What is the risk of electroconvulsive therapy (ECT) producing arrhythmias?

Risk of Arrhythmias During Electroconvulsive Therapy

Electroconvulsive therapy (ECT) carries a low but significant risk of cardiac arrhythmias, with an estimated incidence of 25.83 per 1,000 patients or 4.66 per 1,000 treatments. 1 These arrhythmias are typically transient and rarely lead to serious adverse outcomes when proper precautions are taken.

Types of Arrhythmias Associated with ECT

• Common arrhythmias:

  • Bigeminy/trigeminy
  • Supraventricular tachycardia
  • Sinus bradycardia (20% with thiopental or thiamylal, 8% with methohexital) 2
  • Premature atrial contractions (43-61% depending on anesthetic agent) 2
  • Premature ventricular contractions (27-44% depending on anesthetic agent) 2

• Severe but rare arrhythmias:

  • Acute heart failure (24 per 1,000 patients) 1
  • Pulseless electrical activity (case reports) 3
  • Cardiac arrest (extremely rare)

Risk Factors for ECT-Induced Arrhythmias

• Patient-related factors:

  • Advanced age 4
  • Pre-existing cardiac disease
  • Electrolyte disturbances
  • Inherited arrhythmic syndromes (e.g., long QT syndrome, Brugada syndrome) 5
  • Concurrent medications that prolong QT interval

• Procedure-related factors:

  • Choice of anesthetic agent (higher risk with thiopental and thiamylal compared to methohexital) 2
  • Lack of anticholinergic premedication
  • Prolonged seizure duration (>180 seconds) 5
  • Titration method for electrical dosing (without anticholinergic protection) 5

Risk Mitigation Strategies

1. Pre-ECT Assessment:

   • Comprehensive cardiac risk assessment before starting ECT 5
   • ECG to assess for pre-existing QT prolongation or conduction disorders
   • Evaluation of electrolytes, especially potassium
   • Review of medications for potential drug interactions

2. Procedural Modifications:

   • Use methohexital as the preferred anesthetic agent to minimize arrhythmia risk 2
   • Premedication with atropine or glycopyrrolate is highly recommended, especially when using the titration method for electrical dosing 5
   • Continuous ECG monitoring during and after the procedure 4
   • Adequate oxygenation throughout the procedure

3. Post-ECT Monitoring:

   • Close observation for 1-2 hours after ECT 5
   • Monitoring for 24-48 hours for potential tardive seizures 5
   • Vigilance for T-wave abnormalities that may simulate myocardial infarction 6

Mortality Risk

The overall mortality risk associated with ECT is very low:

• All-cause mortality: 0.42 deaths per 1,000 patients or 0.06 deaths per 1,000 ECT treatments 1
• Cardiac death accounts for approximately 29% of all ECT-related deaths 1

Special Considerations

• Elderly patients require special attention as they show a significant increase in bigeminy/trigeminy and supraventricular tachycardia after ECT 4
• Pre-existing arrhythmias correlate with post-ECT arrhythmias, suggesting that baseline cardiac status is an important predictor 4
• ECT-induced ECG changes may simulate myocardial infarction (deep T-wave inversions) even in the absence of actual cardiac damage 6

Conclusion

While ECT does increase the risk of cardiac arrhythmias, most are benign and transient. The use of appropriate anesthetic agents (preferably methohexital), anticholinergic premedication, and continuous cardiac monitoring significantly reduces the risk of serious arrhythmic events. The overall mortality risk remains extremely low, making ECT a relatively safe procedure from a cardiac perspective when proper precautions are taken.