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INTRODUCTION

Acute coronary syndrome (ACS) is caused by diminished myocardial blood flow secondary to an occlusive or a partially occlusive coronary artery clot1. The clot formation in the coronary artery is formed by plaque, comprising of fatty streaks. Over time, plaque can build up in coronary arteries and prevent them from supplying oxygenated blood to the heart. The plaque can break resulting in clot formation and sudden reduction in blood flow, a condition known as ischemia. Ultimately, ischemia can result in myocyte necrosis or cell death.

PATHOPHYSIOLOGY

ACS is classified into ST elevation myocardial infarction (STEMI) and non-ST segment elevation acute coronary syndromes (NSTE-ACS)1. NSTE-ACS includes both conditions of unstable angina and non-ST segment elevation myocardial infarction (NSTEMI). STEMI results in a complete blockage in one or more coronary arteries, leading to symptoms of myocardial ischemia in conjunction with new ST elevation and a subsequent release of biomarkers of myocardial necrosis, troponin T or I. On the other hand, NSTEMI occurs when an artery is partially blocked and is not as extensive as STEMI. NSTEMI is different from unstable angina due to the myocardial necrosis it causes, leading to the releasing of troponin T or I in the blood stream.

CLINICAL PRESENTATION

In general, patients with ACS are typically in acute distress and may present with acute heart failure, cardiogenic shock, or cardiac arrest1. The classic symptom of ACS is midline anterior chest pain. This pain may radiate to the arm, back, or jaw. Chest pain includes symptoms of crushing, burning, or heavy pressure, and most often occurs when patients are at rest that can last for 20 minutes. Other symptoms may develop with chest discomfort, such as nausea, vomiting, shortness of breath, or diaphoresis.

DIAGNOSIS

Within 10 minutes of a patient arriving in the emergency room, a 12-lead ECG should be obtained and evaluated1. Biomarkers of troponin I or T are used to confirm the diagnosis of MI. These cardiac enzymes are released in the blood stream when myocardial cells die, and are the most sensitive and specific biomarkers for ACS. For this reason, cardiac troponin I or T laboratory test should be obtained at the time of first assessment, and repeated 3-6 hours after ACS symptoms onset. Troponins are detectable in the blood within 6 hours of infarction and stay elevated for up to 10 days.

TREATMENT

Acute treatment desire outcomes aim at providing immediate relief of ischemia and preventing complete occlusion, MI in unstable angina, and death1,2. ACS is a medical emergency. Before admitting into a hospital, patients with ACS may already have been prescribed with sublingual nitroglycerin (NTG), indicated for the relief of chest pain. In the event of acute ACS, sublingual NTG should be taken every 5 minutes, ...

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