# ST-Segment Elevation Myocardial Infarction After Pegfilgrastim: Case Report and Review of Mechanistic Considerations

## TL;DR

A cancer patient developed a heart attack after receiving pegfilgrastim, possibly due to high white blood cell and platelet counts causing blood clotting issues.

## Contribution

First reported case of ST-segment elevation myocardial infarction linked to pegfilgrastim, highlighting a rare thromboembolic complication.

## Key findings

- Acute STEMI occurred in a patient after pegfilgrastim, with coronary artery occlusion and no atherosclerosis.
- Leukocytosis and thrombocytosis likely triggered the myocardial infarction via hyperviscosity and endothelial activation.
- Thrombectomy improved blood flow, suggesting its value in such cases.

## Abstract

Granulocyte-colony stimulating factors (G-CSFs) are widely used to prevent chemotherapy-induced neutropenia, but they have been linked to coronary neovascularization and prothrombotic effects.

A 62-year-old man with small cell lung cancer developed an acute posterior ST-segment elevation myocardial infarction (STEMI) 1 day after receiving 6 mg of pegfilgrastim during his second chemo-immunotherapy cycle. Coronary angiography revealed an occluded right coronary artery without atherosclerosis. Aspiration thrombectomy significantly reduced thrombus burden, restoring TIMI flow grade 3. Initial blood tests showed leukocytosis (white blood cells: 82.13 × 109/L) and thrombocytosis (platelets: 773 × 109/L), which normalized at discharge. Transesophageal echocardiography excluded embolic sources, and hyperviscosity syndrome was considered.

Marked leukocytosis and thrombocytosis after pegfilgrastim plausibly triggered acute myocardial infarction via leukostasis/hyperviscosity, endothelial activation, neutrophil extracellular traps, and platelet reactivity. To our knowledge, this first reported STEMI after pegfilgrastim warrants vigilance for leukocytosis-related thromboembolic complications in oncology patients.

G-CSF–induced leukocytosis should be considered as a rare cause of acute myocardial infarction in patients without significant cardiovascular history. Thrombectomy remains a valuable adjunctive tool.