In a patient with suspected acute coronary syndrome in the ED, what is the most important initial management step before laboratory results are available?

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In suspected acute coronary syndrome, giving chewable aspirin right away is the most impactful initial step because it rapidly inhibits platelet aggregation, reducing the growth of the clot that is causing the ischemia. By irreversibly inhibiting COX-1 in platelets, aspirin lowers thromboxane A2 and prevents further platelet activation for the life of a platelet (about 7–10 days). Chewing speeds absorption, so the anti-platelet effect begins within minutes, which can lower mortality and limit infarct size even before lab results or definitive imaging are available. This benefit applies across ACS presentations and is safe in most patients unless there are clear contraindications (such as active GI bleeding or allergy). After this, clinicians obtain ECGs and labs to guide additional therapies, but aspirin is the essential immediate measure.