Acute renal embolism in atrial fibrillation associated with rheumatic mitral stenosis

A 56-year-old Pakistani female with a history of mild rheumatic mitral stenosis presented to A&E with new fast atrial fibrillation (AF). She was discharged home after rate control with bisoprolol. She was not started on anticoagulation as her CHA2DS2-VASc score was 1 (for female sex). She returned to A&E 5 days later with a 1 day history of left sided abdominal pain, radiating to her left shoulder/scapula and left arm. On admission, she was again in fast AF. CT abdomen showed severe right renal atrophy, and an area of low attenuation medially within the left renal upper pole and posteriorly at the left lower pole, consistent with left renal infarcts. CT pulmonary angiogram excluded pulmonary embolism. Bloods showed stable renal function with creatinine 74 µmol/L and eGFR 72 mL/m/1.73 m. Echocardiogram revealed mild to moderate mitral stenosis with a dilated left atrium with a left atrial end-systolic volume index of 75 mL. She was started on warfarin with bridging dalteparin. Arterial and venous phase renal CT after 6 weeks showed maturing left renal infarcts at the upper pole, lower pole and dorsal midzone, and a normal calibre and normal enhancing main left renal artery and visualised branches. It also showed chronic right renal atrophy with a chronically attenuated main right renal artery. We suggest considering systemic thromboembolic phenomena in symptomatic patients with atrial fibrillation regardless of their CHA2DS2-VASc score. In addition, mitral stenosis itself is prothrombotic and anticoagulation might be considered in this cohort of patients even in sinus rhythm if the left atrium is dilated.