The risk for adverse cardiac events in subjects between 3 and 20 years of age treated with methylphenidate or amphetamine salts for ADHD was determined in a retrospective study at University of Florida, Gainesville, FL. Cardiac events were defined as first ED visit for cardiac disease or symptoms. The percentage of patients observed for at least 6 months on stimulants was similar for MPH (54.5%) and amphetamines (52.6%). A total of 456 youth visited the ED for cardiac reasons during 52,783 years of follow-up. The risk for cardiac ED visits was similar among current users of MPH or amphetamines. Periods of former use had a similar risk in subjects exposed. Variables showing positive associations with ED visits with both models were use of bronchodilators, use of antidepressants, antipsychotics at age 15 and older, congenital anomalies, and history of circulatory disease or cardiac symptoms. 
COMMENT. Spontaneous reports of adverse drug reactions to the FDA show a higher risk of cardiac events with amphetamines than methylphenidate. (FDA News;March 14, 2007). The above authors report a 20% increased risk for ED visits for cardiac symptoms for all stimulants combined . The present study did not confirm the previous report that amphetamines might carry a higher risk of adverse cardiac events than MPH. Further long-term population-based studies are indicated to define the risks of stimulant-induced serious heart events and the prophylactic utility of routine electrocardiograms before and during treatment.