Normal resting electrocardiographic variants in young athletes

Sudden Cardiac Death Risk Stratification of the Early Repolarization Syndrome: An Updated Review of the Literature

PURPOSE OF REVIEW

Early repolarization syndrome (ERS), once thought to be innocuous, has now been shown to be responsible for ventricular arrythmias and sudden cardiac death occurrence. This review will help the clinician to identify the patients who are most at risk for arrhythmias, so that they can adopt a preventive or secondary treatment approach, either of which is still poorly defined.

RECENT FINDINGS

Patients at high risk are found to be particularly young men, with a personal or family history of syncope or sudden death, who have an inferolateral ER on the electrocardiogram, more elevated J-point, longer J-wave duration and wider J angle, a horizontal or descending ST segment, lower T/R ratio, and small and/or inverted waves. The association with a structural heart disease or another channelopathy potentiates this arrhythmic risk. Taken together, these parameters allow prediction of the malignancy of ER pattern with a certain reliability. Further research is however needed to develop concrete risk stratification algorithms and the therapeutic strategies taken in function of it.

Recent Non-Invasive Parameters to Identify Subjects at High Risk of Sudden Cardiac Death

Cardiovascular diseases remain among the leading causes of death worldwide and sudden cardiac death (SCD) accounts for ~25% of these deaths. Despite its epidemiologic relevance, there are very few diagnostic strategies available useful to prevent SCD mainly focused on patients already affected by specific cardiovascular diseases. Unfortunately, most of these parameters exhibit poor positive predictive accuracy. Moreover, there is also a need to identify parameters to stratify the risk of SCD among otherwise healthy subjects. This review aims to provide an update on the most relevant non-invasive diagnostic features to identify patients at higher risk of developing malignant ventricular arrhythmias and SCD.

A Meta-Analysis Comparing Postoperative Complications and Outcomes of Femtosecond Laser-Assisted Cataract Surgery versus Conventional Phacoemulsification for Cataract

Objective. This meta-analysis aimed to compare the outcomes and postoperative complications between femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification cataract surgery (CPCS). Methods. Bibliographic databases, including PubMed, Embase, and Cochrane library, were systematically searched for references on or before September 2015 regarding the outcomes and complications by FLACS or CPCS. Data on corneal endothelial cell loss, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive outcomes, and postoperative complications were retrieved. Results. A total of 9 trials were included in this analysis. Refractive outcomes (MD = -0.21, 95% CI: -0.39~0.03, P = 0.02) were significantly improved after FLACS. Although corneal endothelial cell loss was not significantly reduced after FLACS, there was a trend towards lower corneal endothelial cell loss (mean difference (MD) = 197.82, 95% confidence interval (CI): 2.66~392.97, P = 0.05) after FLACS. There was no significant difference in UDVA (MD = -0.01, 95% CI: -0.13~0.10, P = 0.80) or CDVA (MD = -0.03, 95% CI: 0.07~0.00, P = 0.09) between the two surgeries. Elevated intraocular pressure and macular edema were most commonly developed complications after cataract surgery, and the incidence of these complications associated with the two surgeries was similar. Conclusion. Compared with CPCS, FLACS might achieve higher refractive stability and corneal endothelial cell count. Nevertheless, further study is needed to validate our findings.

12-lead electrocardiogram features of arrhythmic risk: A focus on early repolarization

The 12-lead electrocardiogram (ECG) is still the most used tool in cardiology clinical practice. Considering its easy accessibility, low cost and the information that it provides, it remains the starting point for diagnosis and prognosis. More specifically, its ability to detect prognostic markers for sudden cardiac death due to arrhythmias by identifying specific patterns that express electrical disturbances of the heart muscle, which may predispose to malignant arrhythmias, is universally recognized. Alterations in the ventricular repolarization process, identifiable on a 12-lead ECG, play a role in the genesis of ventricular arrhythmias in different cardiac diseases. The aim of this paper is to focus the attention on a new marker of arrhythmic risk, the early repolarization pattern in order to highlight the prognostic role of the 12-lead ECG.

Long-term follow-up of early repolarization pattern in elite athletes

BACKGROUND

Early repolarization pattern (ERP) is considered a benign variant of the electrocardiogram (ECG), more frequent in athletes. However, prospective studies suggested that ERP is associated with an increased risk of sudden cardiac death (SCD). The purpose of this study is to determine the prevalence, clinical characteristics, and long-term outcome of ERP in elite athletes during professional activity and after retirement.

METHODS AND RESULTS

A cohort of 299 white elite athletes recruited between 1960 and 1999 was retrospectively analyzed. Athletes were eligible if they had participated for at least 6 consecutive months in high competition and retired for a minimum of 5 years before inclusion. Clinical data and ECG were abstracted from the clinical records using a questionnaire, and outcomes after a mean follow-up of 24 years were registered. Among the 299 athletes, 66% were men with a mean age of 20 (SD 6.4) years. ERP was found in 31.4% of participants, and it was located in lateral ECG leads in 57.4% of cases, in inferior leads in 6.4%, and in both leads in the remaining 36.2%. After retirement, ERP still persisted in 53.4% of athletes. Predictive factors for the persistence were: left ventricular hypertrophy signs at the baseline ECG (odds ratio [OR] 4.35; 95% confidence interval [CI], 1.43-13.24; P = .010), sinus bradycardia after retirement (OR 2.56; 95% CI, 1.09-5.99; P = .031), and presence of ERP during the sportive career (OR 20.35; 95% CI, 8.54-48.51; P < .001). After a mean follow-up of 24 years, no episodes of SCD occurred.

CONCLUSIONS

A third of elite athletes presented ERP, and this persisted in 53.4% of cases after retirement. After a long follow-up period, no difference in outcome of SCD was seen.

Association between cardiac dimensions and athlete lineup position: analysis using echocardiography in NCAA football team players

In determining what is "abnormal"-in terms of cardiac electrical and morphologic remodeling in athletes-it is important to identify what is "normal" or expected. With specialization for each position in a football team lineup, we attempted to describe the association between the position played and the physiologic cardiac changes of designated players. We evaluated data from 85 National College Athletic Association football players from a single team. The participants were assigned to 1 of 3 groups based on position and training regimen: lineman (n = 34), mobility/power players (n = 13), and skill players (n = 38). Players underwent assessment with electrocardiography and echocardiography (ECHO), with results interpreted by reviewers blinded to players' positions. Linemen were found to have greater body mass index and body surface area (BSA), as well as longer QRS duration (102 ± 10 ms vs 101 ± 7 ms in mobility/power players, and 96 ± 7 ms in skill players; P < 0.007). Left ventricular (LV) voltage values were lower in linemen (27.7 ± 6.5 mV vs 28.8 ± 7 mV in mobility/power players, and 31.8 ± 7.6 mV in skill players; both, P < 0.05). No differences in ejection fraction between groups were revealed on ECHO, but ECHO did show greater calculated LV mass, LV end-diastolic diameter, aortic root diameter, and LV outflow tract diameter in linemen, whether adjusted for BSA or not, and the differences were statistically different. Multivariate analysis showed that position (P < 0.0004 and QRS duration (P = 0.03) predicted LV mass. Echocardiographic variables found to be associated with player position included LV mass adjusted for BSA (P < 0.0001), LV end-diastolic diameter adjusted for BSA (P < 0.0003), and QTc interval (P = 0.007). On multivariate analysis, racial identity did not demonstrate significant differences; however, differences existed on univariate analysis of electrocardiography and ECHO variables, mostly in skill players. In skill players, QRS duration was shorter in the African American (AA) subgroup compared with that in the white/other subgroup. Lateral ST elevation and LV end-systolic volume were greater in AA players after adjustment for BSA, and AA linemen had greater LV posterior wall thickness after adjustment for BSA. In summary, we found that football players who are linemen had greater heart mass than did other players, despite adjustments for body size.

[Athlete's heart in the young: electrocardiographic and echocardiographic patterns in 107 French athletes]

PURPOSE

Since 2009 in France, every people practicing sport in competition must have a cardiovascular exam with electrocardiogram, to prevent sudden cardiac death. Sometimes, an echocardiography will be necessary. Little is known about athlete's heart in the young, particularly in the French people.

PATIENTS AND METHODS

One hundred and seven French elite adolescent athletes had an electrocardiogram with echocardiography to establish reference values in this population.

RESULTS

QTcorrected (QTc) interval calculated by the Hodges formula, is always in the normal values. Interventricular septal thickness is always ≤ 11 mm and left ventricular end diastolic diameter ≤ 55 mm in about 90 % of the athletes. Females have QTc interval longer than males and interventricular septal thickness finer. Diastolic function (18.9 ± 2.6 cm/s for e', E/e' ratio at 5.3 ± 0.8) is "supernormal" and correlate with age and cardiac frequency. Right ventricular systolic function is always good.

CONCLUSION

Adolescent athlete's heart is normal. If QTc interval is not normal, be afraid of a QT long syndrome. Furthermore, when interventricular septal thickness is > 11 mm or left ventricular end diastolic diameter > 55 mm, myocardiopathy will have to be ruled out.

Early repolarization pattern in competitive athletes: clinical correlates and the effects of exercise training

BACKGROUND

Inferior lead early repolarization pattern (ERP) recently has been associated with sudden cardiac death. Although ERP is common among athletes, prevalence, ECG lead distribution, clinical characteristics, and effects of physical training remain uncertain. We sought to examine the nonanterior ERP in competitive athletes.

METHODS AND RESULTS

ERP was assessed in a cross-sectional cohort of collegiate athletes (n = 879). The relationship between ERP and cardiac structure were then examined in a longitudinal subgroup (n = 146) before and after a 90-day period of exercise training. ERP was defined as J-point elevation ≥ 0.1 mV in at least 2 leads within a nonanterior territory (inferior [II, III, aVF] or lateral territory [I, aVL, V4-V6]). Nonanterior ERP was present in 25.1% (221/879) of athletes, including the inferior subtype in 3.8% (33/879). Exercise training led to significant increases in the prevalence of ERP and the inferior subtype, but there were no associations between ERP and echocardiographic measures of left ventricular remodeling. In a multivariable model, ERP was associated with black race (odds ratio [OR], 5.84; 95% CI, 3.54 to 9.61; P < 0.001), increased QRS voltage (OR, 2.08; 95% CI, 1.71 to 2.52; P < 0.001), and slower heart rate (OR, 1.54; 95% CI, 1.26 to 1.87; P < 0.001).

CONCLUSIONS

Nonanterior ERP, including the inferior subtype, is common and has strong clinical associations among competitive athletes. The finding of increased ERP prevalence after intense physical training establishes a strong association between exercise and ERP.

A wavelet-based ECG delineation algorithm for 32-bit integer online processing

Background

Since the first well-known electrocardiogram (ECG) delineator based on Wavelet Transform (WT) presented by Li et al. in 1995, a significant research effort has been devoted to the exploitation of this promising method. Its ability to reliably delineate the major waveform components (mono- or bi-phasic P wave, QRS, and mono- or bi-phasic T wave) would make it a suitable candidate for efficient online processing of ambulatory ECG signals. Unfortunately, previous implementations of this method adopt non-linear operators such as root mean square (RMS) or floating point algebra, which are computationally demanding.

Methods

This paper presents a 32-bit integer, linear algebra advanced approach to online QRS detection and P-QRS-T waves delineation of a single lead ECG signal, based on WT.

Results

The QRS detector performance was validated on the MIT-BIH Arrhythmia Database (sensitivity Se = 99.77%, positive predictive value P+ = 99.86%, on 109010 annotated beats) and on the European ST-T Database (Se = 99.81%, P+ = 99.56%, on 788050 annotated beats). The ECG delineator was validated on the QT Database, showing a mean error between manual and automatic annotation below 1.5 samples for all fiducial points: P-onset, P-peak, P-offset, QRS-onset, QRS-offset, T-peak, T-offset, and a mean standard deviation comparable to other established methods.

Conclusions

The proposed algorithm exhibits reliable QRS detection as well as accurate ECG delineation, in spite of a simple structure built on integer linear algebra.