Carcinoid Heart Disease: Prognostic Value of 5-Hydroxyindoleacetic Acid Levels and Impact on Survival – A Systematic Literature Review

Background Carcinoid heart disease (CHD) can develop in patients with carcinoid syndrome (CS), itself caused by overproduction of hormones and other products from some neuroendocrine tumours. The most common hormone is serotonin, detected as high 5-hydroxyindoleacetic acid (5-HIAA). This systematic literature review summarises current literature on the impact of CHD on survival, and the relationship between 5-HIAA levels and CHD development, progression and mortality. Methods MEDLINE, Embase, Cochrane databases and grey literature were searched using terms for CHD, 5-HIAA, disease progression, and mortality/survival. Eligible articles were non-interventional and included patients with CS and predefined CHD and 5-HIAA outcomes. Results Publications reporting on 31 studies were included. The number and disease states of patients varied between studies. Estimates of CHD prevalence and incidence among patients with a diagnosis/symptoms indicative of CS were 3-65% and 3-42%, respectively. Most studies evaluating survival found significantly higher mortality rates among patients with vs without CHD. Patients with CHD reportedly had higher 5-HIAA levels; median urinary levels in patients with vs without CHD were 266-1381 vs 67.5-575 micromol/24 h. Higher 5-HIAA levels were also found to correlate with disease progression (median progression/worsening-associated levels: 791-2247 micromol/24 h) and increased odds of death (7% with every 100 nmol/L increase). Conclusions Despite the heterogeneity of studies, the data indicate that CHD reduces survival, and higher 5-HIAA levels are associated with CHD development, disease progression and increased risk of mortality; 5-HIAA levels should be carefully managed in these patients.