Hyperviscosity-related ischemic stroke in TOF with marked secondary erythrocytosis successfully managed with therapeutic phlebotomy

Background Ischemic stroke is an uncommon but potentially devastating complication of cyanotic congenital heart disease [1,2]. Chronic hypoxia in Tetralogy of Fallot can result in secondary polycythemia and hyperviscosity, predisposing patients to thrombotic events [2,3]. The role of therapeutic phlebotomy in this setting remains controversial and is generally reserved for selected patients with symptomatic hyperviscosity [2,4]. We report a rare case of hyperviscosity-related ischemic stroke in an adult with Tetralogy of Fallot and pulmonary atresia successfully managed with therapeutic phlebotomy. Case Presentation A 43-year-old man with Tetralogy of Fallot and pulmonary atresia presented with acute right-sided hemiparesis, slurring of speech, and altered sensorium. He had a previous history suggestive of a transient ischemic event. Neuroimaging demonstrated a large left middle cerebral artery territory infarct with evidence of a prior right parietal infarct. Clinical examination revealed central cyanosis and grade 4 digital clubbing. Haematological evaluation showed marked secondary polycythemia with haemoglobin 18.9 g/dL, haematocrit 60%, and red blood cell count 7.85 × 10⁶/µL. Serum erythropoietin was markedly elevated at 426 mIU/mL, consistent with chronic hypoxia-driven erythrocytosis. Iron studies demonstrated concomitant iron deficiency with microcytosis. Echocardiography confirmed Tetralogy of Fallot with pulmonary atresia, a large ventricular septal defect with bidirectional shunting, overriding aorta, and right ventricular hypertrophy. In view of symptomatic hyperviscosity associated with acute ischemic stroke, two sessions of therapeutic phlebotomy were performed with the removal of approximately 350 mL of blood during each session, accompanied by isotonic saline replacement and hemodynamic monitoring. Hematocrit decreased from 60% to 47.6% and haemoglobin from 18.9 g/dL to 14 g/dL, with clinical improvement and no procedure-related complications. Conclusions This case highlights hyperviscosity as a potentially modifiable contributor to ischemic stroke in adults with cyanotic congenital heart disease. Therapeutic phlebotomy, when used judiciously with adequate volume replacement and monitoring, may be an effective adjunctive intervention in selected patients with symptomatic secondary polycythemia. Early recognition of hyperviscosity-related neurological complications is essential for timely management and improved clinical outcomes.