A recent study led by Bill McEvoy, Professor of Preventive Cardiology at NUI Galway, found no evidence that diastolic blood pressure can be dangerous to patients when lowered to levels that had been previously believed to be harmful. Their findings have the potential to influence how doctors effectively treat high blood pressure. 

High blood pressure is a leading cause of heart disease. Readings for blood pressure consist of a systolic reading (top value), measuring arterial pressure when your heart beats, and a diastolic reading (bottom value), measuring arterial pressure when your heart rests between beats. Previous research indicated ideal levels for blood pressure, but a recent study is now bringing this into question.

A common blood pressure pattern among older adults consists of a high systolic value and a low diastolic value. Older studies that used less reliable research methods reported that the risk of a heart attack increases when diastolic blood pressure is below 70mmHg or above 90mmHg. This became the basis for screening and risk assessment. 

This previous research influenced treatment for hypertension by focusing on diastolic levels. Treating patients with high systolic values and low diastolic values created uncertainty among professionals. Medications that cause a drop in both systolic and diastolic values are the most common treatment, causing doctors to worry that diastolic values would drop too low.  

The new research identified no danger in diastolic values dropping below 70mmHg, which allows clinical care to take a new approach to the treatment of heart disease. Professor McEvoy and the international research team analyzed genetic and survival data from 47,407 patients worldwide with a median age of 60.

Their genetic-based research found:

♦ No genetic evidence of increased risk of heart disease in patients with diastolic blood pressure value as low as 50mmHg

♦ No lower limit of normal diastolic blood pressure

♦ No evidence supporting that diastolic blood pressure values can be too low

♦ Systolic blood pressure values above 120 are associated with an increased risk of heart disease or stroke. 

By previously focusing on keeping diastolic blood pressure values between 70mmHg and 90mmHg, some patients with high systolic blood pressure may have experienced undertreatment. There was a more significant risk of heart disease by not treating blood pressure based on the more dangerous reading (elevated systolic values). With this new research, doctors can change their focus.

Treatment can be based on the dangerous systolic values (between 100 and 130mmHg) without worrying if diastolic values are falling. There is no longer a need to keep readings within the so-called ‘sweet spot’ of 70-90mmHg. This new research opens the door for new clinical care approaches, allowing doctors to focus on the numbers that matter to provide more effective treatment for hypertension. 

Journal reference:

Arvanitis M, Qi G, Bhatt DL, et al. Linear and Nonlinear Mendelian Randomization Analyses of the Association Between Diastolic Blood Pressure and Cardiovascular Events. Circulation, 2021; 143 (9): 895-906 DOI: 10.1161/CIRCULATIONAHA.120.049819