What is the percentage of young patients with seizures who have a true cardiac problem versus electrocardiogram (ECG)-related seizures?

From the Guidelines

Approximately 1.5% to 6% of young patients with seizures have a true cardiac problem, while the majority have ECG-related seizures or primary seizures with secondary cardiac changes. The distinction between true cardiac causes of seizures and primary seizures with secondary ECG changes is crucial, as it guides treatment and management decisions. According to the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1, cardiac syncope represents 1.5% to 6% of pediatric cases, usually defined as up to 18 years of age.

Key factors that raise suspicion of a cardiac etiology include:

• Absence of prodromal symptoms
• Presence of preceding palpitations within seconds of loss of consciousness
• Lack of a prolonged upright posture
• Syncope during exercise or in response to auditory or emotional triggers
• Family history of sudden cardiac death (SCD)
• Abnormal physical examination
• Abnormal ECG

A comprehensive evaluation, including a detailed medical history, physical examination, family history, and a 12-lead ECG, should be performed in all pediatric patients presenting with syncope or seizures 1. Noninvasive diagnostic testing, such as exercise stress testing and prolonged heart rhythm monitoring, may be helpful in diagnosing channelopathies, such as long QT syndrome and catecholaminergic polymorphic ventricular tachycardia (CPVT) 1.

In contrast, primary seizures with secondary cardiac changes are more common, and seizure activity itself can cause transient ECG abnormalities, including QT prolongation, ST-segment changes, and arrhythmias 1. These ECG changes typically normalize after the seizure resolves. A combined cardiology and neurology evaluation may be warranted in patients with syncope and seizure-like activity to distinguish between primary cardiac events and primary seizures with secondary ECG changes. A thorough evaluation, including witness accounts of the events, neurological examination, EEG, and cardiac workup, is essential to determine the underlying cause of seizures in young patients.

From the Research

Prevalence of Cardiac Problems versus ECG-Related Seizures in Young Patients

• The exact percentage of young patients with seizures who have a true cardiac problem versus ECG-related seizures is not directly stated in the provided studies.
• However, a study from 2 found that among 74 patients previously diagnosed with epilepsy, an alternative diagnosis was found in 31 patients (41.9%), including 13 (36.1%) of 36 patients taking an anticonvulsant medication, suggesting that a significant portion of patients with apparent epilepsy may have a cardiovascular cause for their symptoms.
• Another study from 3 indicated that up to 35% of seizures induced by long QT may be misdiagnosed as other causes of seizure, highlighting the potential for cardiac problems to be overlooked in patients with seizures.
• A study from 4 found that only 58.1% of pediatric patients with syncope received an electrocardiogram as part of their diagnostic work-up, suggesting that cardiac abnormalities may not always be thoroughly investigated in young patients with syncope or seizure-like symptoms.
• Additionally, a study from 5 found that ECG testing in patients younger than 40 years had a diagnostic yield of 0% for identifying a cardiac cause of syncope, although it was associated with a 10% frequency of abnormal findings, which may not be directly related to the seizure or syncope.

Diagnostic Yield of ECG Testing

• The diagnostic yield of ECG testing in young patients with syncope or seizure-like symptoms appears to be low, with one study from 5 finding a diagnostic yield of 0% in patients younger than 40 years.
• However, other studies, such as 3, suggest that ECG testing can be useful in identifying cardiac abnormalities, such as long QT interval, which may be associated with seizures.
• The study from 2 also highlights the importance of considering cardiovascular causes in patients with apparent epilepsy, and the use of ECG testing as part of a comprehensive diagnostic work-up.

Implications for Diagnosis and Management

• The studies suggest that a thorough diagnostic work-up, including ECG testing, should be considered in young patients with seizures or syncope-like symptoms to rule out underlying cardiac abnormalities.
• However, the low diagnostic yield of ECG testing in young patients, as found in 5, suggests that other diagnostic approaches, such as Holter monitoring or electrophysiologic testing, may also be necessary to identify cardiac causes of seizures or syncope.
• The study from 4 highlights the need for increased use of ECG testing in pediatric patients with syncope, while also tempering the use of CT/MRI imaging in this population.