Diet, lifestyle changes, exercise and medications can often help patients lower their blood pressure. Yet, lowering blood pressure too much may be just as risky, especially diastolic pressure.

Franz Messerli, M.D., Cardiologist with St. Luke's-Roosevelt Hospital Center in New York City, says the heart is a unique muscle. Other organs and tissues of the body fill with blood during the systolic part of the heart beat, or when the heart is pumping. But the heart muscle itself gets its blood supply during the diastolic part of the heart beat. If the diastolic pressure is too low, the heart muscle may not get enough blood.

Messerli says as blood pressure rises, so does the risk for a heart attack. But the risk for a heart attack also increases when blood pressure is too low. In a study, Messerli and his colleagues found in patients with diastolic pressure lower than 70, the risk for a heart attack doubled. In patients with diastolic pressure lower than 60, heart attack risk quadrupled.

Doctors must treat patients with high blood pressure on a case by case basis. Blood pressure should be monitored regularly and adjustments in medications may need to be made in small increments to prevent blood pressure from dropping too low.

One important class of high blood pressure medications, the beta-blockers, may need to be avoided in some patients because these drugs may lower blood pressure more than other medications and tend to slow heart rate, which may not be good when the heart muscle isn’t getting enough oxygenated blood.