A 52-year-old man with a 25-year history of alcohol dependence presents to the emergency department with tremors, diaphoresis, and autonomic hyperactivity 18 hours after his last drink. Which is the most common cause of mortality in alcohol withdrawal syndrome?

Explanation

## Most Common Cause of Mortality in Alcohol Withdrawal **Key Point:** Cardiac arrhythmias due to electrolyte disturbances (particularly hypomagnesaemia, hypokalaemia, and hypophosphataemia) are the leading cause of death in alcohol withdrawal syndrome, not seizures. ### Pathophysiology of Withdrawal-Related Arrhythmias 1. **Magnesium depletion** — chronic alcohol use impairs renal reabsorption and GI absorption; Mg²⁺ is critical for cardiac conduction stability 2. **Potassium and phosphate depletion** — contribute to prolonged QT interval and torsades de pointes 3. **Sympathetic hyperactivity** — catecholamine surge increases myocardial irritability 4. **Direct cardiotoxic effects** — alcohol cardiomyopathy predisposes to re-entrant arrhythmias ### Why Seizures Are Not the Leading Cause of Death **Clinical Pearl:** While seizures occur in 5–15% of patients undergoing alcohol withdrawal and are a medical emergency requiring immediate benzodiazepines, they are self-limited in most cases. Death from seizures alone is rare; mortality is usually from concurrent arrhythmias or aspiration during seizure activity. ### Mortality Risk Stratification | Complication | Frequency | Mortality if Untreated | Primary Mechanism | |---|---|---|---| | Seizures | 5–15% | Low (unless status epilepticus) | GABA↓, glutamate↑ | | Cardiac arrhythmias | 10–20% | **Highest** | Electrolyte depletion + sympathetic surge | | Delirium tremens | 1–5% | Moderate (5–15%) | Autonomic instability + complications | | Aspiration pneumonia | Variable | Moderate | Seizure-related or altered consciousness | **High-Yield:** The classic teaching is "seizures are the most feared complication" — but epidemiologically, **arrhythmias kill more patients**. This distinction is heavily tested in NEET PG. ### Management Implications - **Aggressive electrolyte repletion** (Mg²⁺, K⁺, PO₄³⁻) is as critical as benzodiazepines - **ECG monitoring** mandatory in moderate–severe withdrawal - **Thiamine + glucose** to prevent Wernicke's encephalopathy (separate from withdrawal mortality but part of the syndrome) **Mnemonic:** **CRASH-B** (Complications of alcohol withdrawal): - **C**ardiac arrhythmias (most common cause of death) - **R**enal dysfunction (from dehydration) - **A**spiration (from seizures/altered consciousness) - **S**eizures (medical emergency, but not the leading cause of death) - **H**ypertension / **H**yperglycaemia - **B**enzodiazepines (treatment) [cite:Harrison 21e Ch 391]