Objective: To investigate whether parathyroidectomy (PTx) reverses risk factors for arrhythmias related to the QT dynamic changes evaluated during bicycle ergometry exercise test (ET). Methods: Twenty-four postmenopausal women with primary hyperparathyroidism (PHPT) (mean age 60.0G8.4 years) and 30 sex-and age-matched controls underwent ET, echocardiography, and biochemical evaluation. The following stages were considered during ET: rest, peak exercise, and recovery. The patients were randomized to two groups: 12 underwent PTx (group A) and 12 were followed-up conservatively (group B). After 6 months, the patients were studied again. Results: Groups A and B showed no differences in mean baseline biochemical values, echocardiographic parameters, and QTc interval. PHPT patients showed an increased occurrence of ventricular premature beats (VPBs) during ET compared with controls (37.0 vs 6.6%, PZ0.03). Serum calcium level was a predictor of VPBs (PZ0.05). Mean value of QTc was in the normal range at baseline (group A: 401G16.9; group B: 402.25G13.5 ms) but significantly lower than controls (417.8G25.1 ms, P!0.01). A negative correlation was found between QTc and calcium values (PZ0.03). Physiological reduction of QTc interval from rest to peak exercise was not observed in PHPT patients before surgery. After PTx, group A had a significant reduction in VPBs compared with baseline (at baseline, 5 of 12 vs none of 12 patients after PTx, PZ0.03) and a restored normal QT adaptation during ET. Group B showed no significant changes after a 6-month period. Conclusions: PTx reduces the occurrence of VPBs and restored the QTc adaptation during ET.

Our pilot study suggests that there is no direct acute effect of ZA on kidney function. The increase in plasma MCP-1 and serum IL-18 concentration could be associated with the stimulation of immunity mechanisms occurring soon after the administration of the drug. Secondary hyperparathyroidism develops shortly after the infusion of ZA and is maintained even after 1 month.

There have been recent concerns regarding the risk of serious adverse events, such as cardiac dysrhythmia and atrial fibrillation (AF), associated with bisphosphonate use in osteoporosis. This open-label, non-randomized, crossover pilot study evaluated short-term effects of zoledronic acid and placebo on the occurrence of cardiac dysrhythmias and prodysrhythmic profile in postmenopausal women with osteoporosis and low risk of cardiac dysrhythmias. Fifteen postmenopausal women (mean age 70.7 ± 6.9 years) with osteoporosis received placebo infusion on day 1 and zoledronic acid 5 mg on day 7. Standard 12-lead resting EKG measured QT parameters at baseline and up to 24 h after infusion. Continuous 24-h EKG assessed dysrhythmic events and heart rate variability (HRV) for 24 h after infusion. There were no statistically significant differences in resting EKG parameters between placebo and zoledronic acid: QTc (404.28 ± 9.28 and 410.63 ± 18.43 ms), no significant differences in mean serum electrolytes at baseline and after infusion, and no significant association between QT/QTc parameters and serum electrolytes before and after each infusion (QTc: 401.83 ± 17.73 for zoledronic acid and 404.65 ± 16.79 for placebo). There was no significant difference in HRV parameters between placebo and zoledronic acid, and no dysrhythmias were recorded at rest or with 24 h EKG monitoring. Zoledronic acid does not produce dysrhythmia or prodysrhythmic effects in the short term. Among possible mechanisms proposed for cardiac dysrhythmias with zoledronic acid, no serum electrolyte or autonomous nervous system balance perturbations have been reported.