Myocardial infarction (MI), commonly known as a heart attack, is a medical emergency caused by sudden interruption of blood supply to the heart muscle. If not treated promptly, it leads to ischemia and irreversible myocardial cell death.
Definition
Myocardial infarction is defined as necrosis of heart muscle due to prolonged ischemia. It usually results from acute obstruction of a coronary artery.
Epidemiology
- One of the leading causes of mortality worldwide.
- More common in older adults, males, and individuals with cardiovascular risk factors.
Etiology
- Most commonly caused by atherosclerotic plaque rupture with thrombosis.
- Less common causes include coronary artery spasm or embolism.
Risk Factors
Non-modifiable: Age, male gender, genetic predisposition.
Modifiable: Smoking, hypertension, diabetes, dyslipidemia, obesity, sedentary lifestyle.
Pathophysiology
- Plaque rupture exposes thrombogenic material.
- Clot formation reduces coronary blood flow.
- Prolonged ischemia causes myocardial cell death.
Types of Myocardial Infarction
STEMI: Complete coronary artery occlusion with ST-segment elevation on ECG.
NSTEMI: Partial occlusion with ST depression or T-wave inversion.
Clinical Presentation
- Severe central chest pain
- Pain radiating to left arm, neck, jaw, or back
Associated Symptoms
- Sweating
- Nausea
- Shortness of breath
- Atypical or silent symptoms in diabetics
Physical Examination Findings
- Anxiety, pallor, diaphoresis
- Tachycardia or hypotension
- Signs of heart failure
Diagnostic Investigations
Electrocardiography (ECG): Essential for early diagnosis.
Cardiac Biomarkers: Troponin I and T are highly specific and rise within hours.
Management – Acute Phase
- Oxygen (if indicated)
- Antiplatelet therapy
- Analgesia
- Immediate reperfusion therapy
Reperfusion Strategies
Percutaneous Coronary Intervention (PCI): Preferred method.
Thrombolytic therapy: Used if PCI is unavailable.
Pharmacological Management
- Antiplatelets
- Anticoagulants
- Beta-blockers
- Statins
Complications
Early: Arrhythmias, cardiogenic shock.
Late: Heart failure, ventricular aneurysm.
Prevention and Secondary Prophylaxis
- Lifestyle modification
- Control of blood pressure, diabetes, and lipids
- Long-term medications
Prognosis
Prognosis depends on infarct size and timeliness of treatment. Early diagnosis and management significantly improve survival and outcomes.
