Venous thromboembolism is often treated with direct oral anticoagulants. In order for direct oral anticoagulants to be effective, patients must adhere to a specific dosing strategy. We report a case of apixaban failure, the clinical workup that ensued, and the eventual discovery of unsuccessful medication adherence as the cause.

Here, we report the outcome of an 87-year-old man with permanent non-valvular atrial fibrillation who initially presented with complete heart block and received a single right ventricle lead pacemaker programmed to ventricular demand pacing (VVIR). Over the next 10 months, the patient was readmitted to the hospital four times with recurrent edema, pleural effusions, and ascites. He was diagnosed with new onset systolic heart failure with mid-range (40-49%) ejection fraction and cardiorenal syndrome requiring dialysis. The underlying cause of his presentation was determined to be pacemaker syndrome mediated by new onset severe tricuspid regurgitation. He was treated with reimplantation of a pacemaker with His bundle pacing with subsequent improvement in his cardiac status and renal function. Implantation of dualchamber pacing (DDDR) or His bundle pacing to achieve a narrow QRS complex over ventricular demand pacemaker is recommended whenever possible to reduce the incidence of pacemaker syndrome and improve patient outcomes.