Heart Rate Variability in Postoperative Patients with Nonfunctioning Pituitary Adenoma

BACKGROUND: Decreased heart rate variability (HRV) has been reported to be associated with cardiac autonomic dysfunction. Hypopituitarism in nonfunctioning pituitary adenoma (NFPA) is often linked to increased cardiovascular mortality. We therefore hypothesized that postoperative NFPA patients with hormone deficiency have an elevated risk of HRV alterations indicating cardiac autonomic dysfunction. METHODS: A total of 22 patients with NFPA were enrolled in the study. Between 3 and 6 months after surgery, a combined pituitary function test (CPFT) was performed, and HRV was measured. The period of sleep before the CPFT was deemed the most stable period, and the hypoglycemic period that occurred during the CPFT was defined as the most unstable period. Changes in HRV parameters in stable and unstable periods were observed and compared depending on the status of hormone deficiencies. RESULTS: In patients with adrenocorticotropic hormone (ACTH) deficiency with other pituitary hormone deficiencies, the low frequency to high frequency ratio, which represents overall autonomic function and is increased in the disease state, was higher (P=0.005). Additionally, the standard deviation of the normal-to-normal interval, which decreases in the autonomic dysfunction state, was lower (P=0.030) during the hypoglycemic period. In panhypopituitarism, the low frequency to high frequency ratio during the hypoglycemic period was increased (P=0.007). CONCLUSION: HRV analysis during CPFT enables estimation of cardiac autonomic dysfunction in patients with NFPA who develop ACTH deficiency with other pituitary hormone deficiencies or panhypopituitarism after surgery. These patients may require a preemptive assessment of cardiovascular risk.