ECG reliable screen for SCD but concerns remain

The electrocardiogram (ECG) and the echocardiogram are acceptable screening tools for detecting common causes of sudden cardiac death (SCD) in children, according to a recent meta-analysis of the literature. However, more data are needed before adopting screening programs for asymptomatic children as public policy.

Sudden cardiac death in children is rare but tragic, leading some to advocate screening for all children or in certain subgroups. How well the ECG performs as a screening tool is not known, however. For a screening test to be acceptable, it must be "highly discriminatory" and identify the disorder in all affected patients (sensitivity) and rule it out in healthy children (specificity).

Researchers reviewed 30 studies for the effectiveness of the ECG with or without echocardiography to identify in asymptomatic children hypertrophic cardiomyopathy (HCM), long QT syndrome (LQTS), and Wolff-Parkinson-White syndrome (WPW), the most common disorders associated with SCD detectable by ECG.

The low summary phenotypic prevalence of these disorders (45 for HCM, 7 for LQTS, and 136 for WPW per 100,000 asymptomatic children) substantially affected their predictive value. The negative predictive value of identifying HCM or LQTS by ECG was high. The positive predictive value, however, varied depending on cutoff values for sensitivity and specificity, allowing for a high rate of false positives.

A high rate of false-positive results could lead to additional diagnostic tests and possibly unnecessary treatments and physical activity restrictions, as well as unwarranted child and parent anxiety, the researchers note. In addition, families need to be aware that a negative ECG does not definitely rule out risk for SCD because other causes of SCD are not diagnosed by ECG. Also, HCM may not manifest until adolescence, so repeat testing may be necessary.

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