Nebivolol compared with metoprolol for erectile function in males undergoing coronary artery bypass graft.

To the Editor,

I have read the article entitled “Nebivolol compared with metoprolol for erectile function in males undergoing coronary artery bypass graft” by Aldemir et al. (1) with great interest, which was recently published in Anatolian Journal of Cardiology 2016; 16: 131-6. The investigators reported that nebivolol had a protective effect on the sexual activity of men undergoing coronary artery bypass surgery with cardiopulmonary bypass (1). Brixius et al. (2) have demonstrated beneficial effects of nebivolol on the erectile function in hypertensive men. Another study revealed that serum asymmetrical dimethylarginine, prolactin, testosterone, and hemoglobin levels may affect erectile function in patients with chronic kidney disease (3). Hormonal causes such as hypogonadism, thyroid dysfunction, and hyperprolactinemia may result in ED (4). The prevalence of ED increases with age, ranging from 1% to 10% men aged ≤40 years, 20% to 40% men aged 60–69 years, and 50% to 100% men in their 70s and 80s (5).

I would like to emphasize some important points to clarify the findings of this article. First serum hemoglobin, prolactin, thyroid function tests, and testosterone levels are important factors in erectile function (4). Therefore, authors should mention patients’ hemoglobin, testosterone, thyroid function tests, and prolactin levels along with whether patients with anemia and thyroid dysfunction were excluded. Second, there was no data regarding blood pressure and heart rate after initiating the beta-blocker treatment. The mean ejection fraction of patients in the metoprolol and nebivolol groups was 51.6% and 48.7%, respectively. Considering that the patients had heart failure and were on beta-blocker treatment, did they adjust beta-blocker doses according to blood pressure and heart rate? Third, the prevalance of ED is 50% to 100% men in 70s and 80s (5). They should have reported the number of patients over the age of 70 years because of the high incidence of erectil dysfunction. In addition, the exclusion of patients over the age of 70 years should be considered.

In conclusion, ED is more common in men with cardiovascular disease. Nebivolol seems to have benefical effects on ED. Nebivolol is a reasonable beta-blocker option for men with cardiovascular disease. However, further prospective, randomized, placebo-controlled studies are needed to confirm the benefical effect of nebivolol on ED.