Summary
Background
Athlete’s heart patterns have been widely described. However, to our knowledge, few studies have focused on professional rugby players, who train differently according to their field position.
Aim
To describe electrocardiographic and echocardiographic patterns observed in elite rugby players according to their field position.
Methods
One hundred and thirty-five professional rugby players at the end of the competitive season were included.
Results
According to a modified Pelliccia’s classification, 68.1% of electrocardiograms were normal or had minor abnormalities, 27.2% were mildly abnormal and 3.7% were distinctly abnormal. Heart rate was higher in scrum first-row players ( P < 0.05). Absolute and indexed left ventricular end-diastolic internal diameters (LVIDd; absolute value 59.3 ± 4.7 mm) exceeded 65 mm and 32 mm/m 2 in 13% and 1.5% of players, respectively. Indexed LVIDd values were higher in back players ( P < 0.001). Left ventricular interventricular septum and posterior wall thicknesses (absolute values 9.4 ± 1.7 mm and 9.2 ± 1.6 mm, respectively) exceeded 13 mm in 3.7% of players. Concentric cardiac hypertrophy was noted in 3.7% of players. Except for one Wolff–Parkinson–White pattern, players with significant ECG or echocardiographic abnormalities showed no cardiovascular event or disease during follow-up.
Conclusion
Thus, elite rugby players present similar heart patterns to elite athletes in other sports. Major electrocardiographic and echocardiographic abnormalities are quite rare. Eccentric cardiac remodelling is more frequent in back players.
Résumé
Contexte
Les caractéristiques du cœur d’athlète ont largement été décrites dans la littérature. À notre connaissance, trop peu d’études se sont cependant intéressées aux joueurs professionnels de rugby, qui s’entraînent différemment selon leur position occupée sur le terrain.
Objectifs
Étudier les paramètres électrocardiographiques et échocardiographiques de joueurs professionnels de rugby selon leur position sur le terrain.
Méthodes
Cent trente-cinq joueurs à la fin de la période de compétition (de la saison sportive) ont été inclus.
Résultats
En accord avec la classification de Pelliccia, 68,1 % des ECG étaient normaux ou présentaient des anomalies mineures, 27,2 % des ECG présentaient des anomalies modérées et 3,7 % des ECG étaient anormaux. Les valeurs de fréquence cardiaque sont plus élevées chez les joueurs de première ligne ( p < 0,05). Les diamètres télédiastoliques du ventricule gauche (DTDVG), absolus (59,3 ± 4,7 mm) et indexés, sont supérieurs à 65 mm et 32 mm/m 2 chez respectivement 13 % et 1,5 % des joueurs. Les valeurs DTDVG indexées sont plus élevées chez les arrières ( p < 0,001). Les épaisseurs du septum interventriculaire (9,4 ± 1,7 mm) et de la paroi postérieure du VG (9,2 ± 1,6 mm) sont supérieures à 13 mm chez 3,7 % des joueurs. Une hypertrophie cardiaque concentrique a été observée chez 3,7 % des joueurs. À l’exception d’un Wolff–Parkinson–White, aucun évènement ou pathologie cardiovasculaire n’a été observé chez les joueurs présentant des anomalies majeures sur l’électrocardiogramme et/ou sur l’échocardiographie.
Conclusion
Les joueurs professionnels de rugby présentent les mêmes caractéristiques du cœur d’athlète que les autres sportifs. Les évènements cardiaques majeurs sur l’électrocardiogramme et sur l’échocardiographie sont assez rares. Le remodelage cardiaque excentrique est plus fréquent chez les arrières.
Background
A high level of intensive physical training can be associated with electrical, structural and functional myocardial adaptations – the so-called athlete’s heart . It is well known that athlete’s heart patterns depend on age, sex, body size and race . However, the sport’s specificities are accepted as the main determinant of cardiac adaptations in athletes .
Rugby is described as a sport with moderate isometric components and moderate or high dynamic components . However, these components vary in accordance with the player’s position on the field. The main static component concerns scrum first-row players, equal dynamic and static stresses are imposed on scrum second- and third-row players and the higher dynamic component concerns back players . To the best of our knowledge, only one purely descriptive study specifically concerning a small population of rugby players has been published . Thus, the aims of this study were to describe electrocardiography and echocardiography patterns in high-level rugby players and to look for specific cardiac adaptations in accordance with the player’s position on the field.
Methods
Population
This prospective study consecutively included 135 healthy rugby players (116 Caucasians, 10 Polynesians and nine Africans) from the French first league from 1998 to 2008. All players were selected from only two professional clubs. Players were distributed according to their field position: group 1, scrum first-row ( n = 34); group 2, scrum second- and third-row ( n = 46); and group 3, backs ( n = 55). Each player had a cardiovascular examination performed in a blinded manner by the same cardiologist (L.C.) between July and August, which included personal and family history, physical examination, twelve-lead electrocardiogram (ECG) and echocardiography at rest.
All experimental procedures were performed in accordance with the ethical standards of the Helsinki Declaration and were approved by the university’s human subjects review board. All players gave written informed consent to the investigators before participating.
Data recording
Electrocardiogram
Standard twelve-lead ECGs were recorded at rest (AT-5, Schiller, Baar, Switzerland, 1998–2003; Mac 1200, Marquette/GE, Milwaukee, WI, USA, 2003–2010). All ECGs were interpreted by the same experienced observer (G.K.) who was blinded to the players’ clinical data. Heart rate, QRS duration, and QT and PR intervals were measured with a tracer table (Graph’Image, Gennevilliers, France).
ECG data were classified as normal/minor, mild or major abnormalities according to a modified Pelliccia’s classification and current recommendations .
Echocardiography
Two-dimensional echocardiograms were registered with three successive ultrasound systems from the same company (Vivid 5, Vivid 3 and Vivid I systems; General Electric, Milwaukee, WI, USA). Standard views of the heart were obtained with a 3.5 MHz frequency phased-array transducer and analysed according to the protocol recommended by the American Society of Echocardiography . M-mode measurements were obtained from the two-dimensional parasternal short axis; they concerned left atrial diameter (LAd), aortic diameter (Aod), left ventricular (LV) end-diastolic and end-systolic internal diameters (LVIDd and LVIDs, respectively) and left ventricular end-diastolic interventricular septum and posterior wall thicknesses (IVSd and PWd, respectively). The Devereux formula was used for calculation of left ventricular mass (LVM). As recommended , all these absolute values were indexed to body surface area (BSA) and LVM was also indexed to height 2.7 . Left ventricular hypertrophy (LVH) was defined as LVM/BSA > 116 g/m 2 or LVM/height 2.7 > 49 g/m 2.7 (mildly abnormal 49–55; moderately abnormal 56–63; severely abnormal ≥ 64) . LVH index was calculated with the IVSd + PWd/LVIDd ratio. Concentric and eccentric myocardial remodelling were defined as values higher than 0.44 and below 0.30, respectively, as proposed in sedentary people .
Two-dimensional echocardiograms were recorded from the apical four-chamber view. End-systolic LA and right atrial (RA) areas were measured in their largest area to avoid foreshortening, excluding the appendages and pulmonary vein confluence . Early (E) and atrial (A) peak velocities were measured with pulsed Doppler and the E/A ratio was then calculated .
All scans were reviewed by a cardiologist (L.C.) blinded to the athletes’ identities.
A preliminary intraobserver analysis carried out on a sample of 30 subjects showed a variation of 2.8% for M-mode and two-dimensional variables and of 2.0% for the Doppler criteria.
Clinical findings and follow-up in athletes with abnormalities
Athletes showing a distinctly abnormal ECG pattern and/or increased cardiac dimensions above the normal limits (defined arbitrarily here as LVIDd > 65 mm and/or left ventricular wall thickness > 13 mm) underwent recommended further investigations (48-hour Holter ECG, maximal exercise test and cardiac magnetic resonance imaging [MRI] with gadolinium intravenous administration) to exclude a pathological cardiac condition .
Data analysis
Continuous data are expressed as means ± standard deviations. The training specificity’s effect was analysed with a comparison between the three groups using a Kruskall–Wallis test, followed by a Mann–Whitney test when appropriate. A Chi 2 test was used for qualitative data comparisons. The significance threshold was always set at 0.05.
Results
Demographic data
All players were of similar age (25.8 ± 4.0 years for group 1; 25.6 ± 4.4 years for group 2; and 24.1 ± 3.7 years for group 3). All were asymptomatic with no personal or family history of cardiovascular disease. Concerning height, players were taller in group 2 (194.3 ± 4.7 cm) than in group 1 (182.3 ± 4.5 cm) and group 3 (181.9 ± 5.9 cm) ( P < 0.001); no difference was noted between groups 1 and 3. Concerning weight, players were lighter in group 3 (87.1 ± 8.8 kg) compared with group 1 (113.0 ± 12.0 kg) and group 2 (109.0 ± 10.1 kg) ( P < 0.001); no difference was observed between groups 1 and 2. The BSA range was 2.2–2.7 m 2 , with the smallest BSA in group 3 ( P < 0.001).
Electrocardiographic patterns
Global population
Most ECGs were normal (16%) or had minor abnormalities (52%). Minor abnormalities constituted mostly of bradycardia (61%) and incomplete right bundle branch block (27%) ( Table 1 ). The ECG mild abnormalities (27%) were mainly flat, particularly tall or minimally inverted T waves (13%). Biphasic T waves in lead V2 were noted in one player. LA enlargement was noted in 12% of players. Distinctly abnormal ECGs were seen in five (4%) players: one Caucasian player with Wolff–Parkinson–White pattern; one Polynesian player and one African player with right QRS axis deviation; and one Polynesian player and one African player with deeply inverted T waves.
| Variables | Total ( n = 135) | Group 1 ( n = 34) | Group 2 ( n = 46) | Group 3 ( n = 55) |
|---|---|---|---|---|
| Quantitative variables | ||||
| Heart rate (beats/min) | 58.6 ± 11.5 | 61.1 ± 11.8 * | 55.4 ± 10.0 | 59.9 ± 12.1 |
| PR duration (ms) | 171.4 ± 23.4 | 174.8 ± 19.6 | 173.5 ± 22.0 | 167.6 ± 26.4 |
| QRS duration (ms) | 89.5 ± 9.9 | 89.1 ± 9.4 | 90.9 ± 10.5 | 88.7 ± 9.9 |
| QT duration (ms) | 391.8 ± 30.6 | 386.9 ± 33.1 | 399.9 ± 26.6 | 388.0 ± 31.3 |
| QTc duration (ms) | 383.4 ± 26.5 | 385.8 ± 22.1 | 381.0 ± 25.2 | 383.9 ± 30.1 |
| Qualitative variables | ||||
| Normal or minor alterations | 92 (68.1) | 22 (64.7) | 34 (73.9) | 36 (65.4) |
| Normal | 22 (16.3) | 8 (23.5) | 6 (13.0) | 8 (14.5) |
| Sinus bradycardia (< 60 beats/min) | 82 (60.7) | 16 (47.0) | 32 (69.5) | 34 (61.8) |
| PR interval (> 0.20 s) | 13 (9.6) | 3 (8.8) | 6 (13.0) | 4 (7.3) |
| R or S wave (25–29 mm) in any lead | 17 (12.6) | 5 (14.7) | 5 (10.8) | 7 (12.7) |
| Early repolarization in ≥ 2 leads | 15 (11.1) | 2 (5.9) | 4 (8.7) | 9 (16.4) |
| IRBBB | 37 (27.4) | 8 (23.5) | 14 (30.4) | 15 (27.3) |
| Mildly abnormal ECG | 37 (27.4) | 11 (32.3) | 10 (21.7) | 16 (29.1) |
| R or S wave (30–34 mm) in any lead | 1 (0.7) | 0 (0) | 1 (2.2) | 0 (0) |
| Q waves (2–3 mm) in ≥ 2 leads | 2 (1.5) | 0 (0) | 0 (0) | 2 (3.6) |
| Mild repolarization peculiarity in ≥ 2 leads | 17 (12.6) | 5 (14.7) | 3 (6.5) | 9 (16.4) |
| Abnormal R wave progression (V1 to V3) | 10 (7.4) | 5 (14.7) | 0 (0) | 5 (9.1) |
| CRBBB | 3 (2.2) | 0 (0) | 2 (4.3) | 1 (1.8) |
| LA enlargement | 16 (11.8) | 5 (14.7) | 8 (17.4) | 3 (5.4) |
| PR interval (≤ 0.12 s) | 2 (1.5) | 0 (0) | 1 (2.2) | 1 (1.8) |
| Distinctly abnormal ECG | 5 (3.7) | 1 (2.9) | 1 (2.2) | 3 (5.4) |
| Inverted T wave > 2 mm in ≥ 2 leads | 2 (1.5) | 1 (2.9) | 0 (0) | 1 (1.8) |
| QRS axis deviation (≤ –30° or ≥ 110°) | 2 (1.5) | 0 (0) | 1 (2.2) | 1 (1.8) |
| WPW pattern | 1 (0.7) | 0 (0) | 0 (0) | 1 (1.8) |
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