Massive Biatrial Thrombus Formation 3 Decades After Heart Transplantation.

BACKGROUND: Atrial thrombus formation decades after cardiac transplantation is rare but can be life-threatening, particularly in patients with biatrial anatomy. CASE SUMMARY: We report a 63-year-old man with prior orthotopic heart transplantation using the Shumway technique who presented with dyspnea and was found to have large thrombi in both atria. Urgent surgical thrombectomy removed organized thrombi, the largest measuring 88 × 47 × 37 mm. Postoperatively, he developed cardiogenic shock because of thrombotic/thromboembolic left anterior descending occlusion requiring extracorporeal membrane oxygenation support and emergency percutaneous coronary interventions. After successful extracorporeal membrane oxygenation weaning and explant, and initiation of guideline-directed heart failure therapy, he stabilized and was ultimately discharged under a structured palliative care plan. DISCUSSION: We discuss differential diagnoses of atrial masses after transplantation, including thrombus, myxoma, pseudomass, post-transplant lymphoproliferative disorder, and infection. Predisposing factors include atrial dilation and suture lines that predispose to stasis, graft vasculopathy, hypercoagulability, and interruption of anticoagulation. Literature suggests such thrombi, although uncommon, remain a risk even decades after surgery. TAKE-HOME MESSAGES: Atrial thrombi post-transplant may present late; prevention requires adherence to anticoagulation therapy and multidisciplinary follow-up.