Produção Nacional
Revisado por pares
Interpretation of the Electrocardiogram of Young Athletes
2011; Lippincott Williams & Wilkins; Volume: 124; Issue: 6 Linguagem: Inglês
10.1161/circulationaha.110.013078
ISSN1524-4539
AutoresAbhimanyu Uberoi, Ricardo Stein, Marco Pérez, James V. Freeman, Matthew T. Wheeler, Frederick E. Dewey, Roberto Peidro, David Hadley, Jonathan A. Drezner, Sanjay Sharma, Antonio Pelliccia, Domenico Corrado, Josef Niebauer, N.A. Mark Estes, Euan A. Ashley, Victor F. Froelicher,
Tópico(s)Cardiac Arrhythmias and Treatments
ResumoHomeCirculationVol. 124, No. 6Interpretation of the Electrocardiogram of Young Athletes Free AccessBrief ReportPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissionsDownload Articles + Supplements ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toSupplementary MaterialsFree AccessBrief ReportPDF/EPUBInterpretation of the Electrocardiogram of Young Athletes Abhimanyu Uberoi, MD, MS, Ricardo Stein, MD, ScD, Marco V. Perez, MD, James Freeman, MD, MPH, Matthew Wheeler, MD, PhD, Frederick Dewey, MD, Roberto Peidro, MD, David Hadley, PhD, Jonathan Drezner, MD, Sanjay Sharma, FRCP, Antonio Pelliccia, MD, Domenico Corrado, MD, Josef Niebauer, MD, PhD, MBA, N.A. Mark EstesIII, MD, Euan Ashley, MRCP, DPhil and Victor Froelicher, MD Abhimanyu UberoiAbhimanyu Uberoi From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , Ricardo SteinRicardo Stein From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , Marco V. PerezMarco V. Perez From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , James FreemanJames Freeman From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , Matthew WheelerMatthew Wheeler From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , Frederick DeweyFrederick Dewey From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , Roberto PeidroRoberto Peidro From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , David HadleyDavid Hadley From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , Jonathan DreznerJonathan Drezner From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , Sanjay SharmaSanjay Sharma From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , Antonio PellicciaAntonio Pelliccia From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , Domenico CorradoDomenico Corrado From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , Josef NiebauerJosef Niebauer From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , N.A. Mark EstesIIIN.A. Mark EstesIII From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). , Euan AshleyEuan Ashley From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). and Victor FroelicherVictor Froelicher From the Stanford University School of Medicine, Palo Alto, CA (A.U., J.F., M.W., F.D., M.V.P., E.A., V.F.); Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil (R.S.); University of Washington, Seattle, WA (J.D.); Department of Cardiac and Vascular Sciences, St. George's Hospital of London, London, UK (S.S.); Institute of Sports Medicine and Science, Largo Piero Gabrielli, Rome, Italy (A.P.); University of Padua Medical School, Padova, Italy (D.C.); Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, and Sports Medicine of the Olympic Center Salzburg–Rif, Salzburg, Austria (J.N.); Tufts University School of Medicine, Boston, MA (N.A.M.E.); and University of Buenos Aires, Buenos Aires. Argentina (R.P.). Originally published9 Aug 2011https://doi.org/10.1161/CIRCULATIONAHA.110.013078Circulation. 2011;124:746–757Sudden cardiac death in a young athlete is a tragic and high-profile event. The best way to prevent such deaths is, however, highly debated. The Italian experience informed the European recommendation for the inclusion of a 12-lead ECG in screening tests for all athletes.1,2 Although American authors have acknowledged the possible benefits of such an approach, many have expressed concern over the portability of such a model to the US healthcare system. Concern has focused in particular on the idea of mandatory testing, cost effectiveness, the availability of practitioners qualified to interpret ECGs, and the burden of false-positive results. With professional sports organizations such as the International Olympic Committee, the National Basketball Association, the National Football League, and the Union of European Football Associations endorsing or implementing screening programs for their athletes, with a recent analysis suggesting a degree of cost effectiveness in line with other accepted medical interventions,3 and with the American Heart Association offering a cautious endorsement to the idea of local programs,4 volunteer-led testing programs across the US have begun to emerge. Thus, although no detailed guidance for the interpretation of the athlete's ECG exists, many physicians will be called on to interpret an athlete's ECG.Editorial see p 669A principal obstacle to such interpretation is the difficulty in distinguishing abnormal patterns from physiological effects of training. Many clinical and ECG findings that may be a cause of concern in the general population are normal for athletes. In addition, the test characteristics of the ECG for different findings vary according to age, sex, ethnicity, sport, and level of training. In particular, different challenges exist for younger athletes because of the evolution of the ECG with age. This is further complicated by historical inconsistencies in the definition of ECG abnormalities and the uncertainty about criteria for final diagnosis of several diseases in secondary testing.5–11 Finally, low disease prevalence limits the positive predictive value of many ECG criteria, even for those with otherwise favorable sensitivity and specificity.Although this document focuses in large part on the diagnostic gray area presented by ECG screening, we have where possible included suggestions for secondary testing strategies. Current recommendations for patients diagnosed with cardiomyopathy or channelopathy are clearly against participation in high-level or competitive exercise.11,12Revised European Guidelines Relating to the Athlete's ECGAn international group of experts under the auspices of the European Society of Cardiology (ESC) recently published new recommendations for the interpretation of the ECG in athletes.13 As part of this report, they reanalyzed the 1005 highly trained athletes previously presented by Pelliccia and colleagues in a landmark study.13,14 Originally, 40% (n=402) were considered to have findings possibly associated with cardiovascular disease. However, using the new ESC recommendations this percentage was lowered to 11%, which implies a meaningful increase in specificity. The age range of these athletes was 9 to 55 years with 25% female, 99% white, and most participating in Olympic sports. In a US context, we applied this reclassification scheme to a study of Stanford collegiate athletes (age range 18 to 22, 46% female, 10% black).15 In our original analysis of 658 athletes, 62% of the men and 32% of the women had abnormal ECGs and 63 (10%) were considered to have ECG patterns possibly associated with cardiovascular diseases that warranted further testing. This latter classification category was similar to the group defined as "distinctly abnormal" by Pelliccia et al.14 When these 63 "abnormal" ECGs were evaluated using our interpretation of the new ESC criteria, 34 (6%) were reclassified to the normal range and only 29 (4%) remained in the abnormal category. Thus, implied specificity rises to above 95%. These data seem to support the assertion by Corrado et al13 that the new criteria improve the specificity of the ECG as part of the preparticipation examination, but this remains to be tested in a prospective study.Training-Related ECG ChangesThe principal change in the approach of the new ESC guidelines, which mirrors that of most practitioners in the US carrying out ECG screening in young people, is the recognition of the range of findings that are the direct result of training.Increased QRS VoltageA significant change in the most recent ESC guidelines document relates to the treatment of isolated QRS voltage. The largest proportion of athletes with ECGs classified as abnormal using previous criteria exhibited isolated increases in QRS voltage (prevalence of up to 80% in some series). Because of this and other evidence that such voltage correlates poorly with left ventricular mass in young athletes,16 there is widespread acceptance that in the absence of other markers suggesting actual left ventricular hypertrophy (axis changes, changes in repolarization, atrial abnormalities, increased QRS width), high QRS voltage is not a sufficient reason in isolation to refer an athlete for further evaluation.17,18Early RepolarizationThe finding of ST elevation in V3–6 with an elevated J point and a peaked upright T wave (or more commonly in athletes of African descent, a domed ST segment followed by a biphasic or inverted T wave) is present in >50% of trained athletes. It is particularly prevalent in men. Of note, ECG changes of high voltage and abnormal repolarization can precede echocardiogram changes in hypertrophic cardiomyopathy. Although a normal echocardiogram in this setting (in the absence of other factors) may allow participation, such athletes should be followed up serially. In athletes, although the mechanism is uncertain, early repolarization seems to regress with age and when training declines and often changes or disappears during a bout of exercise or with increasing heart rate (suggesting potentially a vagally mediated or heart rate–sensitive mechanism). It is important to distinguish these findings from the Brugada-like ECG pattern that is recognized in V1–2.19Recent interest in early repolarization focused on the finding of its increased prevalence in 206 patients with idiopathic ventricular tachycardia (VT)/ventricular fibrillation (VF).20 Community epidemiological studies reported that J waves or terminal slurring of the QRS, particularly in the inferior leads, had an adjusted hazard ratio of 2 to 4 for cardiac death.21,22 Although a hazard ratio of 2 is an important finding, it does not provide adequate differentiation for screening. Cappoto et al studied athletes with sudden cardiac death (SCD) and 365 healthy athletes.19 J wave and/or QRS slurring was found more frequently among athletes with cardiac arrest/sudden death than in control athletes. Nevertheless, the presence of this ECG pattern did not confer a higher risk for recurrent malignant ventricular arrhythmias. Of additional note is that ST elevation >2 mm seems to be unusual even in athletes.Manifestations of Increased Vagal ToneSinus bradycardia, prolonged PR interval, and Wenckebach phenomenon are common in athletes as a result of the high resting vagal tone, or significantly lower intrinsic heart rates.23Authors' RecommendationWe do not recommend further evaluation for any degree of QRS voltage as long as it is isolated (ie, there are no other findings and it is associated with normal axis, acceptable repolarization, and normal atrial activation). Similarly, we do not recommend further evaluation for sinus bradycardia as low as 30 bpm (with sinus arrhythmia, some RR intervals could be prolonged to 3 seconds) or isolated early repolarization. A prolonged PR interval up to 300 ms should not prompt further workup, but longer intervals should be resolved with an exercise test (the PR interval should shorten as vagal tone is withdrawn). Similarly, Wenckebach phenomenon in isolation need not prompt further work up, but an exercise test could resolve any concern.Comparison With European Society of Cardiology DocumentThese recommendations are in line with those of the ESC.Q WavesThe pathophysiological basis of Q waves differs depending on the disease process (eg, ischemic or infiltrative myocardial disease versus classical asymmetrical hypertrophic cardiomyopathy (HCM). Notably, the diagnostic criteria also differ. Q-wave criteria for myocardial infarction range from the World Health Organization criteria (≥40 ms and amplitude >24% of the following R wave in 2 contiguous leads) to the computer-applied vectorial area criteria and Minnesota Code scores.24,25 Q waves in HCM appear to be caused by ventricular asymmetry, as demonstrated by magnetic resonance imaging (MRI).26 Distinct criteria for HCM have been tested that differ with respect to the definition of Q waves.27 The best test characteristics for Q waves in HCM were found with >3 mm in depth and/or >40 ms duration in at least 2 leads. In this case, the "and/or" yields more positives than the "and" qualifier for Q wave criteria in coronary artery disease. Scores including28 or excluding Q wave criteria29 have been shown to have reasonable diagnostic yield in patients with HCM. The Q waves of HCM most often are seen in the inferior and/or lateral leads (Figure 1). The high QRS voltage seen in both athletes and HCM patients, however, means that these criteria could lead to the identification of many more athletes than those based on 25% of the proceeding R wave alone.Download figureDownload PowerPointFigure 1. A 5-mm Q wave in lead V5 in a patient with hypertrophic cardiomyopathy. Note this is considered abnormal by ESC criteria and by our recommendation, but not by the 25% of the R wave criterion.Authors' RecommendationCoronary artery disease is rare in individuals 3 mm in depth and/or >40 ms duration in any lead except AVR, III, and V1). We do not endorse the use of standard coronary disease criteria for Q waves in young athletes, but they should apply in athletes >40 years of age.Comparison With the European Society of Cardiology DocumentSpecific criteria for Q waves are not discussed in the most recent ESC document, but prior publications from the group suggest an amplitude of 4 mm for Q-wave classification (adopted from the Pelliccia et al criteria for markedly abnormal). Athletes with Q waves should be referred for further evaluation.Further EvaluationFurther evaluation for an athlete found to have Q waves should include a more detailed history, physical examination, and a full resting echocardiogram. This study should include standard measurements of chamber size, wall thickness, and valvular function. In addition, it is valuable to estimate left and right ventricular as well as left atrial volumes using the Simpson rule. Measures of diastolic function including the tissue Doppler of the lateral or medial mitral annulus can be particularly valuable for detecting subclinical cardiomyopathy.30 Modern echocardiography probes can detect coronary ostia in most adults. Depending on availability, cardiac MRI can provide accurate estimations of all these parameters as well as providing the additional value of delayed gadolinium enhancement for the detection of myocardial fibrosis or infiltrative disease, clearer delineation of proximal coronary arteries, and characterization of the subvalvular apparatus of the mitral valve. Cardiopulmonary exercise testing, though not necessary, may provide additional value in the differentiation of cardiomyopathy from athlete's heart if this is still not clear from imaging studies and ECG.31 In particularly borderline cases, a full 4-generation family pedigree and genetic testing may be able to rule in cardiomyopathy or channelopathy. Convincingly causal mutations are found in ≈50% of patients who clearly have the disease, implying that the yield for athletes with borderline findings would be considerably lower than this. However, more extensive genetic testing, including whole-genome sequencing, may change this in the near future. For patients with findings that remain truly in a gray zone (ie, not diagnostic for cardiomyopathy), we recommend full disclosure of the unknown nature of the risk with a personal decision by the athlete on whether to participate. Examples include isolated wall thickness 120 ms should be referred for further evaluation. This is one area where digital analysis can outperform standard visual measurement because the first onset and last offset in all of the leads can be considered. When an isolated RBBB pattern is present at <120 ms duration, most would not refer for further evaluation. However, the association of this pattern with atrial septal defect leads some practitioners to recommend an echocardiogram with contrast.Comparison With the European Society of Cardiology DocumentThese recommendations are in line with the ESC document.Further EvaluationA standard secondary testing strategy (see Q-wave section) is indicated. A cardiac MRI may be particularly useful for ruling out infiltrative disease.QRS Axis DeviationThe axis of the QRS complex is greatly dependent on age: it begins rightward at birth and shifts leftward with age. As most screened athletes are at an age when the axis is still in transition, right-axis deviation is a common finding (reported prevalence as high as 20%36). In older populations, right-axis deviation is rare and generally associated with pulmonary disease. Left-axis deviation occurs in 8% of healthy air crewmen and is the most common abnormal ECG finding in the 30 to 40s age group. Several large cohort studies have attempted to define normal axis for age. The largest of these studied 46 129 individuals with a low probability of cardiovascular disease and found that 95% of athletes 7 mm in V1, R/S ratio >1 in V1, and the sum of R wave in V1 and S wave in V5/6>10.5 mm (Sokolow-Lyon). Although the Sokolow-Lyon voltage criteria for right ventricular
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