What are the considerations for cardioversion in a patient with a Watchman (left atrial appendage closure device) implant and atrial fibrillation?

Cardioversion in Patients with Watchman Devices

Electrical cardioversion is safe and feasible in patients with Watchman left atrial appendage closure devices, using standard cardioversion protocols with anterior-posterior paddle positioning and appropriate pre-procedural anticoagulation assessment. 1, 2

Key Safety Principles

The Watchman device does not contain electronic circuitry that can be damaged by electrical discharge, unlike pacemakers or ICDs, making cardioversion fundamentally safe from a device integrity standpoint. 1 This is a critical distinction—the device is a passive structural implant without vulnerable electronic components. 1

Paddle Positioning

• Position cardioversion paddles in the anterior-posterior configuration, keeping them as far as possible from the device location in the left atrium. 1, 3 This minimizes any theoretical risk of current traveling through the device area. 1
• Anterior-posterior placement is superior to anterolateral positioning for all implanted cardiac devices. 1, 3

Energy Protocol

• Use standard cardioversion energy protocols: start with 200 J for biphasic waveforms or 200-360 J for monophasic waveforms. 1, 3
• Biphasic waveforms are preferred as they require less energy (median 100 J vs 200 J for monophasic) and achieve higher success rates (99.1% vs 92.4%). 3
• The presence of a Watchman device does not require energy modification. 1, 2

Pre-Cardioversion Requirements

Anticoagulation Assessment

All patients must undergo transesophageal echocardiography (TEE) before cardioversion to exclude device-related thrombus and assess peridevice leak. 2 In a multicenter study of 148 patients with LAAO devices undergoing cardioversion, 100% had pre-procedural TEE, which detected device-related thrombus in 2.7% of cases. 2

• If device-related thrombus is detected, treat with oral anticoagulation for 6-8 weeks before proceeding with cardioversion. 2 All patients with detected thrombus in the multicenter study were successfully treated and able to undergo subsequent cardioversion. 2
• Cardioversion can proceed safely if TEE demonstrates good device position, absence of device-related thrombus, and peridevice leak ≤5 mm. 2

Standard Cardioversion Precautions

All standard cardioversion contraindications remain fully applicable regardless of Watchman presence: 1, 3

• Exclude digitalis toxicity—cardioversion is contraindicated in digitalis toxicity as it may precipitate difficult-to-terminate ventricular arrhythmias. 3 While therapeutic digoxin levels are generally safe, clinical and ECG signs of toxicity require delaying cardioversion for >24 hours after digoxin withdrawal. 3
• Ensure serum potassium is in the normal range—hypokalemia increases risk of ventricular tachycardia and fibrillation. 3, 1
• Provide appropriate sedation/anesthesia during the procedure. 1

Anticoagulation Strategy Post-Cardioversion

Direct oral anticoagulants (DOACs) are recommended over warfarin for patients undergoing cardioversion. 3, 1 However, the decision about post-cardioversion anticoagulation depends on timing after device implantation and individual thromboembolic risk:

• Patients undergoing cardioversion within the first 3-6 months post-implantation typically require continuation or initiation of oral anticoagulation. 2 In the multicenter study, patients receiving anticoagulation post-cardioversion underwent the procedure earlier after implantation (median 3.6 months vs 8.6 months; p=0.003). 2
• After complete device endothelialization (typically >6 months), cardioversion can be performed without post-procedural anticoagulation if pre-procedural TEE is reassuring. 2 This represents a major advantage over traditional cardioversion protocols requiring 4 weeks of post-cardioversion anticoagulation. 3
• Long-term anticoagulation decisions should be based on individual thromboembolic risk profile (CHA₂DS₂-VASc score), not the cardioversion itself. 3

Hemodynamic Instability

Proceed immediately to electrical cardioversion if the patient is hemodynamically unstable (acute MI with rapid ventricular response, symptomatic hypotension, angina, or heart failure unresponsive to pharmacological measures), regardless of Watchman device presence or anticoagulation status. 3, 1 This is a Class I recommendation. 3

Post-Cardioversion Monitoring

Monitor patients for at least 3 hours after cardioversion for arrhythmias and hemodynamic stability. 1 Common post-cardioversion arrhythmias include: 3, 1

• Ventricular and supraventricular premature beats (usually benign and self-limited) 3
• Bradycardia and sinus arrest (particularly in patients with underlying sinus node dysfunction) 3, 1
• Ventricular tachycardia/fibrillation (rare, associated with hypokalemia or digitalis toxicity) 3

Cardioversion may unmask underlying sinus node dysfunction in patients with long-standing AF—anticipate this and have temporary pacing available if needed. 3

Clinical Outcomes Data

The largest multicenter study of cardioversion in Watchman patients (n=148) demonstrated: 2

• 100% success rate in restoring sinus rhythm 2
• Zero cardioversion-related thromboembolic complications 2
• No device dislodgement, new device leaks, or device/left atrial thrombosis during median 12.8-month follow-up 2
• Three transient ischemic attacks occurred during follow-up but were unrelated to the cardioversion procedure 2

Important Caveats

• Avoid attempting electrical isolation of the left atrial appendage during catheter ablation procedures in Watchman patients, as this increases risk of peridevice leaks. 4 In a multicenter ablation registry, LAA isolation attempts resulted in new significant peridevice leaks (≥5 mm) in 10% of patients. 4
• Repeat TEE at 45 days and 12 months post-implantation to assess for peridevice flow and device-related thrombus, regardless of cardioversion. 5 This is standard Watchman follow-up protocol. 5
• If AF recurs after cardioversion, repeat cardioversion is reasonable provided sinus rhythm can be maintained for clinically meaningful periods. 3 The presence of a Watchman device does not limit the number of cardioversion attempts. 1, 2