The risk and severity of developing symptomatic palpitations when prescribed mirabegron for overactive bladder

Area of Science:

• Pharmacology
• Cardiology
• Urology

Background:

• Mirabegron, a selective β3-adrenoreceptor agonist, is used for overactive bladder (OAB).
• Clinical trials indicate mirabegron has a favorable side-effect profile.
• Limited data exists on mirabegron's risks in unselected patient populations, particularly concerning cardiovascular events due to β-adrenoreceptor presence in cardiac and vascular tissues.

Purpose of the Study:

• To assess the risk and severity of palpitations in patients with OAB treated with mirabegron.
• To identify potential risk factors for developing palpitations while on mirabegron.
• To evaluate cardiovascular safety in an unselected OAB population using mirabegron.

Main Methods:

• A consecutive cohort study of 279 OAB patients prescribed 50mg daily mirabegron.
• Outcomes assessed at 6 weeks, excluding patients with known cardiac arrhythmias.
• Palpitations, symptoms, medical history, and 12-lead ECGs (heart rate, QT interval) were documented.

Main Results:

• Eight patients (2.9%) reported palpitations.
• Two patients with prior palpitations experienced worsening symptoms.
• Two patients showed QT interval prolongation; three reported chest pain/tightness. Palpitations resolved upon stopping mirabegron without serious adverse events.

Conclusions:

• The incidence of palpitations with mirabegron in an unselected population mirrors previous trial data.
• Palpitations may indicate a potential for worsening cardiovascular dysfunction in some patients.
• Mirabegron appears generally safe, with palpitations being the primary noted adverse event, typically manageable.