Racial Differences in Electrocardiographic Characteristics and Prognostic Significance in Whites Versus Asians

Comparison of machine learning and conventional criteria in detecting left ventricular hypertrophy and prognosis with electrocardiography

Aims

Left ventricular hypertrophy (LVH) is clinically important; current electrocardiography (ECG) diagnostic criteria are inadequate for early detection. This study aimed to develop an artificial intelligence (AI)-based algorithm to improve the accuracy and prognostic value of ECG criteria for LVH detection.

Methods and results

A total of 42 016 patients (64.3 ± 16.5 years, 55.3% male) were enrolled. LV mass index was calculated from echocardiographic measurements. Left ventricular hypertrophy screening utilized ECG criteria, including Sokolow-Lyon, Cornell product, Cornell/strain index, Framingham criterion, and Peguero-Lo Presti. An AI algorithm using CatBoost was developed and validated (training dataset 80% and testing dataset 20%). F1 scores, reflecting the harmonic mean of precision and recall, were calculated. Mortality data were obtained through linkage with the National Death Registry. The CatBoost-based AI algorithm outperformed conventional ECG criteria in detecting LVH, achieving superior sensitivity, specificity, positive predictive value, F1 score, and area under curve. Significant features to predict LVH involved QRS and P-wave morphology. During a median follow-up duration of 10.1 years, 1655 deaths occurred in the testing dataset. Cox regression analyses showed that LVH identified by AI algorithm (hazard ratio and 95% confidence interval: 1.587, 1.309-1.924), Sokolow-Lyon (1.19, 1.038-1.365), Cornell product (1.301, 1.124-1.505), Cornell/strain index (1.306, 1.185-1.439), Framingham criterion (1.174, 1.062-1.298), and echocardiography-confirmed LVH (1.124, 1.019-1.239) were all significantly associated with mortality. Notably, AI-diagnosed LVH was more predictive of mortality than echocardiography-confirmed LVH.

Conclusion

Artificial intelligence-based LVH diagnosis outperformed conventional ECG criteria and was a superior predictor of mortality compared to echocardiography-confirmed LVH.

A Review of Racial Differences and Disparities in ECG

The electrocardiogram (ECG) is a widely used, non-invasive tool for diagnosing a range of cardiovascular conditions, including arrhythmia and heart disease-related structural changes. Despite its critical role in clinical care, racial and ethnic differences in ECG readings are often underexplored or inadequately addressed in research. Variations in key ECG parameters, such as PR interval, QRS duration, QT interval, and T-wave morphology, have been noted across different racial groups. However, the limited research in this area has hindered the development of diagnostic criteria that account for these differences, potentially contributing to healthcare disparities, as ECG interpretation algorithms largely developed from major population data may lead to misdiagnoses or inappropriate treatments for minority groups. This review aims to help cardiac researchers and cardiovascular specialists better understand, explore, and address the impact of racial and ethnic differences in ECG readings. By identifying potential causes-ranging from genetic factors to environmental influences-and exploring the resulting disparities in healthcare outcomes, we propose strategies such as the development of race-specific ECG norms, the application of artificial intelligence (AI) to improve diagnostic accuracy, and the diversification of ECG databases. Through these efforts, the medical community can advance toward more personalized and equitable cardiovascular care.

Association of Cardiovascular Risk Factors With Major and Minor Electrocardiographic Abnormalities: A Report From the Cross-Sectional Phase of Tehran Cohort Study

Background and Aims

In the current study, we aimed to identify the association between major and minor electrocardiographic abnormalities and cardiovascular risk factors.

Methods

We used the Tehran cohort study baseline data, an ongoing multidisciplinary, longitudinal study designed to identify cardiovascular disease risk factors in the adult population of Tehran. The electrocardiograms (ECGs) of 7630 Iranian adults aged 35 years and above were analyzed. ECG abnormalities were categorized into major or minor groups based on their clinical importance. Results were obtained by multivariable logistic regression and are expressed as odds ratios (ORs).

Results

A total of 756 (9.9%) participants had major ECG abnormalities, while minor abnormalities were detected in 2526 (33.1%). Males comprised 45.8% of the total population, and 41.8% of them had minor abnormalities. Individuals with older age, diabetes (OR = 1.35; 95% CI: 1.11-1.64), and hypertension (OR = 2.21; 95% CI: 1.82-2.68) had an increased risk of major ECG abnormalities. In contrast, intermediate (OR = 0.69; 95% CI: 0.57-0.84) and high physical activity levels (OR = 0.66; 95% CI: 0.51-0.86) were associated with a lower prevalence of major abnormalities. Male sex, older age, hypertension, and current smoking were also associated with an increased prevalence of ECG abnormalities combined (major or minor).

Conclusion

Major and minor ECG abnormalities are linked with important cardiovascular risk factors such as diabetes and hypertension. Since these abnormalities have been associated with poor outcomes, screening patients with cardiovascular risk factors with an ECG may distinguish high-risk individuals who require appropriate care and follow-up.

Prolonged QRS duration in patients with acute poisoning occurs both xenobiotics and with low level of potassium: a single-center retrospective case control study

Prolongation of QRS duration (prolonged QRS) is associated with severe outcomes in non-tricyclic antidepressant poisoning. However, factors other than xenobiotics affecting QRS duration have not yet been investigated. Hence, this study aimed to identify factors contributing to prolonged QRS. This study was a single-center retrospective case control study. Patients who had overdosed on drugs or orally ingested xenobiotics that they would not normally ingest orally were included in the study. Patients were divided into two groups: prolonged QRS and normal QRS. Subsequently, these groups were compared. We performed a logistic regression analysis with the factors extracted by comparison as explanatory variables and prolonged QRS as the objective variable. In total, 108 patients were analyzed; 19 belonged to the prolonged QRS group. In the prolonged QRS group, factors such as male sex, low level of potassium, and xenobiotic ingestion resulted in prolonged QRS. In a logistic regression analysis, significant differences were observed in terms of male sex (odds ratio [OR], 27.00; 95% confidence interval [CI], 5.93-123.00; p<0.001), xenobiotics ingested that resulted in prolonged QRS (OR, 8.55; 95% CI, 1.84-39.70; p<0.001), and potassium levels (OR, 0.15; 95% CI, 0.03-0.88; p=0.035). Ingestion of sodium channel blockers, male sex, and low level of potassium may contribute to prolonged QRS.

Age-dependent implications of left ventricular hypertrophy regression in patients with hypertension

Left ventricular hypertrophy (LVH) is a significant risk factor for cardiovascular mortality and morbidity in patients with hypertension. However, the effect of age on LVH regression or persistence and its differential prognostic value remain unclear. Therefore, we investigated the clinical implications of LVH regression in 1847 patients with hypertension and echocardiography data (at baseline and during antihypertensive treatment at an interval of 6-18 months) according to age. LVH was defined as a left ventricular mass index (LVMI) > 115 g/m2 and >95 g/m2 in men and women, respectively. LVH prevalence at baseline was not different according to age (age < 65 years: 42.6%; age ≥65 years: 45.7%; p = 0.187), but LVH regression was more frequently observed in the younger group (36.4% vs. 27.5%; p = 0.008). Spline curves and multiple linear regression analysis showed a significant relationship between reductions in systolic blood pressure and LVMI in the younger group (β = 0.425; p < 0.001), but not the elderly group (β = 0.044; p = 0.308). LVH regression was associated with a lower risk of the study outcome (composite of cardiovascular death and hospitalization for heart failure) regardless of age. In conclusion, the association between the reduction in blood pressure and LVH regression was prominent in patients with age < 65 years, but not in those with age ≥65 years. However, an association between LVH regression and lower risk of cardiovascular death and hospitalization for heart failure was observed regardless of patient age, suggesting the prognostic value of the LVH regression not only in the younger patients but also in elderly patients.

Race, Sex, and Age Disparities in the Performance of ECG Deep Learning Models Predicting Heart Failure

BACKGROUND

Deep learning models may combat widening racial disparities in heart failure outcomes through early identification of individuals at high risk. However, demographic biases in the performance of these models have not been well-studied.

METHODS

This retrospective analysis used 12-lead ECGs taken between 2008 and 2018 from 326 518 patient encounters referred for standard clinical indications to Stanford Hospital. The primary model was a convolutional neural network model trained to predict incident heart failure within 5 years. Biases were evaluated on the testing set (160 312 ECGs) using the area under the receiver operating characteristic curve, stratified across the protected attributes of race, ethnicity, age, and sex.

RESULTS

There were 59 817 cases of incident heart failure observed within 5 years of ECG collection. The performance of the primary model declined with age. There were no significant differences observed between racial groups overall. However, the primary model performed significantly worse in Black patients aged 0 to 40 years compared with all other racial groups in this age group, with differences most pronounced among young Black women. Disparities in model performance did not improve with the integration of race, ethnicity, sex, and age into model architecture, by training separate models for each racial group, or by providing the model with a data set of equal racial representation. Using probability thresholds individualized for race, age, and sex offered substantial improvements in F1 scores.

CONCLUSIONS

The biases found in this study warrant caution against perpetuating disparities through the development of machine learning tools for the prognosis and management of heart failure. Customizing the application of these models by using probability thresholds individualized by race, ethnicity, age, and sex may offer an avenue to mitigate existing algorithmic disparities.

Cold pressor stress effects on cardiac repolarization

The cold pressor test (CPT) elicits strong cardiovascular reactions via activation of the sympathetic nervous system (SNS), yielding subsequent increases in heart rate (HR) and blood pressure (BP). However, little is known on how exposure to the CPT affects cardiac ventricular repolarization. Twenty-eight healthy males underwent both a bilateral feet CPT and a warm water (WW) control condition on two separate days, one week apart. During pre-stress baseline and stress induction cardiovascular signals (ECG lead II, Finometer BP) were monitored continuously. Salivary cortisol and subjective stress ratings were assessed intermittently. Corrected QT (QTc) interval length and T-wave amplitude (TWA) were assessed for each heartbeat and subsequently aggregated individually over baseline and stress phases, respectively. CPT increases QTc interval length and elevates the TWA. Stress-induced changes in cardiac repolarization are only in part and weakly correlated with cardiovascular and cortisol stress-reactivity. Besides its already well-established effects on cardiovascular, endocrine, and subjective responses, CPT also impacts on cardiac repolarization by elongation of QTc interval length and elevation of TWA. CPT effects on cardiac repolarization share little variance with the other indices of stress reactivity, suggesting a potentially incremental value of this parameter for understanding psychobiological adaptation to acute CPT stress.

Sex differences in the association between minor nonspecific ST-segment and T-wave abnormalities and coronary artery calcification

BACKGROUND AND AIMS

Although minor nonspecific ST-segment and T-wave abnormalities (NSSTTA) have been associated with adverse cardiovascular outcomes, their relationship with subclinical atherosclerosis remains controversial. Therefore, the associations between electrocardiographic (ECG) abnormalities, including NSSTTA, and coronary artery calcification (CAC) were investigated in this study.

METHODS

This cross-sectional study included 136,461 Korean participants with no known cardiovascular disease or cancer, who underwent a health checkup including ECG and computed tomography to measure the coronary artery calcium score (CACS) by Agatston method between 2010 and 2018. ECG abnormalities were defined in accordance with the Minnesota Code using an automated ECG analysis program. A multinomial logistic regression model was used to calculate prevalence ratios (PRs) with 95% confidence intervals (CI) for each CACS category.

RESULTS

In men, both NSSTTA and major ECG abnormalities were associated with all levels of CACS. The multivariable-adjusted PRs (95% CI) for CACS >400 comparing NSSTTA and major ECG abnormalities to the reference (neither NSSTTA nor major ECG abnormalities) were 1.88 (1.29-2.74) and 1.50 (1.18-1.91), respectively. Women with major ECG abnormalities were more likely to have a CACS of 101-400, the PRs (95% CI) comparing major ECG abnormalities to the reference group was 1.75 (1.18-2.57). NSSTTA were not associated with any CACS level in women.

CONCLUSIONS

NSSTTA and major ECG abnormalities are associated with CAC in men, though NSSTTA were not associated with CAC in women, suggesting that NSSTTA should be considered sex-specific risk factors for coronary artery disease in men, but not in women.

Polypharmacy, Gender Disparities, and Ethnic and Racial Predispositions in Long QT Syndrome: An In-Depth Review

Long QT syndrome (LQTS) is a complex disorder of cardiac electrophysiology. It is characterized by delayed myocardial polarization leading to QT prolongation and alterations on the ST segment and T wave visible on electrocardiogram (ECG). Syncope is a common manifestation, and torsade de pointes (TdP) can lead to sudden cardiac death. Three major LQTS genes (KCI31, KCNH2, and SCN5) lead to most of the cases of LQTS. Lifestyle modifications, beta blockers, and implantable cardioverter defibrillator (ICD) placement are the main treatments for LQTS. Polypharmacy, including QT-prolonging drugs, has been shown to worsen LQTS. The impact on potassium channels and the human ether-a-go-go-related gene (hERG) is the mechanism behind the QT interval prolongation caused by these medications. There is an increased incidence of LQTS among African-American men and women as compared to Caucasians. Women with LQTS tend to have a higher mortality rate from the condition, especially during menstruation and shortly after giving birth. Genetic testing is reserved to those patientswho exhibit either a strong clinical index of suspicion or experience persistent QT prolongation despite their lack of symptoms. Knowing the genetics, racial, and gender discrepancies can help improve patient management and a better comprehension on each case. Proper understanding of how ion channels function and their interaction with medications will lead to a better comprehension and to develop effective forms to treat those patients.

Epidemiology and Outcomes Associated with PR Prolongation

PR prolongation is defined primarily as delayed conduction through the AV node, but can also signify delayed electrical impulse propagation through any part of the conduction system. The prevalence of PR prolongation ranges from 1% to 5% in patients younger than 50 years, with increasing prevalence, after the sixth decade of life and in patients with organic heart disease. Contemporary studies have documented increased risk of atrial arrhythmias, heart failure, and mortality in patients with PR prolongation. Future studies are needed to more accurately risk stratify elderly patients with PR prolongation who may be at increased risk of adverse outcomes.

Are Electrocardiographic Criteria Reliable for Left Ventricular Hypertrophy Detection in Indian Adults?

BACKGROUND

Left ventricular hypertrophy (LVH) detection is vital to the risk stratification of adults at risk of adverse cardiovascular events such as coronary heart disease, cerebrovascular disease, and aortic aneurysms. Electrocardiogram (ECG), a non-invasive, cost-effective instrument has been widely used as a screening tool for LVH. The objective of this study was to determine the diagnostic accuracy of seven frequently used ECG criteria in high-risk Indian adults in comparison with echocardiography.

METHODS

ECG and transthoracic echocardiography were performed in adults older than 18 years with at least one cardiac risk factor (chronic hypertension, obesity, ischemic heart disease, and type 2 diabetes mellitus). Precision and accuracy were calculated for the various ECG criteria against LVH based on left ventricular mass index (LVMI) and cardiac remodeling by echocardiography.

RESULTS

A total of 220 participants were enrolled. Of these, 96 had LVH by echocardiography. There was marked variability in LVH detection by the different ECG criteria: 28 by Sokolow-Lyon criteria, 26 by Cornell criteria, 24 by Lewis criteria, 46 by Scott criteria, eight by Romhilt-Estes criteria, six by Modified Cornell criteria, and only two by Roberts criteria. Agreement statistics between ECG criteria and LVMI showed that none of them had a good agreement for LVH detection.

CONCLUSION

None of the ECG criteria were sensitive enough to rule out ventricular hypertrophy. In the context of cardiac remodeling, the ECG criteria had high sensitivity but low specificity and, hence, limited clinical relevance.

Electrocardiographic and biochemical analysis of anthracycline induced cardiotoxicity in breast cancer patients from Southern Sri Lanka

BACKGROUND

The clinical application of anthracycline chemotherapy is hindered due to the cumulative dose-dependent cardiotoxicity followed by the oxidative stress initiated during the mechanism of action of anthracyclines. Due to a lack of prevalence data regarding anthracycline-induced cardiotoxicity in Sri Lanka, this study was conducted to determine the prevalence of cardiotoxicity among breast cancer patients in Southern Sri Lanka in terms of electrocardiographic and cardiac biomarker investigations.

METHODS

A cross-sectional study with longitudinal follow-up was conducted among 196 cancer patients at the Teaching Hospital, Karapitiya, Sri Lanka to determine the incidence of acute and early-onset chronic cardiotoxicity. Data on electrocardiography and cardiac biomarkers were collected from each patient, one day before anthracycline (doxorubicin and epirubicin) chemotherapy, one day after the first dose, one day and six months after the last dose of anthracycline chemotherapy.

RESULTS

Prevalence of sub-clinical anthracycline-induced cardiotoxicity six months after the completion of anthracycline chemotherapy was significantly higher (p < 0.05) and there were strong, significant (p < 0.05) associations among echocardiography, electrocardiography measurements and cardiac biomarkers including troponin I and N-terminal pro-brain natriuretic peptides. The cumulative anthracycline dose, > 350 mg/m² was the most significant risk factor associated with the sub-clinical cardiotoxicity in breast cancer patients under study.

CONCLUSION

Since these results confirmed the unavoidable cardiotoxic changes following anthracycline chemotherapy, it is recommended to carry out long-term follow-ups in all patients who were treated with anthracycline therapy to increase their quality of life as cancer survivors.

Artificial intelligence enabled ECG screening for left ventricular systolic dysfunction: a systematic review

Screening for left ventricular systolic dysfunction (LVSD), defined as reduced left ventricular ejection fraction (LVEF), deserves renewed interest as the medical treatment for the prevention and progression of heart failure improves. We aimed to review the updated literature to outline the potential and caveats of using artificial intelligence-enabled electrocardiography (AIeECG) as an opportunistic screening tool for LVSD.We searched PubMed and Cochrane for variations of the terms "ECG," "Heart Failure," "systolic dysfunction," and "Artificial Intelligence" from January 2010 to April 2022 and selected studies that reported the diagnostic accuracy and confounders of using AIeECG to detect LVSD.Out of 40 articles, we identified 15 relevant studies; eleven retrospective cohorts, three prospective cohorts, and one case series. Although various LVEF thresholds were used, AIeECG detected LVSD with a median AUC of 0.90 (IQR from 0.85 to 0.95), a sensitivity of 83.3% (IQR from 73 to 86.9%) and a specificity of 87% (IQR from 84.5 to 90.9%). AIeECG algorithms succeeded across a wide range of sex, age, and comorbidity and seemed especially useful in non-cardiology settings and when combined with natriuretic peptide testing. Furthermore, a false-positive AIeECG indicated a future development of LVSD. No studies investigated the effect on treatment or patient outcomes.This systematic review corroborates the arrival of a new generic biomarker, AIeECG, to improve the detection of LVSD. AIeECG, in addition to natriuretic peptides and echocardiograms, will improve screening for LVSD, but prospective randomized implementation trials with added therapy are needed to show cost-effectiveness and clinical significance.

Age, sex and race bias in automated arrhythmia detectors

Despite the recent explosion of machine learning applied to medical data, very few studies have examined algorithmic bias in any meaningful manner, comparing across algorithms, databases, and assessment metrics. In this study, we compared the biases in sex, age, and race of 56 algorithms on over 130,000 electrocardiograms (ECGs) using several metrics and propose a machine learning model design to reduce bias. Participants of the 2021 PhysioNet Challenge designed and implemented working, open-source algorithms to identify clinical diagnosis from 2- lead ECG recordings. We grouped the data from the training, validation, and test datasets by sex (male vs female), age (binned by decade), and race (Asian, Black, White, and Other) whenever possible. We computed recording-wise accuracy, area under the receiver operating characteristic curve (AUROC), area under the precision recall curve (AUPRC), F-measure, and the Challenge Score for each of the 56 algorithms. The Mann-Whitney U and the Kruskal-Wallis tests assessed the performance differences of algorithms across these demographic groups. Group trends revealed similar values for the AUROC, AUPRC, and F-measure for both male and female groups across the training, validation, and test sets. However, recording-wise accuracies were 20% higher (p < 0.01) and the Challenge Score 12% lower (p = 0.02) for female subjects on the test set. AUPRC, F-measure, and the Challenge Score increased with age, while recording-wise accuracy and AUROC decreased with age. The results were similar for the training and test sets, but only recording-wise accuracy (12% decrease per decade, p < 0.01), Challenge Score (1% increase per decade, p < 0.01), and AUROC (1% decrease per decade, p < 0.01) were statistically different on the test set. We observed similar AUROC, AUPRC, Challenge Score, and F-measure values across the different race categories. But, recording-wise accuracies were significantly lower for Black subjects and higher for Asian subjects on the training (31% difference, p < 0.01) and test (39% difference, p < 0.01) sets. A top performing model was then retrained using an additional constraint which simultaneously minimized differences in performance across sex, race and age. This resulted in a modest reduction in performance, with a significant reduction in bias. This work provides a demonstration that biases manifest as a function of model architecture, population, cost function and optimization metric, all of which should be closely examined in any model.

A Retrospective Clinical Evaluation of an Artificial Intelligence Screening Method for Early Detection of STEMI in the Emergency Department

BACKGROUND

Rapid revascularization is the key to better patient outcomes in ST-elevation myocardial infarction (STEMI). Direct activation of cardiac catheterization laboratory (CCL) using artificial intelligence (AI) interpretation of initial electrocardiography (ECG) might help reduce door-to-balloon (D2B) time. To prove that this approach is feasible and beneficial, we assessed the non-inferiority of such a process over conventional evaluation and estimated its clinical benefits, including a reduction in D2B time, medical cost, and 1-year mortality.

METHODS

This is a single-center retrospective study of emergency department (ED) patients suspected of having STEMI from January 2021 to June 2021. Quantitative ECG (QCG™), a comprehensive cardiovascular evaluation system, was used for screening. The non-inferiority of the AI-driven CCL activation over joint clinical evaluation by emergency physicians and cardiologists was tested using a 5% non-inferiority margin.

RESULTS

Eighty patients (STEMI, 54 patients [67.5%]) were analyzed. The area under the curve of QCG score was 0.947. Binned at 50 (binary QCG), the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 98.1% (95% confidence interval [CI], 94.6%, 100.0%), 76.9% (95% CI, 60.7%, 93.1%), 89.8% (95% CI, 82.1%, 97.5%) and 95.2% (95% CI, 86.1%, 100.0%), respectively. The difference in sensitivity and specificity between binary QCG and the joint clinical decision was 3.7% (95% CI, -3.5%, 10.9%) and 19.2% (95% CI, -4.7%, 43.1%), respectively, confirming the non-inferiority. The estimated median reduction in D2B time, evaluation cost, and the relative risk of 1-year mortality were 11.0 minutes (interquartile range [IQR], 7.3-20.0 minutes), 26,902.2 KRW (22.78 USD) per STEMI patient, and 12.39% (IQR, 7.51-22.54%), respectively.

CONCLUSION

AI-assisted CCL activation using initial ECG is feasible. If such a policy is implemented, it would be reasonable to expect some reduction in D2B time, medical cost, and 1-year mortality.

Physiological QT Interval Changes in Early Infancy Using Post-Menstrual and Post-Natal Age Calculation for Electrocardiogram Long QT Interval Screening in Taiwan

BACKGROUND

Prolongation of the QT interval is associated with the risk of sudden infant death syndrome. QT interval differs depending on age at the time of screening. Screening protocols have yet to be established for Taiwanese patients.

OBJECTIVES

To construct QT interval reference values during early infancy, to investigate whether QT interval change differs according to age calculation methods, and to identify an optimal QT correction method and associated infant factors.

METHODS

Electrocardiographic readings and QT intervals were recorded cross-sectionally in 595 healthy infants and screened prospectively for long QT interval. Corrected QT intervals with Bazett's (QTc-B) and Fridericia's (QTc-F) formulas were compared by post-natal and post-menstrual screening age, sex, body mass index (BMI), heart rate (HR), birth and family history.

RESULTS

QTc-B and QTc-F decreased in the second month (31-60 days), and peaked in the third month (61-90 days). QT interval length was similar between post-menstrual and post-natal ages for QTc-B. Simple linear regression showed that post-menstrual age, post-natal age, HR and BMI were associated with QTc-F, while only sex and HR were associated with QTc-B. Although both QTc-B and QTc-F were significantly associated with HR, QTc-B was less affected by HR than QTc-F (β = -0.1, p < 0.05 for QTc-B vs. β = -0.3, p < 0.001 for QTc-F). Female infants tended to have slightly longer QTc intervals.

CONCLUSIONS

QT interval in early infancy changed physiologically, peaking in the third month. The rate of QT change was not affected by different age correction methods. QTc-B was less affected by age, BMI and HR, although differences in sex should be noted.

Epidemiology and Outcomes Associated with PR Prolongation

PR prolongation is defined primarily as delayed conduction through the AV node, but can also signify delayed electrical impulse propagation through any part of the conduction system. The prevalence of PR prolongation ranges from 1% to 5% in patients younger than 50 years, with increasing prevalence, after the sixth decade of life and in patients with organic heart disease. Contemporary studies have documented increased risk of atrial arrhythmias, heart failure, and mortality in patients with PR prolongation. Future studies are needed to more accurately risk stratify elderly patients with PR prolongation who may be at increased risk of adverse outcomes.

Corrected QT Interval Is Associated With Stroke but Not Coronary Heart Disease: Insights From a General Chinese Population

Background: Prolonged heart rate-corrected QT (QTc) interval has been associated with incident cardiovascular diseases (CVD) in general Western populations. However, this association is unclear in Asian population. We aim to estimate the association between QTc interval and incident CVD in a general Chinese population.

Methods: We analyzed 8,867 participants age ≥35 years and free of CVD at baseline in the Northeast China Rural Cardiovascular Health Study. A resting 12-lead electrocardiogram was performed on all participants, and QTc interval computed using the Framingham formula. Cox proportional hazards models were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) for associations between QTc interval and incident stroke, coronary heart disease, and combined CVD events.

Results: Over a median follow-up of 4.66 years, a total of 439 CVD events occurred (298 stroke cases and 152 CHD cases). After full adjustment, prolonged QTc defined by a sex-specific cutoff was associated with increased risk of developing stroke (HR: 1.82, 95% CI 1.20–2.75, P = 0.004) and combined CVD (HR: 1.52, 95% CI 1.05–2.19, P = 0.026). Spline analyses demonstrated no clear thresholds; when modeled as a linear relationship, each 10 ms increase of QTc interval was associated with an HR of 1.12 (95% CI 1.06–1.19, P < 0.001) for stroke and an HR of 1.10 (95% CI 1.05–1.15, P < 0.001) for combined CVD. Baseline QTc interval was not associated with incident CHD with either modeling strategy.

Conclusions: Baseline QTc interval is associated with incident stroke and CVD in adults without prior CVD from a general Chinese population.

Electrocardiographic features and their echocardiographic correlates in peripartum cardiomyopathy: results from the ESC EORP PPCM registry

AIMS

In peripartum cardiomyopathy (PPCM), electrocardiography (ECG) and its relationship to echocardiography have not yet been investigated in large multi-centre and multi-ethnic studies. We aimed to identify ECG abnormalities associated with PPCM, including regional and ethnic differences, and their correlation with echocardiographic features.

METHODS AND RESULTS

We studied 411 patients from the EURObservational PPCM registry. Baseline demographic, clinical, and echocardiographic data were collected. ECGs were analysed for rate, rhythm, QRS width and morphology, and QTc interval. The median age was 31 [interquartile range (IQR) 26-35] years. The ECG was abnormal in > 95% of PPCM patients. Sinus tachycardia (heart rate > 100 b.p.m.) was common (51%), but atrial fibrillation was rare (2.27%). Median QRS width was 82 ms [IQR 80-97]. Left bundle branch block (LBBB) was reported in 9.30%. Left ventricular (LV) hypertrophy (LVH), as per ECG criteria, was more prevalent amongst Africans (59.62%) and Asians (23.17%) than Caucasians (7.63%, P < 0.001) but did not correlate with LVH on echocardiography. Median LV end-diastolic diameter (LVEDD) was 60 mm [IQR 55-65] and LV ejection fraction (LVEF) 32.5% [IQR 25-39], with no significant regional or ethnic differences. Sinus tachycardia was associated with an LVEF < 35% (OR 1.85 [95% CI 1.20-2.85], P = 0.006). ECG features that predicted an LVEDD > 55 mm included a QRS complex > 120 ms (OR 11.32 [95% CI 1.52-84.84], P = 0.018), LBBB (OR 4.35 [95% CI 1.30-14.53], P = 0.017), and LVH (OR 2.03 [95% CI 1.13-3.64], P = 0.017).

CONCLUSIONS

PPCM patients often have ECG abnormalities. Sinus tachycardia predicted poor systolic function, whereas wide QRS, LBBB, and LVH were associated with LV dilatation.

Do sex differences in the prevalence of ECG abnormalities vary across ethnic groups living in the Netherlands? A cross-sectional analysis of the population-based HELIUS study

OBJECTIVES

Major ECG abnormalities have been associated with increased risk of cardiovascular disease (CVD) burden in asymptomatic populations. However, sex differences in occurrence of major ECG abnormalities have been poorly studied, particularly across ethnic groups. The objectives were to investigate (1) sex differences in the prevalence of major and, as a secondary outcome, minor ECG abnormalities, (2) whether patterns of sex differences varied across ethnic groups, by age and (3) to what extent conventional cardiovascular risk factors contributed to observed sex differences.

DESIGN

Cross-sectional analysis of population-based study.

SETTING

Multi-ethnic, population-based Healthy Life in an Urban Setting cohort, Amsterdam, the Netherlands.

PARTICIPANTS

8089 men and 11 369 women of Dutch, South-Asian Surinamese, African Surinamese, Ghanaian, Turkish and Moroccan origin aged 18-70 years without CVD.

OUTCOME MEASURES

Age-adjusted and multivariable logistic regression analyses were performed to study sex differences in prevalence of major and, as secondary outcome, minor ECG abnormalities in the overall population, across ethnic groups and by age-groups (18-35, 36-50 and >50 years).

RESULTS

Major and minor ECG abnormalities were less prevalent in women than men (4.6% vs 6.6% and 23.8% vs 39.8%, respectively). After adjustment for conventional risk factors, sex differences in major abnormalities were smaller in ethnic minority groups (OR ranged from 0.61 in Moroccans to 1.32 in South-Asian Surinamese) than in the Dutch (OR 0.49; 95% CI 0.36 to 0.65). Only in South-Asian Surinamese, women did not have a lower odds than men (OR 1.32; 95% CI 0.96 to 1.84). The pattern of smaller sex differences in ethnic minority groups was more pronounced in older than in younger age-groups.

CONCLUSIONS

The prevalence of major ECG abnormalities was lower in women than men. However, sex differences were less apparent in ethnic minority groups. Conventional risk factors did not contribute substantially to observed sex differences.

Predictive value of electrocardiographic left ventricular hypertrophy in the general population: A meta-analysis

BACKGROUND

Conflicting results have been reported on the predictive value of the electrocardiographic left ventricular hypertrophy (LVH) in the general population. This meta-analysis sought to compare the predictive value of different electrocardiographic criteria of LVH in the general population.

METHODS

We comprehensively searched PubMed and Embase databases until May 9, 2020 to identify observational studies investigating the predictive value of different electrocardiographic criteria for LVH (Sokolow-Lyon voltage, Cornell voltage or Cornell product) in the general population. Outcome measures were major adverse cardiovascular events (MACEs), cardiovascular or all-cause mortality.

RESULTS

Ten studies enrolling 58,400 individuals were included. Comparison with and without electrocardiographic LVH, the pooled risk ratio (RR) of MACEs was 1.62 (95% confidence interval [CI] 1.40-1.89) for the Sokolow-Lyon voltage criteria, 1.70 (95% CI 1.27-2.29) for the Cornell voltage criteria, and 1.56 (95% CI 1.17-2) for the Cornell product criteria. The pooled RR of all-cause mortality was 1.47 (95% CI 1.10-1.97) for the Sokolow-Lyon voltage criteria and 1.87 (95% CI 1.29-2.71) for the Cornell voltage criteria. Furthermore, the pooled RR of cardiovascular mortality was 1.38 (95% CI 1.19-1.60) for the Sokolow-Lyon criteria, 1.66 (95% CI 1.24-2.33) for the Cornell voltage criteria, and 1.82 (95% CI 0.65-5.09) for the Cornell product criteria.

CONCLUSIONS

Different electrocardiographic criteria for evaluating LVH had a similar value in predicting MACEs among the general population. LVH detected by the Cornell voltage appeared to have a stronger predictive value in prediction of cardiovascular or all-cause mortality.

Influence of relative wall thickness on electrocardiographic voltage measures in left ventricular hypertrophy: a novel factor contributing to poor diagnostic accuracy

Objective: To characterize the influence of relative wall thickness (RWT) on Cornell, Sokolow-Lyon and Peguero-Lo Presti voltages and elucidate its potential impacts on their diagnostic accuracy for LVH in a large general Chinese population.Methods: A total of 10,614 permanent residents aged ≥ 35 years were recruited for this study. All the participants were subjected to ECG and echocardiogram during the same visit. Multivariate linear and logistic regression analyzes were conducted to assess the influence of RWT on the voltages and their diagnostic performance for LVH detection.Results: A distinct correlation was identified between RWT and Cornell and Peguero-Lo Presti voltages following adjustments for age, gender and left ventricular mass (LVM) (β = 0.675 and 1.342, respectively; Ps < 0.001). Besides, subjects with RWT > 0.42 exhibited higher rates of LVH diagnosed by Cornell (OR = 1.78, 95% CI: 1.45-2.20), Sokolow-Lyon (OR = 1.30, 95% CI: 1.08-1.56), and Peguero-Lo Presti voltage (OR = 1.48, 95% CI: 1.29-1.70) after adjustments for age, gender and echocardiographic LVH. Furthermore, concentric remodeling or concentric hypertrophy displayed higher rates of LVH diagnoses via Cornell and Peguero-Lo Presti voltage criteria, as compared with normal geometry or eccentric hypertrophy, respectively (all Ps < 0.05), findings of which were independent of age, gender and LVMI.Conclusion: Echocardiographic RWT was independently correlated with electrocardiographic voltage measures of LVH, which influenced their positive rates and contributed to poor diagnostic performance.

Prognostic implications of QRS dispersion for major adverse cardiovascular events in asymptomatic women and men: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

QRS dispersion measured as the difference between maximal and minimal QRS duration in the standard 12-lead electrocardiogram has been shown to be associated with increased mortality in heart failure (HF) patients and increased arrhythmic events in patients with cardiomyopathy.

AIMS

This study sought to examine the prognostic association between baseline QRS dispersion and future cardiovascular events in individuals without known prior cardiovascular disease.

METHODS

The association of QRS dispersion with cardiovascular events was examined in 6510 MESA (Multi-Ethnic Study of Atherosclerosis) participants. Participants with bundle branch block were excluded. Study participants were divided into two groups based on the 95th percentile of QRS dispersion (QRS dispersion < 34 ms [group I] and QRS dispersion ≥ 34 ms [group II]). Cox proportional hazard models adjusting for demographic and clinical risk factors were used to examine the association of QRS dispersion with incident cardiovascular events (major adverse cardiovascular events [MACE]) and mortality. Analysis was repeated by forcing Framingham risk factors.

RESULTS

Mean age was 62 ± 10 years in group I and 63 ± 10 years in group II (P = 0.02). QRS dispersion ≥ 34 ms was associated significantly with MACE (HR 1.30; 95% CI 1.04-1.62) and mortality (HR 1.33; 95% CI 1.03-1.73) after adjustment for cardiovascular risk factors and potential cofounders. Similar results were seen for mortality after adjustment for Framingham risk factors.

CONCLUSION

QRS dispersion ≥ 34 ms predicts cardiovascular events and mortality.

Cohort Study of ECG Left Ventricular Hypertrophy Trajectories: Ethnic Disparities, Associations With Cardiovascular Outcomes, and Clinical Utility

BACKGROUND

ECG left ventricular hypertrophy (LVH) is a well-known predictor of cardiovascular disease. However, no prior study has characterized patterns of presence/absence of ECG LVH ("ECG LVH trajectories") across the adult lifespan in both sexes and across ethnicities. We examined: (1) correlates of ECG LVH trajectories; (2) the association of ECG LVH trajectories with incident coronary heart disease, transient ischemic attack, ischemic stroke, hemorrhagic stroke, and heart failure; and (3) reclassification of cardiovascular disease risk using ECG LVH trajectories.

METHODS AND RESULTS

We performed a cohort study among 75 412 men and 107 954 women in the Northern California Kaiser Permanente Medical Care Program who had available longitudinal exposures of ECG LVH and covariates, followed for a median of 4.8 (range <1-9.3) years. ECG LVH was measured by Cornell voltage-duration product. Adverse trajectories of ECG LVH (persistent, new development, or variable pattern) were more common among blacks and Native American men and were independently related to incident cardiovascular disease with hazard ratios ranging from 1.2 for ECG LVH variable pattern and transient ischemic attack in women to 2.8 for persistent ECG LVH and heart failure in men. ECG LVH trajectories reclassified 4% and 7% of men and women with intermediate coronary heart disease risk, respectively.

CONCLUSIONS

ECG LVH trajectories were significant indicators of coronary heart disease, stroke, and heart failure risk, independently of level and change in cardiovascular disease risk factors, and may have clinical utility.

Effect of age and gender on the QTc-interval in healthy individuals and patients with long-QT syndrome

Age- and gender-related differences in QTc-interval are most likely the result of changes in sex-specific hormones. Although the exact mechanisms and pathophysiology of sex hormones on the QTc-interval are not known, testosterone appears to shorten the QTc-interval. In females, however, there is a more complex interaction between progesterone and estrogen. In patients with an impaired repolarization, such as long-QT syndrome (LQTS), the effect of these sex hormones on the QTc-interval is more pronounced with a differing sensitivity between the LQTS genotypes.

Racial Differences in Electrocardiographic Characteristics and Prognostic Significance in Whites Versus Asians

Background

Racial differences in electrocardiographic (ECG) characteristics and prognostic significance among Whites and Asians are not well described.

Methods and Results

We studied 2677 White Framingham Heart Study participants (57% women) and 2972 Asian (64% women) Singapore Longitudinal Aging Study participants (mean age 66 years in both) free of myocardial infarction or heart failure. Racial differences in ECG characteristics and effect on mortality were assessed. In linear regression models, PR interval was longer in Asians compared with Whites (multivariable‐adjusted β±SE 5.0±1.4 ms in men and 6.6±0.9 ms in women, both P<0.0006). QT interval was shorter in Asian men (β±SE −6.2±1.2 ms, P<0.0001) and longer in Asian women (β±SE 3.6±0.9 ms, P=0.02) compared to White men and women, respectively. Asians had greater odds of having ECG left ventricular hypertrophy (LVH) compared with Whites (odds ratio [OR] 3.56, 95% confidence interval [CI] 1.36–9.35 for men, OR 1.93, 95% CI 1.35–2.76 for women, both P<0.02). Over a mean follow‐up of 11±3 years in Framingham and 8±3 years in Singapore, mortality rates were 24.5 and 13.4 per 1000 person‐years among Whites and Asians, respectively. In Cox models, the presence of LVH had a greater effect on all‐cause mortality in Asians compared with Whites (hazard ratio [HR] 2.66, 95% CI 1.83–3.88 vs HR 1.30, 95% CI 0.90–1.89, P for interaction=0.02).

Conclusion

Our findings from two large community‐based cohorts show prominent race differences in ECG characteristics between Whites and Asians, and also suggest a differential association with mortality. These differences may carry implications for race‐specific ECG reference ranges and cardiovascular risk.