A Case of acute Myocardial Infarction in a Patient with Essential Thrombocythaemia Treated with Anagrelide

Abstract

Anagrelide is a medication primarily used to manage thrombocytosis, an abnormal increase in platelet levels in the blood. It is often prescribed for patients with myeloproliferative disorders, such as essential thrombocythaemia (ET). Given the heightened susceptibility to thromboembolism associated with this condition, the primary emphasis in treatment revolves around reducing the risk of thrombotic events through the administration of cytotoxic agents. While anagrelide is generally effective in reducing platelet counts, it comes with potential side effects, including an increased risk of certain thrombotic events. Anagrelide acts by inhibiting megakaryocyte maturation and platelet release, thereby reducing platelet production. However, this platelet-lowering effect may be accompanied by an increase in platelet activation and reactivity, which could contribute to a prothrombotic state. We present a case of a 60-year-old female with a history of ET, managed with anagrelide and hydroxyurea therapy, who experienced an acute ST-elevation myocardial infarction.

Learning points: The dual role of anagrelide: although anagrelide is effective in lowering platelet levels in essential thrombocythaemia, it can increase platelet activation, raising thrombotic risk. Clinicians need to monitor patients closely for thrombotic events.Balancing efficacy and side effects: the risk of severe side effects such as myocardial infarction, as seen in this case report, necessitates a balanced approach in using anagrelide, weighing its benefits against potential risks.

Keywords: Essential thrombocythaemia; anagrelide; myocardial infarction; thrombosis.

Figure 1

ECG performed during triage showed inverted T-waves in leads V2 and V3. The patient had a ventricular rate of 69 beats per minute (BPM), an atrial rate of 69 BPM, a P-R interval of 146 milliseconds, a QRS duration of 70 milliseconds, a Q-T interval of 404 milliseconds, a calculated QTc (Bazett) of 432 milliseconds, a P axis of 27 degrees, an R axis of 14 degrees and a T axis of 135 degrees.

Figure 2

During cardiac angiography, the patient was found to have one vessel disease with 99% stenosis in the proximal LAD (red arrow).

Figure 3

Percutaneous coronary intervention (PCI) was successfully performed with the placement of one drug-eluting stent (Megatron 4.0 x 16) in the proximal LAD (red arrow).

Figure 4

ECG performed after revascularisation showed resolution of previously inverted T-waves in leads V2 and V3. The patient had a ventricular rate of 62 beats per minute (BPM) and a corresponding atrial rate of 62 BPM. The P-R interval is measured at 144 milliseconds, while the QRS duration is 70 milliseconds. The Q-T interval is observed to be 402 milliseconds, and the QTc calculation using Bazett’s formula yields a value of 408 milliseconds. The P axis is determined to be at 30 degrees, the R axis at 12 degrees and the T axis at 118 degrees.