Although progress in the medical and surgical management of patients with metastatic neuroendocrine tumors (NETs) has resulted in improved symptoms and survival, carcinoid heart disease (CHD) remains a major cause of morbidity and mortality among patients with carcinoid syndrome. CHD has been previously described in up to 50% of patients with carcinoid syndrome,1,2 although recent studies suggest the prevalence has fallen to approximately 20%,3,4 perhaps secondary to the more widespread use of somatostatin analog therapy. It is reported to occur most frequently in patients with primary small bowel NETs (72%), followed by NETs arising from the lung, large bowel, pancreas, appendix, and ovaries.1 A slight male predominance has been reported (approximately 60%), with a mean age at diagnosis 59 (
۱۱) years. Without treatment, the prognosis of CHD is poor, with 3-year survival as low as 31% (compared with 68% in patients with NETs but without CHD).1 CHD with advanced symptoms (New York Heart Association [NYHA] functional class III or IV) carries a particularly poor prognosis, with median survival only 11 months.5 Over the past few decades, however, the prognosis of patients with CHD has improved. In a retrospective series of 200 patients with carcinoid syndrome and CHD,6 the median survival improved from 1.5 years in the 1980s to 4.4 years in the late 1990s, with the data suggesting this improvement is related to increased rates of cardiac surgery and the use of somatostatin analogs.

PATHOPHYSIOLOGY

The pathogenesis of CHD is thought to be multifactorial and is not completely understood. A variety of vasoactive substances secreted by the tumor, including serotonin, prostaglandins, histamine, bradykinin, and other substances with fibroblast proliferative properties, such as tachykinins (substance P, neurokinin A, neuropeptide K) or transforming growth factor-beta, are thought to be involved in the disease pathogenesis.