Role of myocarditis in athletes with minor arrhythmias and/or echocardiographic abnormalities

Myocardial Fibrosis in Athletes

Myocardial fibrosis (MF) is a common phenomenon in the late stages of diverse cardiac diseases and is a predictive factor for sudden cardiac death. Myocardial fibrosis detected by magnetic resonance imaging has also been reported in athletes. Regular exercise improves cardiovascular health, but there may be a limit of benefit in the exercise dose-response relationship. Intense exercise training could induce pathologic cardiac remodeling, ultimately leading to MF, but the clinical implications of MF in athletes are unknown. For this comprehensive review, we performed a systematic search of the PubMed and MEDLINE databases up to June 2016. Key Medical Subject Headings terms and keywords pertaining to MF and exercise (training) were included. Articles were included if they represented primary MF data in athletes. We identified 65 athletes with MF from 19 case studies/series and 14 athletic population studies. Myocardial fibrosis in athletes was predominantly identified in the intraventricular septum and where the right ventricle joins the septum. Although the underlying mechanisms are unknown, we summarize the evidence for genetic predisposition, silent myocarditis, pulmonary artery pressure overload, and prolonged exercise-induced repetitive micro-injury as contributors to the development of MF in athletes. We also discuss the clinical implications and potential treatment strategies of MF in athletes.

Physiologic and pathophysiologic changes in the right heart in highly trained athletes

Exercise causes changes in the heart in response to the hemodynamic demands of increased systemic and pulmonary requirements during exercise. Understanding these adaptations is of great importance, since they may overlap with those caused by pathological conditions. Initial descriptions of athlete's heart focused mainly on chronic adaptation of the left heart to training. In recent years, the substantial structural and functional adaptations of the right heart have been documented, highlighting the complex interplay with left heart. Moreover, there is evolving evidence of acute and chronic cardiac damage, mainly involving the right heart, which may predispose subjects to atrial and ventricular arrhythmias, configuring an exercise-induced cardiomyopathy. The aim of this article is to review the current knowledge on the physiologic and pathophysiologic changes in the right heart in highly trained athletes.

Right Ventricular Changes in Highly Trained Athletes: Between Physiology and Pathophysiology

Several studies have described the adaptive remodeling of the heart during exercise. In some more practiced endurance athletes, there is a disproportionate load on the right ventricle (RV), at least during exercise, and this might be the basis for a chronic pro-arrhythmic RV remodeling. Especially, in these kinds of athletes the recovery after detraining might be incomplete, in particular for RV changes. The observation of acute myocardial injury based on transient elevation of biomarkers and chronic myocardial scar, not completely reversible changes of the RV and an increased prevalence of some arrhythmias support the existence of an “exercise-induced cardiomyopathy.” The aim of this paper is to review current knowledge about changes in the right heart in highly trained athletes and how these change influence cardiac function.

[Myocarditis and sudden cardiac death in athletes. Diagnosis, treatment, and prevention]

Myocarditis is the reason for sudden cardiac death in 5-22% of athletes < 35 years of age. Actually, parvovirus B19 and human herpes virus 6 are the most important pathogens. Clinical presentation of myocarditis is heterogeneous, with all courses between asymptomatic and fulminant reported. Especially in athletes it is important to take subtle discomforts seriously and initiate further evaluation. Electrocardiogram, laboratory parameters, serologic markers, and echocardiography are helpful in diagnosis of myocarditis, but are not specific. Magnetic resonance imaging (MRI) of the heart has become an important tool in the evaluation of patients with myocarditis and allows noninvasive appraisal of myocardial inflammation using late enhancement. However, MRI is not able to assess viral persistence. Therefore, endomyocardial biopsy (EMB) remains the gold standard in diagnosis of myocarditis. When considering EMB in these athletes one should not ignore spontaneous healing in 50% of patients with myocarditis. Contrariwise, specific therapy (e.g., immunosuppression, interferon, immunoglobulins) for myocarditis is only feasible after getting results of EMB. When myocarditis is verified, athletes have to withdraw from sport for at least 6 months. Before restarting physical activity, a detailed examination is necessary and most of the patients will undergo another EMB. For prevention of myocarditis and sudden cardiac death it is recommended to stop elite sport for 4 weeks after an unspecific infection. Whether moderate sport can be started earlier is unclear.

Cardiac tissue Doppler imaging in sports medicine

The differentiation of training-induced cardiac adaptations from pathological conditions is a key issue in sports cardiology. As morphological features do not allow for a clear delineation of early stages of relevant pathologies, the echocardiographic evaluation of left ventricular function is the technique of first choice in this regard. Tissue Doppler imaging (TDI) is a relatively recent method for the assessment of cardiac function that provides direct, local measurements of myocardial velocities throughout the cardiac cycle. Although it has shown a superior sensitivity in the detection of ventricular dysfunction in clinical and experimental studies, its application in sports medicine is still rare. Besides technical factors, this may be due to a lack in consensus on the characteristics of ventricular function in relevant conditions. For more than two decades there has been an ongoing debate on the existence of a supernormal left ventricular function in athlete's heart. While results from traditional echocardiography are conflicting, TDI studies established an improved diastolic function in endurance-trained athletes with athlete's heart compared with controls.The influence of anabolic steroids on cardiac function also has been investigated by standard echocardiographic techniques with inconsistent results. The only TDI study dealing with this topic demonstrated a significantly impaired diastolic function in bodybuilders with long-term abuse of anabolic steroids compared with strength-trained athletes without abuse of anabolic steroids and controls, respectively.Hypertrophic cardiomyopathy is the most frequent cause of sudden death in young athletes. However, in its early stages, it is difficult to distinguish from athlete's heart. By means of TDI, ventricular dysfunction in hypertrophic cardiomyopathy can be disclosed even before the development of left ventricular hypertrophy. Also, a differentiation of left ventricular hypertrophy due to hypertrophic cardiomyopathy or systemic hypertension is possible by TDI. Besides the evaluation of different forms of left ventricular hypertrophy, the diagnosis of myocarditis is also of particular importance in athletes. Today, it still requires myocardial biopsy. The analysis of focal disturbances in myocardial velocities might be a promising non-invasive method; however, systematic validation studies are lacking. An important future issue for the implementation of TDI into routine examination will be the standardisation of procedures and the establishment of significant reference values for the above-mentioned conditions. Innovative TDI parameters also merit further investigation.

Myocarditis

Viruses are the most common cause of myocarditis in economically advanced countries.

Enteroviruses and adenoviruses are the most common etiologic agents.

Viral myocarditis is a triphasic process. Phase 1 is the period of active viral replication in the myocardium during which the symptoms of myocardial damage range from none to cardiogenic shock. If the disease process continues, it enters phase 2, which is characterized by autoimmunity triggered by viral and myocardial proteins. Heart failure often appears for the first time in phase 2. Phase 3, dilated cardiomyopathy, is the end result in some patients. Diagnostic procedures and treatment should be tailored to the phase of disease.

Viral myocarditis is a significant cause of dilated cardiomyopathy, as proved by the frequent presence of viral genomic material in the myocardium, and by improvement in ventricular function by immunomodulatory therapy.

Myocarditis of any etiology usually presents with heart failure, but the second most common presentation is ventricular arrhythmia. As a result, myocarditis is one of the most common causes of sudden death in young people and others without preexisting structural heart disease.

Myocarditis can be definitively diagnosed by endomyocardial biopsy. However, it is clear that existing criteria for the histologic diagnosis need to be refined, and that a variety of molecular markers in the myocardium and the circulation can be used to establish the diagnosis.

Treatment of myocarditis has been generally disappointing. Accurate staging of the disease will undoubtedly improve treatment in the future. It is clear that immunosuppression and immunomodulation are effective in some patients, especially during phase 2, but may not be as useful in phases 1 and 3. Since myocarditis is often selflimited, bridging and recovery therapy with circulatory assistance may be effective. Prevention by immunization or receptor blocking strategies is under development.

Giant cell myocarditis is an unusually fulminant form of the disease that progresses rapidly to heart failure or sudden death. Rapid onset of disease in young people, especially those with other autoimmune manifestations, accompanied by heart failure or ventricular arrhythmias, suggests giant cell myocarditis.

Peripartum cardiomyopathy in economically developed countries is usually the result of myocarditis.

Myocarditis: when to suspect and how to diagnose it in athletes

Myocarditis should be suspected in athletes with unexplained cardiac arrhythmias and dysfunction, especially if preceded by a flu-like syndrome. An early diagnosis is desirable in order to avoid the risk of fatal consequences, since physical activity can enhance the inflammatory process. Although several diagnostic tools can be useful for the diagnosis of myocarditis, endomyocardial biopsy is still the gold standard. Athletes with myocarditis should be withdrawn from all competitive sports for at least 6 months and resume training when ventricular function and cardiac dimensions return to normal and the clinically relevant arrhythmias disappear. In the presence of life-threatening arrhythmias or rapidly progressive cardiac dysfunction an antiviral or an immunosuppressive treatment should be considered depending on whether a viral agent is present or absent, respectively, in the myocardium.

Imaging of cardiopulmonary diseases

Clear physiologic adaptations to endurance and resistance training occur in the myocardium. These morphologic changes have been identified primarily by echocardiography. In the evaluation of the symptomatic athlete, imaging is a valuable tool. To differentiate athletic hypertrophy from hypertrophic cardiomyopathy, echocardiography, or MRI may be used, although the latter may be superior in the accurate assessment of wall thickness. Either imaging modality may be used to differentiate athletic dilatation from dilated cardiomyopathy in which systolic dysfunction always accompanies the dilatation. To exclude anomalous coronary arteries, either MRI or CT is a reasonable examination, although the latter requires x-ray exposure and iodinated contrast dye. Chest radiograph continues to be the standard imaging modality for athletic lung disease, whereas fluoroscopy and laryngoscopy are useful for identifying vocal cord dysfunction. Knowledge of the utility of these different imaging modalities is crucial to the practitioner of sports medicine.

Long-term clinical significance of frequent and complex ventricular tachyarrhythmias in trained athletes

OBJECTIVES

The aim of this study was to clarify the clinical relevance of ventricular tachyarrhythmias assessed by 24-h ambulatory electrocardiograms (ECG) in a large, unique, and prospectively evaluated athletic population.

BACKGROUND

For athletes with ventricular tachyarrhythmias, the risk of sudden cardiac death associated with participation in competitive sports is unresolved. METHODS; We assessed 355 competitive athletes with ventricular arrhythmias (VAs) on a 24-h ambulatory (Holter) ECG that was obtained because of either palpitations, the presence of > or = 3 premature ventricular depolarizations (PVDs) on resting 12-lead ECG, or both.

RESULTS

Athletes were segregated into three groups: Group A with > or = 2,000 PVDs/24 h (n = 71); Group B with > or = 100 <2,000 PVDs/24 h (n = 153); and Group C with only <100 PVDs/24 h (n = 131). Cardiac abnormalities were detected in 26 of the 355 study subjects (7%) and were significantly more common in Group A (21/71, 30%) than in Group B (5/153, 3%) or Group C athletes (0/131, 0% p < 0.001). Only the 71 athletes in Group A were excluded from competition. During follow-up (mean, 8 years), 70 of 71 athletes in Group A and each of the 284 athletes in Groups B and C have survived without cardiovascular events. The remaining Group A athlete died suddenly of arrhythmogenic right ventricular cardiomyopathy while participating in a field hockey game against medical advice. Frequent and complex ventricular tachyarrhythmias are common in trained athletes and are usually unassociated with underlying cardiovascular abnormalities. Such VAs (when unassociated with cardiovascular abnormalities) do not convey adverse clinical significance, appear to be an expression of "athlete's heart syndrome," and probably do not per se justify a disqualification from competitive sports.

Heart disease in children

Advances in the understanding of the pathophysiology, diagnosis, and medical and surgical management of neonates with cardiovascular disease has led to their improved survival rates. These improvements have resulted in an increased number of pediatric patients presenting to the primary care physician's office with underlying heart disease. Understanding the genetic, congenital, or acquired etiologies to the various pediatric heart diseases is crucial to preventing these lesions and treating these patients.

A survey of the causes of sudden death in sport in the Republic of Ireland

BACKGROUND

Sudden death in sport is rare, but when it occurs the effects are devastating. There have not been any reports to date describing the frequency and causes of sudden death in sport in the Republic of Ireland.

AIM

To describe the incidence, possible causes, associated factors, and pathological findings in people who died while exercising in the Republic of Ireland in the 10 year period from January 1987 to December 1996.

METHODS

All 49 regional coroners in the Republic of Ireland were approached and details on all cases of sudden death in sport from 1 January 1987 to 31 December 1996 were requested. A questionnaire was used to document age, sex, participating sport, previous symptoms, previous medical investigations, circumstances of death, and main pathological finding in all reported cases.

RESULTS

Of the 49 coroners surveyed, 45 replied. A total of 51 cases of sudden death in sport were identified. The median age was 48 (range 15-78). Fifty of the deaths were of men. Golf was the most popular participating sport. In 42 cases, the pathological cause of death was atherosclerotic coronary artery disease.

CONCLUSIONS

This is the first time the incidence of sudden death in sport in the Republic of Ireland has been described. The main cause of death in all age groups was atherosclerotic coronary artery disease.

Biopsy evidence of atrial myocarditis in an athlete developing transient sinoatrial disease

Atrial myocarditis causing transient sinoatrial disease (incessant atrial tachycardia alternating with sinoatrial pauses of up to 6 s in duration) in an athlete is reported. Diagnosis was undertaken by endomyocardial biopsy; biventricular and right atrial specimens were obtained. After a 6-month rest period, the atrial arrhythmias disappeared, and the athlete was able to resume his professional sporting activities.