Post-Myocardial Infarction Arrhythmia: Leading Cause of Early Mortality

Fatal arrhythmia (primarily ventricular fibrillation/tachycardia) is the most common cause of death within the first hours to days after acute myocardial infarction (MI).

Mechanism

• Ischemic myocardium develops electrical instability.
• Scar tissue creates reentrant circuits.
• Autonomic imbalance (sympathetic surge) lowers fibrillation threshold.
• Electrolyte shifts (K⁺, Mg²⁺) exacerbate instability.

High-Risk Period

• First 48 hours: Highest VF risk.
• First 30 days: Elevated sudden cardiac death risk.

Prevention Strategies

• Early reperfusion: PCI or fibrinolysis restores flow, reduces ischemic burden.
• Beta-blockers: Reduce sympathetic drive, mortality benefit.
• ACE inhibitors/ARBs: Prevent remodeling.
• Mineralocorticoid receptor antagonists: In reduced EF.
• ICD implantation: For EF ≤35% after 40 days post-MI (per guidelines).
• Electrolyte monitoring/repletion.

Continuous cardiac monitoring in CCU for 24–48h post-MI is standard for early arrhythmia detection and treatment.