Purpose: Highly publicized sudden cardiac deaths (SCD) in asymptomatic children and young adults have stimulated public interest in pre-athletics and school-based screening for asymptomatic cardiac disorders to avert these tragedies. However, the performance and trade-offs of the electrocardiogram (ECG) as a screening tool for the most common of these cardiac conditions is less understood.
Method: We systematically reviewed published literature on hypertrophic cardiomyopathy (HCM), long QT syndrome (LQTS), and Wolff-Parkinson-White syndrome (WPW), the three most common disorders associated with SCD and detectable by ECG. Using this information, we estimated (1) phenotypic prevalence, (2) sensitivity and specificity of ECG in detecting these disorders, (3) and predictive values using the illustrative point where sensitivity and specificity were equally weighted and the illustrative point where specificity was maximized.
Result: We identified and screened 6,954 abstracts, yielding 396 articles, and extracted data from 30. Summary prevalence estimates per 100,000 asymptomatic children were low at 45 (95% CI: 10, 79) for HCM; 7 (95% CI: 0, 14) for LQTS; and 136 (95% CI: 55, 218) for WPW. The areas under the receiver operating characteristic (ROC) curves for ECG were 0.91 for detecting HCM and 0.92 for LQTS. When sensitivity and specificity were weighted equally, the positive predictive value (PPV) of detecting either HCM or LQTS using ECG was less than 1%, there were many false positives per case detected (399 for HCM and 2,323 for LQTS), and the false negative rate was 15% for HCM and LQTS. However, when specificity was maximized, the PPV increased to 2% for HCM and 1% for LQTS, the false positives per case detected declined (57 for HCM and 135 for LQTS), as did the false negative rate (<1% for HCM and LQTS). Regardless of sensitivity and specificity cut-point, the negative predictive value (NPV) was near 100% and the false reassurance rate was low (<45 per 100,000 screened) for HCM and LQTS.
Conclusion: Because HCM, LQTS, and WPW have very low prevalence rates, population screening with ECG would yield substantial false positives. Guidelines regarding ECG screening will need to balance trade-offs between identification and treatment of affected individuals against the additional costs and risks associated with post-screening cardiac evaluations to rule out these disorders as well as potential overdiagnosis and overtreatment of asymptomatic individuals.