Sudden cardiac death (SCD) of a young athlete represents the first manifestation of cardiac disease in up to 80 percent of young athletes who remain asymptomatic before sudden cardiac arrest occurs, which explains the limited power of screening modalities based solely on history and physical exam, according to a paper in the April issue of European Journal of Cardiovascular Prevention & Rehabilitation.
Domenico Corrado, MD, from the University of Padova in Padova, Italy, and colleagues noted that "abrupt ventricular fibrillation as a consequence of an underlying cardiovascular disease" is the most common mechanism of cardiac arrest in young competitive athletes. In addition, culprit diseases are "often clinically silent and unlikely to be suspected or diagnosed on the basis of spontaneous symptoms."
They suggested that screening with 12-lead ECG offers the potential to identify cardiovascular problems in asymptomatic athletes.
Corrado and colleagues said that some underlying cardiovascular diseases, such as coronary artery disease, are not identifiable by 12-lead ECG, which further justifies the "efforts for implementing programs of early external defibrillation of unpredictable arrhythmic cardiac arrest," they wrote.
Atherosclerotic disease is more commonly the cause of SCD during sports activity for those older than 35 years, while cardiomyopathies are more commonly the cause in younger athletes.
The researchers wrote that hypertrophic cardiomyopathy is reportedly the cause of one-third of fatal cases in young athletes the U.S., and arrhythmogenic right ventricular cardiomyopathy/dysplasia accounted for approximately one-quarter of fatal cases in the Veneto region of Italy.
Other underlying causes of SCD in the young include myocarditis, dilated cardiomyopathy, mitral valve prolapse, conduction system diseases and Wolff-Parkinson-White syndrome. Up to 5 percent of young people and athletes who die suddenly have no evidence of structural heart diseases and the cause of their cardiac arrest is "in all likelihood related to a primary electrical heart disease such as inherited cardiac ion channel defects (channelopathies), including long and short QT syndromes, Brugada syndrome and polymorphic ventricular tachycardia," according to the study.
The purpose of screening athletes is to better identify those at risk of SCD, and both the American Heart Association (AHA) and the European Society of Cardiology consensus panel agree that cardiovascular screening for young competitive athletes is "justifiable and compelling on ethical, legal and medical grounds," the authors noted. However, "intense debate exists on the screening protocol used."
In Italy, screening athletes with 12-lead ECG has been the practice for 25 years and it has proven to be effective in identifying "asymptomatic athletes with previously undiagnosed cardiovascular abnormalities," the authors said. Although this experience is observational and not backed up by randomized controlled trials.
Corrado et al wrote that while echo is the main diagnostic tool for recognition of hypertrophic cardiomyopathy, "it is expensive and impractical for screening large athletic population." In addition, their experience with ECG shows that it can identify hypertrophic cardiomyopathy in the general population of young competitive athletes.
They noted that recent U.S. studies have shown the efficacy of using ECG in the screening protocol, albeit with a higher rate of false positives. "Defining what ECG changes are physiological (common and training-related ECG abnormalities) and what are pathological (uncommon and training-unrelated ECG abnormalities) has significant favorable effects on the athlete's cardiovascular management including clinical diagnosis, risk stratification and cost savings," they wrote.
The cost of adding ECG to routine screening was about $14 and the false positive rate of about 9 percent had a "modest proportional impact on cost."
In an accompanying editorial, Arend Mosterd, MD, from the Meander Medical Center, Amersfoort, the Netherlands, and colleagues wrote: "The interpretation of the athlete's ECG can be difficult and it remains to be proven that mass ECG screening of asymptomatic athletes can reliably identify clinically relevant conditions."
They noted that screening will result in a large number of false positives, "while at the same time providing a false sense of security to screen negative athletes, as a negative screening does