Intracardiac Thrombus Following Pediatric Heart Transplant: New Heart, New Problem?

Introduction Development of an intracardiac thrombus (IT) has been reported following pediatric heart transplantation (HT), however the incidence and risk factors are unknown. Pre-HT ventricular assist device (VAD) support can result in a hypercoagulable state and can be associated with the development of anti-phospholipid (APL) antibodies. Over 200 transplants have been performed at our institution in the last 10 years with 2 cases of IT post-HT identified. Case Report Case 1: A 9 year old female was bridged to HTx with VAD. She developed cardiac allograft vasculopathy and recalcitrant arrhythmias 7 years post-HT. She underwent a repeat HTx with total ischemic time 236 minutes. She had normal biventricular function without arrhythmia. On post-operative day (POD) 8, an echocardiogram revealed 3 IT in the left atrium (LA) as seen in figure 1. She was emergently taken to the OR. Her previously normal coagulation profile prior to initial transplant was now notable for + IgM anti-cardiolipin, an antibody that is detected in APL syndrome. She never developed any neurological sequelae. No additional thrombotic compilations have occurred over 3 months on enoxaparin. Case 2: A 15 year old male with failing Fontan physiology was supported on VAD for 5 months prior to a technically challenging HT with total ischemic time 366 minutes. He had ventricular tachycardia and junctional rhythm treated with antiarrhythmics and pacing with normal biventricular function by POD 4. On POD 7, he developed altered mental status. Brain MRI showed multiple small ischemic infarcts and an IT extending from the LA appendage was found on echocardiogram. His IT was medically managed, and while no hypercoagulable workup was completed at the time, he was subsequently continued on enoxaparin as an outpatient without recurrence. Summary We postulate that each patient may have developed an acquired thrombophilia. These cases highlight the importance of future studies to risk stratify post-HTx patients who may warrant a pre-emptive hypercoagulable workup.