What is the role of epicardial pacing in managing arrhythmias, specifically ectopics (premature ventricular contractions), in patients undergoing Coronary Artery Bypass Grafting (CABG)?

Role of Epicardial Pacing in Managing Ectopics in CABG Patients

Temporary epicardial pacing wires should be placed routinely in all patients undergoing CABG surgery, with specific attention to patients with pre-existing conduction disorders or those experiencing ectopics, as they provide critical management options for post-operative arrhythmias with minimal risk. 1

Indications for Epicardial Pacing in CABG Patients

Primary Indications

• Life-threatening arrhythmias: Epicardial pacing is particularly valuable in patients with ventricular arrhythmias (including ectopics/PVCs) that are ischemic in origin, especially with significant coronary disease 2
• Hemodynamic compromise: Patients experiencing hemodynamic instability due to bradyarrhythmias or ectopic beats affecting cardiac output
• Post-bypass arrhythmias: Patients requiring pacing to separate from cardiopulmonary bypass 3, 4
• Pre-existing conduction disorders: Particularly those with bundle branch blocks or other pre-operative arrhythmias 1, 4

Risk Factors Warranting Epicardial Wire Placement

• Pre-existing arrhythmias (including frequent ectopics)
• Need for pacing during separation from bypass
• Use of antiarrhythmic medications in the operating room
• Advanced age
• Diabetes mellitus (though findings are mixed) 3, 4

Management Protocol for Ectopics in CABG Patients

Immediate Post-Operative Period

1. Continuous ECG monitoring for at least 48 hours in all patients after CABG 2
2. Optimize determinants of coronary perfusion (heart rate, diastolic/mean arterial pressure, ventricular end-diastolic pressure) to reduce myocardial ischemia that can trigger ectopics 2
3. For hemodynamically significant ectopics:
   • Utilize temporary epicardial pacing to override ectopic foci
   • Consider overdrive pacing to suppress ventricular ectopics
   • Adjust pacing rate and mode based on patient response

Specific Pacing Strategies for Ectopics

• Overdrive suppression: Setting pacing rate slightly above the intrinsic rate to suppress ectopic foci
• Rate-responsive pacing: To maintain adequate cardiac output during periods of increased demand
• Dual-chamber pacing: To maintain AV synchrony when needed

Duration of Temporary Epicardial Pacing

• Observe patients for 5-7 days post-CABG to determine if permanent pacing is needed 1
• Most patients requiring pacing will need it within the first 48-72 hours post-operatively
• Remove temporary wires if no longer needed after observation period

Transition to Permanent Pacing

Permanent pacing is only indicated if:

• New postoperative sinoatrial node dysfunction or AV block develops
• Persistent symptoms or hemodynamic instability that doesn't resolve within 5-7 days 1
• Recurrent life-threatening ventricular arrhythmias despite optimal medical therapy 2

Important Considerations and Pitfalls

• Do not use epicardial pacing for ventricular tachycardia with scar and no evidence of ischemia (Class III: HARM recommendation) 2
• Avoid unnecessary permanent pacemaker implantation - studies show only 2.9-8.6% of CABG patients actually require pacing postoperatively 3, 4
• Risk-benefit assessment: While complications from temporary wires are rare (bleeding, tamponade), the benefit of having temporary pacing available when needed outweighs these risks 1
• Monitor for wire-related complications during removal, especially in anticoagulated patients

Practical Implementation

• Place atrial and ventricular epicardial wires during CABG closure
• Test wire function before chest closure
• Document threshold values for capture
• Ensure proper wire fixation to prevent dislodgement
• Have external pacemaker immediately available at bedside

By following these recommendations, clinicians can effectively manage ectopics and other arrhythmias in the post-CABG setting while minimizing complications and optimizing outcomes.