Viagra can reduce the burden placed on the heart by stress in healthy men and women, but taking the drug is not advised for heart patients, according to a new study.
The drug, also called sildenafil citrate, has been taken by tens of millions of men for treatment of erectile dysfunction. More recently, it has been used to treat high blood pressure in the arteries that supply the lungs. It had not been thought to have direct effects on the human heart.
But in a report published online yesterday by the journal Circulation, researchers at the Johns Hopkins School of Medicine show that Viagra blunts the strengthened heartbeat caused by chemically induced stress.
“Sildenafil effectively puts a brake on chemical stimulation of the heart,” said Dr. David Kass, the study’s lead author.
Dr. Kass said the study also shows that Viagra helps control heart function only when the heart is under stress, and has little effect under normal conditions.
Other research done by Dr. Kass and his team, published this year in the journal Nature, had shown that, in mice, sildenafil could reverse the negative effects on heart muscles weakened by heart failure and enlargement, a condition called hypertrophy.
“But we had no firm evidence as to whether this therapy might work in the human heart,” he said. The latest research, however, shows “this drug does, indeed, have an important impact on the heart,” Dr. Kass said.
After initial reports of heart attacks among some men taking Viagra in the first few years after it was approved, medical specialists have become cautious about men using the drug if they’ve had a heart attack or stroke within the past six months, have a chronic heart condition such as unstable angina, or are taking nitrate drugs for their hearts.
Researchers think the same action of the drug that prevents relaxation of blood vessels also affects a molecule that helps control stress reactions to the heart.
Dr. Kass said the research sets the stage for more specific studies of its use to treat heart problems.