Supraventricular Tachycardia as an Initial Manifestation of Malignancy-Related Cardiac Invasion: A Case Report.

Cardiac tumors are exceedingly rare, with metastatic lesions occurring more frequently than primary tumors. These tumors generally present with non-specific symptoms, reflecting tumor location and invasion of adjacent structures, and diagnosis is frequently incidental. A 66-year-old male smoker presented with hemoptysis and weight loss. Echocardiography revealed external invasion and compression of the left atrium by a left lung mass. His hospital course was complicated by recurrent supraventricular tachycardia (SVT). CT imaging showed a necrotic lung mass infiltrating the left atrium and pericardium, and biopsy confirmed invasive pulmonary adenocarcinoma. Atrial tachyarrhythmias via direct malignancy-related cardiac infiltration as an initial presentation of cancer are exceedingly rare and can significantly delay diagnosis and treatment due to vague symptoms. However, this entity can lead to life-threatening arrhythmia, underscoring the importance of early diagnosis and management. This case highlights the importance of considering malignancy-related cardiac invasion in patients with underlying malignancy with new-onset arrhythmias, as with our case with pulmonary adenocarcinoma and potentially life-threatening SVT through direct pericardial and atrial infiltration and involvement.