ECGs in Athletes

Corrado et al. have published an ESC consensus document on the screening of athletes for competitive sports.[1] Besides a good medical history and examination, a 12 lead ECG is also part of the screening. They have set up special ECG criteria for participants in competitive sports (table 1). If one of the described findings are present on the ECG, the ECG is considered 'positive' and further evaluation is mandatory which can include echocardiography, 24-h ambulatory Holter monitoring, and exercise testing. ECG Features of cardiac diseases detectable at pre-participation screening in young competitive athletes are shown in table 2.

Prevalence of ECG abnormalities in competitive athletes has been studied by Pellicia et al.[2](see table below). ECG abnormalities in their study increased with age and level of exercise. In young amateur athletes they found ECG abnormalities in about 7%, a number that rose to 40% in "adult elite athletes". Especially RBBB and left ventricular hypertrophy were often seen.

Recently fierce debate has been going on about whether an ECG should be part of the screening of apparently healthy young sporters. In Italy this screening is compulsory by law and this country is a strong advocate of the use of an ECG as part of this screening. However, others[3] have stated that costs are too high for the yield (expressed in dollars per prevented sudden cardiac death) and an ECG is not included in the screening protocol of the American Heart Association.[4][5]

Criteria for a positive ECG

Table 1: Criteria for a positive 12-lead ECG

P wave	left atrial enlargement: negative portion of the P wave in lead V1 ≥ 0.1 mV in depth and ≥ 0.04 s in duration right atrial enlargement: peaked P wave in leads II and III or V1 ≥ 0.25 mV in amplitude
QRS complex	frontal plane axis deviation: right ≥ +120° or left –30° to –90°; increased voltage: amplitude of R or S wave in in a standard lead ≥2 mV, S wave in lead V1 or V2 ≥ 3 mV, or R wave in lead V5 or V6 ≥ 3 mV; abnormal Q waves ≥ 0.04 s in duration or ≥ 25% of the height of the ensuing R wave or QS pattern in two or more leads; right or left bundle branch block with QRS duration ≥ 0.12 s; R or R' wave in lead V1 ≥ 0.5 mV in amplitude and R/S ratio ≥ 1.
ST-segment, T-waves, and QT interval	ST-segment depression or T-wave flattening or inversion in two or more leads; prolongation of heart rate corrected QT interval (QTc) > 0.44 s in males and > 0.46 s in females.c
Rhythm and conduction abnormalities	premature ventricular beats or more severe ventricular arrhythmias; supraventricular tachycardias, atrial flutter, or atrial fibrillation; short PR interval (< 0.12 s) with or without ‘delta’ wave; sinus bradycardia with resting heart rate ≤ 40 beats/min;a first (PR ≥ 0.21 sb), second or third degree atrioventricular block.
aIncreasing less than 100 beats/min during limited exercise test. bNot shortening with hyperventilation or limited exercise test. cA recent study suggests athletes with a QTc > 500ms should be recommended not to participate in competitive sports[6][7]

Cardiac diseases and their ECG features

Table 2: ECG Features of cardiac diseases detectable at pre-participation screening in young competitive athletes

Disease	QTc interval	P wave	PR interval	QRS complex	ST interval	T wave	Arrhythmias
HCM	Normal	(left atrial enlargement)	Normal	Increased voltages in mid-left precordial leads; abnormal Q waves in inferior and / or lateral leads; (LAD, LBBB); (delta wave)	Down-sloping (up-sloping)	Inverted in mid-left precordial leads; (giant and negative in the apical variant)	(Atrial fibrillation); (PVB); (VT)
Arrhythmogenic right ventricular cardiomyopathy / dysplasia	Normal	Normal	Normal	Prolonged > 110 ms in right precordial leads; epsilon wave in right precordial leads; reduced voltages <= 0.5 mV in frontal leads; (RBBB)	(Up-sloping in right precordial leads)	Inverted in right precordial leads	PVB with a LBBB pattern; (VT with a LBBB pattern)
Dilated cardiomyopathy	Normal	(Left atrial enlargement)	(Prolonged >= 0.21s)	LBBB	Down-sloping (up-sloping)	Inverted in inferior and / or lateral leads	PVB; (VT)
Long QT syndrome	Prolongedc > 440ms in males > 460ms in females	Normal	Normal	Normal	Normal	Bifid or biphasic in all leads	(PVB); (torsade de pointes)
Brugada Syndrome	Normal		Prolonged >= 0.21s	S1S2S3 pattern; (RBBB/LAD)	Up-sloping coved-type in right precordial leads	Inverted in right precordial leads	(Polymorphic VT); (atrial fibrillation) (sinus tachycardia)
Lenègre disease	Normal	Normal	Prolonged >= 0.21s	RBBB; RBBB/LAD; LBBB	Normal	Secondary changes	(2nd or 3rd degree AV block)
Short QT Syndrome	Shortened < 300 ms	Normal	Normal	Normal	Normal	Normal	Atrial fibrillation (polymorphic VT)
Pre-excitation syndrome (WPW)	Normal	Normal	Shortened < 0.12s	Delta wave	Secondary changes	Secondary changes	Supraventricular tachycardia; (atrial fibrillation)
Coronary artery diseasesa	(Prolonged)	Normal	Normal	(Abnormal Q waves)b	(Down-or up-sloping)	Inverted in >= 2 leads	PVB; (VT);
Less common or uncommon ECG findings are reported in brackets. QTc: QT interval corrected for heart rate by Bazett’s formula. LBBB: left bundle branch block. RBBB: right bundle branch block. LAD: left axis deviation of –30 degrees or more. PVB: either single or coupled premature ventricular beats. VT: either non-sustained or sustained ventricular tachycardia. aCoronary artery diseases: either premature coronary atherosclerosis or congenital coronary anomalies. bAbnormal Q waves (table 1) cA recent study suggests athletes with a QTc > 500ms should be recommended not to participate in competitive sports[6][7]

Prevalence of ECG abnormalities in athletes

Table 3: Prevalence of ECG abnormalities in an unselected population of 32 652 young individuals undergoing the pre-participation cardiovascular screening

ECG abnormalities	Athletes, n (%)
Negative T-waves in precordial/standard leads	751 (2.3)
RBBB	351 (1.0)
Increased R/S wave voltages (suggestive of LVH)	247 (0.8)
Left anterior fascicular block	162 (0.5)
Pre-excitation pattern	42 (0.1)
LBBB	19 (0.1)
Prolonged corrected QT interval	1 (0.003)
Others (incomplete RBBB, prolonged PR interval, early repolarization pattern)	2280 (7.0)
Total	3853 (11.8)
RBBB, right bundle branch block; LVH, left ventricular hypertrophy; LBBB, left bundle branch block.[2]

Classification of abnormalities of the athlete’s electrocardiogram

Table 4: Classification of abnormalities of the athlete’s electrocardiogram[8]

Group 1: common and training-related ECG changes	Group 2: uncommon and training-unrelated ECG changes
Sinus bradycardia First-degree AV block Incomplete RBBB Early repolarization Isolated QRS voltage criteria for left ventricular hypertrophy	T-wave inversion ST-segment depression Pathological Q-waves Left atrial enlargement Left-axis deviation/left anterior hemiblock Right-axis deviation/left posterior hemiblock Right ventricular hypertrophy Ventricular pre-excitation Complete LBBB or RBBB Long- or short-QT interval Brugada-like early repolarization
RBBB, right bundle branch block; LBBB, left bundle branch block.

References

<biblio>

1. Corrado pmid=15689345
2. Pellicia pmid=17623682
3. Maron pmid=17353433
4. Myerburg pmid=18040041
5. Chaitman pmid=18040040
6. Basavarajaiah pmid=17947213
7. Moss pmid=17967824

</bilbio>