Sports heart

The German doctor Herbert Reindell (1908 - 1990) was the first to deal with the effects of high-performance sport on the heart. In addition to the sports heart, he also described other physiological standard variants such as incomplete right thigh block, AV blockages I. and II. degree, type Wenckebach (Kindermann 2008).

In 2007, J. Scharhag published the first standard of sports medicine for the ECG of athletes.

In the same year, the Seattle criteria were published, which additionally differentiate between cardiomyopathies and primarily electrical heart diseases in the case of unusual, non-training ECG changes (Scharhag 2013). The Seattle criteria have become the standard for ECG evaluation in athletes (Löllgen 2017).

An athlete's heart is defined as a physiological adaptation of the heart caused by regular, competitive endurance training of considerable extent (at least 5 - 10 h per week such as at least 70 km running or 200 km - 300 km cycling / week), which leads to a harmonious, eccentric hypertrophy of all cardiac cavities (Herold 2020).

It is prognostically important to distinguish changes in a sports heart from pathological changes, especially congenital, genetically determined pathological hypertrophic cardiomyopathy, since the latter is the most frequent cause of stress-induced sudden cardiac death (Bahlmann 2015).

An athlete's heart can be developed by athletes who practice endurance sports. Sports that involve a high degree of endurance also result in the development of an athlete's heart - to a lesser extent (Herold 2020). Overall, however, an athlete's heart is less common than one would expect (Stierle 2017).

Only 15% of all athletes have an end diastolic diameter of the left ventricle of 60 mm. Wall thicknesses of > 12 mm occur in only 2 % (Kindermann 2014).

There are ethnic differences in the structural sports adaptations. Coloured athletes have thicker chamber walls, in individual cases up to 16 mm maximum (Kindermann 2008).

There are no gender-specific differences. The athlete's heart occurs equally frequently in men and women (Kindermann 2014).

However, a study by Prof. Sanjay Sharma of 1,082 healthy athletes showed that the left ventricular mass and relative wall thickness were slightly lower in women. However, the enddiastolic enlargement of the left ventricle was more pronounced in them. In summary, eccentric hypertrophy is more common in women and concentric hypertrophy is more common in men (Fortmüller 2015).

Excessive athletic performance with high endurance can lead to hypertrophy of the myocardium. This causes an increase in the stroke volume and thus also an increase in cardiac output. The heart rate decreases and this results in a more economical operation of the heart - with the same load (Siebert 2004).

X-ray thorax: Radiologically, an enlargement of the heart is found. However, since the 1980s, heart size has been determined by echocardiography. Thus, X-ray is no longer of importance in the case of a sports heart nowadays (Kindermann 2014).

Echocardiography: Echocardiography represents the most important examination method with regard to the differentiation of a sports heart from pathological cardiac hypertrophy (Scharhag 2013). The following changes are found in the sports heart:

• systolic function is normal to low-normal
• regular increase of systolic function under stress (stress echo)
• the diastolic function is normal to high-normal
• left ventricular end-diastolic diameter is > 60 mm in about 15% of athletes and can be up to 67 mm in large body dimensions
• left ventricular wall thickness is max. 13mm - 16 mm in athletes of color (see below "Occurrence")
• the relative wall thickness is ≤ 42% to 43%.
• the PA pressures are normal

Cardio- MRI: If cardiomyopathy or myocarditis is suspected in an athlete, an MRI- examination should be performed.

Normally, in athletes:

• both left ventricular and right ventricular function is normal to low-normal (ejection fraction (EF) at rest is normal to 45% in each case, lower in rare cases)
• regular increase in EF under stress (Herold 2020).

Computed tomography: Studies have shown an increased coronary calcium score with plaque stabilization in middle-aged endurance athletes. This has sport-associated protective significance and is probably not pathological.

• BNP and NT- proBNP normal
• Troponins negative. Slightly elevated values are possible after intensive, prolonged exercise. However, these normalize within 24 h - 72 h.

Resting ECG

In athletes, changes in the ECG occur in about 60%. These can be:

• Sinus bradycardia
• sinus arrhythmia
• ectopic atrial rhythm
• simple AV dissociation
• AV block I degree
• AV block of II degree
• isolated increased QRS amplitudes
• incomplete right bundle branch block
• early repolarization (Scharhag 2013)
• shortened QT duration (Löllgen 2017).

In one study, Berge et al. demonstrated that PC-assisted ECG interpretation is superior to visual interpretation (Löllgen 2017).

• concentric hypertrophy of the heart
• dilated cardiomyopathy (DCM)
• hypertrophic cardiomyopathy (HCM)
• arrhythmogenic right ventricular cardiomyopathy (ARVC)
• Non-compaction cardiomyopathy

The functional and structural changes of the heart caused by competitive sports are physiological and do not cause any damage to the healthy heart. They are even combined with a positive effect in terms of life expectancy (Scharhag 2013).

After reduction of the endurance training, however, there is a complete or incomplete regression of the sports heart.

Atrial fibrillation occurs more frequently in middle and older age among endurance athletes (Herold 2020).

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