Erectile dysfunction often referred to as impotence, is a common disorder that frequently coexists with cardiovascular disease. It is defined as the inability to get or keep an erection firm enough to have sexual intercourse. It is estimated that erectile dysfunction affects >30% of men between 40 and 70 years of age (1).
Cardiovascular disease is a term that describes diseases of the heart and the body’s vascular system, particularly the arteries. Heart attack, coronary artery disease, and stroke are all examples of cardiovascular disease.
The majority of cardiovascular disease is caused by risk factors that can be controlled, treated or modified, such as high blood pressure, disorders of blood lipids, overweight/obesity, tobacco use, lack of physical activity, and diabetes.
In a U.S study, the overall prevalence of erectile dysfunction in men above age 20 was 18.4%. The prevalence correlated strongly with age but was particularly high among men with cardiovascular risk factors. Thus, erectile dysfunction was significantly more common among men who smoked, those who were obese, those who lacked regular physical exercise, had hypertension or diabetes. More than half of men with diabetes have impotence (2).
Several arguments support a relationship between erectile dysfunction and cardiovascular disease (3). Firstly, these disorders share the same risk factors. Secondly, erectile dysfunction is commonly present among men with coronary artery disease, hypertension, vascular disease of the brain (cerebrovascular disease), peripheral arterial disease, and diabetes. Thirdly, several studies suggest that endothelial dysfunction is shared by erectile dysfunction and coronary artery disease.
The endothelium is the innermost layer of the arteries and plays a significant role in regulating blood flow. Abnormal endothelial function usually termed endothelial dysfunction is present in most cardiovascular disorders.
When endothelial dysfunction is present, the arteries will not able to dilate when appropriate. When the blood vessels that supply the penis are not able to dilate during sexual stimulation because of endothelial dysfunction, the penis cannot fill with blood, and erectile dysfunction develops.
Although erectile dysfunction may have many causes, it is now recognized to be of cardiovascular etiology in the majority of cases.
The Modifiable Risk Factors
Smoking, diabetes, lipid disorders, obesity, hypertension, lack of physical exercise, poor diet, excess alcohol consumption psychological stress and depression are examples of modifiable risk factors shared by erectile dysfunction and cardiovascular disease. Modifying these risk factors may reduce the risk of cardiovascular disease and erectile dysfunction.
Diabetes mellitus is associated with both erectile dysfunction and increased cardiovascular risk. The Massachusetts Male Aging Study (MMAS) showed that the prevalence of erectile dysfunction was higher in men with diabetes compared with non-diabetics (4). In another study of 365 diabetic patients, 75% had erectile dysfunction by age 65 years (5).
Studies have suggested a relationship between obesity and erectile dysfunction (6). However, this relationship may be difficult to comprehend because of the close association between obesity and diabetes. Central obesity is inversely related to levels of circulating testosterone, which may contribute independently to the development of erectile dysfunction. Physical inactivity also correlates with erectile dysfunction, obesity, and overall cardiovascular health.
Erectile dysfunction is associated with insulin resistance and the metabolic syndrome (7). The metabolic syndrome is characterized by central obesity, high blood levels triglycerides, low levels of HDL-cholesterol, high blood glucose and hypertension.
Lipid disorders have been implicated in the development of erectile dysfunction. In a prospective review of 3.250 men aged 26 to 83 years without erectile dysfunction at their first examination, high total cholesterol, and low HDL cholesterol levels were found to be strongly predictive of the onset of erectile dysfunction after controlling for other risk factors (8). The authors concluded that a high level of total cholesterol and a low level of HDL cholesterol were important risk factors for erectile dysfunction.
In the MMAS, low HDL cholesterol levels were associated with the presence of erectile dysfunction (4).
Erectile dysfunction is more prevalent among smokers than nonsmokers. The MMAS 9-year follow-up study found that the risk of developing moderate or complete erectile dysfunction in smokers was nearly doubled compared with that in matched nonsmokers (9).
The MMAS 9-year follow-up study found that hypertension was an independent, although modest, predictor of erectile dysfunction (9). However, the relationship between hypertension and erectile dysfunction has not been assessed definitively and is often complicated by the effects of medications used to treat hypertension.
Can Lifestyle Changes Improve Erectile Dysfunction?
A systematic review and meta-analysis published 2011 addressed the question how lifestyle interventions and pharmacotherapy for cardiovascular risk factors affect the severity of erectile dysfunction (10).
The study found that lifestyle modifications and drug therapy aimed at modifying risk factors were associated with significant improvement in sexual function. The results confirm that healthy dietary habits and increased physical activity improve quality of life in men by improving sexual health.
Physical activity was significantly inversely associated with erectile dysfunction. Men who ran for nearly 90 minutes per week or did rigorous outdoor activity for 180 minutes per week had a 30% reduced risk of developing erectile dysfunction.
Another study demonstrated that lifestyle changes, including a reduced calorie diet and increased exercise, improve erectile function in obese men and resulted in about one-third of men with erectile dysfunction regaining sexual function after treatment. This improvement was associated with amelioration of both endothelial function and markers of systemic vascular inflammation (11).
Lifestyle measures targeted at modifying risk factors may not only improve erectile dysfunction but also reduce the risk of future cardiovascular events.
Erectile Dysfunction May Predict Coronary Artery Disease
Erectile dysfunction has long been ascribed to a normal aging process. Therefore, patients presenting with erectile dysfunction often had their symptoms ignored. Searching for an underlying cause was believed to be of limited clinical value, also, partly because treatment options were limited.
As erectile dysfunction often precedes other symptoms of cardiovascular disease, a man with erectile dysfunction and no other symptoms of cardiovascular disease should be considered a vascular patient until proved otherwise (12).
In 2001, two reports suggested that erectile dysfunction might indeed be a marker for silent coronary artery disease (13,14). It was found that the onset erectile dysfunction may pre-date the symptoms of coronary artery disease. Hence, the presence of coronary artery disease should be considered in men who present with erectile dysfunction.
A meta-analysis of 12 prospective cohort studies published 2011 suggested that erectile dysfunction significantly increases the risk of cardiovascular disease, coronary heart disease, stroke, and all-cause mortality, and the increase is probably independent of conventional cardiovascular risk factors (15).
Another systematic review and meta-analysis showed that erectile dysfunction was associated with increased risk of cardiovascular events and all-cause mortality. The relative risk associated with erectile dysfunction was higher at younger ages (16).
It has been suggested that artery size may explain why erectile dysfunction may precede the onset of coronary artery disease. Penile arteries are 1-2 mm in diameter whereas coronary arteries are 3-4 mm in diameter. In theory, plaques in smaller arteries may affect blood flow sooner than plaques in larger arteries.
Assessment and Treatment of Erectile Dysfunction
The link between erectile dysfunction and cardiovascular disease strongly suggests that men who complain of erectile dysfunction should undergo cardiovascular risk assessment (17). Obviously, other causes of erectile dysfunction such as hormonal derangements or neural damage, have to be excluded.
Medical assessment should include clinical examination, measurements of blood pressure, fasting glucose, glycated hemoglobin, lipid panel, waist circumference, thyroid function and measurement of testosterone. Further workup will depend on the clinical situation.
Treatment of erectile dysfunction should primarily aim at modifying cardiovascular risk through lifestyle intervention. Smoking cessation, regular physical exercise, and healthy dietary choices are of crucial importance.
Treatment with so-called phosphodiesterase-5 inhibitors (PDE5-I) often improves erectile function. The most commonly used drugs are Viagra (sildenafil), Cialis (tadalafil), or Levitra (vardenafil). Each of these drugs improves erections when taken before sexual activity.
The PDE5-Is work by dilating the blood vessels that supply blood to the penis, thus improving blood flow. The drugs decrease blood pressure slightly, but they can be used safely with most other drugs apart from nitrate medications like nitroglycerin, Nitrostat, Nitro Paste, Imdur, isosorbide mononitrate, and Isordil. Mixing a PDE5-Is with a nitrate medication can cause harm through severe lowering of blood pressure.
There is some evidence that herbal supplements containing extracts from Tribulus Terrestris may improve impotence.
The Take Home Message
Erectile dysfunction (impotence) is a common disorder among adult men.
Erectile dysfunction and cardiovascular disease share the same risk factors.
Erectile dysfunction often precedes other clinical symptoms of cardiovascular disease. Hence, it has been proposed that erectile dysfunction may predict future cardiovascular events.
Treatment of erectile dysfunction should aim at modifying cardiovascular risk factors. A healthy diet, regular physical exercise and abstaining from smoking are all important.
Lifestyle measures aimed at modifying risk factors may not only improve erectile dysfunction but also reduce the risk of future cardiovascular events.
Treatment with phosphodiesterase-5 inhibitors (PDE5-I) often improves erectile function, sexual performance and quality of life.