USA Today:

A popular class of blood pressure medicines may double a woman’s risk of dying from heart disease, especially when given in certain combinations, a large study out recently indicates.

The study likely will resurrect a debate over the safety of the drugs called calcium channel blockers, thought to have been resolved two years ago in Allhat, the largest study of high blood pressure drugs. That study found that diuretics, then falling from favour and being replaced by costly new medicines, were still the best treatment for high blood pressure. Calcium channel blockers are a back-up treatment that lowers blood pressure by relaxing blood vessel walls. Among the best known are Cardizem, Norvasc and Procardia. Previous studies, including Allhat, found that the drugs can contribute to heart failure, but they did not increase death rates. The new study indicates calcium channel blockers may indeed double the risk of dying of heart disease, especially when paired with diuretics, which reduce the amount of fluid in the blood. Although the study involved women, the authors believe the findings also apply to men. “This raises serious questions about using calcium channel blockers in patients with uncomplicated high blood pressure,” says lead author Sylvia Wassertheil-Smoller of Albert Einstein College of Medicine, New York. “If I were on that combination, I would want to know, ‘Why this one?’” The new study in recent Journal of the American Medical Association involved almost 20,000 women being treated for high blood pressure in the long-term study of postmenopausal women called the Women’s Health Initiative.

It found that women who took diuretics plus calcium blockers had twice the risk of death as women who took diuretics with beta-blockers, drugs that reduce the heart’s workload. Women took a calcium blocker alone had a 55 per cent higher risk of death than women who took a diuretic alone. The authors cautioned that the study’s design, in which patients are followed for a number of years, doesn’t yield the same “gold-standard” evidence that comes from randomly dividing patients into treatment and control groups.