Objective:

Existing myocardial damage in coronary artery disease patients causes prolonged QT syndrome. The primary objective of this trial is to explore the effects of different doses of the muscle relaxant agent rocuronium (0.6 mg kg-1 and 1.2 mg kg-1) on QTc following anaesthetic induction. The second objective is to determine the incidence and kinds of arrhythmias.

Methods:

In this prospective and randomized trial, patients undergoing elective coronary artery revascularization surgery were included in one of two groups. Both groups took the same anaesthetic induction agents: midazolam and fentanyl. Rocuronium was administered in Group 1 (n=20) with dose of 0.6 mg kg-1 and in Group 2 (n=20) with a dose of 1.2 mg kg-1 for muscle relaxation. Heart rate, average arterial pressure and QTc were recorded before induction (T0), after induction (T1), after muscle relaxant (T2), and 2 minutes (T3) and 5 minutes after intubation (T4).

Results:

QTc was significantly longer 2 minutes after intubation (in Group 1 and Group 2, respectively, 447.9±28.3 and 466.1±37.8 ms) than at the beginning (respectively, 426.9±25.7, 432.0±35.5 ms) (p<0.01). In the intergroup comparison, average QTc values were similar in all trial periods (p>0.05). The prevalence of arrhythmias in between Group 1 (35%, n=7) and Group 2 (15%, n=3) was similar (p=0.06). Arrhythmias were recorded 2 minutes after intubation in both groups (n=10, 25%).

Conclusion:

In patients undergoing coronary artery revascularization surgery, rocuronium doses of 0.6 mg kg-1 and 1.2 mg kg-1 prolong the QTc interval after intubation. Cardiac arrhythmias related to long QTc arising after intubation should be taken into consideration.

Keywords: Rocuronium, QTc, coronary artery disease