Carcinoid heart disease: how to manage it. A practical guide for the clinician

Carcinoid heart disease is a main complication of carcinoid syndrome, in patients with metastatic small intestine neuroendocrine tumors. The pathophysiology of carcinoid heart disease is only partially understood, but chronic exposure to excessive circulating serotonin is considered one of the most important contributing factors. This hormone leads to the development of fibrous plaques, predominantly affecting the right side of the heart. The tricuspid and pulmonary valves are particularly involved, becoming thickened, retracted, and immobile, which results in regurgitation or stenosis. Carcinoid heart disease poses a significant diagnostic and therapeutic challenge for patients with neuroendocrine tumors and carcinoid syndrome, and is associated with increased morbidity and mortality. Generally, carcinoid heart disease manifests 2-5 years after the diagnosis of metastatic neuroendocrine tumor, but it can be diagnosed late as patients often remain asymptomatic for an extended period despite severe heart valve involvement. Managing carcinoid heart disease is complex and requires a multidisciplinary approach, including antitumor treatments, control of carcinoid syndrome, and surgical valve replacement for severe cases. However, cardiac surgery carries a high risk of mortality, mainly due to perioperative carcinoid crisis and right ventricular dysfunction. The timing of surgery is critical and must be determined on a case-by-case basis, balancing tumor progression, cardiac symptoms, and carcinoid syndrome control.