Complications of Myocardial Infarction 

1️⃣ Classification of MI Complications

A. Electrical

• Arrhythmias
• Conduction blocks
• Sudden cardiac death

B. Mechanical

• Papillary muscle rupture
• Ventricular septal rupture
• Free wall rupture
• LV aneurysm
• Cardiogenic shock

C. Ischemic

• Recurrent MI
• Post-infarct angina

D. Inflammatory

• Pericarditis
• Dressler syndrome

E. Thromboembolic

• LV thrombus
• Systemic embolism

2️⃣ Timeline-Based Approach 

3️⃣ Electrical Complications (Most Common Cause of Early Death)

A. Ventricular Arrhythmias

• Ventricular tachycardia (VT)
• Ventricular fibrillation (VF)

Most common within first 24 hours.

Mechanism:

• Ischemic myocardium → electrical instability
• Re-entry circuits
• Increased automaticity

Management:

• Immediate defibrillation (if VF/pulseless VT)
• Amiodarone
• Correct electrolytes (K⁺ > 4, Mg²⁺ > 2)

B. Conduction Blocks

More common in:

• Inferior wall MI → AV block
• Anterior wall MI → bundle branch blocks

High-grade AV block in anterior MI indicates large infarct and poor prognosis.

Management:

• Atropine (inferior MI)
• Temporary pacing (Mobitz II / complete heart block)

4️⃣ Mechanical Complications (High Mortality)

A. Papillary Muscle Rupture

Timing:

3–5 days post MI

Most commonly involved:Posteromedial papillary muscle
(Single blood supply from RCA)

Results in:Acute severe mitral regurgitation

Clinical Clues:

• Sudden pulmonary edema
• Hypotension
• New loud systolic murmur
• Flash pulmonary edema

Diagnosis:

• Urgent echocardiography

Management:

• Afterload reduction (nitroprusside)
• IABP
• Emergency surgery

B. Ventricular Septal Rupture (VSD)

Timing:

3–5 days

Pathology:

Septal wall necrosis → left-to-right shunt

Clinical:

• Sudden shock
• Harsh pansystolic murmur
• Biventricular failure

Diagnosis:

• Echo with Doppler
• Step-up in oxygen saturation in RV

Management:

• IABP
• Urgent surgical repair

C. Free Wall Rupture

Timing:

5–14 days

Leads to:

Hemopericardium → Cardiac tamponade → Sudden death

Clinical:

• Sudden collapse
• PEA arrest
• Pulsus paradoxus

Diagnosis:

• Echo → pericardial effusion

Management:

• Emergency pericardiocentesis
• Immediate surgery

Most common in:

• Elderly
• First MI
• No reperfusion therapy

D. Left Ventricular Aneurysm

Timing:Weeks to months

Features:

• Persistent ST elevation
• Heart failure
• Ventricular arrhythmias
• LV thrombus

True aneurysm:

• Wide neck
• Low rupture risk

Management:

• Anticoagulation (if thrombus)
• Surgical repair if severe HF

5️⃣ Cardiogenic Shock

Most common cause:Extensive LV infarction (>40%)

Mechanism:

• Severe LV dysfunction
• Low cardiac output
• Hypoperfusion

Clinical:

• SBP < 90 mmHg
• Cold extremities
• Oliguria
• Raised lactate

Management:

• Revascularization (primary PCI)
• Inotropes (dobutamine)
• Mechanical support (IABP/Impella)

6️⃣ Pericardial Complications

A. Early Fibrinous Pericarditis

Timing:
1–3 days

Cause:
Inflammation over necrotic myocardium

Features:

• Chest pain
• Pericardial friction rub

Treatment:

• High-dose aspirin

Avoid NSAIDs early post MI (interfere with healing)

B. Dressler Syndrome (Late)

Autoimmune pericarditis weeks after MI

Features:

• Fever
• Pleuritic chest pain
• Pericardial effusion

Treatment:

• Aspirin
• Colchicine

7️⃣ Thromboembolic Complications

LV Mural Thrombus

Most common in:Large anterior MI

Risk:

• Stroke
• Limb ischemia

Diagnosis:-Echo

Management:-Anticoagulation (3–6 months)

8️⃣ Recurrent Ischemia

• Reinfarction
• Post-infarct angina

Indicates:
Incomplete revascularization or stent thrombosis

9️⃣ Summary 

• Most common early cause of death → Ventricular fibrillation
• Most common mechanical complication → Papillary muscle rupture
• Most catastrophic complication → Free wall rupture
• Persistent ST elevation weeks after MI → LV aneurysm
• Sudden MR + shock on day 4 → Papillary rupture
• Sudden shock + loud murmur → VSD