Ventricular fibrillation is often associated with which underlying condition?

Ventricular fibrillation is often associated with which underlying condition?

• A. Large myocardial infarction
• B. Pulmonary embolism
• C. Severe hypertension
• D. Hypothyroidism

Answer: (A)

Ventricular fibrillation is most tightly linked to acute ischemia from a large myocardial infarction because extensive damage to the ventricular myocardium creates marked electrical instability. When a large region of tissue is ischemic and necrotic, the normal orderly conduction is disrupted, generating heterogeneous conduction zones and re-entry circuits that produce chaotic, rapid, ineffective ventricular activity. This substrate makes the heart prone to VF, especially in the period around a major infarction when the risk of sudden electrical instability is highest.

Other conditions can cause cardiac arrest or different arrhythmias, but they’re not as classically associated with VF. Pulmonary embolism can lead to sudden collapse due to right heart strain and hypoxia, but VF is not the typical arrest rhythm in PE. Severe hypertension tends to cause hypertensive heart disease and can lead to other rhythm disturbances or heart failure rather than VF as the most common initial rhythm. Hypothyroidism more often predisposes to bradyarrhythmias and slowed conduction rather than the rapid, disorganized ventricular activity seen in VF.