Recurrent acute coronary syndrome caused by refractory vasospastic angina in a patient with essential thrombocythemia: a case report

Essential thrombocythemia (ET) is a myeloproliferative disorder that increases the thrombotic risk and induces coronary spasms. Anagrelide, a common treatment for ET, has been suspected of trigger coronary spasm potentially leading to acute coronary syndrome (ACS).

A 51-year-old woman with ET who was treated with anagrelide developed recurrent ACS caused by refractory vasospastic angina. She initially underwent percutaneous coronary intervention (PCI) with a drug-eluting stent (DES) for severe stenosis of the proximal left anterior descending artery. However, her symptoms recurred, and progressive restenosis at the distal edge of the stent caused by vasospasm was confirmed using optical coherence tomography (OCT), histology, and invasive provocation tests. The patient underwent PCI with DES after directional coronary atherectomy, which helped to reduce the plaque volume and allowed for histopathological analysis. Her ET medication was switched from anagrelide to hydroxyurea and vasodilatory therapy was intensified with benidipine, diltiazem, and nicorandil. Follow-up assessments, including invasive provocation tests under treatment with vasodilators, demonstrated effective suppression of coronary spasm, and the patient remained stable without further ischaemic events.

This case underscores the role of coronary spasm in recurrent ACS in patients with ET and highlights the potential side effects of anagrelide. A multidisciplinary diagnostic approach, including OCT and histopathological evaluation and spasm provocation, can help to identify the underlying pathophysiology of ACS. Tailored therapy, verified through invasive provocation tests under vasodilation, successfully controlled the symptoms and prevented recurrence.