High On-Treatment Platelet Reactivity as a Tool for Risk Stratification in STEMI Patients

<b>Background/Objectives:</b> In the last decade, several studies revealed individual response variability to different antiplatelet agents, and patients who have no response to these drugs are considered poor responders. Some studies explored platelet function during antiplatelet treatment to identify those patients with "high on-treatment platelet reactivity" (HPR), which exposes them to increased risk of major adverse cardiovascular events (MACE). <b>Methods:</b> We conducted a study with patients with ST-elevation myocardial infarction (STEMI) treated with dual antiplatelet therapy (DAPT) with ticagrelor and aspirin, including long-term follow-up after 5 years. We used thromboelastography, the total thrombus formation analysis system, and vasodilator-stimulated phosphoprotein phosphorylation assay (VASP) to analyze HPR with different methods; selected laboratory parameters were measured during hospitalization to check significant correlations. <b>Results:</b> We identified STEMI patients treated with DAPT with HPR as a risk group for MACE in a 5-year follow-up. Additionally, we have shown that HPR is associated with atherosclerosis by analyzing lipid profile parameters. <b>Conclusions:</b> High on-treatment platelet reactivity (HPR) increases the risk of major adverse cardiovascular events in the long term, especially with elevated C-reactive protein or an atherogenic lipid profile. Standardizing HPR assessment is crucial for optimizing individualized antiplatelet therapy and improving patient outcomes post-STEMI.