(Philadelphia, PA) -- Erectile dysfunction, which affects up to 30 million men in the United States, may be particularly common in patients with heart disease because of the presence of overlapping risk factors -- including age, diabetes, hypertension, hypercholesterolemia, and smoking. Following the approval by the Food and Drug Administration of oral sildenafil (Viagra) for the treatment of erectile dysfunction, a number of serious cardiovascular events -- including heart attack and sudden cardiac death -- were noted associated with the use of the drug. Consequently, physicians and patients have remained uncertain about whether these reported events were related directly (and solely) to the use of Viagra or to the patient's underlying cardiovascular disease ... or, perhaps, some combination of these and other factors, including the physical exertion of sexual activity.
To determine what adverse cardiovascular effects, if any, Viagra might produce in men with heart disease, Penn researchers identified and measured a number of systemic, pulmonary and coronary function variables -- including heart rate, blood pressure and coronary blood flow -- both before and after the oral administration of the drug in 14 male patients. "We found that Viagra had no direct adverse cardiovascular effects in men with severe cornary artery disease," said Howard C. Herrmann, MD, Professor of Medicine at the University of Pennsylvania Medical Center and lead author of the study, which appears in the June 1 issue of the New England Journal of Medicine. "In addition, we noted a small beneficial effect on coronary blood flow reserve.
"Our data support the consensus position of the American College of Cardiology and the American Heart Association that sildenafil is safe for patients with stable coronary artery disease who are not taking medications containing nitrates, " adds Dr. Herrmann.
All study participants had severe stenosis (or narrowing) of at least one coronary artery and had been referred to the Hospital of the University of Pennsylvania (in Philadelphia) for angioplasty. Among these men -- whose mean age was 61 years -- there were high rates of hypertension (57%), diabetes (43%), and smoking (57%). All patients had stable symptoms that permitted the discontinuation of nitrates at least 24 hours prior to the ingestion of Viagra. Other prescribed medications -- including beta-blockers, aspirin, heparin, and vessel-dilating drugs -- were continued.
To obtain base-line data, researchers measured systemic, pulmonary and coronary blood pressures and flows in patients prior to the ingestion of Viagra while they were undergoing cardiac catheterization. Then, one hour after drug intake, the same measurements were repeated. The research team found small, but significant, decreases in arterial blood pressure and pulmonary pressure; and noted no significant changes in coronary artery diameter and blood flow, or coronary vascular resistance. Overall, they found no adverse effects attributable to Viagra; and no patient had angina or any other side effect that could be attributed to sildenafil.
Dr. Herrmann cautions that, while his study shows that Viagra has no measurable negative effect on the circulation of blood in men with severe coronary disease, it does not address the possibility that severe cardiac events may be caused in some patients by an interaction with other drugs (particularly nitrates) or by the combination of Viagra use with sexual activity -- which increases heart oxygen demand.
The study also does not address the risks of either Viagra or sexual activity in patients with unstable angina, recent heart attack, or congestive heart failure. "This study does, however, show that Viagra itself if a safe drug that could benefit many patients who have both erectile dysfunction and coronary artery disease," adds Dr. Herrmann.
The study was supported by a grant from Pfizer, Inc., which manufactures Viagra.
Editor's Note: Dr. Herrmann has no financial interest in Pfizer, Inc..
Journal
New England Journal of Medicine