Supplementary Material for: Carcinoid Heart Disease and a Complicated Course of Progressive Gastroenteropancreatic Neuroendocrine Neoplasia: A Case Report

Introduction: Gastroenteropancreatic neuroendocrine tumours (GEP-NETs) are a relatively rare, heterogenous group of malignancies originating from secretory cells of the neuroendocrine system. Carcinoid syndrome is a complication of neuroendocrine tumours, characterized by a triad of flushing, bronchospasm, and diarrhoea. This is due to the release of serotonin and other vasoactive substances by the tumour. Elevated levels of serotonin can also cause fibrotic changes in the structures of the heart, which can lead to cardiac complications termed carcinoid heart disease. We report the case of a 64-year-old man diagnosed with carcinoid heart disease 19 years after his initial diagnosis of grade 2 GEP-NET with liver metastases. Case Presentation: The patient presented with symptoms of shortness of breath, lower limb swelling, abdominal swelling, and chest pain. He was on treatment with subcutaneous lanreotide 120 mg twice weekly prior to admission. An echocardiogram showed moderate tricuspid regurgitation and mitral regurgitation but preserved left ventricular systolic function, consistent with right heart failure. A CT pulmonary angiogram showed a small volume left lingula pulmonary embolism with bilateral pleural effusions and stable pericardial effusion with evidence of right ventricular strain. The patient was started on IV furosemide 40 mg twice daily, SC octreotide 100 μg three times daily, and therapeutic tinzaparin. The patient was discharged following successful diuresis. Conclusion: This case report highlights the importance of regular echocardiogram and cardiovascular checkups in patients with carcinoid tumours and liver metastases. A multidisciplinary approach involving medical oncologists, cardiothoracic surgeons, and cardiologists is vital in ensuring early treatment and preventing late-stage complications of carcinoid heart disease.