Is the excess cardiovascular morbidity in pheochromocytoma related to blood pressure or to catecholamines?

BACKGROUND It is generally accepted that pheochromocytoma is associated with an increased cardiovascular risk. This is however not based on studies with an appropriate control group of patients with essential hypertension. AIM OF THE STUDY We examined whether patients with pheochromocytoma have an excess cardiovascular morbidity as compared to hypertensive patients. METHODS In a retrospective case-control study we reviewed the medical charts of 109 pheochromocytoma patients for cardiovascular events within 5 years prior to the diagnosis. These patients were matched to control patients with essential hypertension for gender and year of birth and diagnosis. Outcome variables were ischemic heart disease, cerebrovascular accidents, and transient ischemic attacks. Classical cardiovascular risk factors were also assessed. RESULTS A significantly higher rate of patients with pheochromocytoma suffered a cardiovascular event (13.8%; 95% confidence interval: 7.9%-21.6%) as compared to hypertensive patients (1.1%, 95% confidence interval: 0.1%-3.9%) (P < .001). Blood pressure level was lower in pheochromocytoma patients (153/91 ± 35/15 mm Hg) than in hypertensive patients (170/103 ± 18/8 mm Hg) (P < .001), even after correction for use of antihypertensive medication (P < .02). The difference in event rates could not be attributed to differences in other cardiovascular risk factors. CONCLUSIONS Pheochromocytoma patients have a clearly higher rate of cardiovascular events than patients with essential hypertension. This cannot be attributed to differences in blood pressure or other cardiovascular risk factors. The most likely explanation for the excess event rate is the prolonged exposure to the toxic effects of tumoral catecholamines. These data underpin the importance of a timely diagnosis and treatment of pheochromocytoma.