Summary

Acute myocardial infarction (AMI or heart attack) is death of heart muscle due to lack of blood supply, usually caused by a blocked coronary artery. Think of your heart as a pump that needs its own blood supply through coronary arteries—when one of these arteries gets blocked (usually by a blood clot on top of a cholesterol plaque), the heart muscle downstream doesn't get enough blood and dies. This is a medical emergency that can cause death, heart failure, or dangerous arrhythmias if not treated promptly. There are two main types: STEMI (ST-elevation MI—complete blockage, needs urgent reperfusion) and NSTEMI (non-ST-elevation MI—partial blockage, still needs urgent treatment). The key to management is recognizing the MI (chest pain, ECG changes, troponin elevation), classifying the type (STEMI vs NSTEMI), providing immediate treatment (aspirin, dual antiplatelets, statin, reperfusion for STEMI—PCI or thrombolysis), and preventing complications (monitor for arrhythmias, heart failure, mechanical complications). Early recognition and prompt reperfusion (especially for STEMI—within minutes to hours) are essential—time is muscle, and every minute of delay means more heart muscle dies.

Key Facts

• Definition: Death of heart muscle due to blocked coronary artery
• Incidence: Very common (thousands of cases/year)
• Mortality: 5-10% overall, higher if delayed treatment
• Peak age: Older adults (50+ years), but can occur at any age
• Critical feature: Chest pain, ECG changes, troponin elevation
• Key investigation: ECG, troponin, clinical assessment
• First-line treatment: Aspirin, dual antiplatelets, reperfusion (STEMI), statin

Clinical Pearls

"Time is muscle" — Every minute of delay in reperfusion means more heart muscle dies. For STEMI, aim for door-to-balloon time <90 minutes or door-to-needle time <30 minutes.

"ECG within 10 minutes" — All patients with suspected MI should have an ECG within 10 minutes. Don't delay—this guides treatment.

"STEMI = urgent reperfusion" — STEMI (ST elevation) needs urgent reperfusion (PCI or thrombolysis). NSTEMI needs urgent treatment but not necessarily immediate reperfusion.

"Don't forget the basics" — Aspirin, dual antiplatelets, statin, beta-blocker (if no contraindications), ACE inhibitor (if heart failure or anterior MI). These save lives.

Why This Matters Clinically

AMI is a leading cause of death worldwide and requires urgent recognition and treatment. Early recognition (especially ECG within 10 minutes), prompt reperfusion (for STEMI), and appropriate medical management are essential. This is a condition that emergency clinicians and cardiologists manage, and prompt treatment saves lives and prevents complications.

Structured Approach: ABCDE

A - Airway

• Assessment: Usually patent
• Action: Secure if compromised

B - Breathing

• Look: May have respiratory distress (if heart failure)
• Listen: May have crackles (pulmonary edema)
• Measure: SpO2 (may be low if heart failure)
• Action: Support if needed, oxygen

C - Circulation

• Look: Signs of shock, heart failure
• Feel: Pulse (may be irregular, fast, or slow), BP (may be abnormal)
• Listen: Heart sounds (may have new murmur, S3, S4)
• Measure: BP (may be abnormal), HR (may be abnormal)
• Action: Monitor, support if needed

D - Disability

• Assessment: Usually normal (may be altered if shock)
• Action: Assess if severe

E - Exposure

• Look: Full examination
• Feel: Assess perfusion
• Action: Complete examination

Specific Examination Findings

Cardiovascular Examination:

• JVP: May be elevated (heart failure)
• Heart sounds:
  • S3: Heart failure
  • S4: Stiff ventricle
  • New murmur: Mechanical complication
• Peripheral pulses: May be weak (shock)

Respiratory Examination:

• Crackles: Pulmonary edema (heart failure)

Special Tests

Natural History (Without Treatment)

Untreated MI:

• High mortality: 20-30% mortality
• Complications: High risk
• Poor outcomes: If not treated

Outcomes with Treatment

Factors Affecting Outcomes:

Good Prognosis:

• Early reperfusion: Better outcomes (especially STEMI)
• Small MI: Better outcomes
• No complications: Better outcomes
• Young, healthy: Better outcomes

Poor Prognosis:

• Delayed treatment: Higher mortality
• Large MI: Higher mortality
• Complications: Worse outcomes
• Older, comorbidities: May have worse outcomes

Prognostic Factors

Key Guidelines

1. ESC Guidelines (2023) — Management of acute coronary syndromes. European Society of Cardiology

Key Recommendations:

• ECG within 10 minutes
• Reperfusion for STEMI (PCI preferred)
• Dual antiplatelets, statin
• Evidence Level: 1A

2. AHA/ACC Guidelines (2023) — Management of patients with ST-elevation myocardial infarction. American Heart Association

Key Recommendations:

• Similar to ESC
• Evidence Level: 1A

Landmark Trials

Multiple studies on reperfusion, medications, outcomes.

Evidence Strength

What is a Heart Attack?

A heart attack (myocardial infarction) is when part of your heart muscle dies because it doesn't get enough blood. Think of your heart as a pump that needs its own blood supply through coronary arteries—when one of these arteries gets blocked (usually by a blood clot), the heart muscle downstream doesn't get enough blood and dies.

In simple terms: One of the blood vessels supplying your heart is blocked, causing part of your heart muscle to die. This is serious and needs urgent treatment, but with prompt treatment, most people recover well.

Why does it matter?

A heart attack is a medical emergency that can cause death, heart failure, or dangerous heart rhythm problems if not treated promptly. Early recognition and prompt treatment (especially opening the blocked artery) are essential. The good news? With prompt treatment, most people recover well.

Think of it like this: It's like a pipe supplying your heart getting blocked—it needs to be opened urgently, but once it's open, most people recover well.

How is it treated?

1. Immediate Treatment (Most Important):

• Medicines: You'll get medicines immediately (aspirin, blood thinners, cholesterol medicine)
• Why: To prevent the clot from getting bigger and prevent new clots
• This is done first: Even before other treatments

2. Open the Blocked Artery (If STEMI):

• What: The doctor will open the blocked artery (usually with a procedure called angioplasty, or with a medicine that dissolves the clot)
• When: Usually within minutes to hours (the sooner the better)
• Why: To restore blood flow to your heart and prevent more damage
• How: Usually through a small tube in your wrist or groin

3. Additional Medicines:

• Other medicines: You'll get other medicines (beta-blocker, ACE inhibitor) if appropriate
• Why: To help your heart recover and prevent complications

4. Monitor and Support:

• Monitoring: You'll be monitored closely for complications (heart rhythm problems, heart failure)
• Support: You'll get support as needed

The goal: Open the blocked artery quickly, prevent complications, and help your heart recover.

What to expect

Recovery:

• Treatment: Usually starts immediately
• Hospital stay: Usually 3-5 days (longer if complications)
• Full recovery: Most people recover well, but it takes time

After Treatment:

• Medicines: You'll need to take medicines long-term (aspirin, blood thinners, cholesterol medicine, etc.)
• Lifestyle changes: You'll need to make lifestyle changes (stop smoking, healthy diet, exercise)
• Cardiac rehabilitation: You'll do cardiac rehabilitation (exercise, education)
• Follow-up: Regular follow-up to monitor your heart

Recovery Time:

• Acute phase: Usually days
• Full recovery: Usually weeks to months
• Long-term: Ongoing management, lifestyle changes

When to seek help

Call 999 (or your emergency number) immediately if:

• You have severe chest pain (especially if it's crushing, central, and doesn't go away)
• You have chest pain that radiates to your arm, jaw, or back
• You have chest pain with sweating, nausea, or breathlessness
• You feel very unwell
• You have symptoms that concern you

See your doctor if:

• You have chest pain that concerns you
• You have risk factors for heart disease and develop symptoms
• You have a known heart condition and develop new symptoms

Remember: If you have severe chest pain, especially if it's crushing, central, doesn't go away, or is associated with sweating, nausea, or breathlessness, call 999 immediately. A heart attack is serious, but with prompt treatment, most people recover well. Don't delay—time matters, and every minute counts.