Safety of Mirabegron in Atrial Fibrillation with Controlled Blood Pressure and Heart Rate
Mirabegron can be prescribed cautiously in patients with atrial fibrillation who have controlled blood pressure and heart rate, but requires close monitoring given the documented association between mirabegron and atrial fibrillation as an adverse event.
Evidence for Cardiovascular Safety
Large pooled clinical trial data from 13,396 patients showed that mirabegron had comparable cardiovascular adverse event rates (0.4%-1.5%) to placebo (0.9%), with no evidence of increased cardiovascular risk when baseline risk factors were controlled 1
Blood pressure changes from baseline were similar between mirabegron and placebo, and did not confer increased risk of cardiovascular adverse events 1
Ambulatory blood pressure monitoring in 715 patients demonstrated no consistent increases in mean 24-hour systolic or diastolic blood pressure with mirabegron therapy over 12 weeks, and no meaningful changes in heart rate 2
Documented Atrial Fibrillation Risk
Real-world pharmacovigilance data from the FDA Adverse Event Reporting System (FAERS) database identified atrial fibrillation as one of the most common adverse events associated with mirabegron, along with blood pressure increases, urinary retention, dry mouth, and tachycardia 3
Additional cardiac adverse events identified in post-marketing surveillance include arrhythmia, palpitations, and tachycardia 3
In an unselected population, 2.9% of patients developed palpitations while taking mirabegron, with some experiencing chest pain or tightness, though these resolved after discontinuation 4
Clinical Decision Algorithm
For patients with pre-existing atrial fibrillation:
Ensure rate control is optimized with first-line agents (beta-blockers or nondihydropyridine calcium channel blockers) before considering mirabegron 5, 6
Verify that resting heart rate is controlled (mean ~80 bpm) and exercise heart rate remains between 90-115 bpm on moderate exertion 7
Confirm blood pressure is stable and within target range 1
Monitoring requirements if prescribing mirabegron:
Obtain baseline ECG to document heart rate and rhythm 4
Monitor blood pressure and heart rate at 2-4 weeks after initiation, as most adverse events occur within 30 days 3
Reassess symptoms of palpitations, chest discomfort, or worsening atrial fibrillation symptoms 4
Consider 24-hour Holter monitoring if symptoms develop to assess for worsening rate control 7
Critical Caveats
Patients with a history of palpitations may experience worsening symptoms on mirabegron, even without documented arrhythmia on baseline ECG 4
The β3-adrenergic agonist mechanism of mirabegron theoretically poses risk in patients with underlying cardiac conditions, despite the selectivity for β3-receptors 4
Adverse events can still occur after 1 year of treatment, necessitating ongoing vigilance 3
If palpitations, chest pain, or worsening atrial fibrillation symptoms develop, discontinue mirabegron immediately 4