Up to 80% of athletes who die suddenly had no symptoms or a family history of heart disease

“Genetic testing for potentially lethal variants is more accessible than ever before and this paper focuses on which athletes should be tested and when,” said author Dr. Michael Papadakis of St George’s, University of London, UK. “Athletes should be informed of the possible outcomes prior to genetic testing as it could mean exclusion or limited play.”

In most cases, the clinical evaluation will determine whether preventive therapy is needed, such as a defibrillator and advice about exercise and participation in competitive sports. Dr. Papadakis explained: “Even if a genetic abnormality is found, recommendations on treatment and return to play usually depend on how severe the disease is clinically. Does it cause symptoms such as fainting? Is the heart excessively weak or fat? Can we see many irregularities in the heart rhythm (arrhythmias) and do they get worse during exercise? If the answer to any of these questions is ‘yes’, there is a good chance the game will be restricted in some way.”

One example is an inherited condition that can cause sudden cardiac death in athletes called hypertrophic cardiomyopathy (HCM), in which the heart muscle is abnormally thick. Dr. Papadakis noted: “We used to be very conservative, but now our advice is more liberal. Athletes with HCM should undergo a comprehensive clinical evaluation to assess their risk of sudden cardiac death and then be offered an exercise prescription. Genetic testing for this condition does. in most cases no impact management. Asymptomatic athletes who are considered to be at low risk may be able to participate in competitive sports after an informed discussion with their doctor. Others at higher risk may be limited to moderate-intensity exercise. The training prescription should be as specific as possible and outline how often, how long, at what intensity and which exercise or sport is safe.”

However, in some cases, genetic testing can dictate management. An example is long QT syndrome (LQTS), an inherited electrical disorder of the heart. Identification of different genetic subtypes (LQT 1-3) can provide insight into the risk of arrhythmias, identify potential triggers to avoid, and aid in targeting medical therapies and planning exercise advice. Dr. Papadakis said: “For example, sudden immersion in cold water is more likely to cause life-threatening arrhythmias in LQT type 1 than in types 2 or 3, so one should be more cautious with swimmers who have the genetic subtype type 1 than runners.”

The one situation where genetic testing alone can result in exclusion from the game is a heart muscle disorder called arrhythmogenic cardiomyopathy (ARVC). “Even if an athlete has no clinical evidence of the disease but does have the gene for the condition, he or she should refrain from intense and competitive sports,” says Dr. Papadakis.2 “This is because studies show that people with the gene who exercise at a high level tend to develop the disease earlier in life and tend to develop a more severe disease that can cause a life-threatening cardiac arrhythmia during exercise.”

Genetic counseling should be conducted prior to testing to discuss the implications for athletes and their families. For example, an athlete’s mother is clinically diagnosed with ARVC and has the causal gene. The athlete is then screened and all clinical tests are normal. The athlete has two choices: 1) clinical monitoring, probably annually, to check for signs of disease; or 2) genetic testing. “The athlete should know that if the test is positive, it could mean the end of his or her career, even if there is no clinical evidence of disease,” said Dr. Papadakis. “On the other hand, if genetic testing is refused, the condition may worsen. Post-test counseling is critical given the potential psychosocial, financial and mental health consequences, especially if the athlete is excluded from the game.”

For child athletes, genetic counseling at an expert pediatric center with assistance from a pediatric mental health specialist may be necessary. Dr. Papadakis pointed out: “The psychological impact of a positive genetic test result can be significant for the child, especially if it leads to exclusion from sport, even in the absence of clinical disease, as with ARVC.”

In children with a clinical diagnosis of a hereditary condition, genetic testing can confirm the diagnosis and in some cases help predict the risk of sudden death during exercise. For example, having the gene for an electrical disturbance of the heart called catecholaminergic polymorphic ventricular tachycardia (CPVT) can lead to advice for preventive therapies, such as beta-blockers, and dictate decisions about exercise. “This is important because CPVT predisposes to cardiac arrhythmias during exercise and can cause sudden death at a very young age,” said Dr. Papadakis. “In contrast, the timing of genetic testing in children with a family history of HCM is controversial because it rarely causes sudden death in childhood in the absence of clinical symptoms.”

The scientific statement was prepared by the Sports Cardiology and Exercise Section of the European Association of Preventive Cardiology, the European Heart Rhythm Association, the ESC Working group on myocardial and pericardial Diseases, the ESC Council on Cardiovascular Genomics, the European Society of Human Genetics and the Society for European Pediatric and Congenital Cardiology.