Circulating plasma and platelet 5-hydroxytryptamine in carcinoid heart disease: a pilot study

Area of Science:

• Cardiology
• Endocrinology
• Oncology

Background:

• Carcinoid heart disease (CaHD) is a rare valvular complication of carcinoid syndrome (CS).
• The precise role of 5-hydroxytryptamine (5-HT) in CaHD pathogenesis remains unclear.
• Investigating the association between 5-HT levels and valvular dysfunction is crucial.

Purpose of the Study:

• To evaluate the association between platelet 5-HT (5-HTplt) and plasma 5-HT (5-HTpls) levels and valvular dysfunction in CaHD.
• To compare 5-HT levels in patients with CaHD, CS, and healthy controls.

Main Methods:

• Recruitment of 12 CaHD patients, 18 CS patients, and 10 healthy controls.
• Cardiac catheterization and echocardiography performed on CaHD patients.
• Blood sampling for 5-HTplt and 5-HTpls from multiple venous sites (femoral, right heart, left ventricle, antecubital fossa).

Main Results:

• Significantly elevated 5-HTpls and 5-HTplt in CaHD and CS patients compared to controls (p < 0.0001 and p = 0.003).
• Increased 5-HTplt and 5-HTpls detected from femoral vein to the right heart (p = 0.007 and p = 0.0002).
• No significant difference in 5-HT levels between the right and left heart sides.

Conclusions:

• Elevated plasma and platelet 5-HT levels are confirmed in CaHD patients.
• Heterogeneous valvular dysfunction development occurs despite similar intracardiac 5-HT exposure.
• Individual heart valve susceptibility, not solely 5-HT levels, likely dictates valvular dysfunction.