Loeffler's Cardiac Syndrome: An In-Depth Review of Pathophysiology, Clinical Manifestations, Diagnostic Strategies, and Management Approaches

Loeffler’s cardiac syndrome, a rare and often severe form of hypereosinophilic syndrome, is characterized by endomyocardial damage and restrictive cardiomyopathy secondary to eosinophilic infiltration and degranulation. This condition progresses through three distinct pathological phases: an acute necrotic stage, a thrombotic stage, and finally, an endomyocardial fibrotic stage, leading to significant cardiac dysfunction. The pathophysiological underpinnings are driven by eosinophil-mediated cytotoxicity, resulting in cardiac inflammation, endomyocardial fibrosis, and subsequent heart failure manifestations. Clinical presentation varies based on the disease stage, ranging from nonspecific symptoms like fatigue and fever to advanced signs of congestive heart failure, thromboembolic events, or restrictive cardiomyopathy. The diagnosis of Loeffler’s cardiac syndrome requires a high index of suspicion, particularly in patients with persistent eosinophilia, and relies on multimodal imaging techniques, including echocardiography and cardiac magnetic resonance imaging (MRI), coupled with laboratory studies and endomyocardial biopsy when indicated. Current treatment strategies focus on eosinophil-lowering therapies, including corticosteroids and cytotoxic agents, to prevent progression to irreversible fibrosis. In cases with established cardiac damage, therapeutic options may extend to surgical interventions, heart transplantation, or advanced heart failure management. This review synthesizes the latest insights into the pathophysiology, clinical features, diagnostic approaches, and therapeutic modalities of Loeffler’s cardiac syndrome, emphasizing the importance of early recognition and tailored intervention to optimize patient outcomes.