Partial Agenesis of the Pericardium: A Rare Cause of Palpitations in a Young Adult.

Partial agenesis of the pericardium is a rare congenital anomaly in which part of the fibroelastic pericardial membrane is absent. Many patients remain asymptomatic, while others present with nonspecific symptoms such as palpitations, chest pain, or dyspnea. The rarity and variable presentation often delay diagnosis. We report a case of a male in his 30s who presented with intermittent palpitations, more pronounced during moderate exertion. Laboratory tests were largely unremarkable except for elevated triglycerides. Electrocardiogram (ECG) showed sinus rhythm with incomplete right bundle branch block. Chest radiography demonstrated leftward cardiac displacement and lucent areas suggestive of absent pericardium. Transthoracic echocardiography revealed normal ventricular function with paradoxical septal motion. Cardiac computed tomography confirmed partial absence of the pericardium, sparing a thin rim at the right antero-inferior aspect, with interposition of lung tissue between the aorta and pulmonary artery. A patient presenting with palpitations as the only symptom highlights the importance to consider pericardial agenesis in the differential diagnosis of unexplained palpitations. Awareness of its characteristic imaging features can prevent misdiagnosis, guide appropriate management, and reduce the risk of complications such as cardiac herniation.