Figure 2 Clinical course during hospitalization. The IVC thrombus showed minimal regression (A). CDT was initiated on day 16, consisting of a 2-mg local bolus of alteplase followed by continuous infusion at 0.5 mg/h for 17 h in combination with unfractionated heparin (400 U/h). After completion of alteplase therapy, the unfractionated heparin dose was increased via the pulse-spray catheter, with continuous infusion (days 16–20). Follow-up contrast-enhanced computed tomography demonstrated regression of the IVC thrombus (B). Although oral apixaban was continued after discharge, the IVC thrombus did not resolve (C, D). After switching to dabigatran on day 72, further thrombus regression was observed (E), with complete resolution confirmed on day 121 (F), followed by successful retrieval of the IVC filter. APTT, activated partial thromboplastin time; CDT, catheter-directed thrombolysis; IVC, inferior vena cava.