When do you order an electrocardiogram (ECG) before prescribing attention deficit hyperactivity disorder (ADHD) medications?

ECG Screening Before Prescribing ADHD Medications

Routine ECG screening is not recommended for healthy children and adolescents before starting ADHD medications; instead, obtain a thorough cardiac history and physical examination, and reserve ECG for those with identified cardiac risk factors. 1

Risk-Based Approach to Cardiac Screening

The 2019 American Academy of Pediatrics guidelines provide clear direction on cardiovascular assessment before initiating ADHD medications:

For All Patients (Mandatory Assessment)

Before prescribing any ADHD medication (stimulant or non-stimulant), obtain:

• Personal cardiac history specifically asking about:

  • Syncope or near-syncope (especially with exertion) 1
  • Chest pain or palpitations 1
  • Exercise intolerance or unexplained shortness of breath 1
  • History of cardiac surgery or known heart disease 1

• Family history specifically screening for:

  • Sudden unexplained death before age 50 (especially in young relatives) 1
  • Wolff-Parkinson-White syndrome 1
  • Hypertrophic cardiomyopathy 1
  • Long QT syndrome 1
  • Other inherited arrhythmia syndromes 1

When to Order an ECG

ECG is indicated only when risk factors are identified through history or physical examination 1:

• Any positive findings from the cardiac history screening above 1
• Abnormal cardiac examination findings (murmur, irregular rhythm, etc.) 1
• Known structural heart disease or congenital heart defects 2, 3
• Personal history of arrhythmias 4

If ECG is abnormal or concerning, refer to pediatric cardiology before initiating ADHD medications 1

Medication-Specific Considerations

Stimulant Medications (Methylphenidate, Amphetamines)

• Cause mild, clinically insignificant increases in heart rate (1-2 bpm) and blood pressure (1-4 mmHg) on average 1
• Do not cause clinically significant QT prolongation 5, 6
• Risk of sudden cardiac death is extremely rare and not increased compared to non-medicated children 1, 6
• ECG only needed if cardiac risk factors present 1

Non-Stimulant Medications (Atomoxetine, Guanfacine, Clonidine)

• Similar cardiovascular risk profile to stimulants 1, 6
• Atomoxetine may increase heart rate and blood pressure 1
• Guanfacine and clonidine may decrease heart rate and blood pressure 1
• Same screening approach: obtain cardiac history and perform ECG only if risk factors identified 1

Evidence Supporting This Approach

The recommendation against routine ECG screening is supported by multiple lines of evidence:

• Population studies show no increased sudden death risk: Large epidemiological studies demonstrate that ADHD medications do not increase the risk of sudden cardiac death beyond baseline rates in children 1, 6

• Low yield of routine screening: Community-based data show that screening ECGs in unselected ADHD patients result in management changes in only 0.14% of cases 7

• History and exam are sufficient for healthy children: Clinical assessment effectively identifies at-risk patients who require further evaluation 4, 3

Canadian Context

While you asked specifically about Canadian guidelines, the approach aligns with international consensus. Norwegian and other European guidelines similarly recommend against routine ECG screening in healthy children, reserving it for those with identified risk factors 4. The risk-benefit analysis strongly favors treating ADHD given its significant morbidity when untreated 3, 8.

Monitoring After Initiation

Once ADHD medication is started:

• Monitor vital signs regularly (heart rate and blood pressure) at follow-up visits 1
• 5-15% of patients may experience clinically significant increases in heart rate or blood pressure requiring intervention 1
• Reassess cardiac symptoms at each visit 1
• If new cardiac symptoms develop, obtain ECG and consider cardiology referral 1

Common Pitfalls to Avoid

• Do not order routine ECGs on all patients: This is not evidence-based and leads to unnecessary testing, false positives, and delayed treatment 7, 4

• Do not skip the cardiac history: A thorough history is the cornerstone of identifying at-risk patients 1, 4

• Do not withhold necessary ADHD treatment due to unfounded cardiac concerns: The cardiovascular risks are extremely low, while untreated ADHD carries substantial morbidity 3, 8

• Do not forget to ask about family history: Inherited cardiac conditions may not be apparent in the patient's personal history 1