What beta blocker (beta-adrenergic blocking agent) is suitable for a patient with a history of Coronary Artery Bypass Grafting (CABG) presenting with penile curvature, likely due to Peyronie's disease?

Beta Blocker Selection for Post-CABG Patients with Penile Curvature

Choose a cardioselective beta blocker (metoprolol, bisoprolol, or atenolol) rather than non-selective agents or carvedilol for this patient, as cardioselective beta blockers are associated with reduced cardiovascular events post-CABG while potentially minimizing the risk of Peyronie's disease progression. 1, 2

Rationale for Beta Blocker Use Post-CABG

Beta blockers are mandatory therapy after CABG surgery and must be continued indefinitely in all patients without contraindications 1. The evidence supporting this is compelling:

• Beta blockers should be prescribed at hospital discharge to all CABG patients, as they reduce mortality during long-term follow-up across all patient subgroups, even those without perioperative ischemia or heart failure 1
• Cardioselective beta blockers specifically reduce major adverse cardiovascular events (MACE) after CABG, with a hazard ratio of 0.93 for MACE and 0.83 for myocardial infarction over median 5.2-year follow-up 2
• This cardiovascular benefit is consistent regardless of presence of previous MI, heart failure, or reduced ejection fraction 2

Beta Blockers and Peyronie's Disease Risk

The relationship between beta blockers and penile curvature requires careful consideration:

• Beta blockade has been associated with onset and progression of Peyronie's disease, though the mechanism remains incompletely understood 3
• Carvedilol (an alpha/beta blocker) has been reported to cause Peyronie's disease in at least one case report, suggesting its vasodilating and anti-inflammatory properties may not fully overcome the vasoconstricting effects of beta blockade 3
• The theoretical mechanism involves vasoconstriction from beta-adrenergic receptor blockade potentially contributing to penile fibrosis 3

Recommended Approach

Select a cardioselective beta blocker (metoprolol succinate, bisoprolol, or atenolol) for the following reasons:

• Cardioselective agents are the most commonly used beta blockers post-CABG, with 92.2% of patients receiving them at baseline in large registry data 2
• They provide proven cardiovascular benefit with consistent MI risk reduction 2
• While no beta blocker is completely free of Peyronie's disease risk, avoiding non-selective agents and carvedilol may be prudent given the case report evidence 3

Managing the Peyronie's Disease

The penile curvature itself requires concurrent evaluation and management:

• Confirm the diagnosis through physical examination with palpation for plaques or induration in the tunica albuginea 1, 4
• Perform intracavernosal injection testing with or without duplex ultrasound to document curvature, plaque characteristics, and erectile function 1
• Assess disease stability: Treatment options differ significantly between active (painful, evolving) and stable disease phases 1

Treatment Options for Stable Peyronie's Disease

If curvature is 30-90 degrees with intact erectile function:

• Intralesional collagenase clostridium histolyticum with modeling is FDA-approved and reduces curvature by mean 17° versus 9.3° with placebo (difference 7.7°) 1
• Penile extender therapy as adjunct shows average length increases of 1 cm and requires 2-8 hours daily use for 3+ months 5
• Combination therapy with PDE5 inhibitors (tadalafil 5mg daily) plus collagenase improves outcomes versus monotherapy 5

Critical Caveat Regarding PDE5 Inhibitors

Phosphodiesterase type 5 inhibitors (sildenafil, tadalafil, vardenafil) must NOT be used concomitantly with nitrate medications due to severe hypotension risk 1. This is particularly relevant post-CABG where nitrates are commonly prescribed:

• Avoid nitroglycerin for ≥24 hours after sildenafil/vardenafil (≥48 hours for tadalafil) 1
• If patient requires chronic nitrate therapy, alternative erectile dysfunction treatments must be considered 1

Monitoring Strategy

• Reassess cardiovascular status to ensure beta blocker therapy remains optimized for cardiac protection 1
• Monitor Peyronie's disease progression with periodic assessment of curvature, pain, and erectile function 1
• Consider switching beta blockers only if clear progression of penile curvature occurs on current therapy, but never discontinue beta blocker therapy entirely given the mortality benefit post-CABG 1, 2

The cardiovascular mortality benefit of beta blockers post-CABG takes absolute priority over theoretical Peyronie's disease risk, but thoughtful agent selection may minimize both concerns 1, 2.