Acute Postcardioversion Left Atrial Appendage Stasis During Left Atrial Appendage Closure Procedures.

BACKGROUND: Acute postcardioversion left atrial appendage (LAA) low-flow states are recognized but likely underdetected, as repeat appendage imaging is not routine after sinus restoration. CASE SUMMARY: Three patients undergoing left atrial appendage closure (LAAC) developed new LAA spontaneous echo contrast, dense spontaneous echo contrast/sludge, or a persistent filling defect suspicious for thrombus within minutes of cardioversion. Ultrasound enhancing agent distinguished slow complete opacification from a persistent filling defect, guiding individualized deploy-vs-abort decisions. DISCUSSION: LAAC uniquely permits appendage imaging immediately before and after cardioversion, and serial intraprocedural transesophageal echocardiography offers a rarely available window on acute LAA stasis. Alternative contributors, including ablation, transseptal instrumentation, and anticoagulation strategy, warrant consideration, particularly in combined atrial fibrillation ablation/LAAC workflows. Prospective studies should define prevalence, risk markers, and mitigation strategies. TAKE-HOME MESSAGE: Serial transesophageal echocardiography during LAAC can reveal acute postcardioversion LAA stasis; ultrasound enhancing agent can differentiate slow flow from thrombus and guide individualized deploy-vs-abort decisions.