By: Thomas Pickering, MD, DPhil, FRCP, Director of Integrative and Behavioral Cardiology Program
of the Cardiovascular Institute at Mount Sinai School of Medicine, New York.

Many people think that the diastolic pressure (the lower of the two readings of blood pressure) is the number that matters most, but they are wrong. An increasing body of evidence shows that of the two, the systolic is more important in determining what the risk of strokes and heart attacks is likely to be. A new analysis of the Framingham Heart Study data, which has provided us with much of the information we have about risk factors, has examined whether the pulse pressure might give an even stronger prediction (pulse pressure is the difference between the systolic and the diastolic pressures). This was done using data from people aged between 50 and 79 years.

The analysis showed that the people at highest risk were those who had the largest pulse pressure. That is the biggest difference between the systolic and diastolic pressures. What this means is that if you have a high systolic pressure, it is better to have a high diastolic pressure than a low diastolic pressure. So why was a high diastolic formerly thought to be bad? The answer is that if you just look at the diastolic pressure, higher levels are associated with a slightly higher risk, but this is because in general, people with a high diastolic pressure have an even higher systolic pressure, so that their pulse pressure is also increased.

Doctor’s comments

This result may come as a surprise, but actually makes good sense. It is probably the oscillations of pressure rather than the steady level, which damage the delicate lining of the inner wall of the arteries, and these oscillations will be bigger in people with a large pulse pressure. This is of particular relevance to older people with systolic hypertension, who have a high systolic pressure and a normal or low diastolic. We know that such people are at increased risk of heart disease and stroke, and also that treating the systolic pressure without having much effect on the diastolic lowers the risk.

Where it was published