Reducing blood pressure in elderly patients with hypertension can significantly cut both rate of cardiovascular events and total mortality, according to a late-breaking clinical trial presented at the meeting of the American College of Cardiology.

The 3,845-patient Hypertension in the Very Elderly Trial (HYVET), which was coordinated by scientists from Imperial College London, is the largest ever clinical trial to look at the effects of lowering blood pressure solely in patients age 80 years and over. Patients were given either a placebo or the diuretic indapamide slow release 1.5 mg, with the addition of the angiotensin-converting enzyme inhibitor perindopril in tablet form once a day.

Benefits of treatment included a 21 percent reduction in total mortality rate, a 39 percent reduction in stroke mortality rate, a 64 percent reduction in fatal and non-fatal heart failure, and a 34 percent reduction in cardiovascular events, with benefits apparent within the first year of follow-up.

The reduction in overall mortality was a novel and unexpected result. Earlier trials had demonstrated that reducing blood pressure in the under-80 population reduces incidence of stroke and cardiovascular events. However, previous smaller and inconclusive studies also suggested that lowering blood pressure in those aged 80 or over reduced the number of strokes, but did not reduce, and even possibly increased, total mortality.

In July 2007 the trial was stopped early on the recommendation of an independent data monitoring committee after they observed significant reductions in overall mortality and stroke in those receiving treatment. The final results of the trial showed a significant reduction in stroke mortality rate, but the reduction in all strokes of 30 percent did not quite reach statistical significance (p=0.06).

Emeritus Professor Christopher Bulpitt, the lead investigator on the study from the Care of the Elderly Group at Imperial College London, said: "Before our study, doctors were unsure about whether very elderly people with high blood pressure could see the same benefits from treatment to lower their blood pressure as those we see in younger people. Our results clearly show that many patients aged 80 and over could benefit greatly from treatment. Populations are living longer and we have growing numbers of people living well into their 80s and beyond, so this is good news. We are very pleased that cardiovascular events were reduced safely with a reduction in total mortality."

The researchers hope that their findings will clear up uncertainty among clinicians about the benefits of treating patients aged 80 and over for high blood pressure.

Dr Nigel Beckett, the trial coordinator from the Care of the Elderly Group at Imperial College London, added "Many very elderly people with high blood pressure are not being treated for it at the moment, because doctors are unsure about whether or not treatment will help them. We hope that following our study, doctors will be encouraged to treat such patients in accordance with our protocol."

As the trial was stopped early, an extension involving patients receiving active treatment is now underway to assess the longer-term benefits of treatment.

Patients with high blood pressure (defined as a systolic blood pressure between 160-199 mmHg), from thirteen countries across the world, were randomized for the double-blind, placebo-controlled trial, which began in 2001. The mean age of participants was 83 years and 7 months.

Patients were given either placebo or indapamide slow release (SR) with the addition of perindopril, in tablet form once a day as required, to achieve a target blood pressure of 150/80 mmHg. The average follow-up of patients was just over 2 years, by which time 20 percent of placebo subjects and 48 percent of those taking medication had achieved the target blood pressure of 150/80 mmHg. In those patients who were followed up for longer, a larger number of patients receiving active treatment achieved target blood pressure.