Beware of low diastolic readings when treated for high blood

Researchers have found evidence that links heart tissue damage to blood pressure treatments that drive diastolic pressure {the bottom number in a reading} too low. 

Last year's SPRINT trial showed cardiovascular benefits when high blood pressure was reduced to 120/80 millimeters of mercury {mm Hg}. In the new study, published Aug. 30, 2016, in the Journal of the American College of Cardiology, researchers followed 11,565 people for 21 years. The participants had blood tests and blood pressure measurements five times during this period.

From the blood samples, scientists performed high-sensitivity cardiac troponin testing, a way to measure a protein involved in heart muscle contraction. The protein rises when there is heart damage from reduced blood flow caused by narrowed coronary arteries. The results found that people with diastolic blood pressure below 60 mm Hg were twice as likely to have troponin-indicated heart damage compared with those in the recommended range of 80 to 89 mm Hg. Those with a diastolic blood pressure of 60 to 69 mm Hg were 52% more likely to have heart damage. 

The scientists cautioned the findings only show an association between low diastolic blood pressure and an increase in heart damage, but that the emphasis on pushing the top number down to a target of 120 mm Hg might lower the bottom number too much in the process. "Men with coronary artery disease need to pay attention to the bottom number when working to reduce the top number," says lead researcher Dr. William McEvoy of Johns Hopkins Medicine.