Is the top or bottom blood pressure number more important

Purpose of review: Diastolic blood pressure has traditionally been considered the most important component of blood pressure and the primary target of antihypertensive therapy. However, over 30 years ago important epidemiological studies pointed out the importance of systolic blood pressure, and research during the 1990s has strengthened this view. Unlike diastolic blood pressure, systolic blood pressure increases progressively with age, and in the ageing societies elevated systolic pressure is the most common form of hypertension. The characteristic changes of systolic and diastolic blood pressure with age lead to increases in pulse pressure (systolic minus diastolic), which has emerged as a new, potentially independent risk factor. In this review we compare the relative importance of various blood pressure components.

Recent findings: Generally, in studies in which readings of systolic and diastolic blood pressure have been compared, systolic blood pressure has been a better predictor of risk. Moreover, isolated systolic hypertension predicts risk better than isolated diastolic hypertension, and the treatment of both isolated systolic hypertension and combined hypertension has reduced cardiovascular events. There are no treatment studies of isolated diastolic hypertension. Pulse pressure reflects stiffening of large arteries and is associated with several cardiovascular risk factors. Pulse pressure also predicts events in epidemiologic studies, but elucidation of an independent role is hampered by the close correlation between pulse pressure and systolic blood pressure.

Summary: Epidemiological and treatment studies suggest that systolic blood pressure should be the primary target of antihypertensive therapy, although consideration of systolic and diastolic pressure together improves risk prediction. The greatest practical concern at the moment is the undertreatment of hypertension, especially systolic, and total cardiovascular risk.

• Normal Blood Pressure
  • What Is a Normal Blood Pressure Range?
• Guide
  • Which Is More Important, Systolic or Diastolic? Topic Guide

There is a greater risk of stroke and heart disease related to higher systolic blood pressures (top number) compared to elevated diastolic (bottom number) pressures, so it is given more weight.

Systolic and diastolic are terms related to blood pressure measurement, which gauges the force of blood pushing against the walls of arteries. 

• The systolic blood pressure (the number on top) is the pressure produced when the heart contracts and pushes out blood
• The diastolic blood pressure (the number on the bottom) is the pressure when the heart relaxes and fills with blood between heartbeats

Blood pressure readings are expressed as the systolic blood pressure number over the diastolic blood pressure number, such as 120/80 mmHg (“120 over 80”). 

Both systolic and diastolic are important readings for monitoring heart health, but the systolic (top number) is often given more weight. Studies show a greater risk of stroke and heart disease related to higher systolic blood pressures compared to elevated diastolic (bottom number) pressures, especially in people over age 50.

What Is a Normal Blood Pressure Range?

Blood pressure ranges for adults are listed in the table below.

9 Blood Pressure Facts

• Some people may have normal or asymptomatic blood pressures lower than 100/60
• In people who have chronically high blood pressure (hypertension), symptoms of low blood pressure may occur at readings above 100/60
• The normal blood pressure for adolescents 13 years or older is less than 120/80 mmHg. 
• In younger children, the normal range for blood pressure is determined by the child's sex, age, and height. The normal range is expressed as a percentile, similar to charts used to track children's growth.
• Blood pressure is divided into three categories based upon the child's blood pressure percentile:
  • High: Either systolic and/or diastolic blood pressure is in the 95th percentile or greater, as measured on three or more separate occasions, or blood pressure exceeds 130/80 mmHg
  • Elevated: Systolic and/or diastolic blood pressure is in the 90th percentile or greater, but less than the 95th percentile, or blood pressure exceeds 120/80 mmHg 
  • Normal: Both systolic and diastolic blood pressure are less than 120/80 mmHg in adolescents 13 years or older, and for younger children blood pressure that is less than the 90th percentile based on the child’s sex, age and height
  • Low: There is no explicit range for low blood pressure in because of children’s variability in sizes and ages 

SLIDESHOW

Reviewed on 3/17/2022

References

Image Source: iStock Images

https://www.nia.nih.gov/health/high-blood-pressure

https://www.uptodate.com/contents/high-blood-pressure-in-adults-the-basics?search=blood%20pressure%20chart&source=search_result&selectedTitle=5~150&usage_type=default&display_rank=5’

https://www.uptodate.com/contents/high-blood-pressure-in-children-beyond-the-basics?search=blood%20pressure%20chart&topicRef=15659&source=see_link

https://www.nhlbi.nih.gov/health-topics/low-blood-pressure

https://www.health.harvard.edu/staying-healthy/which-blood-pressure-number-is-important

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