QT dispersion (QT_d) is an indirect measure of the heterogeneity of ventricular repolarization and can be used as a risk factor for complex ventricular arrhythmias. We measured the effect of remifentanil on QT_d and heart-rate corrected QT dispersion (QT_cd).

Sixty ASA class I and II patients, who were between 20 and 60 years old, and who were scheduled for general anesthesia, were studied. After the patient entered the operating room, a 12 lead EKG recording was taken and intravenous infusion of remifentanil was started. The infusion rate was 0.1 µg/kg/min in group 1 and 0.2 µg/kg/min in group 2. Another EKG recording was taken 10 minutes after infusion had started.

In both groups, QT_d following remifentanil infusion was not significantly different than control values (76.6 ± 23.3 ms vs 81.8 ± 34.9 ms, P = 0.459 in group 1; 70.7 ms ± 29.7 ms vs 73.7 ms ± 37.1 ms, P = 0.734 in group 2). Neither was QT_cd: (83.2 ms ± 25.2 ms vs 89.6 ms ± 36.2 ms, P = 0.371 in group 1; 81.0 ms ± 35.2 ms vs 83.4 ms ± 40.9 ms, P = 0.829 in group 2).

Remifentanil infusion at a rate less than 0.2 µg/kg/min does not change QT_d or QT_cd.