A pericardial friction rub finding most strongly supports which condition?

• A. Pulmonary embolism.
• B. Aortic dissection.
• C. Myocardial infarction.
• D. Pericarditis.

Answer: (D)

Friction rub arises when inflamed pericardial surfaces rub together as the heart moves. That rubbing surface explains why a pericardial friction rub is a classic sign of pericarditis, indicating inflammation of the pericardial sac. The sound is a high-pitched, scratching quality heard best with the patient leaning forward, usually at the left lower sternal border, and it can occur during both systole and diastole. This finding points to pericardial involvement rather than other conditions such as pulmonary embolism, which presents more with acute pleuritic pain and dyspnea; aortic dissection, which features sudden, severe tearing chest pain and often unequal blood pressures; or myocardial infarction, whose hallmark is chest pain with characteristic ECG changes and troponin elevation rather than a pericardial rub. Thus, the pericardial friction rub most strongly supports pericarditis.