P-wave duration and the risk of atrial fibrillation: Results from the Copenhagen ECG Study

Functional feature extraction and validation from twelve-lead electrocardiograms to identify atrial fibrillation

BACKGROUND

Deep learning methods on standard, 12-lead electrocardiograms (ECG) have resulted in the ability to identify individuals at high-risk for the development of atrial fibrillation. However, the process remains a "black box" and does not help clinicians in understanding the electrocardiographic changes at an individual level. we propose a nonparametric feature extraction approach to identify features that are associated with the development of atrial fibrillation (AF).

METHODS

We apply functional principal component analysis to the raw ECG tracings collected in the Chronic Renal Insufficiency Cohort (CRIC) study. We define and select the features using ECGs from participants enrolled in Phase I (2003-2008) of the study. Cox proportional hazards models are used to evaluate the association of selected ECG features and their changes with the incident risk of AF during study follow-up. The findings are then validated in ECGs from participants enrolled in Phase III (2013-2015).

RESULTS

We identify four features that are related to the P-wave amplitude, QRS complex and ST segment. Both their initial measurement and 3-year changes are associated with the development of AF. In particular, one standard deviation in the 3-year decline of the P-wave amplitude is independently associated with a 29% increased risk of incident AF in the multivariable model (HR: 1.29, 95% CI: [1.16, 1.43]).

CONCLUSIONS

Compared with deep learning methods, our features are intuitive and can provide insights into the longitudinal ECG changes at an individual level that precede the development of AF.

Value of P-wave Parameters in Predicting Outcomes of Repeat Catheter Ablation for Paroxysmal Atrial Fibrillation

BACKGROUND

Pulmonary vein isolation (PVI) has been established as an effective management option for symptomatic paroxysmal atrial fibrillation (PAF). We aimed to explore the role of P-wave parameters in a 12-lead electrocardiogram (ECG) in predicting the success of repeat PAF ablation.

METHODS

We enrolled consecutive patients who underwent a second AF ablation procedure for PAF in a UK tertiary center after an index ablation conducted between 2018 and 2019 and a repeat ablation up to 2021. A digital 12-lead ECG was recorded with a 1-50-Hz bandpass filter applied. P-wave duration (PWD), P-wave voltage (PWV), P-wave dispersion (PWDisp), and P-wave terminal force in V1 (PTFV1) were measured before and after the procedure. Changes were correlated with the 12-month clinical outcome. Procedural success was freedom from ECG-documented AF up to 12 months following ablation.

RESULTS

Study criteria were satisfied by 72 patients, of which 43 (60%) had successful repeat PVI at 12 months. The mean age is 65, and 47 (65%) were males. The demographics were comparable between both study arms. PWD decreased after successful repeat ablations (136.7 to 124.6 ms, p = 0.01) and failed repeat ablations (135.4 to 125.3 ms, p = 0.009) without a significant change between both arms. PMV and PWDisp did not change significantly after both study arms. PTFV1 significantly decreased after successful repeat ablations (-3.1 to -4.4 mm.s, p = 0.005) without a significant change after failed ablations (-2.9 to -2.7 mm.s, p = 0.42). Changes were statistically significant between both arms (p = 0.004).

CONCLUSION

PTFV1 reduction following the second AF ablation was correlated with successful repeat AF ablation at 12 months.

The Value of P-Wave Parameters Changes in Predicting Catheter Ablation Outcomes for Paroxysmal Atrial Fibrillation

BACKGROUND

Pulmonary vein isolation (PVI) is the most promising management method for paroxysmal atrial fibrillation (PAF). The P wave in the electrocardiogram (ECG) represents atrial depolarization. This study aims to correlate P-wave parameters after PVI with outcomes.

METHODS

This single-center retrospective study included consecutive patients with first-time PVI for PAF between 2018 and 2019 and targeted pulmonary veins (PVs). Procedure success was defined by freedom of ECG-documented AF at 12 months. Digital 12 leads ECGs with 1-50 hertz bandpass filter were monitored before the procedure. P-wave amplitude (PWA) and P-wave terminal force in V1 (PTFV1) Corrected P-wave duration (PWDc), and P-wave dispersion (PWDisp), were measured before and after ablation.

RESULTS

The final analysis included 180 patients, of which 130 (72%) had successful ablations and 53 (30%) had radiofrequency ablation (RF). Males comprised 71% of the patients; the mean age was 60. Demographics were similar between both arms p < 0.001. Patients with failed PVI had increased PWDc after PVI (139-146 ms, p < 0.001) compared to patients with successful PVI. PWA increased significantly after failed PVI (1.6-2 mV, p < 0.001) and successful PVI (1.6-1.8 mV, p = 0.008). PWD (hazard ratio [HR]: 2.5, 95% confidence interval [CI]: 1.4-4.2, p < 0.001) and PWA (HR: 1.7, 95% CI: 1.2-2.9, p = 0.03) were independently associated with PVI failure at 12 months. PWdisp and PTFV1 were not correlated with outcomes.

CONCLUSION

Increased PWDc and PWA after PVI were independently associated with failed ablation for PAF, supporting the role of P-wave parameters in predicting outcomes.

Smoking-associated electrocardiographic abnormalities predict cardiovascular mortality

Background -Smoking is associated with arrhythmia and sudden cardiac death, but the biological mechanisms remain unclear. In electrocardiogram (ECG) recordings abnormal durations of ventricular repolarization (QT interval), atrial depolarization (P wave), and atrioventricular depolarization (PR interval and segment), predict cardiac arrhythmia and mortality. Previous analyses of the National Health and Nutrition Examination Survey (NHANES) database for associations between smoking and ECG abnormalities were incomplete. To elucidate how smoking affects cardiac excitation, we assessed in a nationally representative sample (NHANES III) the association between serum cotinine and P duration, PR interval, PR segment, rate-corrected QT (QTc), QRS duration, and JT interval. Methods and Results-We analyzed data from 5,653 adults using survey-weighted multinomial logistic regression to estimate associations between tobacco use (> 15 ng/ml serum cotinine) and short (< 5th percentile) or long (> 95th percentile) ECG intervals, relative to reference (5-95th percentile). After adjustment for demographics, risk factors, and conduction-altering medications, smoking was associated with a higher odds of short PR interval, PR segment, and QRS, and long JT. Broader effects of smoking on ECG were also assessed by survey-weighted linear regression of continuous cotinine and ECG, which revealed cotinine inversely associated with PR segment and QTc. Over a 22-year follow-up, many ECG abnormalities predicted cardiovascular mortality in smokers, including long JT, QRS, and QTc, and short QRS, whereas only short JT predicted mortality in nonsmokers. Conclusions -Smoking increases likelihood for rapid atrioventricular and ventricular depolarization and slow ventricular repolarization, which may promote cardiac arrhythmia and mortality.

Temporal variations in QTc interval during and after COVID-19 infection: a retrospective study

OBJECTIVE

The aim of this study was to investigate the dynamic changes in QTc interval duration among patients with COVID-19 infection before, during, and after infection, in order to assess the short- and potential long-term impact of COVID-19 on cardiac electrophysiology.

METHODS

A retrospective analysis was conducted on 303 inpatients diagnosed with COVID-19 who visited a tertiary Grade A hospital in China between August 2022 and December 2023. Inclusion criteria required patients to have at least two electrocardiogram (ECG) recordings at three specific time points: before COVID-19 infection, during acute infection, and after recovery (more than one month post-infection).

RESULTS

The mean age of participants was 72.8 ± 14.7 years, with a male preponderance (62%, n = 188). A significant prolongation of QTc interval was observed during COVID-19 infection compared to pre-infection levels (438.3 ± 26.7 ms vs. 433.9 ± 26.6 ms, p = 0.025). QTc interval was positively correlated with age both before (r = 0.23, p = 0.001) and during infection (r = 0.19, p = 0.001). In short-term follow-up (≤ 6 months), QTc interval remained unchanged from the infectious period (p > 0.05), whereas it significantly decreased during long-term follow-up (> 6 months; 429.6 ± 32.5 ms vs. 437.5 ± 28.2 ms, p = 0.002). Additionally, P-wave duration significantly decreased from the infectious period to long-term follow-up (99.5 ± 14.8 ms to 96.4 ± 15.2 ms, p = 0.024).

CONCLUSIONS

COVID-19 infection demonstrated a significant correlation with prolonged QTc interval, persisting in the short term but gradually returning to normal in the long term. Similarly, P-wave duration shortened over time, suggesting potential cardiac electrophysiological recovery.

CLINICAL TRIAL NUMBER

Not applicable.

Feasibility and findings of electrocardiogram recording in older adults with intellectual disabilities: results of the Healthy Ageing and Intellectual Disabilities study

BACKGROUND

Older adults with intellectual disabilities (ID) have a high risk of cardiovascular diseases (CVD). At the same time, challenging diagnostic work-up increases the likelihood of underdiagnosis of CVD in this population. To limit this underdiagnosis, it would be beneficial to use objective measures such as the electrocardiogram (ECG). However, little is known about the feasibility of ECG recording and the prevalence of ECG abnormalities in this population. Therefore, the aims of this study were to investigate the feasibility of resting ECG recording, to study the prevalence of ECG abnormalities, and to compare the frequency of ECG abnormalities with medical records in older adults with ID.

METHOD

A cross-sectional study was performed within a cohort of older adults (≥60 years) with ID as part of the Healthy Ageing and Intellectual Disabilities (HA-ID) study. A resting 12-lead ECG was attempted, and the ECG recording was considered feasible if the recording could be made and if the ECG could be interpreted by a cardiologist and the Modular ECG Analysis System (MEANS). ECGs were assessed for the presence of ECG abnormalities and medical record review was performed. If the cardiologist or MEANS concluded that there was evidence of myocardial infarction, atrial fibrillation or QTc prolongation on the ECG in the absence of this ECG diagnosis in the participant's medical record, this was classified as a previously undiagnosed ECG diagnosis.

RESULTS

ECG recording was feasible in 134 of the 200 participants (67.0%). Of these 134 participants (70.6 ± 5.8 years; 52.2% female), 103 (76.9%) had one or more ECG abnormality, with the most prevalent being prolonged P-wave duration (27.6%), QTc prolongation (18.7%), minor T-wave abnormalities (17.9%), first degree atrioventricular block (12.7%) and myocardial infarction (6.7%). Eight out of 9 (88.9%) myocardial infarctions and all cases of (significant) QTc prolongation (100%) were previously undiagnosed.

CONCLUSIONS

This study showed that ECG recording is feasible in the majority of older adults with ID and revealed a substantial underdiagnosis of ECG abnormalities. These results stress the importance of ECG recording and warrant further research into the yield of opportunistic ECG screening in older adults with ID.

Electrophysiological predictors of susceptible atrial substrate for the onset and recurrence of atrial fibrillation

BACKGROUND

The atrial electroanatomic substrate is an essential component in the pathogenesis of atrial fibrillation (AF). However, the electrophysiological markers of susceptible atria for AF are not well-characterized. This study aimed to assess atrial conduction indices on surface electrocardiogram (ECG) and intracardiac electrogram (EGM) as predictors of initiation and recurrence of AF after successful ablation.

METHODS

We studied all consecutive patients who underwent electrophysiological study and catheter ablation for AF (study group) or atrioventricular nodal reentrant tachycardia (AVNRT) (control group) from 2013 to 2018. Atrial conduction indices were measured on ECG and EGM during the electrophysiology study. Clinical data was obtained from the medical record.

RESULTS

A total of 387 patients with AF (mean age 63 years, 31% female) were studied and compared to 94 patents in control group. The initiation of AF was associated with significant prolongation of atrial conduction indices on ECG and EGM (p < 0.05). During a mean follow up of 5 ± 2 years, recurrence of AF (48%) after successful ablation occurred in patients with prolonged P wave duration, left atrial (LA) conduction interval, proximal to distal coronary sinus (pCS-dCS) interval, and P wave to dCS interval (p < 0.05). Machine learning modeling determined that pCS-dCS interval, QRS duration, and LA duration in leads V1 and II are most impactful conduction indices in association with AF recurrence.

CONCLUSION

Prolonged atrial conduction intervals, particularly LA (pCS-dCS), indicate susceptible substrate for the onset and the recurrence of AF after ablation. LA conduction indices can facilitate early detection and management of AF.

Computed Tomography Confirms Increased Left Atrial Volume in Patients with Bayés Syndrome Referred for Catheter Ablation of Atrial Fibrillation

Background: Bayés syndrome is a recently identified condition that is defined by the presence of an interatrial block on a surface electrocardiogram, in addition to atrial arrhythmias such as atrial fibrillation, tachycardia, or left atrial flutter. This syndrome is linked to an increased risk of stroke, morbidity, and mortality. An interatrial block is a conduction delay between the right atrium and left atrium and can be recognized by a P wave duration >120 ms. It is known that P wave duration can estimate the size of the left atrium measured via echocardiography, which is a marker for stratifying cardiovascular risk. Our study aims to verify whether the duration of the P wave can estimate the volume of the left atrium measured by computed tomography in patients with an interatrial block. Methods: We included 105 patients with a sinus rhythm and a partial or advanced interatrial block (IAB) who underwent contrast-enhanced cardiac computed tomography (CT). The mean age was 62.2 ± 10.1 years, and 38% of the patients were women. Results: The mean P wave duration was 122.6 ± 11.4 ms in the partial IAB group and 150 ± 8.4 ms in the advanced IAB group (p < 0.01). The mean left atrial volume was 115 ± 39 mL in the partial IAB group and 142 ± 34 mL in the advanced IAB group (p = 0.001). P wave duration was longer in patients with an advanced as opposed to partial interatrial block. Left atrial volume and LAVI were higher in patients with an advanced as opposed to partial interatrial block. Conclusions: All the patients (100%) with an advanced IAB had a dilated left atrium. P wave duration can accurately estimate LA volume in patients with an IAB using the formula: LA volume = 0.6 × P wave + 46 mL.

The Role of P Wave Parameters in Predicting Pulmonary Vein Isolation Outcomes for Paroxysmal Atrial Fibrillation: An Observational Cohort Study

BACKGROUND

Pulmonary vein isolation (PVI) is an effective management method for paroxysmal atrial fibrillation (PAF). The P wave in the 12-lead electrocardiogram (ECG) represents atrial depolarisation. This study aims to utilise the P wave to predict PVI outcomes for PAF.

METHODS

This single-centre retrospective study aimed to predict PVI outcomes using P wave parameters. It included 211 consecutive patients with first PVI for PAF between 2018 and 2019 and targeted the pulmonary veins (PVs). Procedure success was defined by freedom of ECG-documented AF at 12 months. Digital 12-lead ECGs with 1-50 hertz bandpass filters were monitored before the procedure. Corrected P wave duration (PWDc), P wave amplitude (PWV), P wave dispersion (PWDisp), intra-atrial block (IAB), P wave area (PWA), and P wave terminal force in V1 (PTFV1) were measured before ablation and correlated with the outcomes.

RESULTS

Successful PVI occurred in 154 patients (73%). Demographics were similar between both arms. P wave parameters correlated with PVI failure included increased PWDc in all leads except for lead III, aVR, and V3, decreased PWV in lead I (hazard ratio [HR]: 0.7, 95% confidence interval [CI]: 0.53-0.95), lead II (HR: 0.45, 95% CI: 0.22-0.65), aVL (HR: 0.58, 95% CI: 0.22-0.98), and aVF (HR: 0.67, 95% CI: 0.58-0.87), decreased PWA in lead I (HR: 0.55, 95% CI: 0.21-0.76), lead II (HR: 0.48, 95% CI: 0.34-0.87), aVL (HR: 0.65, 95% CI: 0.45-0.96), and aVF (HR: 0.61, 95% CI: 0.32-0.89), and the presence of IAB (HR: 2, 95% CI: 1.4-4.2, p = 0.02). PWDisp and PTFV1 were not correlated with PVI outcome.

CONCLUSIONS

PWDc, PWA, PWV, and IAB are valuable predictors for PVI outcome for PAF at 12 months.

Atrial cardiomyopathy revisited-evolution of a concept: a clinical consensus statement of the European Heart Rhythm Association (EHRA) of the ESC, the Heart Rhythm Society (HRS), the Asian Pacific Heart Rhythm Society (APHRS), and the Latin American Heart Rhythm Society (LAHRS)

AIMS

The concept of "atrial cardiomyopathy" (AtCM) had been percolating through the literature since its first mention in 1972. Since then, publications using the term were sporadic until the decision was made to convene an expert working group with representation from four multinational arrhythmia organizations to prepare a consensus document on atrial cardiomyopathy in 2016 (EHRA/HRS/APHRS/SOLAECE expert consensus on atrial cardiomyopathies: definition, characterization, and clinical implication). Subsequently, publications on AtCM have increased progressively.

METHODS AND RESULTS

The present consensus document elaborates the 2016 AtCM document further to implement a simple AtCM staging system (AtCM stages 1-3) by integrating biomarkers, atrial geometry, and electrophysiological changes. However, the proposed AtCM staging needs clinical validation. Importantly, it is clearly stated that the presence of AtCM might serve as a substrate for the development of atrial fibrillation (AF) and AF may accelerates AtCM substantially, but AtCM per se needs to be viewed as a separate entity.

CONCLUSION

Thus, the present document serves as a clinical consensus statement of the European Heart Rhythm Association (EHRA) of the ESC, the Heart Rhythm Society (HRS), the Asian Pacific Heart Rhythm Society (APHRS), and the Latin American Heart Rhythm Society (LAHRS) to contribute to the evolution of the AtCM concept.

Efficacy of atrial fibrillation predictors including MVP ECG risk score compared between single or bilateral internal thoracic artery use

BACKGROUND

Atrial fibrillation (AF) is the most common complication after Coronary Artery Bypass Surgery (CABG). Despite advanced treatment methods, primary prevention is crucial. Many factors have been investigated as markers for AF, but further research is required. CABG is currently superior to Primary Coronary Intervention (PCI) in some cases due to Left Anterior Descending Artery (LAD)- Internal Thoracic Artery (ITA) anastomosis. However, graft choice for non-LAD vessels is still controversial. Our study compared the incidence of arrhythmia between patients with single ITA or bilateral ITA (BITA).

METHODS

The study included 84 isolated CABG patients. The patients were divided into two groups: single ITA and BITA. Patients who developed AF were recorded and compared.

RESULTS

73.8%(n = 62) of the patients were male and 26.2%(n = 22) were female. While single ITA was used in 48.8%(n = 41) of the patients, BITA was used in 51.2%(n = 43). AF was detected in 15.5%(n = 13) of the patients. AF was observed in 5(12.2%) patients in the single ITA group and 8(18.6%) in the BITA group. 76.9%(n = 10) of the patients with AF rhythm had Diabetes Mellitus (DM)(p = 0.011). Biphasic P wave, length of P wave duration, and total Morpholog-Voltage-P Wave ECG (MVP ECG) score height were statistically significantly different.

CONCLUSIONS

The development of AF was similar in both groups. The presence of DM, high blood glucose levels, and ECG findings can detect a predisposition to postoperative AF. MVP ECG risk score is effective as an AF marker and can be used in surgical patient groups.

Body surface mapping of P-waves in sinus rhythm to predict recurrence following cardioversion for atrial fibrillation

Background

Direct current cardioversion (DCCV) is used as elective and emergency rhythm control for atrial fibrillation (AF). We aimed to explore the role of P-wave parameters measured during sinus rhythm using body surface mapping (BSM) in predicting successful DCCV for persistent atrial fibrillation (persAF) at 12 months.

Methods

This case-control study included 56 males >18 years old who underwent DCCV for persAF. P-wave parameter collection after DCCV for AF was done using 128 unipolar leads. A band-pass filter of 1-50 Hz was utilised. Corrected P-wave duration (PWDc), P-wave amplitude, and P-wave dispersion were measured to predict 12-month outcomes and time of recurrence.

Results

The mean age was 64 ± 4 years, and 23 patients (44%) were on amiodarone. The 12-month success rate was 44% (n = 23), while the rest reverted to AF after 2.6 ± 0.4 months. The parameters were comparable between successful and failed DCCV in the entire cohort and patients not on amiodarone. In patients on amiodarone, patients with failed arms had higher PWDc than those with successful arms (188 vs. 150 ms, P = 0.04). Receiver operator characteristic curve analysis for PWDc in the amiodarone cohort showed an area under the curve (AUC) of 0.75 and P = 0.049. A recurrence cut-off >161 ms had a sensitivity of 69% and a specificity of 100%, with a hazard ratio of 10.7, P = 0.004. The parameters were not predictive of the time of recurrence.

Conclusion

In patients on amiodarone, increased PWDc measured using BSM was associated with higher AF recurrence at 12 months following DCCV for persAF.

Role of the Electrocardiogram for Identifying the Development of Atrial Fibrillation

Atrial fibrillation (AF), a prevalent cardiac arrhythmia, is associated with increased morbidity and mortality worldwide. Stroke, the leading cause of serious disability in the United States, is among the important complications of this arrhythmia. Recent studies have demonstrated that certain clinical variables can be useful in the prediction of AF development in the future. The electrocardiogram (ECG) is a simple and cost-effective technology that is widely available in various healthcare settings. An emerging body of evidence has suggested that ECG tracings preceding the development of AF can be useful in predicting this arrhythmia in the future. Various variables on ECG especially different P wave parameters have been investigated in the prediction of new-onset AF and found to be useful. Several risk models were also introduced using these variables along with the patient's clinical data. However, current guidelines do not provide a clear consensus regarding implementing these prediction models in clinical practice for identifying patients at risk of AF. Also, the role of intensive screening via ECG or implantable devices based on this scoring system is unclear. The purpose of this review is to summarize AF and various related terminologies and explain the pathophysiology and electrocardiographic features of this tachyarrhythmia. We also discuss the predictive electrocardiographic features of AF, review some of the existing risk models and scoring system, and shed light on the role of monitoring device for screening purposes.

Digital Electrocardiographic Complex for Risk Stratification of Paroxysmal Atrial Fibrillation

The aim of the study was to develop and clinically test a hardware and software system capable of identifying the predictors of the hidden forms of atrial fibrillation (AF) using 12-lead ECG data in sinus rhythm.

Materials and Methods

There was developed the hardware and software system "Intecard 8.1" to assess a set of markers for atrial electrical instability by 3-5-minute ECG recordings in sinus rhythm. The markers include P-wave amplitude in lead II <0.1 mV, P-wave duration >120 ms, advanced interatrial block, the area of the biphasic P-wave terminal part <-4 mV·ms, and MVP (morphology-voltage- P-wave duration) score >3 points.The clinical testing of "Intecard 8.1" system was carried out on 120 patients with ischemic heart disease or dilated cardiomyopathy. The patients' average age was 57.9±13.1 years.

Results

P-wave detection is a challenging task due to a low signal amplitude, noise, high error probability in atrioventricular block or T-wave and P-wave superposition in case of marked tachycardia. To improve detection, a phase transformation method was used, according to which there was studied its phase component arctg[x(n)/Rv], where x(n) - ECG signal samples, Rv - a constant. We developed an identification algorithm implemented in "Intecard 8.1" software, its clinical trials being conducted.During the 12 [6; 22] month observation period, AF episodes were recorded in 22 from 120 patients (18.3%). The patients with AF episodes exhibited a significant decrease in P-wave amplitude (p=0.029), its duration increase (p<0.001), and a significantly high MVP score (p<0.01). The MVP score with a cut-off point >3 points is of the highest prognostic significance. The area under the ROC curve AUC was 0.988 with a 95% confidence interval: 0.975-0.999 (p<0.001). The prediction model of hidden AF paroxysms has sensitivity and specificity: 92 and 89%, respectively.

Conclusion

The digital electrocardiographic complex "Intecard 8.1" when analyzing 3-5-minute ECG recordings with sinus rhythm enables to identify the patients with high risk or with hidden AF forms. The dynamic assessment of P-wave parameters offers an opportunity to personalize heart rhythm control in this patient cohort.

The Effect of Obesity on Repolarization and Other ECG Parameters

Background: Overweight and obesity are important risk factors in the development of cardiovascular diseases. New repolarization markers, such as the Tpeak-Tend interval and JTpeak intervals, have not yet been profoundly studied in obese patients. The study aims to analyze whether, in patients with obesity and overweight, repolarization markers, including the Tpeak-Tend interval, are prolonged and simultaneously check the frequency of other ECG pathologies in a 12-lead ECG in this group of patients. Methods: A study group consisted of 181 adults (90 females and 91 males) with overweight and first-class obesity. The participants completed a questionnaire, and the ECG was performed and analyzed. Results: When analyzing the classic markers, only QT dispersion was significantly higher in obese people. The Tpeak-Tend parameter (97.08 ms ± 23.38 vs. 89.74 ms ± 12.88, respectively), its dispersion, and JTpeak-JTend parameters were statistically significantly longer in the obese group than in the controls. There were also substantial differences in P-wave, QRS duration, and P-wave dispersion, which were the highest in obese people. Tpeak-Tend was positively correlated with body mass and waist circumference, while JTpeak was with BMI, hip circumference, and WHR. Tpeak/JT was positively correlated with WHR and BMI. In backward stepwise multiple regression analysis for JTpeak-WHR, type 2 diabetes and smoking had the highest statistical significance. Conclusions: Only selected repolarization markers are significantly prolonged in patients with class 1 obesity and, additionally, in this group, we identified more pathologies of P wave as well as prolonged QRS duration.

Deep terminal negative of the P wave in V1 and incidence of ischemic stroke: The atherosclerosis risk in communities (ARIC) study

BACKGROUND

Deep terminal negative of the P wave in V1 (DTNPV1) is a marker of left atrial remodeling. We aimed to evaluate the association of DTNPV1 with incident ischemic stroke.

METHODS

The Atherosclerosis Risk in Communities study is a prospective community-based cohort study. All participants at visit 4 (1996-1998) except those with prevalent stroke, missing covariates, and missing or uninterpretable ECG were included. DTNPV1 was defined as the absolute value of the depth of the terminal negative phase >100 μV in the presence of biphasic P wave in V1. Association between DTNPV1 as a time-dependent exposure variable and incident ischemic stroke was evaluated. The accuracy of the prediction model consisting of DTNPV1 and CHA2DS2-VASc variables in predicting ischemic stroke was analyzed.

RESULTS

Among 10,605 participants (63 ± 6 years, 56% women, 20% Black), 803 cases of ischemic stroke occurred over a median follow-up of 20.19 years. After adjusting for demographics, DTNPV1 was associated with an increased risk of stroke (HR 1.96, [95% CI 1.39-2.77]). After further adjusting for stroke risk factors, use of aspirin and anticoagulants, and time-dependent atrial fibrillation, DTNPV1 was associated with a 1.50-fold (95% CI 1.06-2.13) increased risk of stroke. When added to the CHA2DS2-VASc variables, DTNPV1 did not significantly improve stroke prediction as assessed by C-statistic. However, there was improvement in risk classification for participants who did not develop stroke.

CONCLUSION

DTNPV1 is significantly associated with higher risk of ischemic stroke. Since DTNPV1 is a simplified electrocardiographic parameter, it may help stroke prediction, a subject for further research.

Subclinical variations on ECG and their associations with structural brain aging networks

Impaired cardiac function is associated with cognitive impairment and brain imaging features of aging. Cardiac arrhythmias, including atrial fibrillation, are implicated in clinical and subclinical brain injuries. Even in the absence of a clinical diagnosis, subclinical or prodromal substrates of arrhythmias, including an abnormally long or short P-wave duration (PWD), a measure associated with atrial abnormalities, have been associated with stroke and cognitive decline. However, the extent to which PWD has subclinical influences on overall aging patterns of the brain is not clearly understood. Here, using neuroimaging and ECG data from the UK Biobank, we use a novel regional "brain age" method to identify the brain aging networks associated with abnormal PWD. We find that PWD is inversely associated with accelerated brain aging in the sensorimotor, frontoparietal, ventral attention, and dorsal attention networks, even in the absence of overt cardiac diseases. These findings suggest that detrimental aging outcomes may result from subclinically abnormal PWD.

Electrocardiographic Characteristics in 438 Neonates with Atrial Septal Defects

Arrhythmias and electrocardiographic (ECG) abnormalities are common among patients with atrial septal defects (ASDs). We studied a large cohort of neonates with ASDs to investigate whether ECG abnormalities are present at this early stage or develop later, secondary to hemodynamic changes. We analyzed the echocardiograms and ECGs from the Copenhagen Baby Heart Study, a population-based cohort study. We compared ECG characteristics of 438 neonates with secundum ASDs to 1314 matched controls. In subgroup analyses, we investigated whether electrocardiographic characteristics were associated with age at examination. Neonates with ASDs (median age, 11 days; males, 51%) had longer P-wave durations (58 vs. 56 ms, p < 0.001), PR intervals (100 vs. 96 ms, p < 0.001), and a more rightward-shifted QRS axis (116 vs. 114 degrees, p = 0.032) compared to controls (median age, 10 days; males, 51%). There were no differences between cases and controls in the P-wave area, amplitude, or axis. Subgroup analyses showed that the differences in P-wave duration and PR interval were present in neonates examined in the first week after birth. The difference in the QRS axis was not found in neonates examined this early but was found in neonates examined at age two to four weeks. In conclusion, ASDs are associated with ECG changes from the neonatal phase. The P-wave duration and PR interval are longer in neonates with ASDs when compared to controls as early as the first week after birth, indicating that these changes are not purely secondary, but that neonates with an ASD have altered cardiac electrical activity.ClinicalTrials.gov Identifier NCT02753348 (April 27, 2016).

A Case Report on Multiple Sclerosis Associated With Atrial Fibrillation and Neurogenic Hypertension: Area Postrema Syndrome?

Multiple sclerosis (MS) is an autoimmune demyelinating neurological disorder primarily manifesting with a range of neurological symptoms, with cardiovascular autonomic involvement being a rare occurrence. We report a case where a patient initially presented with Bell's palsy, without other notable symptoms or signs, and subsequently developed atrial fibrillation, hypertension, and hemiparesis. Magnetic resonance imaging (MRI) revealed extensive demyelination in the cerebral hemispheres, brainstem, and notably, the area postrema. The anatomy of the area postrema and its connections, in relation to neurogenic hypertension, are discussed. The demyelination in the area postrema was thought to be the cause of our patient's arrhythmias and acute hypertension. Furthermore, we discuss the cerebral origins of cardiac arrhythmias, with a focus on MS and other neurological conditions. This case underscores the rarity of isolated cranial neuropathies, such as Bell's palsy, as an initial sign of MS, marking the onset of a relapse.

Incidental Arrhythmias During Atrial Fibrillation Screening With Repeat 7-Day Holter ECGs in a Hospital-Based Patient Population

BACKGROUND

Screening for atrial fibrillation (AF) may reveal incidental arrhythmias of relevance. The aim of this study was to describe incidental arrhythmias detected during screening for AF in the STAR-FIB (Predicting SilenT AtRial FIBrillation in Patients at High Thrombembolic Risk) cohort study.

METHODS AND RESULTS

In the STAR-FIB cohort study, we screened hospitalized patients for AF with 3 repeat 7-day Holter ECGs. We analyzed all Holter ECGs for the presence of the following incidental arrhythmias: (1) sinus node dysfunction, defined as sinus pause of ≥3 seconds' duration; (2) second-degree (including Wenckebach) or higher-degree atrioventricular block (AVB); (3) sustained supraventricular tachycardia of ≥30 seconds' duration; and (4) sustained ventricular tachycardia of ≥30 seconds' duration. We furthermore report treatment decisions because of incidental arrhythmias. A total of 2077 Holter ECGs were performed in 794 patients (mean age, 74.7 years; 49% women), resulting in a mean cumulative duration of analyzable ECG signal of 414±136 hours/patient. We found incidental arrhythmias in 94 patients (11.8%). Among these were sinus node dysfunction in 14 patients (1.8%), AVB in 41 (5.2%), supraventricular tachycardia in 42 (5.3%), and ventricular tachycardia in 2 (0.3%). Second-degree AVB was found in 23 patients (2.9%), 2:1 AVB in 10 (1.3%), and complete AVB in 8 (1%). Subsequently, 8 patients underwent pacemaker implantation, 1 for sinus node dysfunction (post-AF conversion pause of 9 seconds) and 7 for advanced AVB. One patient had an implantable cardioverter-defibrillator implanted for syncopal ventricular tachycardia.

CONCLUSIONS

Incidental arrhythmias were frequently detected during screening for AF in the STAR-FIB study and resulted in device therapy in 1.1% of our cohort patients.

ECG predictors of AF: A systematic review (predicting AF in ischaemic stroke-PrAFIS)

In 25% of patients presenting with embolic stroke, a cause is not determined. Atrial fibrillation (AF) is a commonly identified mechanism of stroke in this population, particularly in older patients. Conventional investigations are used to detect AF, but can we predict AF in this population and generally? We performed a systematic review to identify potential predictors of AF on 12-lead electrocardiogram (ECG).

METHOD

We conducted a search of EMBASE and Medline databases for prospective and retrospective cohorts, meta-analyses or case-control studies of ECG abnormalities in sinus rhythm predicting subsequent atrial fibrillation. We assessed quality of studies based on the Newcastle-Ottawa scale and data were extracted according to PRISMA guidelines.

RESULTS

We identified 44 studies based on our criteria. ECG patterns that predicted the risk of developing AF included interatrial block, P-wave terminal force lead V1, P-wave dispersion, abnormal P-wave-axis, abnormal P-wave amplitude, prolonged PR interval, left ventricular hypertrophy, QT prolongation, ST-T segment abnormalities and atrial premature beats. Furthermore, we identified that factors such as increased age, high CHADS-VASC, chronic renal disease further increase the positive-predictive value of some of these parameters. Several of these have been successfully incorporated into clinical scoring systems to predict AF.

CONCLUSION

There are several ECG abnormalities that can predict AF both independently, and with improved predictive value when combined with clinical risk factors, and if incorporated into clinical risk scores. Improved and validated predictive models could streamline selection of patients for cardiac monitoring and initiation of oral anticoagulants.

Smoking-associated Electrocardiographic Abnormalities Predict Cardiovascular Mortality: Insights from NHANES

Background—

Smoking is associated with arrhythmia and sudden cardiac death, but the biological mechanisms remain unclear. Abnormal electrocardiogram (ECG) durations of ventricular repolarization (QT interval), atrial depolarization (P wave), and atrioventricular depolarization (PR interval and segment), predict cardiac arrhythmia and mortality.

Objectives—

To elucidate how smoking affects cardiac excitation, we assessed in a nationally representative sample (NHANES III) associations between cotinine, abnormalities in P duration, PR interval, PR segment, rate-corrected QT (QTc), QRS duration, and JT interval, and long-term mortality.

Methods—

We analyzed data from 5,633 adults using survey-weighted multinomial logistic regression to estimate associations between tobacco use (>15 ng/ml serum cotinine) and short (<5th percentile) or long (>95th percentile) ECG intervals, relative to reference (5 - 95th percentile).

Results—

After adjustment for demographics, risk factors, and conduction-altering medications, smoking was associated with a higher odds of short PR interval, PR segment, and QRS, and long JT. Broader ECG effects of smoking were also assessed by survey-weighted linear regression of continuous cotinine and ECG intervals, which revealed cotinine inversely associated with PR segment and QTc. Over a 22-year follow-up, many ECG abnormalities predicted cardiovascular mortality in smokers, including long JT, QRS, and QTc, and short QRS.

Conclusions—

Smoking increases likelihood for rapid atrioventricular conduction, rapid ventricular depolarization, and slow ventricular repolarization. The ventricular electrophysiologic abnormalities associated with smoking also predict cardiovascular mortality in smokers; however, traditional ECG measures of cardiac risk like QTc can overlook these ventricular defects and their independent predictive value in smokers.

Markers of Atrial Myopathy in the General Population: Prevalence, Predictors, and Inter-Relations

BACKGROUND

Atrial myopathy refers to structural and functional cardiac abnormalities associated with atrial fibrillation and stroke, but appropriate diagnostic criteria are lacking.

OBJECTIVES

This study aimed to assess prevalence, clinical correlates, and overlap between potential atrial myopathy markers.

METHODS

The population-based SCAPIS (Swedish CArdioPulmonary bioImage Study) prospectively included 6,013 subjects without atrial fibrillation with 24-hour electrocardiograms. Resting electrocardiograms measuring P-wave indices were collected at 1 screening site (n = 1,201), and a random sample (n = 385) had echocardiographic left atrial volume index (LAVi). Atrial myopathy markers were defined as ≥500 premature atrial complexes/24 h, LAVi ≥34 mL/m2, P-wave duration >120 milliseconds, or P-wave terminal force in V1 >4,000 ms·s. Clinical correlates included age, sex, body mass index, height, smoking, physical activity, coronary artery disease, diabetes, systolic blood pressure, antihypertensive medication, and low education.

RESULTS

Atrial myopathy was common; 42% of the sample with all diagnostic modalities available had ≥1 atrial myopathy marker, but only 9% had 2 and 0.3% had ≥3. Only P-wave duration and LAVi were correlated (ρ = 0.10; P = 0.04). Clinical correlates of premature atrial complexes, P-wave indices, and LAVi differed; current smoking (34% increase; P < 0.001), systolic blood pressure (4%/mm Hg increase; P = 0.01), diabetes (35% increase; P = 0.001), and coronary artery disease (71% increase; P = 0.003) were associated with premature atrial complexes, physical activity ≥2 h/wk was associated with increased LAVi (β-coefficient = 3.1; P < 0.0001) and body mass index was associated with P-wave duration (β-coefficient = 0.4/kg/m2; P < 0.0001).

CONCLUSIONS

In the general population, indirect markers of atrial myopathy are common but only weakly correlated, and their risk factor patterns are different. More studies are needed to accurately identify individuals with atrial myopathy with diagnostic methods.

Predictors of Atrial Fibrillation in Patients with Embolic Stroke of Unknown Etiology and Implantable Loop Recorders-Further Insights of the TRACK AF Study on the Role of ECG and Echocardiography

Aims-Electrocardiography (ECG) and echocardiographic left atrial (LA) parameters may be helpful to assess the risk of atrial fibrillation (AF) in embolic stroke of unknown etiology (ESUS) and could therefore guide intensity of ECG monitoring. Methods-1153 consecutive patients with ischemic stroke or transient ischemic attack (TIA) were analyzed. An internal loop recorder (ILR) was implanted in 104 consecutive patients with ESUS. Multiple morphologic P-wave parameters in baseline 12-channel ECG and echocardiographic LA parameters were measured and analyzed in patients with and without ILR-detected AF. Using logistic regression, we evaluated the predictive value of several ECG parameters and LA dimensions on the occurrence of AF. Results-In 20 of 104 (19%) patients, AF was diagnosed by ILR during a mean monitoring time of 575 (IQR 470-580) days. Patients with AF were significantly older (72 (67-75) vs. 60 (52-72) years; p = 0.001) and premature atrial contractions (PAC) were more frequently observed (40% vs. 2%; p < 0.001) during baseline ECG. All morphologic P-wave parameters did not show a significant difference between groups. There was a non-significant trend towards a larger LA volume index (31 (24-36) vs. 29 (25-37) mL/m2; p = 0.09) in AF patients. Conclusions-Age and PAC are independently associated with incident AF in ESUS and could be used as markers for selecting patients that may benefit from more extensive rhythm monitoring or ILR implantation. In our consecutive cohort of patients with ESUS, neither morphological P-wave parameters nor LA size were predictive of AF.

Electrocardiographic Morphology-Voltage-P-Wave-Duration (MVP) Score to Select Patients for Continuous Atrial Fibrillation Screening to Prevent Stroke

Morphology-voltage-P-wave-duration (MVP) score combining P-wave duration (PWD), P-wave voltage in lead I (PWVI), and interatrial block (IAB) has been demonstrated to predict atrial fibrillation (AF). Therefore, this study aimed to examine MVP score and its P-wave components as potential predictors of AF screening effects on stroke prevention. This was a secondary analysis of the LOOP Study (Atrial Fibrillation detected by Continuous ECG Monitoring using Implantable Loop Recorder to prevent Stroke in High-risk Individuals) which randomized older persons (aged 70 to 90 years) with additional stroke risk factors to either continuous monitoring with implantable loop recorder and anticoagulation upon detection of AF episodes ≥6 minutes (the intervention group), or usual care. A total of 5,759 participants were included in the present analysis, where PWD, PWVI, and IAB were determined through a computerized analysis of 12-lead electrocardiogram and further employed to calculate baseline MVP score (0 to 6) for each participant. In total, 305 (5.3%) had stroke or systemic embolism during follow-up, with a higher risk in the group with MVP score 5 to 6 than those having score 0 to 2 (hazard ratio (HR) 1.54 [95% confidence interval (CI) 1.01 to 2.35]). This risk increase was mainly upheld by participants with IAB (HR 1.62 [95% CI 1.11 to 2.36] for IAB vs no IAB) and with longer PWD (HR 1.37 [95% CI 1.07 to 1.75] for >110 vs ≤110 ms). Compared with usual care, implantable loop recorder screening did not significantly reduce the risk of stroke or systemic embolism in any MVP risk categories (HR 0.80 [95% CI 0.60 to 1.08] for MVP score 0 to 2, 0.54 [95% CI 0.16 to 1.85] for MVP score 3 to 4, and 0.89 [95% CI 0.35 to 2.25] for MVP score 5 to 6; pinteraction = 0.78). In conclusion, a higher MVP score was associated with an increased stroke risk, but it did not demonstrate an association with effects of AF screening on stroke prevention. These findings should be considered hypothesis-generating and warrant further study.

Determinants of Atrial Fibrillation Progression and Its Influence on Overall Mortality in a Cohort of Patients From South India

BACKGROUND

Atrial fibrillation (AF) is a prevalent cardiac arrhythmia associated with increased morbidity and mortality. However, factors influencing AF progression and their impact on all-cause mortality in South Indian patients remain poorly understood.

METHODS

We conducted a retrospective cohort study involving 500 individuals diagnosed with AF. Patient characteristics, including age, sex, and comorbidities, were collected. Left atrial diameter (LAD) and left ventricular ejection fraction (LVEF) were measured via echocardiography. Participants were followed for a median of three years. Cox proportional hazard regression was used to analyze factors associated with AF progression and all-cause mortality.

RESULTS

Of the participants, 60% exhibited persistent or permanent AF, and 40% had paroxysmal AF. The mean age was 63.5 ± 10.8 years, with 60% males and 40% females. Common comorbidities included hypertension (80%), diabetes (50%), and coronary artery disease (35%). The mean LAD was 42.3 ± 5.6 mm and the mean LVEF was 52.7 ± 6.8%; left atrial appendage thrombus (LAAT) was present in 15% of patients. Over the follow-up, 24% experienced all-cause mortality. Multivariate analysis revealed age, hypertension, diabetes, LAD, and LVEF as significant predictors of AF progression (p<0.05). Patients with persistent or permanent AF exhibited a higher risk of progression than those with paroxysmal AF (hazard ratio=1.74, 95% CI, 1.23-2.45). Age, hypertension, heart failure, and AF progression were independent predictors of all-cause mortality (p<0.05).

CONCLUSION

Our study identified age, hypertension, diabetes, LAD, and LVEF as independent predictors of AF progression. Additionally, age, hypertension, heart failure, and AF progression independently predicted all-cause mortality. These findings underscore the need for early detection and management of AF progression and comorbidities to improve outcomes in South Indian AF patients. Prospective studies with larger cohorts are warranted to confirm these findings and explore interventions to prevent AF progression and enhance patient outcomes.

P-wave duration as a marker of atrial remodeling in patients referred to ablation for atrial fibrillation: A new stratification tool emerging?

Ablation of atrial fibrillation is one of the most widely applied invasive procedures in cardiovascular medicine, and populations with atrial fibrillation continuously rise. Recurrence rates are, however, consistently high, even in patients without severe comorbidities. Robust stratification algorithms to distinguish patients suitable for ablation are generally lacking. This is a fact caused by the inability to incorporate evidence of atrial remodeling and fibrosis, e.g., atrial remodeling, in the decision pathways. Cardiac magnetic resonance is a powerful tool in identifying fibrosis; however, it is costly and not routinely used. Electrocardiography has been generally underutilized in clinical practice during pre-ablative screening. One of the characteristics of the electrocardiogram that can give us valuable data depicting the existence and the extent of atrial remodeling and fibrosis is the duration of the P-wave. Currently, many studies support the implementation of P-wave duration in the routine practice of patient evaluation as a surrogate marker of existing atrial remodeling, that in turn predicts recurrence after ablation of atrial fibrillation. Further research is guaranteed to establish this electrocardiographic characteristic in our stratification quiver.

MedalCare-XL: 16,900 healthy and pathological synthetic 12 lead ECGs from electrophysiological simulations

Mechanistic cardiac electrophysiology models allow for personalized simulations of the electrical activity in the heart and the ensuing electrocardiogram (ECG) on the body surface. As such, synthetic signals possess known ground truth labels of the underlying disease and can be employed for validation of machine learning ECG analysis tools in addition to clinical signals. Recently, synthetic ECGs were used to enrich sparse clinical data or even replace them completely during training leading to improved performance on real-world clinical test data. We thus generated a novel synthetic database comprising a total of 16,900 12 lead ECGs based on electrophysiological simulations equally distributed into healthy control and 7 pathology classes. The pathological case of myocardial infraction had 6 sub-classes. A comparison of extracted features between the virtual cohort and a publicly available clinical ECG database demonstrated that the synthetic signals represent clinical ECGs for healthy and pathological subpopulations with high fidelity. The ECG database is split into training, validation, and test folds for development and objective assessment of novel machine learning algorithms.

Interatrial Block Association With Adverse Cardiovascular Outcomes in Patients Without a History of Atrial Fibrillation

BACKGROUND

Interatrial block (IAB) is associated with thromboembolism and atrial arrhythmias. However, prior studies included small patient cohorts so it remains unclear whether IAB predicts adverse outcomes particularly in context of atrial fibrillation (AF)/atrial flutter (AFL).

OBJECTIVES

This study sought to determine whether IAB portends increased stroke risk in a large cohort in the presence or absence of AFAF/AFL.

METHODS

We performed a 5-center retrospective analysis of 4,837,989 electrocardiograms (ECGs) from 1,228,291 patients. IAB was defined as P-wave duration ≥120 ms in leads II, III, or aVF. Measurements were extracted as .XML files. After excluding patients with prior AF/AFL, 1,825,958 ECGs from 458,994 patients remained. Outcomes were analyzed using restricted mean survival time analysis and restricted mean time lost.

RESULTS

There were 86,317 patients with IAB and 355,032 patients without IAB. IAB prevalence in the cohort was 19.6% and was most common in Black (26.1%), White (20.9%), and Hispanic (18.5%) patients and least prevalent in Native Americans (9.2%). IAB was independently associated with increased stroke probability (restricted mean time lost ratio coefficient [RMTLRC]: 1.43; 95% CI: 1.35-1.51; tau = 1,895), mortality (RMTLRC: 1.14; 95% CI: 1.07-1.21; tau = 1,924), heart failure (RMTLRC: 1.94; 95% CI: 1.83-2.04; tau = 1,921), systemic thromboembolism (RMTLRC: 1.62; 95% CI: 1.53-1.71; tau = 1,897), and incident AF/AFL (RMTLRC: 1.16; 95% CI: 1.10-1.22; tau = 1,888). IAB was not associated with stroke in patients with pre-existing AF/AFL.

CONCLUSIONS

IAB is independently associated with stroke in patients with no history of AF/AFL even after adjustment for incident AF/AFL and CHA2DS2-VASc score. Patients are at increased risk of stroke even when AF/AFL is not identified.

Electrocardiographic markers of subclinical atrial fibrillation detected by implantable loop recorder: insights from the LOOP Study

AIMS

Insights into subclinical atrial fibrillation (AF) development are warranted to inform the strategies of screening and subsequent clinical management upon AF detection. Hence, this study sought to characterize the onset and progression of subclinical AF with respect to 12-lead electrocardiogram (ECG) parameters.

METHODS AND RESULTS

We included AF-naïve individuals aged 70-90 years with additional stroke risk factors who underwent implantable loop recorder (ILR) monitoring in the LOOP Study. Using data from daily ILR recordings and the computerized analysis of baseline ECG, we studied empirically selected ECG parameters for AF detection (≥6 min), cumulative AF burden, long-lasting AF (≥24 h), and AF progression. Of 1370 individuals included, 419 (30.6%) developed AF during follow-up, with a mean cumulative AF burden of 1.5% [95% CI: 1.2-1.8]. Several P-wave-related and ventricular ECG parameters were associated with new-onset AF and with cumulative AF burden in AF patients. P-wave duration (PWD), P-wave terminal force in Lead V1, and interatrial block (IAB) further demonstrated significant associations with long-lasting AF. Among AF patients, we observed an overall reduction in cumulative AF burden over time (IRR 0.70 [95% CI: 0.51-0.96]), whereas IAB was related to an increased risk of progression to AF ≥24 h (HR 1.86 [95% CI: 1.02-3.39]). Further spline analysis also revealed longer PWD to be associated with this progression in AF duration.

CONCLUSION

We identified several ECG parameters associated with new-onset subclinical AF detected by ILR. Especially PWD and IAB were robustly related to the onset and the burden of AF as well as progression over time.

Association of lipid composition and unsaturated fatty acids of VLDL with atrial remodeling in metabolic syndrome

Subjects with metabolic syndrome (MetS) commonly have atrial remodeling, which indicates a risk for atrial fibrillation. This study determined MetS-related changes in lipid components in very-low-density lipoprotein (VLDL), which has been shown to cause atrial remodeling, the effect of statins on these changes, and the correlation between atrial remodeling and VLDL lipid compositions. Blood samples were collected from 12 non-MetS and 27 sex- and age-matched MetS subjects. Fourteen patients with MetS (MetS-off statin) discontinued statin therapy 14 days before the study, while the remaining 13 remained on it (MetS-on statin). The VLDLs were isolated and processed for mass-based lipid profiling. Lipidomic analyses were performed and associated with atrial remodeling markers measured using standard echocardiography and electrocardiography. Compared with the VLDL components of the non-MetS group, glucosyl/galactosyl ceramide, lyso-phosphatidylcholine, lyso-phosphatidylethanolamine, and triglycerides were enriched in the MetS-off statin group. Statin therapy attenuated all abnormally abundant lipid classes in MetS, except for triglycerides. In addition, lyso-phosphatidylcholine, lyso-phosphatidylethanolamine, and triglycerides were significantly correlated with atrial dilatation, and the latter two were also correlated with the PR interval. Enrichment of double bonds, which indicate unsaturated fatty acids, was also significantly correlated with atrial remodeling and P-wave duration. This study suggests that the pathological lipid payload of MetS-VLDL may contribute to atrial remodeling in patients.

Electrocardiographic Predictors of Atrial Fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common pathological arrhythmia, and its complications lead to significant morbidity and mortality. However, patients with AF can often go undetected, especially if they are asymptomatic or have a low burden of paroxysms. Identification of those at high risk of AF development may help refine screening and management strategies.

METHODS

PubMed and Embase databases were systematically searched for studies looking at electrocardiographic predictors of AF from inception to August 2021.

RESULTS

A total of 115 studies were reported which examined a combination of atrial and ventricular parameters that could be electrocardiographic predictors of AF. Atrial predictors include conduction parameters, such as the PR interval, p-wave index and dispersion, and partial interatrial or advanced interatrial block, or morphological parameters, such as p-wave axis, amplitude and terminal force. Ventricular predictors include abnormalities in QRS amplitude, morphology or duration, QT interval duration, r-wave progression and ST segment, i.e., t-wave abnormalities.

CONCLUSIONS

There has been significant interest in electrocardiographic prediction of AF, especially in populations at high risk of atrial AF, such as those with an embolic stroke of undetermined source. This review highlights the breadth of possible predictive parameters, and possible pathological bases for the predictive role of each parameter are proposed.

P-wave durations from automated electrocardiogram analysis to predict atrial fibrillation and mortality in heart failure

BACKGROUND

P-wave indices have been used to predict incident atrial fibrillation (AF), stroke, and mortality. However, such indices derived from automated ECG measurements have not been explored for their predictive values in heart failure (HF). We investigated whether automated P-wave indices can predict adverse outcomes in HF.

METHODS

This study included consecutive Chinese patients admitted to a single tertiary centre, presenting with HF but without prior AF, and with at least one baseline ECG, between 1 January 2010 and 31 December 2016, with last follow-up of 31 December 2019.

RESULTS

A total of 2718 patients were included [median age: 77.4, interquartile range (IQR): (66.9-84.3) years; 47.9 males]. After a median follow-up of 4.8 years (IQR: 1.9-9.0 years), 1150 patients developed AF (8.8/year), 339 developed stroke (2.6/year), 563 developed cardiovascular mortality (4.3/year), and 1972 had all-cause mortality (15.1/year). Compared with 101-120 ms as a reference, maximum P-wave durations predicted new-onset AF at ≤90 ms [HR: 1.17(1.11, 1.50), P < 0.01], 131-140 ms [HR: 1.29(1.09, 1.54), P < 0.001], and ≥141 ms [HR: 1.52(1.32, 1.75), P < 0.001]. Similarly, they predicted cardiovascular mortality at ≤90 ms [HR: 1.50(1.08, 2.06), P < 0.001] or ≥141 ms [HR: 1.18(1.15, 1.45), P < 0.001], and all-cause mortality at ≤90 ms [HR: 1.26(1.04, 1.51), P < 0.001], 131-140 ms [HR: 1.15(1.01, 1.32), P < 0.01], and ≥141 ms [HR: 1.31(1.18, 1.46), P < 0.001]. These remained significant after adjusting for significant demographics, past co-morbidities, P-wave dispersion, and maximum P-wave amplitude.

CONCLUSIONS

Extreme values of maximum P-wave durations (≤90 ms and ≥141 ms) were significant predictors of new-onset AF, cardiovascular mortality, and all-cause mortality.

Variability of expert assessments of ECG time domain parameters

BACKGROUND

In anaesthesiology, time domain parameters of the ECG are frequently used for long QT diagnosis, determination of branch blocks and for identifying atrioventricular blocks. However, this analysis depends on several factors and therefore the time domain parameters are prone to variability.

OBJECTIVE

To determine the variability of expert assessments of ECG time domain parameters in daily clinical practice.

DESIGN

In an observational study 18 physicians labelled the onset, peak and end of the waves (P-QRS-T) for 26 preselected, distinctive beats. Based on this, clinically important durations and intervals were derived: the duration of the P wave, T wave and QRS complex, as well as the length of the PQ and QT interval. These parameters were subsequently analysed with respect to inter-expert variability (for all experts and discipline-based subgroups) and, additionally, were compared with computer-aided analysis.

SETTING

ECG recordings from participating patients were recorded in March 2015 during standard examination in the hospital and stored in the local ECG database.

PATIENTS

We did not define inclusion or exclusion criteria for the patients themselves; the ECG beats were selected by a medical expert with respect to their shapes and abnormalities.

MAIN OUTCOME MEASURES

Variability of clinically relevant ECG wave durations and intervals quantified were expressed as the interquartile range and the Q2/Q98 span for 18 investigators.

RESULTS

The resulting wave durations (Pdur, QRSdur and Tdur) and intervals (PQ and QT) showed high variability, for instance, captured by the Q2/Q98 span ranging from 39 to 99 ms.

CONCLUSION

The observed, inter-investigator variability of assessing the PQ and QT intervals, as well as the wave durations, might result in important variance regarding ECG-associated diagnoses. Whether these variances play a major role in typical clinical situations would have to be demonstrated with further clinical observational studies.

Dysregulated carbohydrate and lipid metabolism and risk of atrial fibrillation in advanced old age

OBJECTIVE

Obesity and dysmetabolism are major risk factors for atrial fibrillation (AF). Fasting and postload levels of glucose and non-esterified fatty acids (NEFAs) reflect different facets of metabolic regulation. We sought to study their respective contributions to AF risk concurrently.

METHODS

We assessed levels of fasting and postload glucose and NEFA in the Cardiovascular Health Study to identify associations with AF incidence and, secondarily, with ECG parameters of AF risk available at baseline. Linear and Cox regressions were performed.

RESULTS

The study included 1876 participants (age 77.7±4.4). During the median follow-up of 11.4 years, 717 cases of incident AF occurred. After adjustment for potential confounders, postload glucose showed an association with incident AF (HR per SD increment of postload glucose=1.11, 95% CI 1.02 to 1.21, p=0.017). Both glucose measures, but not NEFA, were positively associated with higher P wave terminal force in V1 (PTFV1); the association remained significant only for postload glucose when the two measures were entered together (β per SD increment=138 μV·ms, 95% CI 15 to 260, p=0.028). Exploratory analyses showed significant interaction by sex for fasting NEFA (pinteraction=0.044) and postload glucose (pinteraction=0.015) relative to AF, with relationships stronger in women. For postload glucose, the association with incident AF was observed among women but not among men.

CONCLUSIONS

Among older adults, postload glucose was positively associated with incident AF, with consistent findings for PTFV1. In exploratory analyses, the relationship with AF appeared specific to women. These findings require further study but suggest that interventions to address postprandial dysglycaemia late in life might reduce AF.

Assessment of P Wave Indices in Healthy Standardbred Horses

P wave indices are used as non-invasive electrocardiographic markers of atrial remodelling in humans. Few studies have investigated their use in animals. The aim of this study was to measure P wave duration and P wave dispersion (Pd) in healthy standardbred horses and investigate variables that might influence these measurements. A 12-lead electrocardiogram was recorded at rest and P wave indices were calculated in 53 horses. A general linear model was used to investigate the main effects: age, bodyweight, sex, resting heart rate, presence of a murmur, exercise status and the number of years raced. There were significant associations with exercise status for both the maximum P wave duration and Pd, with both values being increased in strenuously exercising versus non-active horses. Furthermore, a significant moderate positive correlation was identified between the duration of exercise (number of years raced) and both Pmax and Pd. No other significant associations were identified. These findings are similar to those reported in elite human athletes versus sedentary individuals. The increases in these P wave indices most likely occur due to prolongation and heterogeneity in atrial conduction time, which are associated with structural and electrical remodelling, and may explain the increased risk of atrial fibrillation in athletic horses.

The prognostic predictive value of the components of the PR interval in hospitalized patients with heart failure

OBJECTIVE

Previous reports on the epidemiology, influencing factors, and the prognostic value of the components of PR interval in hospitalized heart failure patients were limited.

METHODS

This study retrospectively enrolled 1182 patients hospitalized with heart failure from 2014 to 2017. Multiple linear regression analysis was used to explore the association between the components of PR interval and the baseline parameters. The primary outcome was all-cause death or heart transplantation. Multivariable-adjusted Cox proportional hazard regression models were constructed to explore the predictive value of the components of PR interval for the primary outcome.

RESULTS

In multiple linear regression analysis, higher height (for every 10 cm increase in height: regression coefficient 4.83, P < 0.001) as well as larger atrial and ventricular size were associated with larger P wave duration but not with PR segment. The primary outcome occurred in 310 patients after an average follow-up of 2.39 years. Cox regression analyses revealed that the increase in PR segment was an independent predictor of the primary outcome (every 10 ms increase: hazard ratio 1.041, 95% confidence interval [CI] 1.010-1.083, P = 0.023), whereas the P wave duration did not show significant correlation. When adding the PR segment to an initial prognostic prediction model, the likelihood ratio test and categorical net reclassification index (NRI) showed a significant improvement, but the increase in C-index was not significant. In subgroup analysis, increased PR segment was an independent predictor of the primary endpoint in patients taller than 170 cm (each 10 ms increase: hazard ratio 1.153, 95% CI 1.085-1.225, P < 0.001) but not the shorter group (P for interaction = 0.006).

CONCLUSIONS

In hospitalized patients with heart failure, longer PR segment was an independent predictor of the composite endpoint of all-cause death and heart transplantation, especially in the taller group, but it had limited significance in improving the prognostic risk stratification of this population.

P-wave parameters and their association with thrombi and spontaneous echo contrast in the left atrial appendage

BACKGROUND

The aim of this study was to examine the prevalence of abnormal P-wave parameters in patients with thrombus and/or spontaneous echo contrast (SEC) in the left atrial appendage (LAA), and to identify P-wave parameters particularly associated with thrombus and SEC formation.

HYPOTHESIS

We presume a significant relationship of P-wave parameters with thrombi and SEC.

METHODS

All patients in whom a thrombus or SEC was detected in the LAA on transoesophageal echocardiography were included in this study. Patients at risk (CHA2DS2-VASc Score ≥3) and routine transoesophageal echocardiography to exclude thrombi served as the control group. A detailed ECG analysis was performed.

RESULTS

Of a total of 4062 transoesophageal echocardiographies, thrombi and SEC were detected in 302 patients (7.4%). Of these patients, 27 (8.9%) presented with sinus rhythm. The control group included 79 patients. There was no difference in mean CHA2DS2-VASc score in the two groups (p = .182). A high prevalence of abnormal P-wave parameters was detected in patients with thrombus/SEC. Indicators for the presence of thrombi or SEC in the LAA were P-wave duration >118 ms (Odds ratio (OR) 3.418, Confidence interval (CI) 1.522-7.674, p < .001), P-wave dispersion >40 ms (OR 2.521, CI 1.390-4.571, p < .001) and advanced interatrial block (OR 1.431, CI 1.033-1.984, p = .005).

CONCLUSION

Our study revealed that several P-wave parameters are associated with thrombi and SEC in the LAA. The results may help identify patients who are at particularly high risk for thromboembolic events (e.g., in patients with embolic stroke of undetermined source).

The Impact of Standard Ablation Strategies for Atrial Fibrillation on Cardiovascular Performance in a Four-Chamber Heart Model

PURPOSE

Atrial fibrillation is one of the most frequent cardiac arrhythmias in the industrialized world and ablation therapy is the method of choice for many patients. However, ablation scars alter the electrophysiological activation and the mechanical behavior of the affected atria. Different ablation strategies with the aim to terminate atrial fibrillation and prevent its recurrence exist but their impact on the performance of the heart is often neglected.

METHODS

In this work, we present a simulation study analyzing five commonly used ablation scar patterns and their combinations in the left atrium regarding their impact on the pumping function of the heart using an electromechanical whole-heart model. We analyzed how the altered atrial activation and increased stiffness due to the ablation scars affect atrial as well as ventricular contraction and relaxation.

RESULTS

We found that systolic and diastolic function of the left atrium is impaired by ablation scars and that the reduction of atrial stroke volume of up to 11.43% depends linearly on the amount of inactivated tissue. Consequently, the end-diastolic volume of the left ventricle, and thus stroke volume, was reduced by up to 1.4 and 1.8%, respectively. During ventricular systole, left atrial pressure was increased by up to 20% due to changes in the atrial activation sequence and the stiffening of scar tissue.

CONCLUSION

This study provides biomechanical evidence that atrial ablation has acute effects not only on atrial contraction but also on ventricular performance. Therefore, the position and extent of ablation scars is not only important for the termination of arrhythmias but is also determining long-term pumping efficiency. If confirmed in larger cohorts, these results have the potential to help tailoring ablation strategies towards minimal global cardiovascular impairment.

Increased risk of atrial fibrillation in patients with psoriasis: A meta-analysis of observational studies

BACKGROUND

Several epidemiological studies have shown that psoriasis increases the risk of developing atrial fibrillation but evidence of this is still scarce.

AIMS

Our objective was to systematically review, synthesise and critique the epidemiological studies that provided information about the relationship between psoriasis and atrial fibrillation risk.

METHODS

We searched through PubMed, EMBASE and the bibliographies for articles published between 1 January 2000, and 1 November 2017, that reported on the association between psoriasis and atrial fibrillation. All abstracts, full-text articles and sources were reviewed with duplicate data excluded. Summary relative risks (RRs) with 95% CI were pooled using a random effects model.

RESULTS

We identified 252 articles, of these eight unique abstracts underwent full-text review. We finally selected six out of these eight studies comprising 11,187 atrial fibrillation patients. The overall pooled relative risk (RR) of atrial fibrillation was 1.39 (95% CI: 1.257-1.523, P < 0.0001) with significant heterogeneity (I2 = 80.316, Q = 45.723, τ2 = 0.017, P < 0.0001) for the random effects model. In subgroup analysis, the greater risk was found in studies from North America, RR 1.482 (95% CI: 1.119-1.964, P < 0.05), whereas a moderate risk was observed in studies from Europe RR 1.43 (95% CI: 1.269-1.628, P < 0.0001).

LIMITATIONS

We were only able to include six studies with 11,178 atrial fibrillation patients, because only a few such studies have been published.

CONCLUSION

Our results showed that psoriasis is significantly associated with an increased risk of developing atrial fibrillation. Therefore, physicians should monitor patient's physical condition on a timely basis.

Analysis of the amplified p-wave enables identification of patients with atrial fibrillation during sinus rhythm

Aim

This study sought to develop and validate diagnostic models to identify individuals with atrial fibrillation (AF) using amplified sinus-p-wave analysis.

Methods

A total of 1,492 patients (491 healthy controls, 499 with paroxysmal AF and 502 with persistent AF) underwent digital 12-lead-ECG recording during sinus rhythm. The patient cohort was divided into training and validation set in a 3:2 ratio. P-wave indices (PWI) including duration of standard p-wave (standard PWD; scale at 10 mm/mV, sweep speed at 25 mm/s) and amplified sinus-p-wave (APWD, scale at 60-120 mm/mV, sweep speed at 100 mm/s) and advanced inter-atrial block (aIAB) along with other clinical parameters were used to develop diagnostic models using logistic regression. Each model was developed from the training set and further tested in both training and validation sets for its diagnostic performance in identifying individuals with AF.

Results

Compared to standard PWD (Reference model), which achieved an AUC of 0.637 and 0.632, for training and validation set, respectively, APWD (Basic model) importantly improved the accuracy to identify individuals with AF (AUC = 0.86 and 0.866). The PWI-based model combining APWD, aIAB and body surface area (BSA) further improved the diagnostic performance for AF (AUC = 0.892 and 0.885). The integrated model, which further combined left atrial diameter (LAD) with parameters of the PWI-based model, achieved optimal diagnostic performance (AUC = 0.916 and 0.902).

Conclusion

Analysis of amplified p-wave during sinus rhythm allows identification of individuals with atrial fibrillation.

A short P-wave duration is associated with incident heart failure in the elderly: a 15 years follow-up cohort study

BACKGROUND

Early identification of patients at risk of congestive heart failure (HF) may alter their poor prognosis. The aim was therefore to test whether simple electrocardiographic variables, the P-wave and PR-interval, could predict incident HF.

METHODS

The PIVUS (Prospective Investigation of the Vasculature in Uppsala Seniors) study (1016 individuals all aged 70 years, 50% women) was used to identify predictors of HF. Subjects with prevalent HF, QRS duration ≥ 130 ms, atrial tachyarrhythmias, implanted pacemaker/defibrillator, second- and third-degree atrioventricular block or delta waves at baseline were excluded. Cox proportional hazard analysis was used to relate the PR interval, P-wave duration (Pdur) and amplitude (Pamp), measured in lead V1, to incident HF. Adjustment was performed for gender, RR-interval, beta-blocking agents, systolic blood pressure, body mass index and smoking.

RESULTS

Out of 836 subjects at risk, 107 subjects were diagnosed with HF during a follow-up of 15 years. In the multivariate analysis, there was a strong U-shaped correlation between Pdur in lead V1 and incident HF (P = 0.0001) which was significant for a Pdur < 60 ms [HR = 2.75; 95% CI: 1.87-4.06, at Pdur 40 ms] but not for prolonged Pdur. There was no significant relationship between incident HF and the PR-interval or the Pamp. A Pdur < 60 ms improved discrimination by 3.7% when added to the traditional risk factors including sex, RR-interval, beta-blocking agents, systolic blood pressure, BMI and smoking (P = 0.048).

CONCLUSIONS

A short Pdur, an easily measured parameter on the ECG, may potentially be a useful marker of future HF, enabling its early detection and prevention, thus improving outcomes.

Usefulness of P-wave peak time as an electrocardiographic parameter in predicting left ventricular diastolic dysfunction in patients with mitral regurgitation

INTRODUCTION

Conventional Doppler measurements have limitations in predicting left ventricular diastolic dysfunction (LVDD) in patients with mitral regurgitation (MR). Recently, electrocardiographic P-wave peak time (PWPT) has been proposed as a parameter of detecting LVDD. This study aimed to evaluate the association between PWPT and left ventricular end-diastolic pressure (LVEDP) in patients with MR.

METHODS

We performed echocardiography and cardiac catheterization in 82 patients with moderate or severe MR. We classified patients into two groups: low LVEDP group (L-LVEDP) (LVEDP <16 mmHg, n = 40) and high LVEDP group (H-LVEDP) (LVEDP ≥16 mmHg, n = 42). We evaluated LVDD and PWPT based on echocardiographic and electrocardiographic findings in both groups.

RESULTS

The PWPT in lead II (PWPT_II ) was significantly longer in patients in the H-LVEDP group than in those in the L-LVEDP group (67 vs. 47 ms, p < .001). Using correlation analysis, LVEDP was positively correlated with PWPT_II (r = .577, p < .001). Using multivariate analysis, PWPT_II was found to be an independent predictor of increased LVEDP (95% CI: 0.1030-0.110; p < .001). Using receiver operating characteristic (ROC) curve analysis, the optimal cutoff value of PWPT_II for predicting elevated LVEDP was 58.9 ms, with a sensitivity of 80.0% and a specificity of 73.8% (area under curve: 0.809, 95% CI: 0.713-0.905).

CONCLUSION

To the best of our knowledge, this is the first study to assess the effect of a significant valvular disease on PWPT in lead II. These findings suggest that prolonged PWPT_II may be an independent predictor of increased LVEDP in patients with moderate or severe MR.

Short P-Wave Duration Is Associated with Incident Atrial Fibrillation

Atrial fibrillation (AF) is common and increases the risk for stroke and heart failure (HF). The early identification of patients at risk may prevent the development of AF and improve prognosis. This study, therefore, aimed to test the effect of the association between P-wave and PR-interval on the ECG and incident AF.The PIVUS (Prospective Investigation of the Vasculature in Uppsala Seniors) study (1016 individuals all aged 70 years; 50% women) was used to identify whether the ECG variables P-wave duration (Pdur) and PR-duration in lead V1 were related to new-onset AF. Exclusion criteria were prevalent AF, QRS-duration ≥ 130 milliseconds (msec), atrial tachyarrhythmias and implanted pacemaker/defibrillator. Cox proportional-hazards models were used for analyses. Adjustments were made for gender, RR-interval, beta-blocking agents, systolic blood pressure, body mass index, and smoking.Of 877 subjects at risk, 189 individuals developed AF during a 15-year follow-up. There was a U-shaped relationship between the Pdur and incident AF (P = 0.017) following multiple adjustment. Values below 60 msec were significantly associated with incident AF, with a hazard ratio of 1.55 (95% confidence interval 1.15-2.09) for a Pdur ≤ 42 msec. There was no significant relationship between incident AF and the PR-interval.A short Pdur derived from the ECG in V1 may be a useful marker for new-onset AF, enabling the early identification of at-risk patients.

Atrial myxoma surgery and p-wave remodeling

INTRODUCTION

Data regarding atrial electrocardiographic parameters in patients with atrial myxomas are scarce.

METHODS

We aimed to study atrial electrocardiographic features in patients with atrial myxomas, before and after surgery. We also analyze the incidence of atrial fibrillation during follow-up and its correlation with different P-wave indexes. 32 patients in sinus rhythm that underwent atrial myxoma surgery were included.

RESULTS

Mean age was 55.0±12.6 years and 18 (56.3%) were women. Ten patients had left atrial enlargement (31.3%). Only one myxoma was located in the right atrium. At baseline 7 cases of partial interatrial block (IAB) were detected (21.9%), two in the absence of left atrial enlargement. There were significant differences in atrial electrocardiographic indexes before and after surgery, including P-wave duration (108.9±17.9 ms vs. 93.0±12.4 ms; p < 0.001), partial IAB (21.9% vs 3.1%; p = 0.012) and duration of P-wave terminal force in lead V1 negativity (-0.6±0.3 vs -0.5±0.3 mm; p = 0.034). At a mean follow up of 10.0±5.5 years, 10 patients (31.3%) had experienced at least one episode of atrial fibrillation. Post-operative P-wave duration was associated with atrial fibrillation occurrence during follow-up (Hazard ratio: 0.90, 95% confidence interval: 0.83-0.98; p = 0.020).

CONCLUSIONS

Abnormalities in atrial electrocardiographic indexes are common in atrial myxomas and frequently improve after surgery. Post-operative P-wave duration is associated with atrial fibrillation occurrence during follow-up. This article is protected by copyright. All rights reserved.

QTc Interval is Associated with Atrial Fibrillation in Individuals with Metabolic Syndrome Phenotype

Purpose

Manifestations of metabolic syndrome (MetS) carry risks for atrial fibrillation (AF). The study determined whether any electrocardiographic parameter can reflect increased AF risk in individuals with MetS.

Patients and Methods

From our University Hospital database, we examined the presence of AF and its correlation with MetS manifestations, renal function, lipid profiles, and electrocardiographic parameters (P wave duration, PR interval, QRS width, and QTc intervals). Between January 2008 and December 2015, data from 4479 adults (women 41.6% vs men 58.4%) were identified.

Results

The overall prevalence of AF was 12.4%, without sex differences (women, 12.8% vs men, 12.1%). Patients with AF were older (age 73.9 ± 11.8 vs non-AF 67 ± 13.5 years), with lower lipid levels (TG, total cholesterol, and LDL-cholesterol, all p < 0.0001), and at lower eGFR level (64.1 ± 30.9 vs non-AF 68.8 ± 41.4 mL/min/1.73m2, p < 0.0001). Besides, sex differences were present in all electrocardiographic parameters (all p < 0.05). Hypertension had the highest odds ratio (1.33; p = 0.026) for AF. Comparing AF to non-AF, the QTc of quartiles was significantly different (p < 0.0089). The shortest and longest QTc quartiles had an increased incidence of AF.

Conclusion

AF risk in patients with MetS phenotypes can be reflected by QTc quartiles.

Visualization deep learning model for automatic arrhythmias classification

With the improvement of living standards, heart disease has become one of the common diseases that threaten human health. As a widely used reliable, non-invasive technology, the Electrocardiography (ECG) data has been increasingly used for diagnosing cardiovascular diseases. With the rapid growth of ECG examinations and the shortage of cardiologists, accurate and automatic recognition of ECG patterns has become a research hotspot. In order to improve the accuracy in detecting abnormal ECG patterns, this paper proposes a hybrid 1D Resnet-GRU consisting of the Resnet and gated recurrent unit (GRU) modules to implement classification of arrhythmias from 12-lead ECG recordings. In addition, the focal Loss function is used to solve the problem of unbalanced datasets. Based on the proposed 1D Resnet-GRU model, the Grad-CAM++ mechanism, one of class-discriminative visualization methods, has been employed to the trained network model and generate thermal images superimposed on raw signals, so as to improve interpretability and transparency for arrhythmia classification. Experimental results show the proposed Resnet-GRU method can improve the F_1 score and accuracy effectively, and Grad-CAM++ can provide interpretability and clinical information for arrhythmia classification.

The Atrium in Atrial Fibrillation - A Clinical Review on How to Manage Atrial Fibrotic Substrates

Atrial fibrillation (AF) is the most common sustained arrhythmia in the population and is associated with a significant clinical and economic burden. Rigorous assessment of the presence and degree of an atrial arrhythmic substrate is essential for determining treatment options, predicting long-term success after catheter ablation, and as a substrate critical in the pathophysiology of atrial thrombogenesis. Catheter ablation of AF has developed into an essential rhythm-control strategy. Nowadays is one of the most common cardiac ablation procedures performed worldwide, with its success inversely related to the extent of atrial structural disease. Although atrial substrate evaluation remains complex, several diagnostic resources allow for a more comprehensive assessment and quantification of the extent of left atrial structural remodeling and the presence of atrial fibrosis. In this review, we summarize the current knowledge on the pathophysiology, etiology, and electrophysiological aspects of atrial substrates promoting the development of AF. We also describe the risk factors for its development and how to diagnose its presence using imaging, electrocardiograms, and electroanatomic voltage mapping. Finally, we discuss recent data regarding fibrosis biomarkers that could help diagnose atrial fibrotic substrates.