Ticagrelor Resistance Causing Acute In-Stent Thrombosis: Successful Management With Prasugrel and Balloon Angioplasty.

Ticagrelor is a cornerstone of dual antiplatelet therapy (DAPT) post-percutaneous coronary intervention (PCI), but resistance is rarely reported and poorly understood. We present a case of a 51-year-old woman with type 2 diabetes and a family history of coronary artery disease. Patient underwent elective PCI for severe proximal left anterior descending (LAD) and right coronary artery (RCA) stenoses, receiving aspirin and ticagrelor. Post-procedure, she developed syncope, hypotension, and ST-elevation on electrocardiogram (EKG), with repeat angiography revealing acute in-stent thrombosis in the proximal LAD. VerifyNow assay revealed ticagrelor resistance (307 PRU, repeat 293 PRU; cutoff < 208 PRU). Management included balloon angioplasty and transition to prasugrel (60 mg load, 10 mg daily). Angioplasty restored patency with no further events. Follow-up VerifyNow showed adequate inhibition (180 PRU) at 1 month, and the patient remained asymptomatic. Ticagrelor resistance can cause severe complications like in-stent thrombosis; VerifyNow-guided switch to prasugrel may prevent adverse outcomes, underscoring the need for tailored antiplatelet therapy. She underwent successful balloon angioplasty and was transitioned to prasugrel with no further events.