Electrocardiogram before starting stimulant medications: To order or not?

D is an 8-year-old boy brought to his paediatrician for evaluation. His mother is concerned as his teacher has been frequently complaining that he is very restless and often disturbs the rest of the class by getting up on some pretext or the other. He is unable to concentrate on his work and gets distracted very easily. He makes many careless mistakes and can hardly finish his tasks on time. He is frequently reprimanded for talking during class. He often answers out of turn or before the question has been completed; however, so far, he has been managing to get passing grades. At home, he is constantly on the go while he is awake. If he is forced to sit, like at mealtimes, he fidgets a lot. He also needs to be constantly nagged to do everything, even his daily activities such as brushing his teeth, or he forgets to do them or leaves them incomplete. He takes ages to finish his food. It is a major job to get him to do his homework. His mother says that at home he has been like that since the last 2 to 3 years, but now she is concerned because of the difficulties he is experiencing at school as well. After obtaining his medical history, examination, and getting response from parents and teachers - using Vanderbuilt Assessment Scales - the paediatrician diagnoses him to have attention deficit hyperactivity disorder. Besides behavioural interventions, he considers medications for his management. The paediatrician is debating the merits of performing electrocardiogram and/or referring the boy to a cardiologist before starting stimulant medications.