The most appropriate next step in management is a cardiac stress test for this patient with erectile dysfunction (ED) and symptoms indicative of cardiovascular disease. First-line therapy for ED includes lifestyle modification (smoking cessation, exercise, and weight loss) and phosphodiesterase type 5 (PDE-5) inhibitor therapy. ED and cardiovascular disease share many risk factors (diabetes mellitus, hyperlipidemia, and hypertension), and ED is itself a cardiac risk factor that independently predicts mortality and confers a risk similar to that of moderate smoking. Therefore, it is important to assess cardiovascular risk and safety for sexual activity before initiating a PDE-5 inhibitor. This can generally be accomplished using guidelines established by the Third Princeton Consensus Conference. This patient has new-onset exertional dyspnea and fatigue that resolve with rest, raising the possibility of ischemic heart disease. Consequently, this patient should undergo cardiac stress testing, especially before considering medical therapy for ED.

Patients with symptoms of ischemic heart disease should undergo exercise stress testing before initiating a PDE-5 inhibitor such as tadalafil. If stress testing demonstrates that the patient can achieve 5 to 6 metabolic equivalents without ischemia, the patient is at low risk for cardiovascular events with PDE-5 inhibitor therapy and sexual activity. Also, this patient is already taking the α-blocker tamsulosin and has a low-normal blood pressure. PDE-5 medications and α-blockers should be combined with caution due to the risk of profound hypotension.

This patient does not require a psychiatric evaluation because he has no obvious symptoms of mood disorder. Features of his sexual history that point against mood disorder are intact interpersonal relationships, strong libido, gradual onset of erectile dysfunction, and loss of nocturnal erections.

Nearly one third of obese men will have improvement in ED symptoms simply by exercising regularly and losing weight. Attempts should therefore be made to lower the BMI below 30. However, weight loss is not the most appropriate next step in management in this mildly overweight patient who may have untreated coronary artery disease.