Abstract 4367739: Silent Infiltration: Asymptomatic Cardiac Metastasis from Primary Lung Adenocarcinoma

Introduction: Cardiac metastases are more common than primary cardiac tumors and typically indicate poor prognosis. Lung, breast, melanoma, and lymphoma are the most frequent primary sources. Lung cancer involves the heart in only 8–10% of cases, often asymptomatically. Among nonsmokers, non-small cell lung cancer (NSCLC) particularly adenocarcinoma is most common and usually spreads to the pleura due to its peripheral origin. Intracardiac metastases, especially to the myocardium, are rare. We report a case of incidental left ventricular myocardial metastasis discovered during evaluation for syncope. Case Presentation: A 76-year-old woman with a significant smoking history presented with dizziness. Evaluation for syncope revealed normal orthostatic vitals and electrolytes. Electrocardiogram showed sinus bradycardia (heart rate 48 bpm) without QTc prolongation. Non-contrast CT of the head and CT angiography of the head and neck were unremarkable. Chest X-ray demonstrated left upper lobe atelectasis. Contrast-enhanced CT of the chest revealed bronchial obstruction in the left upper lobe and multiple pulmonary nodules in the right lung. Bronchoscopy identified a fungating mass obstructing the left upper lobe bronchus; biopsy confirmed adenocarcinoma. Transthoracic echocardiogram showed preserved left ventricular ejection fraction (60–65%), concentric hypertrophy, and grade I diastolic dysfunction. Cardiac MRI revealed a 3 cm mass along the basal anterior wall of the left ventricle with heterogeneous T2 signal intensity, consistent with myocardial metastasis. With a diagnosis of adenocarcinoma, the patient was advised to follow up as an outpatient for further oncologic management and advanced cardiac imaging. Discussion: This case highlights an incidental myocardial metastasis from lung adenocarcinoma in a patient presenting with bradycardia and dizziness, symptoms that may be related to cardiac involvement. While pericardial metastases are more common, myocardial infiltration is rare and often asymptomatic. Cardiac spread may occur via hematogenous, lymphatic, or transvenous routes and can present with arrhythmias, effusions, or hemodynamic compromise. Echocardiography is useful for initial evaluation, but cardiac MRI provides superior detail in assessing lesion characteristics and differentiating tumor from thrombus. Multimodal imaging plays a key role in identifying occult cardiac metastases that may impact clinical management.