# Non-ST-Elevation Myocardial Infarction as the Initial Manifestation of Calreticulin-Positive Essential Thrombocythemia: A Case Report

## TL;DR

A man with no heart disease risk factors had a heart attack caused by a rare blood cancer, highlighting the need to consider blood disorders in unusual heart attack cases.

## Contribution

This case report highlights CALR-mutated essential thrombocythemia as a rare cause of acute coronary syndrome without atherosclerosis.

## Key findings

- A 62-year-old male with no cardiovascular risk factors presented with NSTEMI and was found to have CALR-mutated essential thrombocythemia.
- Treatment with PCI, antiplatelet therapy, and hydroxyurea led to a favorable clinical outcome.
- The case emphasizes the importance of considering hematologic malignancies in atypical myocardial infarction presentations.

## Abstract

Essential thrombocythemia (ET) is a rare myeloproliferative neoplasm characterized by excessive platelet production and a predisposition to thrombotic or hemorrhagic complications. We report a case of a 62-year-old male with no conventional cardiovascular risk factors who presented with a non-ST-segment elevation myocardial infarction (NSTEMI). Initial coronary angiography showed isolated proximal LAD stenosis. Laboratory tests revealed marked thrombocytosis (>1,000,000/μL) and a CALR mutation, confirming a diagnosis of ET. The patient was treated with percutaneous coronary intervention (PCI), dual antiplatelet therapy, and cytoreductive therapy with hydroxyurea, leading to a favorable outcome. This case illustrates how ET, particularly CALR-mutated subtypes, can manifest as acute coronary syndrome in the absence of atherosclerosis and underscores the need to consider hematologic malignancies in atypical presentations of myocardial infarction.