What are the recommended medications and interventions for symptomatic bradycardia?

From the Guidelines

For symptomatic bradycardia, the first-line medication is atropine, administered at 0.5 mg IV every 3-5 minutes, up to a maximum total dose of 3 mg, as recommended by the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1. This approach is supported by the most recent and highest quality evidence, which prioritizes the use of atropine as the initial treatment for symptomatic bradycardia. The following are key points to consider:

• Atropine is the first-line medication for symptomatic bradycardia, with a recommended dose of 0.5-1 mg IV, repeated every 3-5 minutes as needed, up to a maximum total dose of 3 mg 1.
• If atropine is ineffective, temporary transcutaneous pacing should be initiated while preparing for transvenous pacing if needed.
• Alternative pharmacologic options include dopamine infusion (5-20 mcg/kg/min), epinephrine infusion (2-10 mcg/min), or isoproterenol (20-60 mcg IV bolus followed by doses of 10-20 mcg, or infusion of 1-20 mcg/min) 1.
• In cases of beta-blocker or calcium channel blocker overdose causing bradycardia, specific antidotes like glucagon (3-10 mg IV) or calcium chloride (1-2 g IV) may be used respectively 1.
• Underlying causes such as electrolyte abnormalities, hypothyroidism, or medication side effects should be addressed simultaneously.
• Treatment should be tailored to the patient's clinical status, with more aggressive measures for hemodynamically unstable patients showing signs of hypotension, altered mental status, chest pain, or heart failure. Some key considerations for the use of atropine include:
• Atropine may paradoxically cause high-degree atrioventricular (AV) block in patients after cardiac transplantation 1.
• Atropine administration should not delay implementation of external pacing for patients with poor perfusion 1.
• Use atropine cautiously in the presence of acute coronary ischemia or MI; increased heart rate may worsen ischemia or increase infarction size 1. Overall, the use of atropine as the first-line medication for symptomatic bradycardia is supported by the most recent and highest quality evidence, and treatment should be tailored to the patient's clinical status.

From the FDA Drug Label

Atropine Sulfate Injection, USP, is indicated for temporary blockade of severe or life threatening muscarinic effects, e.g., as an antisialagogue, an antivagal agent, an antidote for organophosphorus or muscarinic mushroom poisoning, and to treat bradyasystolic cardiac arrest. Atropine is a muscarinic antagonist indicated for temporary blockade of severe or life threatening muscarinic effects. Adult dosage Antisialagogue or for antivagal effects: Initial single dose of 0. 5 to 1 mg. Bradyasystolic cardiac arrest: 1 mg dose, repeated every 3 to 5 minutes if asystole persists.

The recommended medication for symptomatic bradycardia is atropine (IV).

• The initial dose for antisialagogue or antivagal effects is 0.5 to 1 mg.
• For bradyasystolic cardiac arrest, the dose is 1 mg, repeated every 3 to 5 minutes if asystole persists 2, 2. Atropine is used to treat bradyasystolic cardiac arrest and can be used for symptomatic bradycardia due to its antivagal effects 2.

From the Research

Recommended Medications for Symptomatic Bradycardia

• Atropine is recommended as a first-line therapy for unstable bradycardic patients 3
• However, paramedics should be prepared to manage unexpected adverse events secondary to atropine administration in patients with heart block 3
• IV adrenaline or isoprenaline may be used if atropine is unsuccessful 3
• Glucagon may have a role in the treatment of symptomatic bradycardia, particularly in the presence of beta-adrenergic blockade and perhaps calcium channel blockade 4
• Aminophylline and theophylline may be used for the treatment of atropine-resistant bradycardia 5

Interventions for Symptomatic Bradycardia

• Transcutaneous cardiac pacing (TCP) is a rapid, time-saving, and noninvasive ventricular stimulation that is tolerated by conscious patients despite the painful intervention for treatment of symptomatic bradycardias 6
• TCP is a clinically effective treatment modality in patients with atropine-resistant unstable bradycardia 6
• Dopamine may be used as an alternative to TCP for unstable bradycardia 7
• Transcutaneous pacing may be used with crossover to dopamine if TCP fails 7

Special Considerations

• Patients with atrioventricular blocks at the level of the His-Purkinje fibres (infranodal) are at an increased risk of adverse events following atropine administration 3
• Patients with spinal cord injury-induced bradycardia may be treated with xanthine derivatives such as aminophylline and theophylline 5