The right heart in athletes. Do we really have sufficient evidence for exercise-induced arrhythmogenic right ventricular cardiomyopathy?

Cardiac Biomarkers and Autoantibodies in Endurance Athletes: Potential Similarities with Arrhythmogenic Cardiomyopathy Pathogenic Mechanisms

The “Extreme Exercise Hypothesis” states that when individuals perform training beyond the ideal exercise dose, a decline in the beneficial effects of physical activity occurs. This is due to significant changes in myocardial structure and function, such as hemodynamic alterations, cardiac chamber enlargement and hypertrophy, myocardial inflammation, oxidative stress, fibrosis, and conduction changes. In addition, an increased amount of circulating biomarkers of exercise-induced damage has been reported. Although these changes are often reversible, long-lasting cardiac damage may develop after years of intense physical exercise. Since several features of the athlete’s heart overlap with arrhythmogenic cardiomyopathy (ACM), the syndrome of “exercise-induced ACM” has been postulated. Thus, the distinction between ACM and the athlete’s heart may be challenging. Recently, an autoimmune mechanism has been discovered in ACM patients linked to their characteristic junctional impairment. Since cardiac junctions are similarly impaired by intense physical activity due to the strong myocardial stretching, we propose in the present work the novel hypothesis of an autoimmune response in endurance athletes. This investigation may deepen the knowledge about the pathological remodeling and relative activated mechanisms induced by intense endurance exercise, potentially improving the early recognition of whom is actually at risk.

Arrhythmogenic right ventricular cardiomyopathy and sports activity: from molecular pathways in diseased hearts to new insights into the athletic heart mimicry

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disease associated with a high risk of sudden cardiac death. Among other factors, physical exercise has been clearly identified as a strong determinant of phenotypic expression of the disease, arrhythmia risk, and disease progression. Because of this, current guidelines advise that individuals with ARVC should not participate in competitive or frequent high-intensity endurance exercise. Exercise-induced electrical and morphological para-physiological remodelling (the so-called 'athlete's heart') may mimic several of the classic features of ARVC. Therefore, the current International Task Force Criteria for disease diagnosis may not perform as well in athletes. Clear adjudication between the two conditions is often a real challenge, with false positives, that may lead to unnecessary treatments, and false negatives, which may leave patients unprotected, both of which are equally inacceptable. This review aims to summarize the molecular interactions caused by physical activity in inducing cardiac structural alterations, and the impact of sports on arrhythmia occurrence and other clinical consequences in patients with ARVC, and help the physicians in setting the two conditions apart.

Competitive sports and the heart: benefit or risk?

BACKGROUND

Controversy surrounds the cardiac effects of competitive sports and the athlete's heart. In this review, we present and discuss the main cardiological findings in competitive athletes.

METHOD

Selective review of pertinent literature retrieved by a search with the keywords "athlete's heart," "ECG," "echocardiography," "endurance exercise," "longevity," and others.

RESULTS

Regular exercise leads to functional and structural adaptations that improve cardiac function. Athlete's heart, which develops rarely, is a typical finding in endurance athletes. This condition is characterized by physiological, harmonically eccentric hypertrophy of all cardiac chambers. The athlete's ECG can be used to distinguish physiological, training-related changes from pathological training-unrelated changes. The athlete's heart function is normal at rest and increases appropriately during exercise. The cardiac markers troponin and B-type natriuretic peptide are within the normal range in healthy athletes at rest, but can temporarily be mildly elevated after exhausting endurance-exercise, without evidence of myocardial damage. The epidemiological data suggest that participation in competitive sports increases life expectancy.

CONCLUSION

Competitive exercise does not induce cardiac damage in individuals with healthy hearts, but does induce physiological functional and structural cardiac adaptations which have positive effects on life expectancy.