Percutaneous coronary intervention in a patient with heparin resistance due to essential thrombocythaemia: a case report

BACKGROUND : Coronary artery disease is uncommon in patients with essential thrombocythaemia (ET); therefore, no treatment strategies have been established. CASE SUMMARY : A 68-year-old man visited our hospital with worsening effort angina complicated with ET. Coronary angiography (CAG) revealed moderate stenosis of the left main trunk and left anterior descending artery (LAD). We planned to perform percutaneous coronary intervention (PCI) only after the patient’s platelet count had fallen below 600 000/μL. Platelet factor 4 levels were markedly elevated (355.0 ng/mL; the normal range is <20 ng/mL). We observed a de novo lesion in the proximal left circumflex artery and stenosis progression in the LAD at the time of the PCI, neither of which had been detected at the previous CAG. During the PCI procedure, argatroban was infused to maintain the activated clotting time (ACT) above 250 s. The PCI was performed successfully without any complications. Follow-up CAG showed no restenosis, and no bleeding complications were observed during the course. DISCUSSION : In patients with ET, it may be useful to measure platelet factor 4 before PCI and to monitor ACT during the procedure. When heparin resistance is suspected based on blood coagulation tests, infusion of direct thrombin inhibitor during PCI may be considered, with anticoagulation monitoring by ACT.