BOCA RATON, FLA. -- The use of methylphenidate or mixed amphetamine salts for attention-deficit/hyperactivity disorder can increase heart rate, blood pressure, and the QT interval in children, adolescents, and adults, according to a review of placebo-controlled and open-label extension trials published since 2000.
The magnitude of the effects appears small for most patients, which points to the importance of screening for preexisting cardiovascular disease and asking about any relevant family or patient history, Dr. Raul R. Silva said.
Despite long-term use and the effectiveness of these stimulant medications to reduce core symptoms of ADHD, concerns arose about increased potential for cardiovascular events. The American Heart Association released guidelines for cardiac monitoring of all children with ADHD before treatment (Circulation 2008;117:2407-23). "Some of what they came out with was severe," said Dr. Silva, vice chair of the department of child and adolescent psychiatry at New York University. For example, he pointed out, the American Academy of Pediatrics said it had to temper its recommendations (Pediatrics 2008;122:451-3).
Ultimately, the two organizations released a clarification statement that recognizes the need for responsible cardiovascular monitoring while not withholding these medications to treat ADHD, Dr. Silva said (J. Dev. Behav. Pediatr. 2008;29:335). Despite the joint clarification, confusion about the actual risks remains, Dr. Silva said.
To determine more, Dr. Silva and his colleagues identified and reviewed five double-blind, placebo-controlled studies and six open-label studies that reported relevant cardiovascular data.
"We looked at 10 years' worth of studies in children and adults that reported heart rate, blood pressure, and EKG changes," Dr. Silva said in an interview at his poster presentation during the meeting, which was sponsored by the National Institute of Mental Health.
Both types of studies were included because double-blind, placebo-controlled studies "are so short, there is not always a clear picture" and because "long-term studies tend to be open label," said Dr. Silva, who also has a private practice in Cresskill, N.J.
In the double-blind studies, mean heart rate increased by 1-8.5 beats per minute after 3-6 weeks of treatment. The percentages of patients who experienced predefined, "clinically notable" heart rate events were similar among groups who received methylphenidate (MPH), mixed amphetamine salts (MAS), or placebo. Significant increases of 1.5-4.4 bpm in mean heart rate were reported by most of the long-term, open-label extension studies. A comparison of the short-term and long-term studies does not suggest an accumulative risk, Dr. Silva said. He added that it is unclear whether long-term increases in heart rate associated with these stimulants could increase the risk for stroke, heart attacks, or dysrhythmias. …