ADHD meds tied to life-threatening heart problems in patients with long-QT syndrome

By Laura Newman

NEW YORK (Reuters Health) - Kids with the rare hereditary long-QT syndrome who are put on stimulants for attention deficit/hyperactivity disorder (ADHD) are at increased risk for cardiac events, according to a new study.

"We saw a signal," said Dr. Valentina Kutyifa from the Heart Research Follow-Up Program at the University of Rochester Medical Center in New York.

While more research is necessary, she told Reuters Health, "We need to use stimulants judiciously, only in kids with significant dysfunction, and in the lowest possible doses. Kids with long-QT syndrome also need to be followed closely."

The results appeared online July 6 in the Journal of Cardiovascular Electrophysiology.

Stimulants are known to counter beta-blocker therapy, which is essential for patients with LQTS. To see if stimulants increased the risk for cardiac events (syncope, aborted cardiac arrest, or long QTS-related sudden cardiac death) in this population, Dr. Kutyifa and colleagues followed patients in the Rochester LQTS Registry from 1979 to the present.

They identified 48 patients who had taken an approved stimulant (methylphenidate, dextroamphetamine/amphetamine, lisdexamfetamine, or dexmethylphenidate) or, in four cases, non-stimulant (atomoxetine or guanfacine) ADHD medication during follow-up, and 96 LQTS patients who had never been exposed to ADHD medications.

Patients in the ADHD-treatment group had a cumulative risk of cardiac events of 62%, compared to 28% in the matched LQTS control group (p<0.001). No difference in rates was seen for LQTS types 1-3.

ADHD medicines were also linked to a heart rate increase of 11 bpm at five years of follow-up.

"We cannot definitively answer the causation question of whether it is the ADHD medication that is exacerbating the clinical course of ADHD patients with LQTS or whether it is the ADHD condition itself since the matched control group did not have ADHD," the authors caution.

Dr. Kutyifa told Reuters that "another option" for safety would be to use nonstimulants. Even though she thinks further study is warranted, she added, "A prospective randomized controlled trial might not be feasible or ethical."

Dr. Davendra Mehta, a cardiologist at Mount Sinai School of Medicine in New York, praised the study.

"This is the first set of data from a group with lots of experience with long QT. It will increase awareness of the drugs and hopefully result in closer monitoring," he told Reuters Health.

However, he added, "There is a big range of QT reserve, from totally safe QT to serious. We will need more studies before practice changes. This is a single group study and very preliminary."

The researchers reported no disclosures.

SOURCE: http://bit.ly/1JhKt1U

J Cardiovasc Electrophysiol 2015.

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