Acute coronary syndrome

Overview

Acute coronary syndrome (ACS) refers to a group of urgent heart conditions caused by sudden, reduced blood flow to the heart muscle. This typically occurs due to blockage or narrowing of the coronary arteries, most often from a ruptured atherosclerotic plaque. ACS encompasses three major presentations: unstable angina, non-ST elevation myocardial infarction (NSTEMI), and ST elevation myocardial infarction (STEMI). Prompt recognition and treatment are critical to prevent permanent heart damage or death.

Causes

The primary cause of acute coronary syndrome is the rupture or erosion of an atherosclerotic plaque in a coronary artery. This event triggers the formation of a blood clot (thrombus) that can partially or completely block blood flow to the heart. Other contributing factors include:

• Coronary artery spasm (rare)

• Embolism or spontaneous coronary artery dissection (SCAD)

• Severe narrowing of coronary arteries due to chronic atherosclerosis

Risk factors for ACS include smoking, high blood pressure, high cholesterol, diabetes, obesity, sedentary lifestyle, and family history of heart disease.

Symptoms

Symptoms of ACS often develop suddenly and may vary based on the type and severity of the condition. Common symptoms include:

• Chest pain or discomfort: Often described as pressure, squeezing, or fullness, typically lasting more than a few minutes

• Pain that radiates: To the shoulders, neck, jaw, arms, or back

• Shortness of breath

• Nausea or vomiting

• Lightheadedness or fainting

• Cold sweat

• Fatigue: Especially in women and older adults

Some people may experience only mild symptoms or atypical signs, particularly women, the elderly, or diabetics.

Diagnosis

Early diagnosis of ACS is essential to initiate life-saving treatments. The diagnostic process typically includes:

• Electrocardiogram (ECG): To identify ST-segment changes indicating ischemia or infarction

• Cardiac biomarkers: Blood tests such as troponin to detect heart muscle damage

• Chest X-ray: To rule out other causes of chest pain

• Coronary angiography: An imaging procedure to view blockages in coronary arteries

• Echocardiogram: To assess heart function and wall motion abnormalities

Treatment

Treatment of acute coronary syndrome aims to restore blood flow to the heart, reduce damage, and prevent complications. Management varies depending on the type of ACS:

Initial Emergency Management:

• Oxygen (if hypoxic)

• Aspirin and P2Y12 inhibitors (e.g., clopidogrel) to prevent clot growth

• Nitroglycerin for chest pain relief

• Anticoagulants such as heparin

• Beta-blockers to reduce heart workload (if appropriate)

Invasive Interventions:

• Percutaneous coronary intervention (PCI): Balloon angioplasty and stenting to open blocked arteries (preferred for STEMI and some NSTEMI)

• Coronary artery bypass grafting (CABG): For severe or complex blockages

• Thrombolytics: In STEMI cases when PCI is not immediately available

Long-Term Medical Therapy:

• Dual antiplatelet therapy (DAPT)

• Statins to lower cholesterol

• ACE inhibitors or ARBs for blood pressure and heart protection

• Beta-blockers for ongoing cardiac support

• Lifestyle modification and cardiac rehabilitation

Prognosis

The prognosis after acute coronary syndrome depends on the extent of heart damage, time to treatment, and overall health. Early and aggressive treatment significantly improves outcomes. STEMI generally has a higher short-term mortality risk than NSTEMI or unstable angina, but all forms of ACS can lead to long-term complications such as:

• Heart failure

• Arrhythmias (e.g., ventricular tachycardia or fibrillation)

• Recurrent heart attacks

• Sudden cardiac death

With timely care, adherence to medications, and lifestyle changes, many patients can resume normal activities and significantly reduce their future cardiovascular risk.