Sudden cardiac death in seemingly healthy athletes is a rare, but shocking and tragic phenomenon. Unfortunately, predicting which individuals are susceptible is a challenge and current cardiac imaging techniques are not suitable as first-line screening tools for athletes at risk, according to a review article published in the September issue of the Journal of the American College of Cardiology: Cardiovascular Imaging.

Cardiac imaging can, however, be extremely useful for second-line screening and assessing athletes with symptoms, an abnormal electrocardiogram (ECG) or a positive family history, explained authors André La Gerche, MD, PhD, of St. Vincent's Hospital, Fitzroy, Australia, and colleagues.

“Current evidence suggests that the accuracy of all cardiac imaging modalities is insufficient to justify their use as primary screening modalities in athletes,” they wrote. “Atypical findings such as marked cardiac dilation, reduced deformation, or small patches of delayed gadolinium enhancement may be commonly encountered in well-trained athletes, but, at present, the prognostic significance of such findings is unknown.”

The incidence of sudden death in athletes 35 years old or younger is 0.6 to 3.6 per 100,000 per year. Men have a 10-fold greater risk than women, and competitive athletes are at a greater risk than nonathletes. Cardiovascular causes account for a majority of the deaths, with inherited cariomyopathies the most frequent cause in young athletes and coronary artery disease the biggest threat for athletes of middle age and older.

Screening ECG has been the central focus of athlete screening efforts to this point, with some sporting bodies also mandating exercise testing and echocardiography for screening, according to La Gerche and colleagues. Cardiac magnetic resonance imaging (CMR), coronary calcium scoring and CT coronary angiography (CTCA) have also been suggested as screening tools.

Of these cardiac imaging modalities, the authors describe echocardiography as the logical candidate for screening due to its low cost, accessibility and lack of adverse effects. Echocardiography may be particularly beneficial in diagnosing hypertrophic cardiomyopathy in young athletes. However, screening an asymptomatic group of athletes could lead to overdiagnosis and the associated financial and psychological strains that accompany it.

La Gerche and colleagues pointed to the promise of CMR for evaluating an athlete’s heart. It has better assessment of the morphology and function of all cardiac chambers compared with echocardiography and can enable tissue characterization. “In the recent era in which familial cardiomyopathies are being diagnosed using cascade screening of effected family members, it is increasingly recognized that CMR represents a more sensitive diagnostic tool.”

The catch with CMR is cost. It’s expensive and has limited availability, making it less than ideal for broad-based screening in a population of asymptomatic athletes.

Coronary calcium scoring and CTCA have also been promoted as promising, but here again cost is a factor, and there is a potential for harm from contrast reactions and radiation exposure, according to the authors.

“As modern imaging further enhances our understanding of the spectrum of athlete's heart, its role may expand from the assessment of athletes with suspected disease to being part of comprehensive pre-participation screening in apparently healthy athletes.”