Acute Coronary Syndrome in a Young Woman With Protein S Deficiency and Von Willebrand Disease Type 1: A Case of Mixed Hemostatic Disorders.

Acute myocardial infarction (AMI) in young adults without conventional cardiovascular risk factors is rare and is often associated with non-atherosclerotic causes, including hereditary thrombophilias. Although protein S deficiency is classically associated with venous thrombosis, it has increasingly been implicated in arterial events. The postpartum period is a state of physiological hypercoagulability, which can reveal underlying prothrombotic conditions. Here, we present a case of a 31-year-old woman who developed septoapical AMI one week following elective cesarean section. Coronary angiography revealed thrombosis of the left coronary trunk and anterior descending artery, with no evidence of atherosclerotic lesions. She underwent percutaneous intervention with multiple stents and commenced anticoagulation therapy with acenocoumarol following the identification of partial protein S deficiency (56%). During follow-up, she experienced spontaneous mucocutaneous bleeding, prompting further investigation. Prolonged activated partial thromboplastin time (aPTT) and reduced activity of factor VIII (20.2%), von Willebrand factor (23.2%), and von Willebrand factor antigen (31.3%), as well as platelet hypofunction on aggregometry, led to a diagnosis of type 1 von Willebrand disease being made. The anticoagulant regimen was switched to dabigatran. The bleeding disorder was likely unmasked by anticoagulation. The final diagnosis was established based on platelet hypofunction and coagulopathy findings, which also guided the therapeutic adjustment. The patient achieved a favorable clinical outcome, characterized by symptom resolution, an absence of new thrombotic or bleeding events, and partial biochemical recovery. This case highlights the importance of comprehensive hematological investigations in young patients presenting with atypical arterial thrombotic events.