What is the most common lethal arrhythmia in the first hour of a myocardial infarction?

Ventricular fibrillation is recognized as the most common lethal arrhythmia that occurs in the first hour of a myocardial infarction. This arrhythmia is characterized by rapid, erratic electrical impulses that disrupt the heart's ability to pump blood effectively, ultimately leading to cardiac arrest if not treated immediately. During a myocardial infarction, the heart muscle suffers from a lack of oxygen due to blocked blood flow, and this can destabilize the heart's electrical system, resulting in ventricular fibrillation.

In the acute phase of a heart attack, the heart's ischemic tissue can trigger this dangerous rhythm, making prompt intervention crucial for survival. Defibrillation is often the required immediate action to restore a normal heart rhythm in patients experiencing ventricular fibrillation.