A new medication to curb high blood pressure is as effective at preventing heart attacks as current treatments but has fewer side effects, a Canadian-led study has found.

Telmisartan rivals the commonly used ramipril in keeping heart attacks at bay, but without the swelling or coughing that usually affects 20 per cent of ramipril users, researchers say.

The study was conducted by scientists at the Population Health Research Institute at McMaster University and Hamilton Health Sciences. The findings are published in the April 10 issue of the New England Journal of Medicine.

Telmisartan, an angiotensin II receptor, is better tolerated by patients, the study found.

"This study is of clinical importance, because it demonstrates that telmisartan is an effective and safe alternative to ramipril," said Dr. Salim Yusuf, director of the Population Health Research Institute at McMaster.

"This means both patients and physicians have choices and can use telmisartan where appropriate with a high degree of confidence."

The study was a collaborative effort by researchers from 733 medical centres in 40 countries and 25,620 patients with coronary heart disease or high-risk diabetes. Patients enrolled were over 55.

They received either 10 mg a day of ramipril, 18 mg a day of telmisartan or a combination of the two medications. The average follow-up period was 55 months.

Compared to 4.4 per cent of ramipril patients who reported coughing as side effect, only 1.1 per cent of the telmisartan patients experienced coughing. As well, 0.1 per cent of the telmisartan group experienced angioedema — a swelling of the throat and airways that can be life-threatening — versus ramipril users (0.3 per cent).

The group of patients taking both drugs was more likely to have low blood pressure leading to dizziness, with 4.8 per cent of those taking the drug reporting the symptom compared to the ramipril group (1.7 per cent).

It also had a greater incidence of renal dysfunction (13.5 per cent) versus 10.2 per cent in the ramipril only group.

"The combination of the two drugs was associated with more adverse events without an increase in benefit," reads the study.

"Our data show that in patients who have vascular disease or high-risk diabetes but do not have heart failure, telmisartan is an equally effective alternative to ramipril and less likely to cause angioedema," the authors write.