The study shows a strong link between renin and the heart's health, researchers said. At a minimum, it also suggests that people with mild to moderate hypertension should have their renin levels tested, though researchers said they were still studying the test's effectiveness for those with normal blood pressure. Renin tests of blood and urine usually cost $50 to $100.

"This is a very inefficient way to prevent heart attacks," [Michael H. Alderman] said. "A renin test would be a much better predictor, and it could be used to determine who should receive treatment to prevent a heart attack." He added that certain anti-hypertensive medications lower blood pressure but also raise the body's renin levels, which increase a person's risk for heart attack. Experiments are under way to see whether drugs that lower renin levels would also protect against heart attacks, and possibly strokes, he said.