Heart of the Matter: Syncope as a Rare Presentation of Lung Cancer Invading the Heart.

Syncope is common, affecting approximately 1 million Americans every year. Although multiple pathophysiological mechanisms regarding its etiology have been documented, neurocardiogenic or vasovagal syncope is the most common cause of these episodes. Other less appreciated etiologies include various cardiac abnormalities in which a structural, electrical, or obstructive disturbance leads to a temporary reduction in blood flow to the brain, resulting in transient loss of consciousness. Cardiac malignancies, while rare, can present with syncope by either disrupting the cardiac conduction apparatus or simply obstructing blood flow through the cardiac chambers. Electrocardiograms and echocardiography are often very helpful in identifying these abnormalities. Here, we report a rare case of late-stage invasive squamous cell carcinoma of the lung presenting with recurrent syncopal events. The cancer invaded the cardiac right atrium causing various dysrhythmias, leading to a very rare cause of cardiogenic syncope. We also discuss how lung cancer can present in a subclinical manner and at times without obvious respiratory symptoms, dramatic physical examination abnormalities, and/or thoracic imaging abnormalities on chest radiograph.