination of blood pressure stage and eligibility for therapy, especially in middle-aged and older persons 6.
- The treatment of isolated systolic hypertension and combined hypertension has reduced cardiovascular events, while there are no treatment studies of isolated diastolic hypertension 2.
- Pulse pressure, which is the difference between systolic and diastolic blood pressure, is a potentially independent risk factor for cardiovascular disease, and its reduction has been associated with reduced morbidity and mortality 3.