Use of Sildenafil (Viagra) in Patients with Cardiovascular Disease
Expert Consensus Document from the American College of Cardiology and the American Heart Association on Use of Sildenafil (Viagra) in Patients with Cardiovascular Disease
The pharmaceutical preparation sildenafil citrate (Viagra) is being widely prescribed as a treatment for male erectile dysfunction, a common problem that in the United States affects between 10 million and 30 million men. The introduction of sildenafil has been a valuable contribution to the treatment of erectile dysfunction, which is a relatively common occurrence in patients with cardiovascular disease. This article is written to appropriately caution and not to unduly alarm physicians in their use of sildenafil in patients with heart disease.
Reported cardiovascular side effects in the normal healthy population are typically minor and associated with vasodilatation (i.e., headache, flushing, and small decreases in systolic and diastolic blood pressures). However, although their incidence is small, serious cardiovascular events, including significant hypotension, can occur in certain populations at risk. Most at risk are individuals who are concurrently taking organic nitrates. Organic nitrate preparations are commonly prescribed to manage the symptoms of angina pectoris. The co-administration of nitrates and Viagra significantly increases the risk of potentially life-threatening hypotension. Therefore, Viagra should not be prescribed to patients receiving any form of nitrate therapy.
Although definitive evidence is currently lacking, it is possible that a precipitous reduction in blood pressure with nitrate use may occur over the initial 24 hours after a dose of Viagra. Thus, for patients who experience an acute cardiac ischemic event and who have taken Viagra within the past 24 hours, administration of nitrates should be avoided. In the event that nitrates are given, especially within this critical time interval, it is essential to have the capability to support the patient with fluid resuscitation and adrenergic agonists if needed. In patients with recurring angina after Viagra use, other non-nitrate anti-anginal agents, such as beta-blockers, should be considered.
Other patients in whom the use of Viagra is potentially hazardous include those with active coronary ischemia; those with congestive heart failure and borderline low blood volume and low blood pressure status; those with complicated, multidrug, antihypertensive therapy regimens; and those taking medications that may affect the metabolic clearance of Viagra. With respect to patients following complicated multidrug, antihypertensive programs, the randomized studies included a large number of hypertensive patients. However, most patients were controlled with one antihypertensive agent, and only a small number were controlled with three antihypertensive agents. Until adequate studies are done in these subgroups of patients, sildenafil should be prescribed with caution.
Viagra acts as a selective inhibitor of cyclic GUANYLIC ACID, resulting in smooth muscle relaxation, vasodilatation, and enhanced penile erection. Although the cardiovascular effects of sildenafil reported in available randomized, controlled clinical trials were relatively minor, heart disease patients represented only a small fraction of studied patients and patients with heart failure, patients with myocardial infarction or stroke within six months, or patients with uncontrolled hypertension were not included in these studies. Thus, there are possible problems in the use of Viagra in these patients that have not been adequately studied.
Given the increasing reports of deaths in which the use of Viagra may be implicated, clinicians need to exercise caution when advising their patients with heart disease about taking this medication. Specific recommendations regarding sildenafil and the cardiac patient are summarized in the following table:
Summary Table of Clinical Recommendations
A. Use of Viagra clearly contraindicated
1. Concurrent use of nitrates
B. Cardiovascular effects of Viagra may be potentially hazardous (use dependent on individual clinical assessment)
1. Patients with active coronary ischemia who are not taking nitrates (e.g., positive exercise test for ischemia)
2. Patients with congestive heart failure and borderline low blood pressure and borderline low-volume status
3. Patients on a complicated, multidrug, anti-hypertensive program
4. Patients taking drugs that can prolong the half-life of Viagra
Recommendations for Sildenafil and the cardiac patient
A. Prescribing Sildnafil to patients at clinical risk
1. Sildnafil is absolutely contraindicated in patients undergoing any long-acting nitrate drug therapy or using short-acting nitrates because of the risk of developing potentially life-threatening hypotension.
2. If a patient has stable coronary disease, is not taking a long-acting nitrate, has short-acting nitrate use as the only contraindication to sildenafil, and does not appear to need the nitrate on a consistent basis, the physician and the patient should carefully weigh the risks and benefits of sildenafil treatment. If the patient requires nitrates for mild or moderate exercise limitation, sildenafil should probably not be used.
3. All patients taking organic nitrates, even if they have not asked for Viagra, should be informed about the nitrate-sildnafil hypotensive interaction. There is a substantial potential for patients to obtain Viagra from another physician, a friend, or through the "black market," circumventing health care providers who could offer appropriate caution.
Because sildenafil also potentiates the hypotensive effect of an inhaled form of nitrate such as amyl nitrate or poppers, the concurrent recreational use of poppers and sildenafil could result in sudden and marked hypotensive response that could be serious or fatal. This interaction may be more pronounced in patients taking protease inhibitors concurrently (e.g., indinavir, ritonavir, nelfinavier, and saquinavir).
4. Similarly, patients must be warned of the contraindication of taking sildenafil in the 24-hour time interval after taking a nitrate preparation, including sublingual nitroglycerin. The administration of sildenafil to a patient who has taken a nitrate in any form in the preceding 24 hours is contraindicated.
5. Although firm data are lacking, pre-Viagra treadmill tests to assess for the presence of stress-induced ischemia in patients with overt and covert coronary artery disease can guide the patient and physician relative to the risk of cardiac ischemia during sexual intercourse. We wish to stress that the physical and emotional stresses of sexual intercourse can be excessive in some people, particularly those who have not performed this activity in some time and who are not in good physical condition. These stresses themselves may produce acute ischemia or precipitate myocardial infarction. Such patients should be advised to use common sense and to moderate their physical exertion and their emotional expectations before they begin their experience with taking Viagra.
6. If patients are taking a combination of antihypertensive medications, they should be cautioned about the possibility of sildenafil-induced hypotension. Because both venous and arterial vasodilation occur with sildenafil, initial monitoring of the blood pressure with the institution of Viagra use would identify patients with an undesired hypotensive blood pressure response. This is an area of particular concern for the patient with congestive heart failure who has a borderline low blood volume and a low blood pressure status as well as for the patient who is following a complicated, multidrug, antihypertensive therapy regimen.
Source: American College of Cardiology, Bethesda, MD, and American Heart Association, Dallas.
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