Abstract

Objective: Children with attention deficit and hyperactivity disorder (ADHD) may have an increased risk of cardiovascular complications due to reduced vagal tone and increased heart rate (HR). Methylphenidate (MPH) is a frequently used drug, and its sympathomimetic effects often cause pediatricians to be concerned when making diagnostic and treatment decisions. We aimed to assess the effects of MPH on the cardiovascular system and autonomic activity of the heart using heart rate variability (HRV) in ADHD patients.

Methods: We retrospectively analyzed physical examination, blood pressure (BP), and 24-hour Holter monitoring in 33 patients (9.7±2.6 years) and 36 healthy subjects (9.54±2.8 years). The results of the examinations at the end of the first month of MPH treatment were compared with the pre-treatment findings in the patient group.

Results: Systolic and diastolic BP measurements were similar between the groups at diagnosis. The patients showed a mild increase in systolic and diastolic BP after treatment, but the differences were not statistically significant (p=0.059 and p=0.063, respectively). However, increase in heart rate and QTc duration on ECG was statistically significant in the patient group (p=0.001 and <0.001, respectively). We did not detect any significant differences in the time-domain analyses. Only the low-frequency index decreased significantly as a frequency domain parameter [871 ms2 (316.6-2198.6) vs. 788.1 ms2 (228.9-1950.3); p=0.039].

Conclusion: MPH has no significant cardiovascular side effects in ADHD. Attention should be paid when prescribing drugs that may prolong the duration of QTc; rhythm and BP should also be monitored during follow-up.