Home SVCC Area: English - Español - Português
Prognostic Implications of ECG
Abnormalities in Highly Trained Athletes
J. Ricardo Serra-Grima, MD
Servicio de Cardiologia, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
Training systems, sporting performance in the many specialties and socio-economic repercussions of sport have reached such a level that a large proportion of the population give top priority to sporting events. Since the days when ancient Greek culture was at its most splendid, athletes have been treated as celebrities as the result of their achievements, not only in their home country but also across borders and continents. With today's media, particularly television, the entire population has access to the excellence of sporting events, leaving aside unpleasant occurrences which may affect an athlete's health or the spirit of sport.
Everything that occurs in the field of sport awakes interest and has a wide repercussion. Great events and outstanding performances are simultaneously shown all around the world. This social repercussion of sport, both the good and the bad, determines the physician's attitude to the medical problems which athletes may present. "It is fear that guards the vineyard" as an old Spanish saying goes, meaning that the physician, when facing an athlete's problem, especially if it is cardiac, adopts a very restrictive attitude regarding the continuity of sporting activity. Is this decision justified? Are there any objective criteria for making such a drastic decision, especially if the athlete is a professional or at Olympic level?
Our objectives in sports cardiology are to search for a scientific basis that will guarantee athletes' health and only restrict sporting activity when there are justified objective reasons. Dr Miguel Torner Soler , whom Professor René Favaloro has met, is a figure many Spanish-American cardiologists refer to. On one occasion, when a congenital heart disease without functional or clinical repercussions was diagnosed in a professional cyclist of 23 years of age, he said with his characteristic common sense, "Let's not crucify him. Let him continue and we will carry out six-monthly check-ups". This has been and still is my criterion in similar situations and I believe it is a valid point of view for all those who work in the wide world of sport, regardless of category.
PHYSICAL TRAINING AND CARDIOVASCULAR
Physical training brings about progressive changes in the cardiovascular system. These affect cardiac electrical activity and cardiac structure, particularly the thickness of the ventricular wall and left ventricle size. The most characteristic ECG sign is sinus bradycardia , which may be less than 40 beats per minute. In extreme cases, heart rate can decrease to 35 beats per minute with no recordings of A-V junction block, escape beats or P-R prolongation interval above normal values (0.20'').
Slight repolarization alterations are frequent in athletes and can be observed in lower and anteroseptal leads. However, marked repolarization abnormalities (MRA) are uncommon and due to their magnitude are suggestive of clinically silent organic heart disease.
Changes in heart structure evaluated by echocardiography affect the thickness of the interventricular wall and posterior wall as well as the left ventricular en-diastole diameter. Normal thickness in untrained individuals is no more than 10 mm while in athletes it may reach 13mm. Values from 10 to 12 mm, however, are normally recorded. Hypertrophy above 13mm is unusual and organic pathology should be ruled out when it is observed.
Some authors have referred to a "gray zone", with values of between 13 and 16 mm. In such cases, very thorough examinations should be performed to exclude hypertrophic cardiomyopathy. Pellicia and Maron established physiological hypertrophy limits at 13 mm based on data obtained in a sample of athletes, and only 2% showed a thickness equal to or above this .
The importance of defining the limits of physiological hypertrophy led us to perform an echocardiography study in a group of over one thousand athletes, in order to record possible cases with the wall thickness which Pellicia established as the limit of hypertrophy. The results of the study, as yet unpublished, were similar and consequently, athletes presenting structural changes of this magnitude undergo a special follow-up.
MRA in athletes do not appear to be related to the degree of hypertrophy or to the intensity of high training. Diagnosis is usually made in the routine medical check up and is not accompanied by symptoms or changes in performance. The impact of the ECG image () contrasts strongly with the absolute clinical and functional normality and lack of repercussion in performance.
Sport in the 21st century encompasses several equally important factors, all worthy of consideration. Medical evaluation of the sporting phenomenon leads us to believe that people who participate in sporting activities, regardless of technical level, are and will be healthier as a result. Athletes must be given the guarantee that physical activity represents no problem for their health. Those who present some sign suggestive of heart disease must undergo the appropriate examinations so that they do not unjustifiably restrict their participation.
Some athletes are professionals and others compete at the highest levels; their interests go beyond the concept of sport as a leisure activity or health reasons, the main objectives for physicians. Follow-up of their state of health is a priority for two main reasons: firstly, they need every guarantee that their physical activity when taken to the limits of adaptation to exercise does not constitute a vital risk; and secondly, any problems which may appear should be investigated and resolved as soon as possible. In this way the athlete does not need to from competition which likely plays a vital role for him both from a social and an economic view point.
Fifty years ago, sinus bradycardia was the conflictive sign for some physicians when determining aptitude to participate in marathon races or for some particular working activities. Today, sinus bradycardia is only a cause for alarm when it is extreme and accompanied by symptoms. Besides, the training and competitive programm may be the origin of chronic fatigue, one of whose most common signs is precisely extreme sinus bradycardia.
MRA are possibly the most common cause of debate in athletes due to their clinical and prognostic implications. Athletes should be advised as to whether they should continue as they have been doing until that moment, or whether it would be wiser to restrict their training.
On continuation we shall discuss the results of a study carried out in a group of athletes with MRA to determine the existence of signs of organic heart disease that would account for the ventricular repolarization abnormalities.
MEDICAL ATTITUDE AND ATHLETES
MRA diagnosis is made in most athletes during medical examination for attitude and training programm follow-up. Drastic measures or immediate withdrawal from competition is not warranted. In some extreme cases the athlete has even been admitted to hospital, despite the lack of symptoms to justify such a measure, thereby provoking a serious emotional problem for the athlete who, at the same time, is unable to understand such a drastic measure. Such medical decisions on occasion have led to athletes not returning for medical check ups on the grounds that they do not want to have to go through the cardiac evaluation.
It is very important to emphasize this as the personal, sporting and economic consequences are high and could be avoided simply by basing the criteria on logic. This does not mean that the cardiology evaluation should not be as thorough as possible in order to reach a precise diagnosis of the problem , but if no organic heart disease can be demonstrated, the most adequate approach is periodic medical check ups.
CARDIAC EVALUATION IN ATHLETES
Athletes whose ECG resembles that shown in figure 1 make up a curious group due to the surprising discrepancy between an ECG which is so suggestive of organic heart disease, and the total lack of clinical symptoms and of sporting performance. Besides, when MRA are detected and a prior ECG is available, the only valuable differences are those derived from the changes in heart rate ( and ). From the start, this finding shows that from a clinical and functional point of view there is no significant repercussion. Another important aspect which should be determined in athletes with MRA, if when the existence of organic cardiac disease has been ruled out is the mid-term and long-term prognosis.
We studied 26 athletes with MRA ( negative T wave > 2 mm in three or more leads in the ECG at rest). None of the athletes presented symptoms suggestive of cardiac disease or decreased physical capacity. An ECG at rest, stress testing with 12-lead recording, echocardiogram and antimyosin studies were performed in all cases. Rest/exercise myocardial perfusion studies with computerized tomography were performed in 17 athletes. Follow up ranged between 4 and 20 years with a mean of 7 years.
Mean age of the group was 29+ 11. Sports played were divided into 8 specialties: athletics (10), football (7), water polo (2), modern pentathlon (2), basketball (2), swimming (1), cycling(1) and triathlon(1).
Four athletes were excluded due to hypertrophic cardiomyopathy. The results of the echocardiogram were as follows in mean values and standard deviation:
Wall thickness: 11 mm+1.4
Posterior wall: 9 mm +1.2
Left ventricle end- diastole: 54 mm + 4.6
Left ventricle end- systole: 33 mm+4.6
Values in all cases are similar to those of trained athletes and the wall thickness is within physiological limits (less than 13 mm).
The stress testing was carried out on a treadmill following Bruce's protocol until exhaustion. Seven athletes withdrew due to muscle fatigue. Maximum heart rate was 166+12.4 (range 141-189). Physical capacity evaluated in METs was 15.2+2.6 (range 10-20), which corresponds to values in trained athletes of a similar age.
Blood pressure increased in relation
to the work performed (7-10 mm MET) in all cases and the decrease in recovery
The ECG recorded during the effort test tended to normalize, the negative T wave decreased and the positive difference of the ST segment tended to return to the isoelectric line. In recovery, the resting image reappeared in less than 7 minutes. There was a total absence of arrhythmias.
The 17 perfusion studies with Tetrofosmina were normal at rest and during the stress testing, with no signs of ischemia.
Antimyosin is a marker of the myocardium myosin in presence of cardiocyte membrane abnormalities. It has been used in the diagnosis of myocarditis and heart transplant rejection. Antimyosin was used in the present study to demonstrate whether there was cellular damage in absence of hypertrophy. Fifteen athletes (68%) showed an uptake index of over 1.55 (slight uptake). There was no correlation between the uptake and left ventricular mass index.
The echocardiogram showed no signs of
cardiomyopathy in any cases studied. The ventricular wall thickness was within
normal physiological limits and the increase was normal for trained athletes
regarding age, type of sport and sex.
The stress testing was normal in all aspects. Some data stand out and deserve emphasis. The behavior of the systolic arterial pressure was proportional to the work performed. In cases with hypertrophic cardiomyopathy, the abnormal behavior of the arterial pressure was a cardiovascular risk marker.
The ECG tends to normalize with disappearance of the negative T wave in some cases; this phenomenon does not occur when ECG abnormalities are due to organic cardiac disease.
It is difficult to explain the slight uptake of the antimyosin in 68% of the athletes; it cannot be ruled out that the increased permeability of the membrane justifies the phenomenon, at least in part. New studies should be carried out to clarify this problem, Athletes with a normal ECG and wall thickness within physiological limits showed slight antimyosin uptake. However, a positive uptake was not observed in any of the sedentary control group.
SIGNIFICANCE OF MRA
There are no reliable data on the prevalence of MRA in athletes. In Spain this is difficult to establish as not all athletes undergo a medical test for sporting aptitude. Although MRA suggest the presence of cardiac disease, these athletes are symptom-free and their performance is optimal in relation to their aptitude and conditioning level. These MRA are not associated to the intensity of training or to the number of years spent in training.
It has been suggested that autonomic dysfunction could be responsible for MRA. In a previous study with athletes who presented MAR no differences were observed in the plasmatic levels of epinephrine and dopamine compared with athletes with a normal ECG. This study does not conclusively to rule out the autonomous nervous system as responsible for the ECG abnormalities.
The ECG in these athletes stands out and suggests the presence of cardiac disease. For this reason, although there are no symptoms and performance is optimal, some at Olympic level, studies should be performed to rule out the existence of organic disease. Indeed, four athletes were excluded due to hypertrophic cardiomyopathy. These four cases represented 15% of the study group, suggesting that, although athletes with MRA show no evidence of disease, this can not be taken as a definitive criterion that they are free of any type of cardiac disorder.
FOLLOW UP AND CLINICAL IMPLICATIONS
During the training period, MRA show slight changes in relation to heart rate modifications and the intensity of training. These changes do not completely disappear and remain for years with similar morphology while training is continued, even though the intensity is less ( and ).
The persistence of MRA in spite of a decrease in training intensity shows the scarce relationship between the repolarization alterations and the type of training or type of sport. Furthermore, during the follow up it has been demonstrated that the loss of physical capacity was in all probability related only to the age and to the reduction of individual physical qualities.
No signs or symptoms of cardiac disease were observed in the follow up of between 6 and 22 years. it should be pointed out that among the athletes studied, one participated at four different Olympic Games (grass hockey) and another in one (athletics). These athletes, with the longest follow up furthermore, still train regularly.
The results of out study indicate that there is no objective reason to preclude physical training or participation in sporting events.
In conclusion, in spite of these ECG abnormalities in athletes, physical ability, absence of clinical signs of cardiac or other disease, together with normal echocardiographic and myocardial perfusion studies , illustrate the lack of pathological implications in such ventricular repolarization abnormalities. Furthermore, the total absence of events in a long follow up justifies the decision not to exclude the athlete from competition once the presence of disease has been ruled out.
To sum up therefore ECG abnormalities indicate a careful cardiac examination should be made before reaching conclusion and making hasty decisions. Although the cause of MRA remains unknown, training appear to be the trigger. Further investigations are needed to determine their origin.
1. Boraita A, Serratosa L. El corazón del deportista. Rev. Esp Cardiol 1998;51:356-68
2. Pelliccia A, Maron BJ, Spataro A, Prtoschan M, Spirito P. The upper limit physiologic cardiac hypertrophy in highly trained elite runners. N Engl J Med 1991;324:295-301
3. Carrió I, Estorch M, Berná L et al. Assesssment of anthracycline-induced myocardial damage by quantitative indium-111-myosin-sdpecific monoclonal antobody studies. Eur J Nucl Med 1991;18:806-12
4. Serra Grima R., Carrió I, Estorch M., et al. ECG alterations in the athlete type "Pseudoischemia" J Sports Cardiol 1986;3:9-16
5. Serra-Grima R., Estorch M. Carrió I. et al. Marked ventricular repolarization abnormalities in highly trained athletes' electrocardiograms: Clinical and prognostic implications. J Am Coll Cardiol 2000;36:1310-6
Your questions, contributions and commentaries
will be answered
by the lecturer or experts on the subject in the Sports Cardiology list.
Please fill in the form (in Spanish, Portuguese or English) and press the "Send" button.
2nd Virtual Congress of Cardiology
Dr. Florencio Garófalo
Dr. Raúl Bretal
Dr. Armando Pacher
Technical Committee - CETIFAC
Copyright© 1999-2001 Argentine Federation of Cardiology
All rights reserved
This company contributed to the Congress: