Electrocardiogram May Fail to Identify Proportion of High-Risk Individuals: Analysis of Series of 50 Sudden Death Cases

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Background: An electrocardiogram (ECG) is an essential and easily available diagnostic test in the management of cardiomyopathies and channelopathies. Different strategies based on ECG have been recommended for general population and athlete screening. Objectives: The purpose of this study was to explore the value of the ECG for the diagnosis of sudden cardiac death (SCD) cases. Methods: ECGs from 50 (aged 37.6 ± 19.9 years, 37 men) resuscitated cardiac arrest (26, 52%) and SCD cases (24, 48%) were analyzed. Relevant medical history and results from clinical tests were reviewed. ECG findings were compared with the final diagnosis. Results: Final ECG classification was as follows: 9 (18%) normal, 15 (30%) unspecific, 14 (28%) suggestive, and 12 (24%) diagnostic. Amongst 13 hypertrophic cardiomyopathy patients, ECGs were diagnostic in 6 (46%) and suggestive in 1 (8%). Arrhythmogenic right ventricular cardiomyopathy was diagnosed in seven patients, two (28%) with suggestive ECG. Dilated cardiomyopathy was diagnosed in four patients, two (50%) with suggestive ECG. Six patients had Brugada syndrome: four (66%) had diagnostic ECGs, and two (33%) had suggestive ECG. Long QT syndrome was diagnosed in four cases; only one (25%) had a diagnostic ECG. Three patients had other cardiomyopathies. After the complete study, 13 (26%) patients remained with a non-conclusive diagnosis; their ECGs were unspecific or normal. Conclusion: ECG can be unspecific or normal in an important percentage of SCD cases (48%). Furthermore, a significant proportion of SCD cases after a comprehensive study remain without a definite diagnosis (26%). These findings should be considered when planning SCD preventive strategies.