What is the next appropriate step for a patient with severe bradycardia (heart rate as low as 20 beats per minute) after receiving sotalol (beta blocker) at 5am, 3 hours prior to the scheduled time, who is scheduled for a procedure the next day?

Immediate Management of Severe Sotalol-Induced Bradycardia

Stop sotalol immediately and administer atropine 0.5-1 mg IV as first-line therapy, with preparation for temporary transcutaneous or transvenous pacing if atropine fails to improve heart rate and hemodynamic status. 1

Initial Stabilization

Discontinue sotalol permanently - this represents drug-induced bradycardia from a reversible cause that must be eliminated before any other intervention. 1 The early administration at 5am (3 hours before the usual 8am dose) created an unintended overlap that precipitated severe bradycardia.

Assess hemodynamic stability immediately:

• Check blood pressure, mental status, presence of chest pain, and signs of heart failure 1
• Heart rate of 20 bpm with hemodynamic compromise constitutes a medical emergency requiring immediate intervention 1
• Obtain 12-lead ECG to assess QT interval and rhythm 2

Pharmacologic Management

Atropine 0.5-1 mg IV bolus should be administered immediately for symptomatic bradycardia. 1, 3 This can be repeated every 3-5 minutes up to a total dose of 3 mg. 1 Atropine enhances automaticity in sinus bradycardia, though the response may be blunted in severe beta-blocker toxicity. 1

If atropine fails or provides inadequate response:

• Glucagon 3-5 mg IV bolus followed by infusion at 3-5 mg/hour is reasonable for beta-blocker-mediated bradycardia 1
• Isoproterenol 2-10 mcg/min IV can be used as second-line therapy, though it increases myocardial oxygen demand and should be avoided if coronary ischemia is suspected 1
• Dopamine 5-20 mcg/kg/min may be considered for refractory hypotension 1

Critical caveat: High-dose insulin therapy, while standard for beta-blocker poisoning, should be avoided or used with extreme caution in sotalol toxicity because iatrogenic hypokalemia can worsen QT prolongation and precipitate torsades de pointes. 4

Temporary Pacing

Transcutaneous pacing should be initiated immediately if pharmacologic therapy fails to improve heart rate above 40 bpm or if hemodynamic instability persists. 1 This can be performed in awake or anesthetized patients and serves as a bridge to more definitive therapy. 1

Transvenous pacing may be required if transcutaneous pacing is ineffective or poorly tolerated. 1, 5 In one case series, approximately 20% of patients with compromising bradycardia required temporary emergency pacing for stabilization. 5 Overdrive pacing is particularly important in sotalol toxicity to prevent pause-dependent torsades de pointes. 4, 6

Monitoring and Electrolyte Management

Continuous cardiac monitoring is mandatory given sotalol's class III antiarrhythmic properties that prolong QT interval and risk torsades de pointes. 2, 7

Check and correct electrolytes immediately:

• Potassium should be maintained >4.0 mEq/L 2
• Magnesium should be repleted to high-normal levels 1
• Hypokalemia dramatically increases the risk of torsades de pointes with sotalol 7, 6

Monitor QT interval closely - if QT exceeds 500 msec, risk of torsades de pointes increases substantially. 2 Magnesium sulfate should be readily available for treatment of torsades if it occurs. 1

Special Consideration: Hemodialysis

If renal dysfunction is present or bradycardia is refractory to standard therapy, consider hemodialysis. 4 Unlike most beta-blockers, sotalol is hydrophilic, renally cleared, and amenable to extracorporeal removal. 4 In one case report, hemodialysis successfully treated refractory hypotension from sotalol toxicity in a patient with acute kidney injury. 4

Disposition

Admit to intensive care or cardiac care unit for continuous telemetry monitoring. 5 The patient should remain hospitalized until:

• Heart rate stabilizes above 50 bpm without pacing 1
• QT interval normalizes to <500 msec 2
• At least 3-5 half-lives of sotalol have elapsed (approximately 36-60 hours with normal renal function) 2

Do not proceed with the scheduled procedure until bradycardia resolves and hemodynamic stability is confirmed for at least 24-48 hours. 1

Key Pitfall to Avoid

Never restart sotalol after this event - the patient has demonstrated severe intolerance to the medication. 1 Alternative antiarrhythmic strategies should be considered after recovery, with careful attention to avoiding other QT-prolonging agents. 1