The Need for a Coagulation Assay after Initiation of New Oral Anticoagulants in Patients with Renal Dysfunction: A Case Report

BACKGROUND: Dabigatran etexilate, a new oral anticoagulant, was recently approved as an efficacious alternative to warfarin for the prevention of first and recurrent stroke in patients with nonvalvular atrial fibrillation. Limited data are available for dabigatran use in patients with a creatinine clearance rate (CrCL) of 15-30 mL/min. Furthermore, current guidelines do not recommend frequent blood monitoring after dabigatran use. We report herein a patient with severe renal dysfunction who exhibited profound coagulopathy after 2 days of dabigatran use. CASE REPORT: An 87-year-old woman was admitted for altered mental status and left-side weakness. She was diagnosed with right middle cerebral artery infarction. The baseline assessment revealed a serum creatinine concentration of 1.29 mg/dL and a CrCL of 27.2 mL/min. Dabigatran therapy was started 5 weeks after admission at a dosage of 110 mg twice daily. After 2 days of dabigatran use, the patient developed multiple bruises and evidence of upper-gastrointestinal bleeding. Laboratory tests demonstrated a severe coagulopathy, with a prothrombin time of 85.9 sec, an international normalized ratio of 11.36, an activated partial thromboplastin time of 119.2 sec, and a thrombin time of 230.8 sec. Serial assessment of the patient's renal function revealed substantial fluctuation of the CrCL (range, 17.9-26.5 mL/min). CONCLUSIONS: The present case emphasizes the need for frequent checking of renal function and assessment using coagulation assays after commencing dabigatran therapy in patients with moderate-to-severe renal impairment.

An Adult Moyamoya Disease Confirmed by Ring Finger Protein 213 Gene Test and Radiological Studies

A 63-year-old female complained of transient dysarthria. MRA was conducted to evaluate this symptom, revealing distal internal carotid artery occlusion with collateral vessel development, suggesting Moyamoya disease, which had not been detected in MRA performed 5 years previously. Vascular risk factors and laboratory findings suggested no cardiac or autoimmune diseases. The diameter of stenosis of the middle cerebral artery on high-resolution MRI was 2.11 mm, and genetic evaluation revealed mutation of the gene encoding ring finger protein 213 (RNF213). High-resolution MRI and gene studies are useful for distinguishing between Moyamoya disease and atherosclerosis.