The inspiring article by Caselli et al about the discrimination between left ventricular hypertrabeculation (HT) and noncompaction (NC) in athletes raises the following concerns: We disagree with the differentiation between NC and HT. The authors vaguely define NC as HT with other functional or morphologic cardiac abnormalities. However, NC may occur with or without other cardiac abnormalities, and why HT is the same as NC as long as there is HT, a bilayered structure of the myocardium, and perfusion of the intertrabecular spaces from the ventricular side. Both terms should be used synonymously and HT/NC should not be restricted to patients with HT and other cardiac morphologic or functional abnormalities. HT/NC can be the initial manifestation of a systemic disease, and other cardiac abnormalities or involvement of other organs may follow later in the course.

We also disagree with the notion that HT/NC is a genetic cardiomyopathy. Arguments against a causal relation are that mutations in >30 different genes unlikely cause the same morphology, only a small number of mutation carriers also develop HT/NC, particular mutations frequently do not segregate with HT/NC, some of these mutations are associated with different cardiac abnormalities in a single family, and HT/NC can be acquired in patients with neuromuscular disorders in athletes under strong training or in pregnant women. Assuming that HT/NC is genetic, it must be mentioned that transmission of the disease does follow not only an autosomal dominant but also an autosomal recessive, X-linked, and particularly maternal trait.

We do not agree with the proposal to test athletes with HT/NC and an ejection fraction <50% genetically. If ejection fraction is never <50% in athletes, why do the authors propose this cutoff for their diagnostic workup? Which genes should be tested? More than 30 are known to be associated with HT/NC. Additionally, HT/NC is frequently associated with chromosomal defects. Should athletes with HT/NC be screened also for chromosomal abnormalities? Results of genetic testing are very much dependent on the technology applied and the amount of genes tested. A negative test result in an athlete with HT/NC not necessarily excludes a genetic defect so far unknown or undetected by the applied techniques. Giving up a sports career should, thus, not rely on a questionable genetic screening.

We also do not agree with the description of HT/NC as part of myotonic dystrophy (DM1). DM1 is regarded as the most prevalent muscle disease in adults, but only a few patients with DM1 and HT/NC have been reported thus far.

Overall, serious counseling of athletes with HT/NC can be offered not before a generally accepted definition of HT/NC is available, the pathogenesis of HT/NC is fully understood, and the genetic implications are fully elucidated. There is agreement, however, that HT/NC can be complicated by heart failure, thrombus formation, arrhythmias, and sudden cardiac death. Patients with HT/NC require close follow-up and all patients with HT/NC require a neurologic investigation. Whether all patients with HT/NC require cardiac magnetic resonance imaging and whether the presence of late gadolinium enhancement is truly associated with a higher risk to develop ventricular arrhythmias than late gadolinium enhancement–negative HT/NC remain to be elucidated.