By: Thomas Pickering, MD, DPhil, FRCP, Director of Integrative and Behavioral Cardiology Program
of the Cardiovascular Institute at Mount Sinai School of Medicine, New York.

Erectile dysfunction (impotence) is very common in men with heart disease and hypertension, and while it is often blamed on the medications, more often than not, it is due to disease of the arteries supplying the penis, which are affected in the same way as arteries elsewhere in the body. Viagra (sildenafil) helps to dilate the arteries in the penis and to promote the flow of blood into it, which is needed to produce an erection. In people without disease of the arteries, Viagra dilates some of the other arteries in the body to a small extent, and hence lowers blood pressure by a few points. It potentiates the effects of nitroglycerine, which also dilates arteries and is used to treat angina. This can result in a much bigger and sudden fall of blood pressure, which could be serious in someone who has heart disease. Viagra should therefore never be used by people who are taking nitroglycerine or related drugs (nitrates) to treat their angina. There have been a few case reports of men having heart attacks after taking Viagra, but these were probably coincidental and not the result of taking the Viagra.

A study was carried out in 14 men who had severe narrowing of at least one coronary artery at the time when they were having angiograms of their hearts, so that it was possible to make measurements of the effects of Viagra on the heart. None of the men were taking nitrates at the time of the testing, although several of them were taking blood pressure lowering drugs, and more than half of them had hypertension. Viagra was given in a dose of 100 milligrams (the usual starting dose is 50), and it lowered the blood pressure from 142/76 to 131/75 mmHg. More importantly, the flow of blood in the coronary arteries was not affected, even in the arteries that had the narrowing. None of the men developed chest pain or other adverse effects. It was concluded that Viagra does not have any bad effects on the heart even when there is disease of the arteries.

Doctor’s comments

This study is reassuring, and suggests that it is safe for men who have disease of the coronary arteries to use Viagra, providing of course that they are not taking nitrates for their angina. Erectile dysfunction is common, in such men, and Viagra often helps to improve the situation.

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