Duration of the surgery and age are risk factors for QTc interval prolongation under general anesthesia with volatile anesthetics

Background: Prolongation of the QT interval signals disordered cardiac repolarization which poses a significant risk to patients undergoing surgical procedures under anesthesia. Methods: This study analyzed the demographic, clinical, and pharmacological factors in relation to QT interval prolongation under different types of anesthesia. This prospective observational study compared demographic characteristics, clinical and pharmacological factors from patients who demonstrated a prolonged QTc interval under GA (general anesthesia) and in those who had QTc interval prolongation while receiving RA (regional) or MAC (monitored anesthesia care). Results: Duration of surgery correlated strongly with QTc interval prolongation in patients who were exposed to volatile anesthetics (r=.228, p=.010), but not in patients who received RA/MAC (r=.121, p=.444). Likewise, older patients were more likely to experience QTc interval prolongation only when they were exposed to volatile anesthetics (r=.190, p=.033), but not in patients who received RA/MAC (r=.019, p=.906). Perioperative use of insulin correlates strongly with QTc interval prolongation in patients who were exposed to volatile anesthetics (F=4.567, p=.035), but not in patients who received RA/MAC (F=1.372, p=.248). Perioperative use of antiemetic (serotonin inhibitors, steroids and metoclopramide), and beta-blockers did not have any significant effect on the QTc interval change. Conclusions: Our results show that the duration of exposure to volatile anesthetics is the most important predictor of postoperative QTc interval prolongation. Volatile anesthetic agents cause greater QTc interval prolongation in older patients who had longer surgery.