1152
Of particular interest in this patient is the fluctuation of the QT interval at a stable dose of methadone, suggesting that a single normal electrocardiogram (ECG) does not guarantee that the patient is not at risk of ventricular arrhythmias.
 ( adverse event: at ,  this patient: Subject, fluctuation of the QT interval: Effect, a stable dose of methadone: Treatment, methadone: Treatment.Drug, a stable dose: Treatment.Dosage) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: adverse event,potential therapeutic event, Arguments type: Treatment.Disorder,Treatment.Time_elapsed,Treatment.Dosage,Subject.Race,Treatment.Drug,Treatment.Route,Subject.Disorder,Treatment.Freq,Treatment,Effect,Subject.Population,Treatment.Duration,Combination.Drug,Subject,Subject.Age,Subject.Gender. 
Text: {0} 
Answer:
 ( adverse event: at ,  this patient: Subject, fluctuation of the QT interval: Effect, a stable dose of methadone: Treatment, methadone: Treatment.Drug, a stable dose: Treatment.Dosage) 