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A1020
October 11, 2014
1:00 PM - 2:30 PM
Room Room 244
A High-Fidelity Analysis of Perioperative QTc-Prolongation in General, Spinal, and Local Anesthesia
Andreas Duma, M.D., Swatilika Pal, M.B., B.S., M.S., Daniel L. Helsten, M.D., Phyllis K. Stein, Ph.D., Peter Nagele, M.D., M.Sc.
Washington University of St. Louis, Saint Louis, Missouri, United States
Background: Prolongation of the QTc-interval indicates abnormal cardiac repolarization. In the perioperative setting, several drugs have been individually shown to cause QTc prolongation, and a recent study has shown that postoperative QTc prolongation is common. However, it is unknown whether QTc prolongation is an isolated postoperative phenomenon or occurs regularly during surgery, and if the type of anesthesia influences its incidence.

Methods: To answer this question, we conducted a prospective cohort study (n=300) where QTc duration was continuously recorded by 12-lead Holter ECG from 30 minutes preoperatively to up to 60 minutes postoperatively. QTc prolongation was compared between adult patients undergoing general (n=101) or spinal anesthesia (n=99) for orthopedic surgery, or local anesthesia for biopsy (n=53) or diagnostic coronary angiography (n=47). Primary outcome was the intraoperative QTc increase (ΔQTc, as defined by the intraoperative-to-preoperative QTc duration difference). The incidence of long QTc (LQTc) episodes (QTc > 500 ms for at least 15 minutes) was determined. P-values were adjusted for multiple comparisons.

Results: Significant QTc prolongation occurred during general (33 ms [22 to 46 ms] (median [IQR]) and spinal (22 ms [12 to 29 ms]) anesthesia, whereas no QTc prolongation was observed during local anesthesia (biopsy, 4 [-4 to 7] ms; coronary angiography: 6 [-5 to 16] ms) (fig. 1). Categorical data shows that ΔQTc > 60 ms occurred in the general anesthesia cohort only (fig. 2).The median [IQR] QTc duration in the preoperative, intraoperative, and postoperative period was (fig. 3): 430 [413-446] ms, 464 [445-483] ms, and 447 [434-465] ms in the general anesthesia cohort (fig. 3, red); 438 [425-450] ms, 457 [446-473] ms, and 461 [444-476] ms in the spinal anesthesia cohort (fig. 3, green); 421 [408-434] ms, 420 [411-437] ms, and 421 [408-437] ms in the local anesthesia for biopsy cohort (fig. 3, blue); 448 [422-475] ms, 454 [431-476] ms, and 450 [428-475] ms in the local anesthesia for coronary angiography cohort (fig. 3, purple). The relative incidence risk (RR) for an LQTc episode was 5.3 [95% CI: 0.7 to 43.0] times higher with general anesthesia than with spinal anesthesia.

Conclusion: These results indicate that QTc prolongation is not an isolated postoperative phenomenon and is common during surgery under general and spinal anesthesia.
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