Risk factors for the development and progression of carcinoid heart disease.

The development of valvular heart disease in patients with carcinoid syndrome is thought to be related to the secretion of vasoactive substances by a tumor. We sought to identify modifiable risk factors for the development of carcinoid heart disease because this may help define strategies to attenuate the disease process. Two hundred fifty-two patients with carcinoid syndrome were prospectively followed with serial echocardiograms at 6-month intervals. Clinical characteristics, biochemical markers, and radiologic markers were measured at set intervals. An echocardiographic scoring system was applied. Patients were defined as having progression of carcinoid heart disease if the echocardiographic score increased by ≥25%. After a median follow-up of 29 months, 44 patients developed carcinoid heart disease or had progression of existing valvular dysfunction. At time of progression of carcinoid heart disease compared to the previous 6 months, there was a significant increase in median levels of 5-hydroxyindoleacetic acid (5-HIAA; 791 vs 460.5 μmol/24 hours) and flushing episodes (4.5 vs 2 episodes per day). Independent predictors of the development or progression of carcinoid heart disease were a 5-HIAA level ≥ 300 μmol/24 hours and ≥ 3 episodes of flushing per day. 5-HIAA levels of ≥ 300 to 599, 600 to 899, and > 900 μmol/24 hours conferred 2.74, 3.16, and 3.40 times the risk of progression of carcinoid heart disease, respectively. In conclusion, a 5-HIAA level ≥ 300 μmol/24 hours and ≥ 3 flushing episodes per day are predictors of the development or progression of carcinoid heart disease.