Case Presentation: A 63-year-old gentleman with a history of unprovoked left lower leg deep vein thrombosis (DVT) on rivaroxaban and seizure disorder on phenytoin, presented with acute onset abdominal pain, hematochezia, vomiting for two days. On presentation patient was tachycardic with a heart rate of 130/min, a physical exam revealed a distended and tender abdomen. Labs were notable for an elevated white blood cell count of 18000, and a lactate of 2.6 mMol/L. Computed tomography imaging revealed findings consistent with acute mesenteric ischemia secondary to SMA occlusion. A small bowel resection was performed immediately. The pathology report from resected small bowel showed transmural ischemic-like changes. An intraoperative transesophageal echocardiogram revealed a new finding of large aortic vegetation with moderate aortic insufficiency. He was started on empiric broad-spectrum antibiotics for suspected bacterial endocarditis. However, three subsequent blood cultures, serologies for Coxiella, Brucella, Bartonella were negative. On day eight of his hospital course, he developed a new right internal jugular DVT despite being therapeutically anticoagulated with heparin. An underlying hypercoagulable state was considered at that time and an extensive rheumatological workup was performed which was notable for a high titer ANA (1:2560 homogenous pattern), weakly positive dsDNA, borderline moderate positive anticardiolipin IgM (39), weakly positive anti-beta2 glycoprotein IgM (23.4), positive lupus anticoagulant, and positive anti-histone antibodies. His serologies coupled with prior history of lower extremity DVT and SMA thrombosis were strongly suspicious for APLS. He eventually underwent mechanical aortic valve replacement. Pathology of the aortic valve vegetation was found to be a fibrotic calcified valve with an attached thrombus. He was diagnosed with marantic endocarditis in the setting of APLS and associated drug-induced lupus in the setting of phenytoin use. The patient was discharged home on hydroxychloroquine and warfarin with a goal INR of 2.5-3.
Discussion: In elderly people with an atherosclerotic disease who present with acute abdomen and SMA thrombosis, an underlying diagnosis of APLS can be easily missed. In our case, the presence of arterial thrombus and aortic vegetation in an anticoagulated patient prompted further workup leading to a diagnosis of APLS and a switch to warfarin. Physicians should be aware of this uncommon presentation of APLS. Early diagnosis and prompt treatment with warfarin, which is superior to direct oral anticoagulants in these patients [1] can help prevent future events in such patients.
Conclusions: Superior mesenteric artery (SMA) occlusion is a rare manifestation of antiphospholipid syndrome (APLS) and anticoagulation with warfarin is preferred over direct oral anticoagulants (DOAC) [1]. We present a case of SMA thrombosis and an incidental aortic vegetation in a patient despite being anticoagulated with rivaroxaban. Further workup revealed antiphospholipid syndrome and drug-induced lupus in the setting of phenytoin use.