Metastatic carcinoid to the conducting system-is it a rare or merely unrecognized manifestation of carcinoid cardiopathy?

We report a unique case of carcinoid cardiopathy. The patient, a 59-year-old white woman with a known carcinoid tumor of the terminal ileum, presented with complete heart block and subsequently died. Because of her clinical presentation, we examined the conducting system at autopsy. The atrioventricular node was heavily infiltrated by metastatic carcinoid. The tumor was also seen in the surrounding atrial myocardium. No other metastatic lesions were seen in the heart. Carcinoid cardiopathy in the form of right-sided endocardial and valvular thickening has been well documented in the literature, and we found these features in our case as well. To our knowledge, carcinoid has never been documented in the cardiac conducting system until now. We found 2 cases of possible involvement of the conducting system reported in the literature. Unfortunately, the conducting system was not examined postmortem in either of these cases. If conducting system involvement is not unique to the present case, patients with metastatic carcinoid and cardiac problems may require different management. We hope that this case will stimulate further postmortem study of the conducting system in patients with metastatic carcinoid tumor.