Management of Bradycardia

Introduction to Bradycardia Management

Bradycardia in patients with recent myocardial infarction requires careful management to avoid worsening ischemia and increasing mortality, as recommended by the American College of Cardiology 1

Isoprenaline is contraindicated in patients with recent myocardial infarction due to its potential to increase myocardial oxygen demand, worsen ischemia, and increase mortality 1
Atropine should be used with caution in patients with acute coronary ischemia, as increased heart rate may worsen ischemia, and in patients with heart transplantation, as it may cause paradoxical high-degree AV block 2, 1
Atropine may be ineffective or harmful in patients with AV block at the infranodal level (type II second-degree or third-degree AV block with wide QRS complexes) 2

The American College of Cardiology recommends atropine (0.5-1.0 mg IV) as the first-line agent for symptomatic bradycardia, with doses given in increments of 0.5 mg every 3-5 minutes and a maximum total dose of 3 mg 1, 2
Low doses of atropine (less than 0.5 mg) can paradoxically cause bradycardia rather than the expected tachycardia, and the sinoatrial node response to atropine is bimodal, with low doses associated with paradoxical slowing of heart rate, and higher doses producing the expected acceleration of heart rate 3, 2
If bradycardia persists despite atropine, transcutaneous pacing should be considered, and epinephrine (2-10 μg/min) or dopamine (5-20 μg/kg/min) may be used in emergency situations with caution, as they can increase myocardial oxygen demand 1

The American College of Cardiology/American Heart Association guidelines recommend aspirin (160-325 mg daily), beta-blockers, ACE inhibitors for patients with LV dysfunction, and nitroglycerin for ongoing ischemia, with careful hemodynamic monitoring for patients with recent MI 1
When treating bradycardia, atropine should be given in increments of 0.5 mg, titrated to achieve minimally effective heart rate (approximately 60 bpm), with close monitoring for response 2, 1
If bradycardia worsens or there is no response to atropine, consideration should be given to transcutaneous pacing or second-line pharmacologic therapy, such as dopamine, epinephrine, or isoproterenol 1