Giant left atrial thrombi despite surgical left atrial appendage resection in rheumatic heart disease: a case report

Although surgical left atrial appendage resection reduces a major source of thromboembolism, left atrial cavity thrombosis may still occur in patients with persistent severe atrial stasis.

An 86-year-old woman was admitted with severe acute decompensated heart failure and a low-output state. She had long-standing persistent atrial fibrillation and had undergone bioprosthetic mitral valve replacement with surgical left atrial appendage resection for rheumatic mitral stenosis one year earlier. She received warfarin for the first 3 months after surgery, followed by edoxaban 30 mg once daily; medication reconciliation on admission suggested suboptimal adherence. Contrast-enhanced computed tomography on Day 2 showed two giant left atrial filling defects. Pretreatment laboratory findings yielded an International Society on Thrombosis and Haemostasis overt disseminated intravascular coagulation score of 6; antithrombin activity was 69.4%, and no overt bleeding was present. Unfractionated heparin (UFH) and heart failure therapy were initiated; fresh-frozen plasma and antithrombin concentrate were administered. Coagulation variables improved, and the filling defects disappeared by Day 39 during ongoing UFH and heart failure therapy, without systemic embolism. After stabilization, warfarin therapy was reintroduced with adherence support.

In this case, severe rheumatic atrial remodelling, marked left atrial enlargement, persistent atrial fibrillation, impaired forward flow, and uncertain anticoagulant exposure probably contributed to giant left atrial cavity thrombus formation despite prior appendage resection. This case highlights that surgical left atrial appendage resection does not eliminate the risk of left atrial cavity thrombosis when severe atrial stasis persists.