A 52-year-old man with acute myocardial infarction is in cardiac arrest. After 8 minutes of high-quality CPR, the rhythm is found to be pulseless electrical activity (PEA). Which feature best distinguishes PEA from asystole during resuscitation?

## Distinguishing PEA from Asystole ### Electrocardiographic Hallmark **Key Point:** PEA is defined by the presence of organized electrical activity on the monitor WITHOUT a palpable pulse, whereas asystole shows a flat line (absent electrical activity). ### Comparison Table | Feature | PEA | Asystole | | --- | --- | --- | | **ECG appearance** | Organized complexes (sinus rhythm, bradycardia, or narrow-complex rhythm) | Flat line / no electrical activity | | **Mechanical activity** | Absent (no pulse despite electrical activity) | Absent | | **Prognosis** | Slightly better if reversible cause found | Generally poor | | **Management** | Treat underlying cause (hypovolemia, tension pneumothorax, etc.) | CPR + epinephrine; consider termination | | **Defibrillation** | Not indicated | Not indicated | ### Clinical Pearl **Clinical Pearl:** PEA is a "mechanical problem masquerading as an electrical problem." The heart has electrical activity but cannot generate a pulse — look for reversible causes (the 4 H's and 4 T's: Hypovolemia, Hypoxia, Hydrogen ion [acidosis], Hyperkalemia; Tension pneumothorax, Tamponade, Thromboembolism, Toxins). ### High-Yield Mnemonic **Mnemonic:** **PEAT** — **P**EA has **E**lectrical activity (organized); **A**systole has **A**bsent activity (flat line). **T**reat the underlying cause in PEA. ### Management Implication **High-Yield:** In PEA, the key is rapid identification and reversal of the underlying cause (e.g., needle decompression for tension pneumothorax, fluid bolus for hypovolemia) rather than defibrillation or escalation of epinephrine dose alone.