Guest blog by Jeffrey W. Skimming, MD, and Jorge McCormack, MD
Attention-deficit hyperactivity disorder (ADHD) is a common neurobehavioral problem that is often treated with stimulants such as methylphenidate and mixed amphetamine salts. Despite their efficacy and long history of use, concerns regarding their potential for adverse cardiovascular effects in children and adolescents with ADHD regularly receive ongoing public attention.Stimulants can increase blood pressure, heart rate and measures of ventricular repolarization (QT interval) on the electrocardiogram (ECG). Also, in some retrospective studies, stimulants have been associated with a higher risk of sudden death in children. However, recent studies have shown no such association, nor has a causative link been established.
On the other hand, leaving ADHD untreated in patients without cardiac risk factors clearly increases morbidity. In young adults, leaving ADHD untreated corresponds with lower school performance, a higher risk for motor vehicle accidents, and a higher prevalence of substance abuse. In older adults, leaving ADHD untreated corresponds with employment difficulties and higher rates of marital problems.
Thus, from a cardiovascular safety perspective, prescribing physicians shouldn’t withhold stimulants from patients with ADHD and without heart disease. In those patients known to have heart problems, the prescribing physicians commonly consult with the patient’s cardiologist when considering the use of stimulants. Both the American Heart Association (AHA) and American Academy of Pediatrics (AAP) recommend careful cardiac evaluations of all children who have a history of cardiac disease and are being considered for stimulant therapy, and referral to a pediatric cardiologist if cardiac problems are suspected.
There is controversy about whether an ECG should be obtained before ADHD treatment. The most recent clarification of the joint guidelines between the American Academy of Pediatrics and the American Heart Association state:
“Acquiring an ECG is a Class IIa recommendation. This means that it is reasonable for a physician to consider obtaining an ECG as part of the evaluation of children being considered for stimulant drug therapy, but this should be at the physician’s judgment, and it is not mandatory to obtain one.”
However, interpreting the ECG, or determining what to do with the result can be tricky. The most common concern is whether the QT interval is long enough to require stopping (or never starting) stimulant medication.
If a patient is already taking a stimulant, then allowing for an expected prolongation seems reasonable. In drug trials, a corrected QTc of greater than 500ms or an increase of greater than 60ms over baseline are commonly used thresholds to consider stopping administration of a drug. In the absence of other formal guidelines, it seems reasonable to apply these industry guidelines to thresholds for patients who may already be taking stimulants.
Take Home Points:
- ECG screening is not mandatory for patients without cardiac risk factors, yet doing so should be considered when ECG testing and interpretation are readily available and not thought to be cost-prohibitive.
- Those patients with an exam or history suggestive of cardiac problems should be evaluated by a pediatric cardiologist (preferably before stimulant therapy is started).