T wave abnormalities in top-ranking athletes: effects of isoproterenol, atropine, and physical exercise

When Manual Analysis of 12-Lead ECG Holter Plays a Critical Role in Discovering Unknown Patterns of Increased Arrhythmogenic Risk: A Case Report of a Patient Treated with Tamoxifen and Subsequent Pneumonia in COVID-19

Several medicines, including cancer therapies, are known to alter the electrophysiological function of ventricular myocytes resulting in abnormal prolongation and dispersion of ventricular repolarization (quantified by multi-lead QTc measurement). This effect could be amplified by other concomitant factors (e.g., combination with other drugs affecting the QT, and/or electrolyte abnormalities, such as especially hypokalemia, hypomagnesaemia, and hypocalcemia). Usually, this condition results in higher risk of torsade de point and other life-threatening arrhythmias, related to unrecognized unpaired cardiac ventricular repolarization reserve (VRR). Being VRR a dynamic phenomenon, QT prolongation might often not be identified during the 10-s standard 12-lead ECG recording at rest, leaving the patient at increased risk for life-threatening event. We report the case of a 49-year woman, undergoing tamoxifen therapy for breast cancer, which alteration of ventricular repolarization reserve, persisting also after correction of concomitant recurrent hypokalemia, was evidenced only after manual measurements of the corrected QT (QTc) interval from selected intervals of the 12-lead ECG Holter monitoring. This otherwise missed finding was fundamental to drive the discontinuation of tamoxifen, shifting to another "safer" therapeutic option, and to avoid the use of potentially arrhythmogenic antibiotics when treating a bilateral pneumonia in recent COVID-19.

T-wave reversion in pediatric patients during exercise stress testing

OBJECTIVE

T-wave inversion in lateral electrocardiogram (ECG) leads (II, III, aVF, V4 -V6 ) is suspicious of cardiac pathology in pediatric patients, though many are found to have structurally normal hearts. The purpose of this study is to evaluate T-wave response during exercise stress testing (EST) in pediatric patients with structurally normal hearts and lateral-lead T-wave inversion on resting ECG.

DESIGN

An IRB-approved, retrospective review of EST databases at two centers identified patients with lateral-lead T-wave inversion on resting ECG. Inclusion criteria were normal exam and echocardiogram, absence of anginal chest pain, and age <18 years. All patients underwent treadmill or cycle ergometer EST. Data recorded included demographics, echocardiogram results, baseline ECG, EST method, peak heart rate and metabolic equivalents (METs), and heart rate and METs at T-wave reversion. T-wave reversion was considered complete if T-waves reverted in all leads, partial if reversion occurred in only some leads, and none if no reversion occurred.

RESULTS

The search identified 14 patients: nine females and five males (10 Caucasians and four African Americans) and an average age of 16 (range 12-18) years. Complete T-wave reversion occurred in 11 (79%) patients, partial in two (14%), and none in one (7%). Reversion occurred in both genders, ethnicities, and EST methods. No complications occurred during EST; no adverse outcomes occurred during 2-year follow-up.

CONCLUSIONS

EST in pediatric patients with lateral-lead T-wave inversion on resting ECG and structurally and functionally normal hearts resulted in either complete or partial T-wave reversion in the vast majority of patients.

Outcomes in athletes with marked ECG repolarization abnormalities

BACKGROUND

Young, trained athletes may have abnormal 12-lead electrocardiograms (ECGs) without evidence of structural cardiac disease. Whether such ECG patterns represent the initial expression of underlying cardiac disease with potential long-term adverse consequences remains unresolved. We assessed long-term clinical outcomes in athletes with ECGs characterized by marked repolarization abnormalities.

METHODS

From a database of 12,550 trained athletes, we identified 81 with diffusely distributed and deeply inverted T waves (> or = 2 mm in at least three leads) who had no apparent cardiac disease and who had undergone serial clinical, ECG, and echocardiographic studies for a mean (+/-SD) of 9+/-7 years (range, 1 to 27). Comparisons were made with 229 matched control athletes with normal ECGs from the same database.

RESULTS

Of the 81 athletes with abnormal ECGs, 5 (6%) ultimately proved to have cardiomyopathies, including one who died suddenly at the age of 24 years from clinically undetected arrhythmogenic right ventricular cardiomyopathy. Of the 80 surviving athletes, clinical and phenotypic features of hypertrophic cardiomyopathy developed in 3 after 12+/-5 years (at the ages of 27, 32, and 50 years), including 1 who had an aborted cardiac arrest. The fifth athlete demonstrated dilated cardiomyopathy after 9 years of follow-up. In contrast, none of the 229 athletes with normal ECGs had a cardiac event or received a diagnosis of cardiomyopathy 9+/-3 years after initial evaluation (P=0.001).

CONCLUSIONS

Markedly abnormal ECGs in young and apparently healthy athletes may represent the initial expression of underlying cardiomyopathies that may not be evident until many years later and that may ultimately be associated with adverse outcomes. Athletes with such ECG patterns merit continued clinical surveillance.

The athlete's electrocardiogram

The electrocardiogram performed in the competitive athlete may manifest abnormal electrocardiographic findings; these findings may indicate either normal variant syndromes as well as true cardiac pathology. The normal variant syndromes include ST-segment and T-wave abnormalities, rhythm disturbances, and intraventricular conduction delay--it must be stressed that these electrocardiographic findings are, in fact, normal variants, not indicative of underlying pathology. Other presentations in these same competitive athletes describe significant cardiac pathology, including syndromes predisposing the patient to sudden cardiac death and other potentially dangerous dysrhythmias and diagnostic of acute coronary syndrome. This article reviews the various findings in this group of patients.

ECG repolarization waves: their genesis and clinical implications

The electrocardiographic (ECG) manifestation of ventricular repolarization includes J (Osborn), T, and U waves. On the basis of biophysical principles of ECG recording, any wave on the body surface ECG represents a coincident voltage gradient generated by cellular electrical activity within the heart. The J wave is a deflection with a dome that appears on the ECG after the QRS complex. A transmural voltage gradient during initial ventricular repolarization, which results from the presence of a prominent action potential notch mediated by the transient outward potassium current (I(to)) in epicardium but not endocardium, is responsible for the registration of the J wave on the ECG. Clinical entities that are associated with J waves (the J-wave syndrome) include the early repolarization syndrome, the Brugada syndrome and idiopathic ventricular fibrillation related to a prominent J wave in the inferior leads. The T wave marks the final phase of ventricular repolarization and is a symbol of transmural dispersion of repolarization (TDR) in the ventricles. An excessively prolonged QT interval with enhanced TDR predisposes people to develop torsade de pointes. The malignant "R-on-T" phenomenon, i.e., an extrasystole that originates on the preceding T wave, is due to transmural propagation of phase 2 reentry or phase 2 early afterdepolarization. A pathological "U" wave as seen with hypokalemia is the consequence of electrical interaction among ventricular myocardial layers at action potential phase 3 of which repolarization slows. A physiological U wave is thought to be due to delayed repolarization of the Purkinje system.

Prevalence of T-wave inversion beyond V1 in young normal individuals and usefulness for the diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia

T-wave inversion in precordial leads V1 to V3 is present in <3% of apparently healthy subjects who are 19 to 45 years of age but is present in 87% of patients who have arrhythmogenic right ventricular cardiomyopathy/dysplasia. T-wave inversion in lead V2 or V3 in a young or middle-aged patients who have no apparent heart disease but do have ventricular arrhythmias of left bundle branch morphology should raise the suspicion of arrhythmogenic right ventricular cardiomyopathy/dysplasia.

T-Wave and Heart Rate Variability Changes to Assess Training in World-Class Athletes

PURPOSE

A decrease of electrocardiographic T-wave voltage with increasing training loads has been reported in elite endurance athletes and ascribed to training-related adaptation in sympathetic activity to the ventricles. A switch from vagal to sympathetic predominance in sino-atrial node regulation on going from low to peak training load has been reported in world-class rowers. In this study on world-class endurance athletes, we tested the hypothesis that training-induced variations in T-wave amplitude at higher training loads are paralleled by changes in HR spectral profile.

METHODS

We studied eight male rowers of the Italian national team in the season culminating with the Rowing World Championship. Athletes were evaluated at 50 and 100% of training load, approximately 20 d before the World Championship, and during the World Championship, when the intensity was markedly reduced. We assessed T-wave maximum amplitude in chest lead V6 and cardiac autonomic regulation by power spectral analysis of R-R interval variability.

RESULTS

The increase in training load from 50 to 100% was accompanied by a significant decrease in high frequency and a significant increase in low-frequency R-R variability (in normalized units) with a concomitant significant decrease in T-wave amplitude (microV). Reduction in training load during the World Championship resulted in a return of spectral profile to the level observed at 50% training load and in a partial recovery of T-wave amplitude. HR did not change significantly.

CONCLUSIONS

In high-performance world-class athletes, training load simultaneously affects both ventricular repolarization and HR variability patterns possibly through variations in cardiac sympathetic modulation to the ventricles and the sino-atrial node. Information on concomitant changes in ventricular repolarization and autonomic cardiac regulation might be employed to tailor training protocols of elite athletes.

The athletic heart syndrome: ruling out cardiac pathologies

Patients who participate in regular vigorous or strenuous physical activities undergo significant changes in cardiac structure and function. Occasionally, these changes may be confused with those of hypertrophic cardiomyopathy (HCM). Differentiating between athletic heart syndrome and HCM requires careful examination. ECG and echocardiograms may be helpful, but other techniques such as detraining can also be useful in resolving the issue. Detraining produces regression of cardiac features in patients with athletic heart syndrome, while enlarged cardiac features remain unchanged in those with HCM.

The athlete's heart: remodeling, electrocardiogram and preparticipation screening

Highly trained athletes show morphologic cardiac changes (ie, athlete's heart) that are the consequence of several determinants, including type of sport, gender, and, possibly, inherited genetic factors. The extent of physiologic cardiac remodeling may occasionally be substantial in highly trained athletes and may raise a differential diagnosis with structural cardiac disease, such as cardiomyopathies. In addition, athletes demonstrate a spectrum of alterations in the 12-lead electrocardiogram (ECG) pattern, including marked increase in precordial R-wave or S-wave voltages, ST segment or T-wave changes, and deep Q waves suggestive of left ventricular hypertrophy, that may raise the possibility of pathologic heart condition, but have also been viewed as a consequence of the cardiac morphologic remodeling induced by athletic conditioning. To evaluate the clinical significance of these abnormal ECGs, the authors compared ECG patterns to cardiac morphology and function (assessed by two-dimensional echocardiography in individual athlete) in a large population of 1005 elite athletes engaged in a variety of sporting disciplines. Forty percent of the athletes had abnormal ECGs, and a subgroup of about 15% showed distinctly abnormal and often bizarre patterns highly suggestive of cardiomyopathies, such as hypertrophic cardiomyopathy, in the absence of pathologic cardiac changes. Such alterations are likely the consequence of athletic conditioning itself and represent another potential component of athlete's heart syndrome. However, such false-positive ECGs represent a potential limitation to the efficacy of routine ECG testing in the preparticipation cardiovascular screening of large athletic populations.

Accuracy of low load exercise-induced T wave normalization in predicting the presence of contractile reserve after an anterior myocardial infarction

BACKGROUND AND METHODS. Exercise-induced T wave normalization occurring at a low (less-than-or-equal50 watt) workload in infarct-related electrocardiographic leads was studied in 30 consecutive patients with a recent transmural anterior acute myocardial infarction. Patients underwent both ergometric stress testing (within 30 days after the infarction) and low dose dobutamine echocardiography. The T wave normalization was considered significant when it occurred in at least two infarct-related leads. A significant contractile reserve was considered present in an infarcted region when 50% or more of the dyskinetic segments functionally improved on exercise during dobutamine infusion. RESULTS. Eighteen patients showed exercise-induced T wave normalization (group 1), and 12 patients did not (group 2). Myocardial contractile reserve in the infarct area was detected in 16 patients of group 1 (88%) and in 3 patients (25%) of group 2 (p=0.004). The overall sensitivity, specificity, and diagnostic accuracy of T wave normalization, as it reflects contractile reserve in the infarct area, were 84%, 82%, and 83%, respectively. CONCLUSION. Low load exercise-induced T wave normalization in infarct-related leads appears to be an accurate marker of residual contractile reserve in the infarct area in patients with recent transmural acute anterior myocardial infarction. (c) 2000 by CHF, Inc.

An echocardiographic assessment of cardiac morphology and common ECG findings in teenage professional soccer players: reference ranges for use in screening

OBJECTIVE

To assess physiological cardiac adaptation in adolescent professional soccer players.

SUBJECTS AND DESIGN

Over a 32 month period 172 teenage soccer players were screened by echocardiography and ECG at a tertiary referral cardiothoracic centre. They were from six professional soccer teams in the north west of England, competing in the English Football League. One was excluded because of an atrial septal defect. The median age of the 171 players assessed was 16.7 years (5th to 95th centile range: 14-19) and median body surface area 1.68 m(2) (1.39-2.06 m(2)).

MAIN OUTCOME MEASURES

Standard echocardiographic measurements were compared with predicted mean, lower, and upper limits in a cohort of normal controls after matching for age and surface area. Univariate regression analysis was used to assess the correlation between echocardiographic variables and the age and surface area of the soccer player cohort. ECG findings were also assessed.

RESULTS

All mean echocardiographic variables were greater than predicted for age and surface area matched controls (p < 0.001). All variables except left ventricular septal and posterior wall thickness showed a modest linear correlation with surface area (r = 0.2 to 0.4, p < 0.001); however, left ventricular mass was the only variable that was significantly correlated with age (r = 0.2, p < 0.01). Only six players (3.5%) had structural anomalies, none of which required further evaluation. All had normal left ventricular systolic function. Sinus bradycardia was found in 65 (39%). The Solokow-Lyon voltage criteria for left ventricular hypertrophy were present in 85 (50%) and the Romhilt-Estes points score (five or more) in 29 (17%). Repolarisation changes were present in 19 (11%), mainly in the inferior leads.

CONCLUSIONS

Chamber dimensions, left ventricular wall thickness and mass, and aortic root size were all greater than predicted for controls after matching for age and surface area. Sinus bradycardia and the ECG criteria for left ventricular hypertrophy were common but there was poor correlation with echocardiographic left ventricular hypertrophy. The type of hypertrophy found reflected the combined endurance and strength based training undertaken.

Athlete's heart electrocardiogram mimicking hypertrophic cardiomyopathy

Highly trained athletes show a variety of electrocardiographic (ECG) changes, including a striking increase of R or S wave voltage, either flat or deeply inverted T waves, and deep Q waves, that suggest the presence of structural cardiovascular disease, such as hypertrophic cardiomyopathy or arrhythmogenic right ventricular cardiomyopathy, which represent the most common causes of sudden death in young competitive athletes. Despite a number of previous observational surveys, the determinants and clinical significance of these abnormal ECG patterns in trained athletes are still uncertain. Therefore, ECG patterns were compared with cardiac morphology (by echocardiography) in a large population of 1005 athletes, who were engaged in a variety of 38 sporting disciplines. We found abnormal ECGs in 40% of our athletes, but structural cardiac diseases were identified in only 5%. In the absence of cardiac disease, other determinants were recognized as responsible for abnormal ECG patterns, including the extent of morphologic cardiac remodeling, participation in an endurance type of sport, and male gender. Finally, a small but important subset of athletes showed striking ECG abnormalities that strongly suggested the presence of cardiovascular disease in the absence of pathologic cardiac conditions or morphologic changes, suggesting that these ECG alterations may be the consequence of athletic conditioning itself.

Marked ventricular repolarization abnormalities in highly trained athletes' electrocardiograms: clinical and prognostic implications

OBJECTIVE

We sought to study the functional, clinical and prognostic implications of marked repolarization abnormalities (MRA) sometimes seen in athletes' electrocardiograms (ECGs).

BACKGROUND

The clinical meaning of ECG MRA in athletes is unknown. No relationship has been drawn between either training intensity or any particular type of sport and MRA. Athletes are usually symptom free and do not show any decrease in their physical performance. It is as yet unclear whether MRA may have a negative effect on the performance of such athletes in competitive sports.

METHODS

We studied 26 athletes with MRA (negative T waves > or =2 mm in three or more ECG leads at rest). No athletes presented clinical symptoms of cardiac disease or decrease in their physical performance. Clinical and physical examinations, ECG at rest, exercise test and echocardiographic and antimyosin studies were performed in all athletes. Rest/exercise myocardial perfusion single-photon emission computed tomography studies were performed in 17 athletes. The follow-up ranged from 4 to 20 years (mean 6.7 years).

RESULTS

Four athletes were excluded due to hypertrophic cardiomyopathy. Echocardiographic studies showed right and left normal ventricular dimensions for highly conditioned athletes. In the exercise test, heart rate was 166 +/- 12.4 beats/min, and exercise tolerance was 15.2 +/- 2.7 metabolic equivalents of the task. All athletes had ECG at rest simulating myocardial ischemia or "pseudoischemia" with a tendency to normalize during exercise. Myocardial perfusion studies were normal in the studied athletes. Antimyosin studies showed mild and diffuse myocardial radiotracer uptake in 15 athletes (68%). No adverse clinical events were observed in the follow-up.

CONCLUSIONS

These results suggest that MRA have no clinical or pathological implications in athletes and should, therefore, not preclude physical training or participation in sporting events.

Clinical significance of abnormal electrocardiographic patterns in trained athletes

BACKGROUND-The prevalence, clinical significance, and determinants of abnormal ECG patterns in trained athletes remain largely unresolved. METHODS AND RESULTS-We compared ECG patterns with cardiac morphology (as assessed by echocardiography) in 1005 consecutive athletes (aged 24+/-6 years; 75% male) who were participating in 38 sporting disciplines. ECG patterns were distinctly abnormal in 145 athletes (14%), mildly abnormal in 257 (26%), and normal or with minor alterations in 603 (60%). Structural cardiovascular abnormalities were identified in only 53 athletes (5%). Larger cardiac dimensions were associated with abnormal ECG patterns: left ventricular end-diastolic cavity dimensions were 56. 0+/-5.6, 55.4+/-5.7, and 53.7+/-5.7 mm (P<0.001) and maximum wall thicknesses were 10.1+/-1.4, 9.8+/-1.3, and 9.3+/-1.4 mm (P<0.001) in distinctly abnormal, mildly abnormal, and normal ECGs, respectively. Abnormal ECGs were also most associated with male sex, younger age (<20 years), and endurance sports (cycling, rowing/canoeing, and cross-country skiing). A subset of athletes (5% of the 1005) showed particularly abnormal or bizarre ECG patterns, but no evidence of structural cardiovascular abnormalities or an increase in cardiac dimensions. CONCLUSIONS-Most athletes (60%) in this large cohort had ECGs that were completely normal or showed only minor alterations. A variety of abnormal ECG patterns occurred in 40%; this was usually indicative of physiological cardiac remodeling. A small but important subgroup of athletes without cardiac morphological changes showed striking ECG abnormalities that suggested cardiovascular disease; however, these changes were likely an innocent consequence of long-term, intense athletic training and, therefore, another component of athlete heart syndrome. Such false-positive ECGs represent a potential limitation to routine ECG testing as part of preparticipation screening.

T wave normalization in infarct-related electrocardiographic leads during exercise testing for detection of residual viability: comparison with positron emission tomography

OBJECTIVES

We investigated the sensitivity and specificity of exercise-induced T wave normalization (TWN) in infarct-related electrocardiographic leads (IRLs) for detection of residual viability in the infarct area.

BACKGROUND

The meaning of exercise-induced TWN on IRLs is not yet well understood. Recent reports suggest that TWN during dobutamine echocardiography could indicate the presence of viable myocardium.

METHODS

We evaluated 40 consecutive patients with a recent acute myocardial infarction and negative T waves in at least two IRLs. All patients underwent exercise testing; positron emission tomography (PET) with nitrogen-13 ammonia and fluorine-18 fluorodeoxyglucose; and coronary angiography.

RESULTS

Twenty-four patients showed exercise-induced TWN: 18 at a work load < or =50 W (group la) and 6 at a work load > or =75 W (group 1b); 16 patients did not show TWN (group 2). On the PET study, viability in the infarct area was present in 17 patients (94%) from group la, in only 1 (16%) from group 1b and in 4 (25%) from group 2 (p < 0.0001). The sensitivity, specificity and diagnostic accuracy of exercise-induced TWN, in comparison with residual viability, were, respectively, 82%, 67%, 75% for TWN at every work load and 77%, 94%, 85% for TWN at a work load < or =50 W. Moreover, the sensitivity and diagnostic accuracy of TWN at the low work load were higher for anterior infarctions (87% and 88%, respectively).

CONCLUSIONS

Exercise-induced TWN on IRLs at low work loads is a sensitive and specific index for the presence of residual viability in the infarct area. Sensitivity and diagnostic accuracy of this sign are higher for anterior infarctions.

Relationship between normalization of negative T waves on exercise ECG and residual myocardial viability in patients with previous myocardial infarction and no post-infarction angina

The usefulness of normalization of negative T waves in exercise ECG was investigated as an index of myocardial viability in patients with previous myocardial infarction with no symptoms or ischemic ST-segment change during exercise test. A total of 39 patients, 20 with T-wave normalization (POS group) and 19 without T-wave normalization (NEG group) on exercise ECG. were studied. Myocardial viability was evaluated by thallium-201 single-photon emission computed tomography (SPECT) during exercise or at rest. We also assessed left ventricular ejection fraction (LVEF) by contrast ventriculography before (n=39) and after percutaneous transluminal coronary angioplasty (PTCA) (n=17). SPECT detected myocardial viability in 16 (80%) of the 20 patients in the POS group and in 4 (21%) of the 19 patients in the NEG group (p<0.01). LVEF increased after successful PTCA in the POS group (from 53+/-13% to 63+/-8%, p<0.025), but fell in the NEG group (from 57+/-10% to 51+/-8%). It is concluded that normalization of negative T waves on exercise ECG is a useful, simple index of myocardial viability in patients with previous myocardial infarction with no symptoms or ischemic ST-segment change during exercise testing.

Cellular basis for the electrocardiographic J wave

BACKGROUND

The J wave is a deflection that appears in the ECG as a late delta wave following the QRS or as a small secondary R wave (R'). Also referred to as an Osborn wave, the J wave has been observed in the ECG of animals and humans for more than four decades, yet the mechanism underlying its manifestation is poorly understood. The present study investigates the cellular basis for the J wave using an isolated arterially perfused preparation consisting of a wedge of canine right or left ventricle.

METHODS AND RESULTS

A 12-lead ECG was initially recorded in vivo. After isolation and arterial perfusion of the right or left ventricular wedge, transmembrane action potentials were simultaneously recorded from epicardial, M region, and endocardial transmural sites with three floating microelectrodes. A transmural ECG was recorded concurrently. A J wave was observed at the R-ST junction of the ECG in 17 of 20 adult dogs, usually in leads II, III, aVR, and aVF and the mid to lateral precordial leads. The J wave in the transmural ECG recorded across the wedge was closely associated with the presence of a prominent action potential notch in epicardium but not endocardium. The shape and amplitude of the J wave were found to depend on (1) the transmural distribution of the action potential notch amplitude, (2) the relative time course of the early phases of the action potential (width of notch) at different sites within the wall, (3) sequence of activation, and (4) conduction time across the wall. A highly significant correlation was demonstrated between the amplitude of the epicardial action potential notch and the amplitude of the J wave recorded during interventions that alter the appearance of the electrocardiographic J wave, including hypothermia, premature stimulation, and block of the transient outward current by 4-aminopyridine. Ventricular activation from endocardium to epicardium, with epicardium activated last, was also an important prerequisite for the appearance of the J wave. This sequence permits the establishment of a voltage gradient of the early phases of the action potential after activation (ie, the QRS) is complete.

CONCLUSIONS

Our results provide the first direct evidence in support of the hypothesis that heterogeneous distribution of a transient outward current-mediated spike-and-dome morphology of the action potential across the ventricular wall underlies the manifestation of the electrocardiographic J wave. The presence of a prominent action potential notch in epicardium but not endocardium is shown to provide a voltage gradient that manifests as a J (Osborn) wave or elevated J-point in the ECG.

Congenital absence of pericardium as unusual cause of T wave abnormalities in a young athlete

The congenital absence of pericardium is a rare condition which may determine electrocardiographic ST-T abnormalities. The case of a 16-year-old athlete who presented T-wave abnormalities at standard electrocardiogram performed during a physical checkup is reported. Ventricular repolarization tended to normalize during exercise and in right lateral decubitus. Chest x-ray and echocardiography showed typical signs of complete absence of the left pericardium. The definite diagnosis was made by computer tomography (CT) scan. The importance of a complete investigation of athletes with T-wave abnormalities is emphasized. Diagnostic and therapeutic features of the congenital absence of pericardium are discussed.

The importance of assessing time-course behaviour of abnormal ST/T changes after exercise

Routine stress electrocardiography has been criticised for yielding too many so-called 'false-positive' results because ST/T changes that develop during and after exercise are prevalent. Recent studies in our institution indicate, however, that the time-course behaviour patterns of these ST/T configurational 'abnormalities' after exercise are different from those reflecting myocardial ischaemia due to epicardial coronary artery disease (CAD). Time-course analysis increases the predictive value of exercise testing and has dramatically decreased the number of asymptomatic subjects or symptomatic patients at low risk of having CAD being subjected to coronary arteriography in our institution. Our method of assessing post-exercise time course patterns of abnormal ST/T are described in detail. Ischaemic ST/T abnormalities have late onset, early offset or early onset, late offset whereas those ST/T changes associated with normal epicardial coronary arteries have late onset, late offset or early onset, early offset post-exercise time course patterns.

ECG variants and cardiac arrhythmias in athletes: clinical relevance and prognostic importance

These findings permit the following conclusions on cardiac changes induced by high-performance sports and high levels of training. Sinus bradycardia and AV block can frequently be observed in athletes, but they do not require attention as long as they are asymptomatic or do not produce pauses exceeding 4 seconds. Persistent rather than transient second-degree AV block or Mobitz second- or third-degree AV block is an extremely unusual finding even in athletes and should be considered a sign of organic lesions until proved otherwise. Supraventricular and AV node ectopic beats are not more frequent in athletes than in the general population except for atrial fibrillation. WPW syndrome is of particular importance, since rapid conduction to the ventricle via the accessory AV pathway is possible, especially if there is a tendency toward atrial fibrillation. Likewise caution is required in athletes with hypertrophic cardiomyopathy. Here hemodynamic deterioration must be anticipated with the occurrence of supraventricular tachycardia. Simple ventricular arrhythmias occur among athletes with the same frequency as in the general population, but they usually disappear with exercise. The occurrence of complex ventricular forms of arrhythmia should always prompt cardiologic examination in search of underlying cardiac disease, particularly hypertrophic or dilated cardiomyopathy. The presence of ventricular arrhythmias without evidence of underlying heart disease does not indicate a special or increased risk of sudden cardiac death. A higher incidence of right and/or left ventricular hypertrophy, exercise-reversible ST elevation, and exercise-reversible changes in T waves (T negativity, sharp and/or excessive T waves) can be considered physiologic changes in the ECGs of athletes. These changes correlate closely with the type of sports activity and degree of training and are reversible when the activity is stopped. Horizontal ST segment depression are by contrast very rare in athletes and should always be clarified by cardiologic examination. Exercise-induced sudden cardiac death in athletes is unusual without preexisting heart disease. The cause of sudden cardiac death among athletes less than 40 years of age can be predominantely ascribed to congenital heart diseases (such as hypertrophic cardiomyopathy or coronary anomalies). In athletes more than 40 years of age and with increasing age, coronary heart disease is the most frequent autopsy finding. A corresponding risk stratification should take these partial dangers into account.

Diurnal change of giant negative T wave in patients with hypertrophic cardiomyopathy

To examine the diurnal change of negative T wave (deeper than 10 mm in precordial leads) in apical hypertrophic cardiomyopathy and the mechanism of giant negative T wave, 24-h ambulatory electrocardiographic monitoring was performed in 8 patients with apical hypertrophic cardiomyopathy, and effect of atropine on electrocardiogram was studied. The mean depth of negative T wave at 1, 2, and 3 P.M. was 9.3 +/- 3.0 mm, and that at 1, 2, and 3 A.M. was 12.6 +/- 4.8 mm. The mean R-R interval at 1, 2, and 3 P.M. was 792 +/- 113 ms and that at 1, 2, and 3 A.M. was 1055 +/- 94 ms. In seven patients (88%), negative T wave was deeper during the night than during the daytime. There was a positive correlation between R-R interval and depth of negative T wave in 6 patients (75%). Despite significant shortening of R-R interval (879 +/- 116 to 804 +/- 110 ms, p less than 0.05), atropine did not significantly change the depth of negative T wave (14 +/- 5 to 14 +/- 5 mm). In conclusion, negative T wave is not fixed, but is variable, diurnally, probably due to the change of sympathetic tone.

Electrocardiographic findings in male veteran endurance athletes

Twenty male veteran endurance runners and 20 controls underwent resting, exercise, and ambulatory electrocardiography. Four athletes and three controls satisfied voltage criteria for left ventricular hypertrophy. The PR interval was longer in the athletes and they had longer mean (SD) treadmill exercise times (19 (4) v 16 (2) min) than the controls. Four athletes but no controls had greater than 2 mm downsloping ST segment depression during exercise. During 48 hour ambulatory electrocardiography the athletes had a consistently lower heart rate but maintained a circadian variation. Profound bradycardia (less than 35 beats/min) occurred in eight athletes but only one control. Eight athletes and two controls had asystolic pauses ranging from 1.8 to 15 seconds. Six athletes had first degree heart block, four had Mobitz II second degree block, and three had complete heart block. Most conduction abnormalities occurred at night and resolved during exercise. Ventricular ectopic activity was not significantly different between the groups. Thus heart block patterns and profound bradycardia are more frequent in older athletes than their youthful counterparts.

[Anesthesia in high class athletes]

A case of general anaesthesia in a 49 year old male, high level specialist in triathlon, is reported. At the preoperative assessment, the patient had a sinus bradycardia of 45 b.min-1. The electrocardiogram (ECG) exhibited 2 mm ST segment elevation in leads V3-V5, an inverted T wave in leads V1 and V4, and a prolonged QT interval. The QRS axis was 60 degrees, the Sokolow index 44 mm; there was a partial right bundle branch block. These ECG anomalies disappeared during exercise. Heart sounds and blood pressure were normal. On chest X-ray the heart was enlarged. Five mg of midazolam were given orally 30 min before induction, and 1 mg atropine intravenously to increase the heart rate (40 b.min-1). Anaesthesia was induced with 2.5 mg.kg-1 propofol and alfentanil 15 micrograms.kg-1. Vecuronium 0.05 mg.kg-1, alfentanil 0.5 mg, 0.5% isoflurane in a mixture of 40% oxygen and 60% nitrous oxide were used to maintain anaesthesia. A further bolus of 0.5 mg atropine was necessary because of persisting sinus bradycardia. Surgery lasted 70 min. Heart rate and blood pressure returned to their initial values when the patient recovered from anaesthesia. Cardiac abnormalities are common in athletes; they must be distinguished from pathological conditions. When carrying out anaesthesia in these patients, it would seem highly recommendable to give 1-2 mg atropine, and to avoid associating negative chronotropic drugs.

Significance of T wave normalization in the electrocardiogram during exercise stress test

Although normalization of previously inverted T waves in the ECG is not uncommon during exercise treadmill testing, the clinical significance of this finding is still unclear. This was investigated in 45 patients during thallium-201 exercise testing. Patients with secondary T wave abnormalities on the resting ECG and ischemic exercise ST segment depression were excluded. On the thallium-201 scans, the left ventricle was divided into anterior-septal and inferior-posterior segments; these were considered equivalent to T wave changes in leads V1 and V5, and aVF, respectively. A positive thallium-201 scan was found in 43 of 45 (95%) patients and in 49 of 52 (94%) cardiac segments that showed T wave normalization. When thallium scans and T wave changes were matched to sites of involvement, 76% of T wave normalization in lead aV, was associated with positive thallium scans in the inferior-posterior segments, and 77% of T wave normalization in V1 and V5 was associated with positive thallium scans in the anterior-septal segments. These site correlations were similar for reversible and fixed thallium defects, and for patients not on digoxin therapy. Similar correlations were noted for the sites of T wave changes and coronary artery lesions in 12 patients who had angiography. In patients with a high prevalence for coronary artery disease, exercise T wave normalization is highly specific for the presence of the disease. In addition, it represents predominantly either previous injury or exercise-induced ischemic changes over the site of ECG involvement, rather than reciprocal changes of the opposite ventricular wall.

Results of screening a large group of intercollegiate competitive athletes for cardiovascular disease

To determine the feasibility of detecting cardiovascular disease in a large group of young competitive athletes, a prospective screening evaluation of intercollegiate student athletes was undertaken at the University of Maryland. Initial clinical screening (including personal and family history, physical examination and 12 lead electrocardiogram) was performed in 501 athletes. Ninety of these subjects had positive findings on one or more of the three studies and agreed to further cardiologic evaluation. The vast majority (75 [84%] of 90) had no definitive evidence of cardiovascular disease, although 1 athlete had mild systemic hypertension and 14 (15%) had echocardiographic evidence of relatively mild mitral valve prolapse that had not been previously suspected. In three athletes with relatively mild ventricular septal hypertrophy (14 to 15 mm), it was not possible to discern with absolute certainty whether the wall thickening was a manifestation of hypertrophic cardiomyopathy or secondary to athletic conditioning ("athlete heart"). Therefore, this screening protocol identified no athletes with definite evidence of hypertrophic cardiomyopathy, Marfan's syndrome or other cardiovascular diseases that convey a significant potential risk for sudden death or disease progression during athletic activity. This failure to identify such diseases could have been due to a lack of sensitivity of the screening tests or to the low frequency with which these diseases occur in youthful healthy athletes. A systematic preparticipation screening program (such as the present one) does not appear to be an efficient means of detecting clinically important cardiovascular disease in young athletes.

Pseudonormalization of T-waves during coronary angioplasty

Myocardial ischemia has been reported occasionally to produce transient T-wave normalization in certain patients. We present a case of "pseudonormalization" of T-waves occurring in the setting of coronary angioplasty. This case illustrates the potential of the transient coronary occlusion which occurs during coronary angioplasty as a model for understanding acute myocardial ischemia.

Physiologic hypertrophy: effects on left ventricular systolic mechanics in athletes

Physiologic hypertrophy resulting from intense athletic participation has been reported to result in normal, reduced and augmented overall left ventricular performance. Rather than representing true differences in left ventricular contractility, these data may reflect the variable degree of ventricular dilation and increased wall thickness that occur with different types of exercise. As such, the resultant altered loading conditions may diminish the ability of the usual indexes of left ventricular function to accurately assess the left ventricular contractile state. Therefore, three groups of elite athletes with distinct patterns of myocardial hypertrophy were investigated utilizing recently developed load-independent contractility indexes. Age-matched control subjects (n = 33) were compared with 11 swimmers, 11 long-distance runners and 11 power lifters. Rest echocardiogram, phonocardiogram and calibrated carotid pulse tracing were used to calculate left ventricular dimensions, wall thickness, mass, fractional shortening, velocity of shortening and mean, peak and end-systolic wall stresses and the stress-time and minute stress-time integrals. Compared with control subjects, all athletes had increased left ventricular mass, even when values were normalized for body surface area. Runners had a dilated left ventricular and normal wall thickness, swimmers had a mildly dilated ventricle with increased wall thickness and power lifters had normal cavity size with markedly increased wall thickness. Peak systolic wall stress was normal in runners and swimmers and reduced in power lifters, whereas end-systolic stress was low in swimmers and power lifters and normal in runners. The minute stress-time integral, a measure of myocardial oxygen consumption, was normal in runners and swimmers but was significantly reduced in lifters.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitral valve prolapse: definition and implications in athletes

Mitral valve prolapse is probably the most common cardiac valve disorder, affecting approximately 5% of the population. Although it is genetically determined, its clinical manifestations do not usually become evident before adulthood. In the setting of a cardiology referral center, a mitral valve prolapse syndrome, consisting of nonspecific symptoms, repolarization changes on the electrocardiogram and arrhythmias, has been identified. However, doubt has recently been expressed about the existence of such a syndrome. The prognosis of mitral valve prolapse is generally favorable but infrequent complications do occur and include transient ischemic attacks, progression of mitral regurgitation with or without ruptured chordae tendineae, infective endocarditis and sudden death. The symptoms and the complications are not usually related to physical activity. A permissive attitude toward participation of patients with mitral valve prolapse in competitive athletics is probably warranted; however, it would appear reasonable to disqualify athletes with mitral valve prolapse in the following circumstances: history of syncope; disabling chest pain; complex ventricular arrhythmias, particularly if induced or worsened by exercise; significant mitral regurgitation; prolonged QT interval; Marfan's syndrome; and family history of sudden death.

Current cardiology problems in sports medicine

The cardiologist involved in the evaluation of the competitive athlete requires knowledge of the normal variations seen on clinical examination and laboratory studies. There is limited information in the literature, currently, that provides guidelines for decision making in the face of cardiac abnormalities. This paper outlines our experience with athletes and cardiac disease. Recommendations are given as guidelines for specific activity allowances.

Electrocardiogram of the athlete: an analysis of 289 professional football players

The electrocardiogram (ECG) of athletes reflects physiologic cardiovascular adaptations that occur in well-conditioned individuals. To more clearly define electrocardiographic changes seen in predominantly power-trained athletes, the ECGs of 289 apparently healthy professional football players were analyzed in detail. The players, aged 21 to 35 years, one-third of whom were black, had a mean body surface area of 2.24 m2, a mean heart rate at rest of 56 +/- 9 beats/min (with 77% (223) having a rate of less than 60 beats/min), and a mean P axis of 30 +/- 25 degrees. A wide QRS-T angle (greater than 60 degrees) was present in 14% (41 players) of the group. The mean PR interval was 0.18 +/- 0.02 second (greater than 0.21 in 9% [26 players]). Although two-thirds of the players had a QRS duration of 0.10 second, only 1 had right bundle branch block and none had left bundle branch block. The sum of S in lead V1 plus R in lead V5 averaged 37 +/- 9 mm, with 35% (101 players) demonstrating voltage criteria for left ventricular hypertrophy. The S + R value varied inversely with weight (r = -0.27, p less than 0.002). The maximum T height in any lead had a mean of 8.6 +/- 3 mm, with 22% (64 players) having a T height greater than or equal to 11 mm. U waves were universally present. ST-T changes mimicking ischemia were noted in 39 of 289 players (13%), 22 (58%) of whom were black (p less than 0.001). The maximal J-point elevation in any lead averaged 1.9 +/- 0.9 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

Significance of high voltage QRS anterior forces in young asymptomatic adults. Evaluation by wide-angle two-dimensional echocardiography

Thirteen asymptomatic adults less than 40 years old who showed tall right precordial R waves on the ECG were examined by VCG, M-mode and two-dimensional echocardiography (2D Echo). Common causes of QRS anterior displacement, such as right ventricular enlargement or right bundle branch block, were excluded in each subject. Although each subject was normal at physical examination, 2D Echo revealed areas of left ventricular hypertrophy in eight of these 13 subjects. Four had a prevailing hypertrophy of the basal portion of the interventricular septum, three had an isolated apical hypertrophy, and one had a diffuse concentric left ventricular hypertrophy. Results were normal in five cases. 2D Echo classification was confirmed by heart catheterization findings, when available. The subjects with asymmetric septal hypertrophy showed low-voltage QRS leftward forces on the ECG and VCG. ECGs and VCGs were not useful in differentiating the subjects with atypically distributed left ventricular hypertrophy from the normals: high-voltage QRS leftward forces and T wave abnormalities were evident in some subjects of both groups. Tall right precordial R waves may constitute a marker of hypertrophic cardiomyopathy in asymptomatic young adults. 2D Echo is useful to exactly classify these subjects.

Functional and myocarditis-induced T-wave abnormalities. Effect of orthostasis, beta-blockade, and epinephrine

Negative T waves in the ECG during an acute infection may be due purely to functional variations, making the diagnosis of acute myocarditis difficult. The effects of orthostasis, beta-blockade, and intravenous epinephrine infusion (0.07-0.21 micrograms/kg/min) on T waves and the Q-T interval was studied in 28 young men with acute myocarditis, in 29 persons with functional T-wave abnormalities, and in 30 healthy subjects. Myocarditis-induced negative T waves were never normalized by beta-blockade. Functional T-wave inversions were normalized by beta-blockade in 22 subjects (76 percent). Orthostasis always augmented the T-wave abnormalities that were normalized by beta-blockade. Functional T-wave abnormalities responding to beta-blockade were augmented by epinephrine in 17 subjects (77 percent); but those unresponsive to beta-blockade were normalized in six of seven subjects. The Q-Tc interval was significantly (p less than 0.01) lengthened in subjects with myocarditis (410 +/- 36 ms) compared with controls (384 +/- 27 ms). The beta-blockade test is useful in differentiating between functional T-wave inversions and acute myocarditis. However, functional T-wave abnormalities are not constantly abolished by beta-blockade but may then be normalized by epinephrine. A clearly prolonged Q-Tc interval speaks for a diagnosis of myocarditis.

Abnormal cardiac enzyme responses after strenuous exercise: alternative diagnostic aids

Serial estimations of activities of creatine kinase and its MB isoenzyme, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase and of concentrations of alpha(1)-acid glycoprotein were performed in 15 healthy well-trained male marathon runners. Estimations were made initially within three days before a race and then one, 24, and 96 hours after the race. Technetium-99m pyrophosphate myocardial scintigraphy was carried out at the initial prerace assessment and repeated 48 to 96 hours after the race. None of the subjects developed cardiac symptoms during or after the race.Activities of creatine kinase and creatine kinase MB became maximal 24 hours after the race. One and 96 hours after the race two and five subjects, respectively, showed amounts of creatine kinase MB totalling 5% or more of total creatine kinase. Lactate dehydrogenase activity peaked at one hour after the race, and activities of aspartate and alanine aminotransferases peaked at 24 and 96 hours after the race, respectively. Activities of all these enzymes showed a significant increase from prerace values during the rest of the study. Electrocardiographic features noted were similar to those reported elsewhere in athletes under similar conditions. They included first-degree heart block, incomplete right bundle-branch block, left ventricular hypertrophy, pseudoischaemic T-wave changes, and early repolarisation of variant ST-segment elevations in precordial leads. Technetium-99m pyrophosphate myocardial scintigraphy did not show evidence of myocardial damage before or after the race. Alpha(1)-acid glycoprotein concentrations were normal throughout.These data suggest that reliance on standard enzyme estimations and electrocardiographic criteria may yield false-positive indicators of myocardial injury during prolonged strenuous exercise. Technetium-99m pyrophosphate scintigraphy and alpha(1)-acid glycoprotein measurements offer additional information and may usefully be employed in evaluating circulatory collapse associated with such exercise.

Ambulatory electrocardiographic recording in endurance athletes

Data from ambulatory electrocardiographic recording in 35 highly trained endurance athletes and in 35 non-athletic controls of similar ages are given. The minimal, mean hourly, and maximal heart rates were significantly lower in the athletes. Thirteen athletes (37 . 1%) but only two controls (5 . 7%) had sinus pauses exceeding 2 . 0 seconds. First degree atrioventricular block was observed in 13 athletes (37 . 1%) and five controls (14 . 3%), second degree Wenckebach type block in eight athletes (22 . 9%) and two controls (5 . 7%), and second degree block with Mobitz II-like pattern in three athletes (8 . 6%) and no control. All athletes with Mobitz II-type pattern also had first degree and Wenckebach-type second degree atrioventricular block. The behavior of sinus rate on development of atrioventricular block varied, not only interindividually but also intraindividually, from absence of change to an increase or decrease in most subjects in both study groups. A decrease in sinus rate on appearance of atrioventricular block was found constantly in only two athletes and one control. Atrioventricular dissociation with junctional rhythm occurred in seven athletes (20%) and with ventricular rhythm in one athlete. Neither of these phenomena was seen in the group of controls. The athletes had slightly fewer ventricular extrasystoles than controls, and no athlete had ventricular tachycardia, whereas two controls had ventricular tachycardia.

Wenckebach second-degree A-V block in top-ranking athletes: an old problem revisited

The occurrence of Wenckebach second-degree (Mobitz I) A-V block in apparently normal persons still provides a puzzle for the cardiologist, as the benign nature of this event has been recently questioned. This problem becomes more intriguing when Wenckebach A-V block is encountered in asymptomatic top-ranking athletes, because of medico-legal implications. We report 10 cases of highly-trained athletes, including three with mitral valve prolapse (MVP) features, with a spontaneous or induced Wenckebach second-degree A-V block. Previous ECGs of six subjects, dating from a maximum of 6 years to a minimum of 18 months, were available. Deterioration of A-V conduction has never been documented and all six cases have remained asymptomatic for the whole follow-up period. Athletes have been submitted to a protocol study consisting of ECG recording at rest, during, and after vagal and sympathetic reflex maneuvers, drug administration (isoproterenol and atropine), submaximal and maximal exercise. Nine subjects have been considered to have "normal" responses of the A-V node to provocative tests, since conduction disturbances were improved or normalized by reflex sympathetic stimulations and were completely normalized by autonomic drug administration and exercise. One athlete showed "abnormal" responses to tests. In order to give a conclusive prognostic and medico-legal assessment, we advised him to submit to an invasive electrophysiological investigation. Wenckebach second-degree A-V block in athletes may be a more common finding than so far described, especially when a systematic search is made. In our opinion, this event can still be considered a vagally-induced benign feature of athlete's heart, provided that an immediate improvement of A-V conduction is obtained in response to reflex sympathetic maneuvers, and that a complete normalization after sympathomimetic and vagolytic drug administration and physical exercise is observed. The clinical histories of our athletes and the observed complete disappearance of conduction disturbances after detraining, strongly support this opinion. Wenckebach second-degree A-V block in asymptomatic athletes with MVP features probably does not affect the prognosis if similar favorable responses to the aforesaid tests are observed.