Systolic blood pressure is more important than diastolic blood pressure. Systolic is the top number or the highest BP when the heart is squeezing and pushing the blood around the body. On the other hand, Diastolic BP is the bottom number or lowest BP between heartbeats. This is because it gives the best idea of your risk of having a stroke or heart attack. However, in certain circumstances, diastolic blood pressure is more important than systolic. For example, this is true in people less than 40 years of age. The fact is that diastolic BP is a better way of assessing risk.