Diagnosis
Athlete's heart is usually an incidental finding during a routine screening or during tests for other medical issues. An enlarged heart can be seen at echocardiography or sometimes on a chest X-ray. Similarities at presentation between athlete's heart and clinically relevant cardiac problems may prompt electrocardiography (ECG) and exercise cardiac stress tests.
The ECG can detect sinus bradycardia, a resting heart rate of fewer than 60 beats per minute. This is often accompanied by sinus arrhythmia. The pulse of a person with athlete's heart can sometimes be irregular while at rest, but usually returns to normal after exercise begins.
Regarding differential diagnosis, left ventricular hypertrophy is usually indistinguishable from athlete's heart and at ECG, but can usually be discounted in the young and fit.
It is important to distinguish between athlete's heart and hypertrophic cardiomyopathy, a serious cardiovascular disease characterized by thickening of the heart's walls, which produces a similar ECG pattern at rest. This genetic disorder is found in 1 out of 500 Americans and is a leading cause of sudden cardiac death in young athletes (although only about 8% of all cases of sudden death are actually exercise-related). The following table shows some key distinguishing characteristics of the two conditions.
| Feature | Athletic Heart Syndrome | Cardiomyopathy |
|---|---|---|
| Left ventricular hypertrophy | < 13 mm | > 15 mm |
| Left ventricular end-diastolic diameter | < 60 mm | > 70 mm |
| Diastolic function | Normal (E:A ratio > 1) | Abnormal (E:A ratio < 1) |
| Septal hypertrophy | Symmetric | Asymmetric (in hypertrophic cardiomyopathy) |
| Family history | None | May be present |
| BP response to exercise | Normal | Normal or reduced systolic BP response |
| Deconditioning | Left ventricular hypertrophy regression | No left ventricular hypertrophy regression |
The medical history of the patient (endurance sports) and physical examination (bradycardia, and maybe a third or fourth heart sound), can give important hints.
- ECG - typical findings in resting position are for example sinusbradycardia, atrioventricular block (I° and II°) and right bundle branch block - all those findings normalize during exercise.
- Echocardiography - differentiation between physiological and pathological increases of the heart's size is possible, especially by estimating the mass of the wall (not over 130 g/m2) and its end diastolic diameter (not much less 60 mm) of the left ventricle.
- X-ray examination of the chest may show increased heart size (mimicking other possible causes of enlargement).
Read more about this topic: Athletic Heart Syndrome