Pericardial decompression syndrome after small-volume pericardiocentesis: A case report when even less is too much

Pericardial decompression syndrome (PDS) is a rare but potentially life-threatening complication following pericardial drainage, typically associated with large-volume effusion removal of more than 1 liter within 1 hour. We report the case of a 62-year-old man with metastatic thymic carcinoma and severe mitral regurgitation who developed acute pulmonary edema and transient left ventricular dysfunction following pericardiocentesis. Despite draining only 600 mL of pericardial fluid, the patient developed respiratory failure, pulmonary edema and required mechanical ventilation. Echocardiography revealed a drop in ejection fraction and elevated filling pressures. Prompt recognition and supportive management, including diuresis and intensive care monitoring, led to full recovery of cardiac function within days. This case highlights that PDS may develop even after small-volume pericardial drainage in patients with compromised cardiac reserve. Proposed mechanisms include preload-afterload mismatch, myocardial stunning, and adrenergic withdrawal. Awareness, early diagnosis, and careful pericardial fluid removal are key to preventing and managing PDS even in draining samll amount especially with underlying structural heart disease or baseline reduced left ventricular function. • Pericardial decompression syndrome (PDS) is a rare but potentially life-threatening complication of pericardiocentesis. • While PDS is typically associated with rapid or large-volume drainage, this case demonstrates its occurrence even after moderate-volume (600 mL) pericardial fluid removal. • Underlying cardiac abnormalities—such as severe mitral regurgitation—may predispose patients to PDS, regardless of the volume drained. • Prompt recognition and ICU-level supportive care led to full recovery of left ventricular function and resolution of pulmonary edema in this case. • This case underscores the importance of cautious fluid removal and close post-procedure monitoring, even in apparently hemodynamically stable patients.