Arrhythmias and conduction abnormalities occur in 12% to 20% of patients admitted to medical or surgical intensive care units (ICUs), which increase morbidity and mortality. New-onset arrhythmias affect about 7% of patients following major noncardiothoracic surgery and up to 60% of patients post cardiac surgery. Atrial fibrillation (AF) is the most common postoperative arrhythmia occurring in 10% to 15% patients with critical illness, about 10% of patients undergoing noncardiac surgery, and up to 42% patients undergoing cardiac surgery.

In this chapter, we review the classification, etiology, and treatment of the arrhythmias most frequently encountered in critical care medicine.