Digitized Electrocardiography Measurements Support the Biological Plausibility of the Pathological Significance of ST Segments in Athletes.

OBJECTIVE: ST segment deviations around the isoelectric line are common findings in manifest cardiovascular disease. In athletes, ST elevation is common, while ST depression is considered rare. However, clinical studies in athletes have associated ST depression with myocardial fibrosis and fatty infiltration and ST elevation with pericarditis and myocarditis. This study aims to explore the association between resting ST segment deviations and resting heart rate, an indicator of training and autonomic tone and electrocardiography (ECG) markers of exercise training effect and cardiovascular health R and T wave amplitude. DESIGN: Retrospective analysis of digitized ECG data. SETTING: Institutional setting. PARTICIPANTS: Seven thousand eight hundred thirty-six (male athletes = 4592, female athletes = 3244) healthy asymptomatic athletes (14-35 years). MAIN OUTCOME MEASURES: A series of correlations and regressions were conducted between ST depression (<0.0 µV) and ST elevation (>0.0 µV), on R and T wave amplitudes, and heart rate in leads V2, V5, and aVF. RESULTS: Positive correlations between ST elevation and R and T wave (S wave in V2) amplitudes and leads V5, V2, and aVF in male and female athletes (range of r = 0.1-0.54). In addition, there was a negative correlation between ST elevation and HR for male and female athletes. Finally, there was a negative correlation between ST depression and R wave and HR for male and female athletes in V5 ( P < 0.01). CONCLUSIONS: In athletes, ST segment elevation is correlated with R and T wave amplitudes and negatively correlated with HR. In addition, ST segment elevation is correlated with low heart rate, consistent with its higher prevalence in athletes. ST segment depression is not influenced by HR but is negatively associated with R and T wave amplitudes.

Premature ventricular contractions (PVCs) in young athletes.

There is a growing body of literature focusing on the morphology, management, and outcomes of PVCs in athletes. This review summarizes this literature and establishes recommendations on management, treatment, and indications for specialist referral in this patient population. The sports medicine physician's responses and recommendation should be made in conjunction with the athletes wishes. Medications or ablations are not always necessary in all athletes if they are followed with regular evaluations.

Guide to the Female Student Athlete ECG: A Comprehensive Study of 3466 Young, Racially Diverse Athletes.

OBJECTIVES: The 12-lead electrocardiogram (ECG) is used in the preparticipation screening examination for athletes. Despite known differences in ECG findings by sex, only QTc prolongation is given a sex-specific threshold. We hypothesize that our large dataset-with diversity in age, race, and sport participation-can be utilized to improve ECG screening in female student athletes. METHODS: Computerized 12-lead ECGs were recorded and analyzed in female athletes who underwent preparticipation screening examination between June 2010 and September 2021. The quantitative, empirical 2017 international criteria for electrocardiographic interpretation were compared with either the 99th percentile in our cohort or the percentile that corresponded to the known disease prevalence. RESULTS: Of 3466 female athletes with ECGs as part of preparticipation screening examination, the 2017 international criteria classified 2.1% of athletes with at least one ECG abnormality requiring cardiological evaluation. Rates were similar across age, race/ethnicity, and sporting discipline. Using ranges based on our population, 2.7% of athletes would require additional workup. Surprisingly, ST depression up to 0.03 mV was a normal finding in this cohort. If RS voltage extremes were considered findings requiring follow-up, an additional 9.6% of the athlete population would be flagged using current definitions. This number decreases to 2.7% if using the 99th percentile in this cohort. CONCLUSION: These results highlight a difference in the reported prevalence of ECG abnormalities when comparing empirically derived thresholds to statistically derived ranges. Consideration of new metrics specific to the female athlete population has the potential to further refine athlete ECG screening.

Modest Gains After an 8-Week Exercise Program Correlate With Reductions in Non-traditional Markers of Cardiovascular Risk.

Background: Although engaging in physical exercise has been shown to reduce the incidence of cardiovascular events, the molecular mechanisms by which exercise mediates these benefits remain unclear. Based on epidemiological evidence, reductions in traditional risk factors only accounts for 50% of the protective effects of exercise, leaving the remaining mechanisms unexplained. The objective of this study was to determine whether engaging in a regular exercise program in a real world clinical setting mediates cardiovascular protection via modulation of non-traditional risk factors, such as those involved in coagulation, inflammation and metabolic regulation. Methods and Results: We performed a prospective, cohort study in 52 sedentary patients with cardiovascular disease or cardiovascular risk factors at two tertiary medical centers between January 1, 2016 and December 31, 2019. Prior to and at the completion of an 8-week exercise program, we collected information on traditional cardiovascular risk factors, exercise capacity, and physical activity and performed plasma analysis to measure levels of fibrinolytic, inflammatory and metabolic biomarkers to assess changes in non-traditional cardiovascular risk factors. The median weight change, improvement in physical fitness, and change in physical activity for the entire cohort were: -4.6 pounds (IQR: +2 pounds, -11.8 pounds), 0.37 METs (IQR: -0.076 METs, 1.06 METs), and 252.7 kcals/week (IQR: -119, 921.2 kcals/week). In addition to improvement in blood pressure and cholesterol, patients who lost at least 5 pounds, expended at least 1,000 additional kcals/week, and/or achieved ≥0.5 MET increase in fitness had a significant reduction in plasminogen activator inhibitor-1 [9.07 ng/mL (95% CI: 2.78-15.35 ng/mL); P = 0.026], platelet derived growth factor beta [376.077 pg/mL (95% CI: 44.69-707.46 pg/mL); P = 0.026); and angiopoietin-1 [(1104.11 pg/mL (95% CI: 2.92-2205.30 pg/mL); P = 0.049)]. Conclusion: Modest improvements in physical fitness, physical activity, and/or weight loss through a short-term exercise program was associated with decreased plasma levels of plasminogen activator inhibitor, platelet derived growth factor beta, and angiopoietin, which have been associated with impaired fibrinolysis and inflammation.

QT Corrections for Long QT Risk Assessment: Implications for the Preparticipation Examination.

BACKGROUND: Because sudden cardiac death (SCD) in the young mainly occurs in individuals with structurally normal hearts, improved screening techniques for detecting inherited arrhythmic diseases are needed. The QT interval is an important screening measurement; however, the criteria for detecting an abnormal QT interval are based on Bazett formula and older populations. OBJECTIVE: To define the normal upper limits for QT interval from the electrocardiograms (ECGs) of healthy young individuals, compare the major correction formula and propose new QT interval thresholds for detecting those at risk of SCD. METHODS: Young active individuals underwent ECGs as part of routine preparticipation physical examinations for competitive sports or community screening. This was a nonfunded study using de-identified data with no follow-up. RESULTS: There were 31 558 subjects: 2174 grade school (7%), 18 547 high school (59%), and 10 822 college (34%). Mean age was 17 (12-35 years), 45% were female, 67% white, and 11% of African descent. Bazett performed least favorably for removing the effect of heart rate (HR), whereas Fridericia performed the best. Fridericia correction also closely fit the raw data best (R of 0.65), and at percentile values applicable to screening. The recommended risk cut points using Bazetts correction identified less than half of the athletes in the 99th or 99.5th percentiles of the uncorrected QT by HR range. Use of Fridericia correction increased capture rates by over 50%. CONCLUSION: Our results support the application of the Fridericia-corrected threshold of 460 for men and 470 milliseconds for women (and 485 milliseconds for marked prolongation) rather than Bazett correction for the preparticipation examination.

Accuracy of non-invasive stress testing in women and men with angina in the absence of obstructive coronary artery disease.

OBJECTIVE: While >20% of patients presenting to the cardiac catheterization laboratory with angina have no obstructive coronary artery disease (CAD), a majority (77%) have an occult coronary abnormality (endothelial dysfunction, microvascular dysfunction (MVD), and/or a myocardial bridge (MB)). There are little data regarding the ability of noninvasive stress testing to identify these occult abnormalities in patients with angina in the absence of obstructive CAD. METHODS: We retrospectively evaluated 155 patients (76.7% women) with angina and no obstructive CAD who underwent stress echocardiography and/or electrocardiography before angiography. We evaluated Duke treadmill score, heart rate recovery (HRR), metabolic equivalents, and blood pressure response. During angiography, patients underwent invasive testing for endothelial dysfunction (decrease in epicardial coronary artery diameter >20% after intracoronary acetylcholine), MVD (index of microcirculatory resistance ≥25), and intravascular ultrasound for the presence of an MB. RESULTS: Stress echocardiography and electrocardiography were positive in 58 (43.6%) and 57 (36.7%) patients, respectively. Endothelial dysfunction was present in 96 (64%), MVD in 32 (20.6%), and an MB in 83 (53.9%). On multivariable logistic regression, stress echo was not associated with any abnormality, while stress ECG was associated with endothelial dysfunction. An abnormal HRR was associated with endothelial dysfunction and MVD, but not an MB. CONCLUSION: Conventional stress testing is insufficient for identifying occult coronary abnormalities that are frequently present in patients with angina in the absence of obstructive CAD. A normal stress test does not rule out a non-obstructive coronary etiology of angina, nor does it negate the need for comprehensive invasive testing.

International recommendations for electrocardiographic interpretation in athletes.

Sudden cardiac death (SCD) is the leading cause of mortality in athletes during sport. A variety of mostly hereditary, structural, or electrical cardiac disorders are associated with SCD in young athletes, the majority of which can be identified or suggested by abnormalities on a resting 12-lead electrocardiogram (ECG). Whether used for diagnostic or screening purposes, physicians responsible for the cardiovascular care of athletes should be knowledgeable and competent in ECG interpretation in athletes. However, in most countries a shortage of physician expertise limits wider application of the ECG in the care of the athlete. A critical need exists for physician education in modern ECG interpretation that distinguishes normal physiological adaptations in athletes from distinctly abnormal findings suggestive of underlying pathology. Since the original 2010 European Society of Cardiology recommendations for ECG interpretation in athletes, ECG standards have evolved quickly over the last decade; pushed by a growing body of scientific data that both tests proposed criteria sets and establishes new evidence to guide refinements. On 26-27 February 2015, an international group of experts in sports cardiology, inherited cardiac disease, and sports medicine convened in Seattle, Washington, to update contemporary standards for ECG interpretation in athletes. The objective of the meeting was to define and revise ECG interpretation standards based on new and emerging research and to develop a clear guide to the proper evaluation of ECG abnormalities in athletes. This statement represents an international consensus for ECG interpretation in athletes and provides expert opinion-based recommendations linking specific ECG abnormalities and the secondary evaluation for conditions associated with SCD.

Limited Relationship of Voltage Criteria for Electrocardiogram Left Ventricular Hypertrophy to Cardiovascular Mortality.

BACKGROUND: Numerous methods have been proposed for diagnosing left ventricular hypertrophy using the electrocardiogram. They have limited sensitivity for recognizing pathological hypertrophy, at least in part due to their inability to distinguish pathological from physiological hypertrophy. Our objective is to compare the major electrocardiogram-left ventricular hypertrophy criteria using cardiovascular mortality as a surrogate for pathological hypertrophy. METHODS: This study was a retrospective analysis of 16,253 veterans < 56 years of age seen at a large Veterans Affairs Medical Center from 1987 to 1999 and followed a median of 17.8 years for cardiovascular mortality. Receiver operating characteristics and Cox hazard survival techniques were applied. RESULTS: Of the 16,253 veterans included in our target population, the mean age was 43 years, 8.6% were female, 33.5% met criteria for electrocardiogram-left ventricular hypertrophy, and there were 744 cardiovascular deaths (annual cardiovascular mortality 0.25%). Receiver operating characteristic analysis demonstrated that the greatest area under the curve (AUC) for classification of cardiovascular death was obtained using the Romhilt-Estes score (0.63; 95% confidence interval, 0.61-0.65). Most of the voltage-only criteria had nondiagnostic area under the curves, with the Cornell being the best at 0.59 (95% confidence interval, 0.57-0.62). When the components of the Romhilt-Estes score were examined using step-wise Wald analysis, the voltage criteria dropped from the model. The Romhilt-Estes score ≥ 4, the Cornell, and the Peguero had the highest association with cardiovascular mortality (adjusted hazard ratios 2.2, 2.0, and 2.1, consecutively). CONCLUSION: None of the electrocardiogram leads with voltage criteria exhibited sufficient classification power for clinical use.

International criteria for electrocardiographic interpretation in athletes: Consensus statement.

Sudden cardiac death (SCD) is the leading cause of mortality in athletes during sport. A variety of mostly hereditary, structural or electrical cardiac disorders are associated with SCD in young athletes, the majority of which can be identified or suggested by abnormalities on a resting 12-lead electrocardiogram (ECG). Whether used for diagnostic or screening purposes, physicians responsible for the cardiovascular care of athletes should be knowledgeable and competent in ECG interpretation in athletes. However, in most countries a shortage of physician expertise limits wider application of the ECG in the care of the athlete. A critical need exists for physician education in modern ECG interpretation that distinguishes normal physiological adaptations in athletes from distinctly abnormal findings suggestive of underlying pathology. Since the original 2010 European Society of Cardiology recommendations for ECG interpretation in athletes, ECG standards have evolved quickly, advanced by a growing body of scientific data and investigations that both examine proposed criteria sets and establish new evidence to guide refinements. On 26-27 February 2015, an international group of experts in sports cardiology, inherited cardiac disease, and sports medicine convened in Seattle, Washington (USA), to update contemporary standards for ECG interpretation in athletes. The objective of the meeting was to define and revise ECG interpretation standards based on new and emerging research and to develop a clear guide to the proper evaluation of ECG abnormalities in athletes. This statement represents an international consensus for ECG interpretation in athletes and provides expert opinion-based recommendations linking specific ECG abnormalities and the secondary evaluation for conditions associated with SCD.

International Recommendations for Electrocardiographic Interpretation in Athletes.

Sudden cardiac death (SCD) is the leading cause of mortality in athletes during sport. A variety of mostly hereditary, structural, or electrical cardiac disorders are associated with SCD in young athletes, the majority of which can be identified or suggested by abnormalities on a resting 12-lead electrocardiogram (ECG). Whether used for diagnostic or screening purposes, physicians responsible for the cardiovascular care of athletes should be knowledgeable and competent in ECG interpretation in athletes. However, in most countries a shortage of physician expertise limits wider application of the ECG in the care of the athlete. A critical need exists for physician education in modern ECG interpretation that distinguishes normal physiological adaptations in athletes from distinctly abnormal findings suggestive of underlying pathology. Since the original 2010 European Society of Cardiology recommendations for ECG interpretation in athletes, ECG standards have evolved quickly over the last decade; pushed by a growing body of scientific data that both tests proposed criteria sets and establishes new evidence to guide refinements. On February 26-27, 2015, an international group of experts in sports cardiology, inherited cardiac disease, and sports medicine convened in Seattle, Washington, to update contemporary standards for ECG interpretation in athletes. The objective of the meeting was to define and revise ECG interpretation standards based on new and emerging research and to develop a clear guide to the proper evaluation of ECG abnormalities in athletes. This statement represents an international consensus for ECG interpretation in athletes and provides expert opinion-based recommendations linking specific ECG abnormalities and the secondary evaluation for conditions associated with SCD.

Optimizing QT Interval Measurement for the Preparticipation Screening of Young Athletes.

PURPOSE: Sudden cardiac death is the leading cause of death in athletes. Long QT syndrome (LQTS) is one of the most common cardiogenetic diseases that can lead to sudden cardiac death and is identified by QT interval prolongation on an ECG. Recommendations for QT monitoring in athletes are adopted from nonathlete populations. To improve screening, ECG data of athletes are assessed to determine a more appropriate method for QT interval estimation. METHODS: ECG (CardeaScreen) data were collected from June 2010 to March 2015. ECG data with HR greater than 100 bpm were excluded. Fiducial points of outliers were manually corrected if the QRS onset or the T wave offset was misidentified. A model of best fit was determined and compared across four QT correction factors. Classification analysis was used to compare the Bazett's corrected QT interval to the 99th percentile of uncorrected QT interval. RESULTS: High school (n = 597), college (n = 1207), and professional athletes (n = 273) (N = 2077) were analyzed. Mean age was 19 ± 3.5 yr. QT interval varied by cohort (HS = 388 ± 30, Col = 410 ± 33, Pro = 407 ± 27, p < 0.0001). A nonlinear power function with a cubic exponent of -0.349 fit the data the best (R = 0.64). Of the four common correction factors, Fridericia had the lowest residual dependence to HR (m = -0.10). With standard screening, 75% of athletes within the top 1% for QT interval were not identified for further investigation for LQTS. CONCLUSION: Up to 75% of athletes possessing an uncorrected QT interval greater than 99% of the population are not identified for investigation for LQTS using the recommended criteria. We propose a new method of risk stratification that replaces QT interval correction. Further study is needed to establish QT interval distributions and risk thresholds in athletes.

Hypertrophic Cardiomyopathy as a Cause of Sudden Cardiac Death in the Young: A Meta-Analysis.

BACKGROUND: Sudden cardiac death is often linked with hypertrophic cardiomyopathy in young athletes, but with a divergence of study results. We performed a meta-analysis to compare the prevalence of sudden cardiac deaths associated with hypertrophic cardiomyopathy vs sudden cardiac deaths associated with structurally normal hearts. METHODS: A structured search of MEDLINE was conducted for studies published from 1990 through 2014. Retrospective cohort studies, patient registries, and autopsy series examining sudden cardiac death etiology in young individuals (age ≤35 years) were included. A random-effects model was applied to generate pooled summary estimates of the percentage of sudden cardiac deaths with structurally normal hearts at postmortem vs those caused by hypertrophic cardiomyopathy. Heterogeneity was assessed using I(2). Subgroup analyses were conducted based on study location, patient age groups, and population types. RESULTS: Thirty-four studies were included, representing a combined sample of 4605 subjects. The overall pooled percentage of sudden cardiac deaths caused by hypertrophic cardiomyopathy was 10.3% (95% confidence interval [CI], 8.0%-12.6%; I(2) = 87.2%), while sudden cardiac deaths with structurally normal hearts at death were more common (P <.001) at 26.7% (95% CI, 21.0%-32.3%; I(2) = 95.3%). In nonathlete subjects, the pooled percentage of sudden cardiac deaths associated with structurally normal hearts (30.7%; 95% CI, 23.0%-38.4%; I(2) = 96.3%) were significantly more common (P <.001) than sudden cardiac death caused by hypertrophic cardiomyopathy (7.8%; 95% CI, 5.8%-9.9%; I(2) = 80.1%). Among athletes, there was no significant difference between summary estimates of hypertrophic cardiomyopathy and structurally normal hearts (P = .57), except in Europe where structurally normal hearts were more common (P = .01). CONCLUSIONS: Hypertrophic cardiomyopathy is not a more common finding at death than structurally normal hearts in young subjects with sudden cardiac death. Increased attention should be directed toward identifying causes of death associated with a structurally normal heart in subjects with sudden cardiac death.

Long-term prognosis of early repolarization with J-wave and QRS slur patterns on the resting electrocardiogram: a cohort study.

BACKGROUND: The prognostic value of early repolarization with J waves and QRS slurs remains controversial. Although these findings are more prevalent in patients with idiopathic ventricular fibrillation, their ability to predict cardiovascular death has varied across studies. OBJECTIVE: To test the hypothesis that J waves and QRS slurs on electrocardiograms (ECGs) are associated with increased risk for cardiovascular death. DESIGN: Retrospective cohort. SETTING: Veterans Affairs Palo Alto Health Care System. PATIENTS: Veterans younger than 56 years who had resting 12-lead electrocardiography, 90.5% of whom were men. MEASUREMENTS: Electrocardiograms were manually measured and visually coded using criteria of 0.1 mV or greater in at least 2 contiguous leads. J waves were measured at the peak of an upward deflection or notch at the end of QRS, and QRS slurs were measured at the top of conduction delay on the QRS downstroke. Absolute risk differences at 10 years were calculated to study the associations between J waves or QRS slurs and the primary outcome of cardiovascular death. RESULTS: Over a median follow-up of 17.5 years, 859 cardiovascular deaths occurred. Of 20 661 ECGs, 4219 (20%) had J waves or QRS slurs in the inferior and/or lateral territories; of these, 3318 (78.6%) had J waves or QRS slurs in inferior leads and 1701 (40.3%) in lateral leads. The upper bound of differences in risk for cardiovascular death from any of the J-wave or QRS slur patterns suggests that an increased risk can be safely ruled out (inferior, -0.77% [95% CI, -1.27% to -0.27%]; lateral, -1.07% [CI, -1.72% to -0.43%]). LIMITATION: The study consisted of predominantly men, and deaths could be classified as cardiovascular but not arrhythmic. CONCLUSION: J waves and QRS slurs did not exhibit a clinically meaningful increased risk for cardiovascular death in long-term follow-up. PRIMARY FUNDING SOURCE: None.

Limitations of Current AHA Guidelines and Proposal of New Guidelines for the Preparticipation Examination of Athletes.

OBJECTIVE: To examine the prevalence of athletes who screen positive with the preparticipation examination guidelines from the American Heart Association, the AHA 12-elements, in combination with 3 screening electrocardiogram (ECG) criteria. DESIGN: Observational cross-sectional study. SETTING: Stanford University Sports Medicine Clinic. PARTICIPANTS: Total of 1596 participants, including 297 (167 male; mean age, 16.2 years) high school athletes, 1016 (541 male; mean age, 18.8 years) collegiate athletes, and 283 (mean age, 26.3 years) male professional athletes. MAIN OUTCOME MEASURES: Athletes were screened using the 8 personal and family history questions from the AHA 12-elements. Electrocardiograms were obtained for all participants and interpreted using Seattle criteria, Stanford criteria, and European Society of Cardiology (ESC) recommendations. RESULTS: Approximately one-quarter of all athletes (23.8%) had at least 1 positive response to the AHA personal and family history elements. High school and college athletes had similar rates of having at least 1 positive response (25.9% vs 27.4%), whereas professional athletes had a significantly lower rate of having at least 1 positive response (8.8%, P < 0.05). Females reported more episodes of unexplained syncope (11.4% vs 7.5%, P = 0.017) and excessive exertional dyspnea with exercise (11.1% vs 6.1%, P = 0.001) than males. High school athletes had more positive responses to the family history elements when compared with college athletes (P < 0.05). The percentage of athletes who had an abnormal ECG varied between Seattle criteria (6.0%), Stanford criteria (8.8%), and ESC recommendations (26.8%). CONCLUSIONS: Many athletes screen positive under current screening recommendations, and ECG results vary widely by interpretation criteria. CLINICAL RELEVANCE: In a patient population without any adverse cardiovascular events, the currently recommended AHA 12-elements have an unacceptably high rate of false positives. Newer screening guidelines are needed, with fewer false positives and evidence-based updates.

Diagnostic utility of a novel leadless arrhythmia monitoring device.

Although extending the duration of ambulatory electrocardiographic monitoring beyond 24 to 48 hours can improve the detection of arrhythmias, lead-based (Holter) monitors might be limited by patient compliance and other factors. We, therefore, evaluated compliance, analyzable signal time, interval to arrhythmia detection, and diagnostic yield of the Zio Patch, a novel leadless, electrocardiographic monitoring device in 26,751 consecutive patients. The mean wear time was 7.6 ± 3.6 days, and the median analyzable time was 99% of the total wear time. Among the patients with detected arrhythmias (60.3% of all patients), 29.9% had their first arrhythmia and 51.1% had their first symptom-triggered arrhythmia occur after the initial 48-hour period. Compared with the first 48 hours of monitoring, the overall diagnostic yield was greater when data from the entire Zio Patch wear duration were included for any arrhythmia (62.2% vs 43.9%, p <0.0001) and for any symptomatic arrhythmia (9.7% vs 4.4%, p <0.0001). For paroxysmal atrial fibrillation (AF), the mean interval to the first detection of AF was inversely proportional to the total AF burden, with an increasing proportion occurring after 48 hours (11.2%, 10.5%, 20.8%, and 38.0% for an AF burden of 51% to 75%, 26% to 50%, 1% to 25%, and <1%, respectively). In conclusion, extended monitoring with the Zio Patch for ≤14 days is feasible, with high patient compliance, a high analyzable signal time, and an incremental diagnostic yield beyond 48 hours for all arrhythmia types. These findings could have significant implications for device selection, monitoring duration, and care pathways for arrhythmia evaluation and AF surveillance.