Blood pressure study to alter treatment goals for many

The results of the groundbreaking SPRINT trial will change blood pressure (BP) treatment goals for thousands of Irish people. Anyone over 50 with systolic blood pressure of more than 130 mm Hg and who has existing heart disease or an elevated risk of developing a heart attack or stroke in the future will be affected by this key piece of research.

For decades, normal blood pressure was set at 140/90. The upper number is the systolic blood pressure and corresponds with the pressure as the heart pumps blood from its chambers; the lower number or diastolic blood pressure coincides with the heart filling up again. When treating most people with hypertension, doctors currently aim their treatment at keeping blood pressure below 140/90.

SPRINT researchers enrolled some 9,361 participants, divided into two groups: a more intensive treatment goal of keeping systolic blood pressure below 120 mm Hg applied to one group; the aim for the other was to keep systolic BP at or below 140 mm Hg. To enter the study all participants had to have a systolic BP of at least 130, be over 50, and at high risk of heart attack or stroke.

Among the strengths of the trial is that participants were enrolled before any intervention commenced and the funding for the research was by the US National Institutes of Health, rather than a pharmaceutical company.

The intention was to run the trial for five years. However it was prematurely stopped in September because of the magnitude of the benefits among those whose target systolic BP was 120 mmHg.

Reduced risk

They were shown to have a much reduced chance of heart attack, stroke, heart failure or death from cardiovascular disease. The impact of the research can be gauged by the fact that in the US it is estimated new guidelines to reflect these findings will affect about 7.6 per cent of the population, whose BP target will be lowered and intensified. Guideline groups around the globe, including the European Society for Cardiology, are likely to issue new treatment targets within months. And the increased treatment costs for national health services will also be significant.

Although side effects of more aggressive treatment, such as fainting and kidney malfunction, affected some participants, the investigators were surprised that the number of falls, due to low BP in older patients, did not increase.

However Irish hypertension specialist Annette Neary warned that some people will not feel well if BP is lowered too much. "There should be an individualised approach, especially when there is a fall in blood pressure on standing."