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In treating people with high blood pressure, most experts believe that the lower the better. But a new study suggests that that there are limits beyond which there is no benefit.

High blood pressure increases the risk for cardiovascular disease, and current guidelines advise a maximum systolic blood pressure (the top number) of 140. Still, some doctors believe a reading below 120 is even more beneficial.

The observational study, published online in JAMA Internal Medicine, involved 4,480 people. In the 22 years covered by the study, there were 1,622 heart attacks and other serious cardiac problems. Cardiac events were more common in people whose blood pressure exceeded 140, and particularly among those with readings over 160.

But there was no difference in the risk for heart failure, stroke or heart attack between those in the normal range (120 to 140) and those with a level below 120. Researchers controlled for smoking, use of blood pressure drugs, and other variables.

The lead author, Dr. Carlos J. Rodriguez, an associate professor of epidemiology and medicine at Wake Forest Baptist Medical Center, said some people should still aim for a reading under 120 — those who already have heart disease or diabetes, for example. But, he said, “the notion of ‘lower is better’ across the board should probably be questioned, and there should be a discussion with your doctor.”