Simple electrocardiographic markers for the prediction of paroxysmal idiopathic atrial fibrillation

Automatically assessed P-wave predicts cardiac events independently of left atrial enlargement in patients with cardiovascular risks: The Japan Morning Surge-Home Blood Pressure Study

A prolonged P‐wave in electrocardiography (ECG) reflects atrial remodeling and predicts the development of atrial fibrillation (AF). The authors enrolled 810 subjects in the Japan Morning Surge Home Blood Pressure (J‐HOP) study who had ≥1 cardiovascular (CV) risk factor. The duration of P‐wave was automatically analyzed by standard 12‐lead electrocardiogram. Left atrial (LA) enlargement and left ventricular hypertrophy (LVH) were measured on echocardiography. The primary end points were fatal/nonfatal cardiac events: myocardial infarction, sudden death, and hospitalization for heart failure. The maximum P‐wave duration (Pmax) from the 12 leads was selected for analysis. The authors compared four prolonged P‐wave cutoffs (Pmax = 120, 130, 140, 150 ms) and cardiac events. LA diameter and left ventricular mass index (LVMI) were significantly associated with Pmax (r = 0.08, P = .02 and r = 0.17, P < .001, respectively). When the cutoff level was Pmax 120 or 130 ms, prolonged P‐wave was not associated with cardiac events (P = .45 and P = .10), but when a prolonged P‐wave was defined as Pmax ≥ 140 ms (n = 50) or Pmax ≥ 150 ms (n = 19), the patients in those groups had significantly higher incidence of cardiac events than others (P < .001 and P = .03). A Cox proportional hazards model including age, gender, body mass index, smoking, regular drinker, hypertension, dyslipidemia, diabetes, office systolic blood pressure, heart rate, LA enlargement, and LVH revealed that prolonged P‐wave defined as Pmax ≥ 140 ms was independently associated with cardiac events (hazard ratio: 4.23; 95% confidence interval: 1.30–13.77; P = .02). In conclusion, the automatically assessed prolonged P‐wave was associated with cardiac events independently of LA enlargement and LVH in Japanese patients with CV risks.

Index of cardiac-electrophysiological balance and the effects of thrombolytic therapy on the electrocardiogram of patients with pulmonary embolism

OBJECTIVE

Different parameters on electrocardiograms (ECG) have been investigated to predict arrhythmia and mortality in patients with acute pulmonary embolism (APE). The acute effect of thrombolytic therapy (TT) on these parameters has not been investigated yet.

METHODS

We examined the data of 83 patients who were evaluated as high-risk APE and discharged from the hospital after TT. First, the high-risk APE patients' ECGs were compared with healthy control subjects (n = 55). After their admission and 24 hours later, the ECGs of patients with APE were compared. Heart rate, P-wave morphology, QRS duration, QT distance, Tp-e, and the index of cardiac electrophysiological balance (iCEB) were analyzed.

RESULTS

Although P maximum was not different between the groups' ECGs, heart rate, QT, QTc (corrected QT) interval, Tp-e intervals, Tp-e/QT ratio, and P wave dispersion were significantly higher in the APE group ( P values < 0.031). iCEB or iCEBc (corrected iCEB) values were lower in APE group ( P < 0.001). After TT, we determined a decrease in heart rate, Tp-e interval, and Tp-e/QT ratio ( P < 0.001). Although we detected a decrease in the QT and QTc interval and QT dispersion (QTd), QTd had no statistical significance (respectively P -value 0.013, 0.029, and 0.096). The iCEB and iCEBc levels were lower after TT ( P -value was 0.035 and 0.044 respectively).

CONCLUSION

The QT, QTc, Tp-e interval, Tp-e/QTc ratio, iCEB, and iCEBc values significantly decreased after TT. It may be thought that effective TT causes partial improvement in ventricular repolarization in an early period.

Atrial conduction explains the occurrence of the P-wave dispersion phenomenon, but weakly

BACKGROUND

P-wave dispersion (PWD) is believed to be caused by inhomogeneous atrial conduction. This statement, however, is based on limited little solid evidence. The aim of this study was to determine the relationship between atrial conduction and PWD by means of invasive electrophysiological studies.

METHODS

Cross-sectional study in 153 patients with accessory pathways and atrioventricular node reentry tachycardia (AVNRT) undergoing an electrophysiological study. Different atrial conduction times were measured and correlated with PWD.

RESULTS

Only the interatrial (P-DCS) and left intra-atrial conduction times (ΔDCS-PCS) showed a significant correlation with PWD, but this correlation was weak. Multivariate linear regression analysis determined that both P-DCS (β = 0.242; P = .008) and ΔDCS-PCS (β = 0.295; P < .001) are independent predictors of PWD. Performing the multivariate analysis for arrhythmic substrates, it is observed that only ΔDCS-PCS continued to be an independent predictor of PWD. Analysis of the receiver operating characteristic curves showed that regardless of the types of arrhythmic substrates, PWD discriminates significantly, but moderately, to patients with P-DCS and ΔDCS-PCS ≥75 percentile.

CONCLUSIONS

Interatrial and intraleft atrial conduction times were directly and significantly correlated with PWD, but only weakly, and were independent predictors of PWD. In general, PWD correctly discriminates patients with high values in interatrial and intraleft atrial conduction times, but moderately. This is maintained in cases with accessory pathways; however, in patients with AVNRT it only does so for intraleft atrial conduction times. Interatrial and intraleft atrial conduction times weakly explains PWD.

The effect of diclofenac sodium intoxication on the cardiovascular system in rats

OBJECTIVES

Diclofenac sodium (DS) is a widely used nonsteroidal anti-inflammatory drug. Although its high doses are known to cause toxic effects in many tissues including liver and kidney, the effects on the cardiovascular system (CVS) have not been fully elucidated yet. Therefore, this study aimed to investigate the effect of DS on CVS.

METHODS

The Control group did not receive medication; however, a single dose of 240 mg/kg DS was administered orally to the DS group. Electrocardiography (ECG) measurements were performed in all animals before (0thhour) and after (1st,6th,12th,24thhour) intoxication. After 24 h, All animals were sacrificed. Biochemical (malondialdehyde [MDA], and glutathione (GSH), Apelin, Elabela, Meteorin, Endoglin, Keap1, and Nrf2) and histopathological analyzes were performed on heart tissue samples.

RESULTS

ECG results showed that there was a statistically significant increase in QTc, QRS, and heart rate at the 12th and 24th hours in the DS group. The biochemical analysis showed that GSH, Apelin, Keap1, and NRF2 values decreased significantly while Meteorin and Endoglin levels increased in the DS group. When histopathological results were evaluated, distinct lesions were observed in the DS group.

CONCLUSION

In conclusion, high doses of DS intake can cause adverse effects on and damage to CVS.

Evaluation of electrocardiographic markers of cardiac arrhythmic events and their correlation with cardiac iron overload in patients with β-thalassemia major

Iron overload is associated with an increased risk of atrial and ventricular arrhythmias. Data regarding the relationship between electrocardiographic parameters of atrial depolarisation and ventricular repolarisation with cardiac T2* MRI are scarce. Therefore, we aimed to investigate these electrocardiographic parameters and their relationship with cardiac T2* value in patients with β-thalassemia major. In this prospective study, 52 patients with β-thalassemia major and 52 age- and gender-matched healthy patients were included. Electrocardiographic measurements of QT, T peak to end interval, and P wave intervals were performed by one cardiologist who was blind to patients' data. All patients underwent MRI for cardiac T2* evaluation. Cardiac T2* scores less than 20 ms were considered as iron overload. P wave dispersion, QTc interval, and the dispersions of QT and QTc were significantly prolonged in β-thalassemia major patients compared to controls. Interestingly, we found prolonged P waves, QT and T peak to end dispersions, T peak to end intervals, and increased T peak to end/QT ratios in patients with T2* greater than 20 ms. No significant correlation was observed between electrocardiographic parameters and cardiac T2* values and plasma ferritin levels. In conclusion, our study demonstrated that atrial depolarisation and ventricular repolarisation parameters are affected in β-thalassemia major patients and that these parameters are not correlated with cardiac iron load.

Evaluation of early electrocardiographic changes after successful percutaneous stent implantation to isolated coarctation of aorta

BACKGROUND

Coarctation of aorta (CoA) is a congenital obstructive lesion characterized by narrowing of the aorta in which concludes as increase in afterload. Percutaneous stent implantation to CoA is a treatment of choice in older children and adults. Pathology related to CoA mainly caused by increased afterload and left ventricular hypertrophy. Electrocardiographic (ECG) findings are also related to left ventricular hypertrophy (LVH). Evidence shows that, in variety of diseases, the correction of the pathology might normalize ECG findings and ventricular dysfunction related to increase in afterload. Therefore the aim of this study was to compare the pre- and postprocedural ECG findings of the patients who underwent percutaneous intervention for isolated CoA.

METHODS

After exclusion criterion was applied, 30 patients were included into study, retrospectively. ECG records before the procedure and 3 months after the procedure of the patients were evaluated. The parameters related to LVH, ventricular and atrial conduction were evaluated and compared between pre- and post-procedural ECG records.

RESULTS

The findings showed that parameters of atrial conduction including P wave maximum duration (p < 0.001) and p wave dispersion (p < 0.001) were significantly decreased after stent implantation. Additionally, ventricular repolarization parameters including QT duration (p = 0.039), Tpe interval (p < 0.001), Tpe / QT (p = 0.038) and Tpe / QTc (p = 0.003) were significantly decreased after stent implantation. Sokolow-Lyon criteria (p < 0.003) and voltage in selected leads were significantly decreased after intervention.

CONCLUSION

Percutaneous intervention to CoA might regress LVH parameters in ECG and improve atrial and ventricular repolarization in ECG, which might lead to decreased event of atrial and ventricular arrhythmias in patients with isolated CoA.

Heart Rate Variability and Electrocardiographic Parameters Predictive of Arrhythmias in Dogs with Stage IV Chronic Kidney Disease Undergoing Intermittent Haemodialysis

Simple Summary

Monitoring the cardiovascular system plays an important role in this treatment to detect cardiovascular repercussions in dogs with chronic kidney disease (CKD) treated with intermittent haemodialysis (IHD). This study aimed to describe the time-domain and frequency-domain heart rate variability indexes, P and QT dispersions and electrocardiographic alterations observed in dogs with Stage IV CKD undergoing IHD. Animals were divided into three groups, control (10 healthy dogs), clinical treatment (10 dogs with CKD IV submitted to clinical treatment) and IHD (10 dogs with CKD IV submitted to clinical treatment and to dialysis treatment). Clinical, laboratory, HRV indexes and electrocardiographic parameters, as well as QT and P-wave dispersions, were assessed in both CKD groups, prior to and after the end of each clinical treatment/IHD session during the first three sessions. Dogs with CKD IV undergoing IHD had clinically important electrolyte imbalances, electrocardiographic findings, such as the occurrence of arrhythmias and increases in possible predictive parameters for arrhythmias. HRV indexes were better in IHD group, and haemodialysis was more effective at reducing levels of creatinine, urea and phosphorus when compared to intravenous fluid therapy treatment.

Abstract

Intermittent haemodialysis (IHD) is used in dogs with chronic kidney disease (CKD) to reduce azotaemia. Monitoring the cardiovascular system plays an important role in this treatment to detect cardiovascular repercussions. Heart rate variability (HRV) and dispersions of the QT interval and P wave are important markers for mortality risk in humans. This study aimed to describe the time-domain and frequency-domain heart rate variability indexes, P and QT dispersions and electrocardiographic alterations observed in dogs with Stage IV CKD undergoing IHD. Thirty dogs of both sexes, of varying ages and breeds, and weighing between 15 and 30 kg were used. Animals were divided into three groups, control (10 healthy dogs), clinical treatment (10 dogs with CKD IV submitted to clinical treatment twice a week) and IHD (10 dogs with CKD IV submitted to clinical treatment and to dialysis treatment with intermittent haemodialysis twice a week). Clinical, laboratory, HRV indexes and electrocardiographic parameters, as well as QT and P-wave dispersions, were assessed in both CKD groups, prior to and after the end of each clinical treatment/IHD session during the first three sessions. Dogs with CKD IV undergoing IHD had clinically important electrolyte imbalances, primarily hypokalaemia, and pertinent electrocardiographic findings, such as the occurrence of supraventricular arrhythmias and increases in possible predictive parameters for arrhythmias. In spite of these observations, HRV indexes were better in animals undergoing haemodialysis and, in addition, IHD was more effective at reducing levels of creatinine, urea and phosphorus compared to intravenous fluid therapy treatment.

The effect of P wave indices on new onset atrial fibrillation after trans-catheter aortic valve replacement

OBJECTIVES

Data is scarce regarding the relation between P wave indices and new onset atrial fibrillation (NOAF) after trans-catheter aortic valve replacement (TAVR).

AIMS

The present study aimed to find out certain characteristics of P wave that may predict NOAF after TAVR procedure.

METHOD

Patients with severe calcific aortic stenosis who had undergone TAVR procedure between 2013 and 2019 in two centers were investigated. P wave abnormalities that have been resumed to reflect impaired atrial conduction; partial and advanced inter atrial block (IAB), P-wave terminal force in lead V1, P wave dispersion, reduced amplitude of P- wave in lead I, P wave peak time in D2 and V1 were evaluated on pre- procedural 12 derivation surface electrocardiography (ECG). The relationship between these parameters and incidence of NOAF during index hospitalization was evaluated.

RESULTS

A total of 227 consecutive patients (median age 79 [74-83]; 134 [59%] female) were included in the study. NOAF occurred in 46 (20.3%) patients. P wave duration, P wave dispersion, number of patients with partial and advanced IAB, left atrium diameter, STS score were higher in NOAF patients. Use of general anesthesia and history of prior open heart surgery were also more frequent in NOAF group. In multivariable logistic regression analysis; advanced IAB (OR 6.413 [2.555-16.095] p < 0.01), P wave dispersion (OR 3.544 [1.431-8.780] p = 0.006) and use of general anesthesia (OR 2.736 [1.225-6.109] p = 0.014) were independent predictors of NOAF.

CONCLUSION

Among P wave abnormalities evaluated on pre-procedural 12-derivation surface ECG, advanced IAB and P wave dispersion may predict NOAF after TAVR procedure.

A Review of Atrial Fibrillation Detection Methods as a Service

Atrial Fibrillation (AF) is a common heart arrhythmia that often goes undetected, and even if it is detected, managing the condition may be challenging. In this paper, we review how the RR interval and Electrocardiogram (ECG) signals, incorporated into a monitoring system, can be useful to track AF events. Were such an automated system to be implemented, it could be used to help manage AF and thereby reduce patient morbidity and mortality. The main impetus behind the idea of developing a service is that a greater data volume analyzed can lead to better patient outcomes. Based on the literature review, which we present herein, we introduce the methods that can be used to detect AF efficiently and automatically via the RR interval and ECG signals. A cardiovascular disease monitoring service that incorporates one or multiple of these detection methods could extend event observation to all times, and could therefore become useful to establish any AF occurrence. The development of an automated and efficient method that monitors AF in real time would likely become a key component for meeting public health goals regarding the reduction of fatalities caused by the disease. Yet, at present, significant technological and regulatory obstacles remain, which prevent the development of any proposed system. Establishment of the scientific foundation for monitoring is important to provide effective service to patients and healthcare professionals.

A Deep Learning Method to Detect Atrial Fibrillation Based on Continuous Wavelet Transform

Atrial fibrillation (AF) is one of the most common arrhythmias. The automatic AF detection is of great clinical significance but at the same time it remains a big problem to researchers. In this study, a novel deep learning method to detect AF was proposed. For a 10 s length single lead electrocardiogram (ECG) signal, the continuous wavelet transform (CWT) was used to obtain the wavelet coefficient matrix, and then a convolutional neural network (CNN) with a specific architecture was trained to discriminate the rhythm of the signal. The ECG data in multiple databases were divided into 4 classes according to the rhythm annotation: normal sinus rhythm (NSR), atrial fibrillation (AF), other types of arrhythmia except AF (OTHER), and noise signal (NOISE). The method was evaluated using three different wavelet bases. The experiment showed promising results when using a Morlet wavelet, with an overall accuracy of 97.56%, an average sensitivity of 97.56%, an average specificity of 99.19%. Besides, the area under curve (AUC) value is 0.9983, which showed that the proposed method was effective for detecting AF.

The association of inflammatory markers and echocardiographic parameters in Behçet's disease

Background: The main objective of the current study is to find out if any association exists between specific inflammatory markers such as homocysteine (Hcy) and pentraxin-3 (PTX-3) and cardiac involvement determined by means of echocardiographic parameters in patients with Behçet disease (BD).Methods: From January 2011 to January 2012, a total of 62 Behçet's patients were enrolled in the study. Thirty-two healthy subjects constituted the control group. The diagnosis of BD was made as proposed by International Study Group of BD.Results: The mean PTX-3, Hcy, and C-reactive protein levels were significantly higher in patients with BD compared to the control group. The electromechanical delay (EMD) times were found to be prolonged in patients with BD. Also, the aortic stiffness index (SI) and elastic modulus (Ep) were significantly higher, while the aortic dispensibility was significantly lower in patients with BD. The left atrial volume, left atrial volume index, E/A ratio, E/E' septal, IRight-EMD, PA'-ML, PA'-MS, PA'-TL, SI, and Ep were correlated with PTX-3 levels. In addition, the E/A, PA'-ML, PA'-MS, SI, and Ep displayed correlation with Hcy levels in patients having BD.Conclusion: Elevated levels of PTX-3 and Hcy were found to be correlated with cardiac involvement determined by means of echocardiographic parameters in patients with BD.

P wave dispersion in assessment of dysrhythmia risk in patients with secundum type atrial septal defect and the effect of transcatheter or surgical closure

Atrial dysrhythmia is an important cause of mortality and morbidity in patients with atrial septal defect. Increased P wave duration can predict the risk of atrial dysrhythmia. The aim of this study is to evaluate the risk of atrial dysrhythmia by measuring P wave dispersion, and to observe the effect of surgical and transcatheter closure. Sixty-one patients and 30 controls were investigated. In patient group, before and after closure and in control group at the time of presentation, 12-lead electrocardiography records were evaluated. P wave duration and amplitude, P wave axis, PR interval, P wave dispersion, QRS axis, corrected QT interval, and QT dispersion were calculated. The measurements in patient and control groups, measurements before and after closure, and measurements of surgical and transcatheter group were compared. There were 27 patients in surgical group and 34 patients in transcatheter group. In patient group, signs of right heart volume overload were apparent but there was no significant difference in terms of P wave dispersion between two groups. We compared patient group in itself and found that while the use of medication, cardiothoracic index, ratio of right ventricular dilation, and paradoxical movement in interventricular septum were increased, mean age of closure was younger in surgical group. While P wave dispersion decreased in transcatheter group after closure, it increased in surgical group (p = 0.021). In conclusion, atrial septal defects may cause atrial repolarisation abnormalities and this effect persists even after surgical closure. Transcatheter closure in childhood may decrease dysrhythmia risk in long-term follow-up.

P Wave Peak Time for Predicting an Increased Left Atrial Volume Index in Hemodialysis Patients

OBJECTIVE

An increased left atrial volume index (LAVI) is related to increased mortality in hemodialysis patients. In the present study, we evaluated the association between the LAVI and the P wave peak time (PWPT), a newly introduced electrocardiographic parameter, in hemodialysis patients.

METHODS

The study population was made up of 79 hemodialysis patients with a mean age of 53 ± 18 years (55.7% were males). These patients were divided into a normal LAVI (≤28 mL/m2) group (n = 45) and an increased LAVI (>28 mL/m2) group (n = 34). The demographic, clinical, laboratory, echocardiographic, and electrocardiographic variables of the groups were compared.

RESULTS

The P wave terminal force from lead V1, P wave dispersion and PWPTs obtained from leads V1 and D2 (PWPTD2) were significantly higher in the patients with increased LAVIs. In multivariable analysis, only the PWPTD2was an independent predictor of an increased LAVI (odds ratio = 1.117, 95% CI = 1.052-1.185, p < 0.001). The receiver-operating characteristic curve analysis showed that the best PWPTD2 cutoff value for predicting an increased LAVI was 60 ms, with a sensitivity of 76.5% and a specificity of 66.7% (area under the curve = 0.736, 95% CI = 0.625-0.829, p < 0.001).

CONCLUSION

This study showed that a prolonged PWPTD2 was independently associated with an increased LAVI in hemodialysis patients. Therefore, measuring the PWPTD2 duration on an electrocardiogram may help define high-risk hemodialysis patients with increased LAVIs.

Applied Veterinary Informatics: Development of a Semantic and Domain-Specific Method to Construct a Canine Data Repository

Animals are used to study the pathogenesis of various human diseases, but typically as animal models with induced disease. However, companion animals develop disease spontaneously in a way that mirrors disease development in humans. The purpose of this study is to develop a semantic and domain-specific method to enable construction of a data repository from a veterinary hospital that would be useful for future studies. We developed a two-phase method that combines semantic and domain-specific approaches to construct a canine data repository of clinical data collected during routine care at the Matthew J Ryan Veterinary Hospital of the University of Pennsylvania (PennVet). Our framework consists of two phases: (1) a semantic data-cleaning phase and (2) a domain-specific data-cleaning phase. We validated our data repository using a gold standard of known breed predispositions for certain diseases (i.e., mitral valve disease, atrial fibrillation and osteosarcoma). Our two-phase method allowed us to maximize data retention (99.8% of data retained), while ensuring the quality of our result. Our final population contained 84,405 dogs treated between 2000 and 2017 from 194 distinct dog breeds. We observed the expected breed associations with mitral valve disease, atrial fibrillation, and osteosarcoma (P < 0.05) after adjusting for multiple comparisons. Precision ranged from 60.0 to 83.3 for the three diseases (avg. 74.2) and recall ranged from 31.6 to 83.3 (avg. 53.3). Our study describes a two-phase method to construct a clinical data repository using canine data obtained during routine clinical care at a veterinary hospital.

Effects of angiotensin receptor neprilysin inhibition on P-wave dispersion in heart failure with reduced ejection fraction

BACKGROUND

Angiotensin receptor neprilysin inhibitors (ARNI; sacubitril/valsartan combination) decrease morbidity and mortality in heart failure with reduced ejection fraction (HFrEF). Increased P‑wave duration and P‑wave dispersion (P_d) reflect prolongation of atrial conduction and correlate with atrial fibrillation. Here, we aimed to assess the effects of switching from valsartan to ARNI treatment on the basis of P‑wave indices.

METHODS

A total of 28 patients with HFrEF (mean age, 64.8 ± 10.6 years; 18 males, 78.6% ischemic etiology) were included. All patients had New York Heart Association functional class II-III, left ventricular ejection fraction ≤35%, and had been switched from valsartan to ARNI treatment. Standard 12-lead electrocardiograms from patients on valsartan treatment and electrocardiograms 1 month after ARNI treatment were analyzed; heart rate, maximum P‑wave duration (P_max), minimum P‑wave duration (P_min), and P_d were calculated. Minnesota Living with Heart Failure Questionnaire (MLWHFQ) scores and N‑terminal pro-brain natriuretic peptide (NT-proBNP) values were recorded.

RESULTS

The P_max (135.6 ± 32.1 ms vs. 116.1 ± 14.1 ms, p = 0.041) and P_d (33.6 ± 7.9 vs. 28.6 ± 5.3, p = 0.006) values were significantly reduced after ARNI treatment. Furthermore, ARNI treatment was associated with an improvement in MLWHFQ scores (31.2 ± 6.2 ms vs. 23.2 ± 7.0 ms, p < 0.001) and with a reduction in NT-proBNP values (1827.3 ± 1287.3 pg/ml vs. 1074.4 ± 692.3 pg/ml, p < 0.001). There were moderately positive correlations between the reduction in P_d and the improvement in MLWHFQ scores (r = 0.408, p = 0.031) and the reduction in NT-proBNP values (r = 0.499, p = 0.007) CONCLUSION: Switching to ARNI treatment alters P_d and P_max favorably in patients with HFrEF. The reduction in atrial inhomogeneous conduction assessed by P_d was correlated with clinical improvement and reduced NT-proBNP levels in patients with HFrEF.

Symbolic Recurrence Analysis of RR Interval to Detect Atrial Fibrillation

Atrial fibrillation (AF) is a sustained cardiac arrhythmia associated with stroke, heart failure, and related health conditions. Though easily diagnosed upon presentation in a clinical setting, the transient and/or intermittent emergence of AF episodes present diagnostic and clinical monitoring challenges that would ideally be met with automated ambulatory monitoring and detection. Current approaches to address these needs, commonly available both in smartphone applications and dedicated technologies, combine electrocardiogram (ECG) sensors with predictive algorithms to detect AF. These methods typically require extensive preprocessing, preliminary signal analysis, and the integration of a wide and complex array of features for the detection of AF events, and are consequently vulnerable to over-fitting. In this paper, we introduce the application of symbolic recurrence quantification analysis (SRQA) for the study of ECG signals and detection of AF events, which requires minimal pre-processing and allows the construction of highly accurate predictive algorithms from relatively few features. In addition, this approach is robust against commonly-encountered signal processing challenges that are expected in ambulatory monitoring contexts, including noisy and non-stationary data. We demonstrate the application of this method to yield a highly accurate predictive algorithm, which at optimal threshold values is 97.9% sensitive, 97.6% specific, and 97.7% accurate in classifying AF signals. To confirm the robust generalizability of this approach, we further evaluated its performance in the implementation of a 10-fold cross-validation paradigm, yielding 97.4% accuracy. In sum, these findings emphasize the robust utility of SRQA for the analysis of ECG signals and detection of AF. To the best of our knowledge, the proposed model is the first to incorporate symbolic analysis for AF beat detection.

Optimized Electrode Locations for Wearable Single-Lead ECG Monitoring Devices: A Case Study Using WFEES Modules based on the LANS Method

Body surface potential mapping (BSPM) is a valuable tool for research regarding electrocardiograms (ECG). However, the BSPM system is limited by its large number of electrodes and wires, long installation time, and high computational complexity. In this paper, we designed a wearable four-electrode electrocardiogram-sensor (WFEES) module that measures six-channel ECGs simultaneously for ECG investigation. To reduce the testing lead number and the measurement complexity, we further proposed a method, the layered (A, N) square-based (LANS) method, to optimize the ECG acquisition and analysis process using WFEES modules for different applications. Moreover, we presented a case study of electrode location optimization for wearable single-lead ECG monitoring devices using WFEES modules with the LANS method. In this study, 102 sets of single-lead ECG data from 19 healthy subjects were analyzed. The signal-to-noise ratio of ECG, as well as the mean and coefficient of variation of QRS amplitude, was derived among different channels to determine the optimal electrode locations. The results showed that a single-lead electrode pair should be placed on the left chest above the electrode location of standard precordial leads V1 to V4. Additionally, the best orientation was the principal diagonal as the direction of the heart's electrical axis.

The Pattern of Tpeak-Tend Interval and QTdis, and Pdis in Children with Brucellosis

OBJECTIVE

To investigate the effect of inflammation on the conducting system of the heart in patients diagnosed with brucellosis.

METHODS

A total of 42 patients diagnosed with brucellosis and 39 age and sex-matched healthy children were enrolled into the study. Pre- and post-treatment electrocardiographic parameters in brucellosis and control group were recorded from an electrocardiogram for each patient.

RESULTS

The results indicated that the parameters including Pmax, Pdis, QTmax, QTdis, QTcdis, Tp-edis interval and Tp-emax/QTmax and Tp-emax/QTcmax ratios, which are known to be key indicators for the prediction of severe atrial or ventricular arrhythmia and sudden cardiac death and also important parameters used as the indicators for the non-invasive evaluation of the transmural heterogeneity were significantly longer in the study group compared with the control group (p < 0.05).

CONCLUSION

In this study, it was determined that the brucella disease had more cardiac involvement than thought, and this was more in the subclinical form of cardiac involvement.

Intra-Atrial Block: Definition and Relationship to Atrial Fibrillation and Other Adverse Outcomes

In 1916, Bachmann first reported on the inter-auricular time interval. However relatively little attention was paid to this ECG measurement for decades. Then, in 1956, Samuel Bradley and Henry JJ Marriott reported on intra-atrial block (IAB) in 4,500 ECGs.As defined by them, IAB was a P wave duration of 0.12 sec or longer. Since that time, others have defined IAB as 0.11 sec or longer or 0.12 sec or longer. Several authors have suggested subcategories, such as first-, second-, and third-degree patterns and some have defined specific intra-atrial and inter-atrial pathways. These are of electrocardiographic interest but have not been substantiated as related to different clinical outcomes. Many disorders have been associated with IAB. More importantly, however, IAB has been associated with several adverse outcomes, including sinus node dysfunction, atrial tachyarrhythmias - especially atrial fibrillation, thromboembolic events, and increased mortality. This brief review will detail the above to emphasize to ECG readers the importance of not overlooking IAB in their interpretations.

P wave indices, heart rate variability and anthropometry in a healthy South Asian population

Background

South Asians have a low prevalence of atrial fibrillation (AF) in comparison with White Europeans despite a higher burden of hypertension, diabetes mellitus and coronary artery disease. The reason for this disparity is unclear but may relate to electrophysiological or structural differences within the atria or variations in autonomic function. We aimed to assess these areas using a range of non-invasive cardiac investigations.

Methods

A prospective cohort study was performed on 200 South Asian and 200 Caucasian healthy volunteers aged 18–40 years. All subjects underwent electrocardiography (ECG), echocardiography and anthropometric measurements. Eighty subjects in each cohort underwent 24 hour ambulatory ECG and fifty subjects in each cohort underwent exercise testing.

Results

Compared with White Europeans, South Asians were of a smaller height with lower lean body mass and smaller left atrial size. They had reduced P wave dispersion and P wave terminal force in lead V₁. South Asians had a lower burden of supraventricular ectopy. They had a higher mean heart rate and South Asian males had lower heart rate variability, suggestive of sympathetic predominance. Exercise capacity was lower in South Asians.

Conclusions

South Asians have differences in left atrial size, P wave indices, burden of supraventricular ectopy, heart rate, heart rate variability and anthropometric measurements. These differences may relate to variations in atrial morphology, atrial electrophysiology and autonomic function and might help to explain why South Asians are less susceptible to developing AF.

Immediate And Long Term Effects Of Percutaneous Mitral Balloon Valvuloplasty On Atrial Conduction Velocities In Patients With Mitral Stenosis

Background

P-wave dispersion (PWD) is an electrocardiographic (ECG) marker of nonuniform and heterogeneous atrial conduction with ECG leads of different orientation. The aim of our study was to investigate the immediate and long term effects of successful percutaneous mitral balloon valvuloplasty (PMBV) on PWD in severe rheumatic MS patients and to analyse the restenosis, atrial fibrillation (AF) and redo balloon valvuloplasty rate.

Methods

We enrolled 41 consecutive MS patients with sinus rhythm who underwent PMBV. A 12-lead ECG and transthoracic echocardiography were performed for each patient one day before, within 72 hours after the procedure and followed up by clinical visit at a mean of 5,57±1,46 (3-8) year.The mean patient age was 44.1±10.86 years.

Results

Pmax 1(pre PMBV) and PWD 1(pre PMBV) decreased 1-3 days after PMBV. MVA improved immediately after the procedure; but lately the mean MVA decreased significantly indicating the initiation of restenosis. Composite endpoints were associated with LA 1 (p = 0.02), MVA 2 (1-3 days after PMBV) (p= 0.019), mean gradient 2 (p= 0.028), PWD 3 (3 years after PMBV) (p < 0.001) and Pmax 3 (3 years after PMBV) (<0,001). AF incidence was associated with PWD 2 (p=0,019) and PWD 3 (p=0,010). There was 14 composite endpoint on follow up and at multivariate analysis PWD 3 was identified as an independent predictor of the composite endpoint (p=0.048, hazard ratio=1.36, 95% confidence interval (CI): 1,002-1.867).

Conclusions

This study has demonstrated that Pmax and PWD significantly decreased within 3 days after PMBV. Furthermore, long term PWD was associated with AF and identified as an independent predictor of the composite endpoint.

Biomarkers Associated with Atrial Fibrosis and Remodeling

Atrial fibrillation is the most common rhythm disturbance encountered in clinical practice. Although often considered as solely arrhythmic in nature, current evidence has established that atrial myopathy constitutes both the substrate and the outcome of atrial fibrillation, thus initiating a vicious, self-perpetuating cycle. This myopathy is triggered by stress-induced (including pressure/volume overload, inflammation, oxidative stress) responses of atrial tissue, which in the long term become maladaptive, and combine elements of both structural, especially fibrosis, and electrical remodeling, with contemporary approaches yielding potentially useful biomarkers of these processes. Biomarker value becomes greater given the fact that they can both predict atrial fibrillation occurrence and treatment outcome. This mini-review will focus on the biomarkers of atrial remodeling (both electrical and structural) and fibrosis that have been validated in human studies, including biochemical, histological and imaging approaches.

Biomarkers of Atrial Fibrillation in Hypertension

Background:

Atrial fibrillation (AF) is the most frequently encountered cardiac arrhythmia globally and substantially increases the risk for thromboembolic disease. Albeit, 20% of all cases of AF remain undiagnosed. On the other hand, hypertension amplifies the risk for both AF occurrences through hemodynamic and non-hemodynamic mechanisms and cerebrovascular ischemia. Under this prism, prompt diagnosis of undetected AF in hypertensive patients is of pivotal importance.

Method:

We conducted a review of the literature for studies with biomarkers that could be used in AF diagnosis as well as in predicting the transition of paroxysmal AF to sustained AF, especially in hypertensive patients.

Results:

Potential biomarkers for AF can be broadly categorized into electrophysiological, morphological and molecular markers that reflect the underlying mechanisms of adverse atrial remodeling. We focused on P-wave duration and dispersion as electrophysiological markers, and left atrial (LA) and LA appendage size, atrial fibrosis, left ventricular hypertrophy and aortic stiffness as structural biomarkers, respectively. The heterogeneous group of molecular biomarkers of AF encompasses products of the neurohormonal cascade, including NT-pro BNP, BNP, MR-pro ANP, polymorphisms of the ACE and convertases such as corin and furin. In addition, soluble biomarkers of inflammation (i.e. CRP, IL-6) and fibrosis (i.e. TGF-1 and matrix metalloproteinases) were assessed for predicting AF.

Conclusion:

The reviewed individual biomarkers might be a valuable addition to current diagnostic tools but the ideal candidate is expected to combine multiple indices of atrial remodeling in order to effectively detect both AF and adverse characteristics of high risk patients with hypertension.

Predictive value of P-wave and QT interval dispersion in children with congenital heart disease and pulmonary arterial hypertension for the occurrence of arrhythmias

OBJECTIVES

To evaluate P-wave dispersion (PWD) and QT dispersion (QTd) in children with congenital heart disease and pulmonary arterial hypertension (PAH-CHD) and to investigate the predictive value of both PWD and QTd for prediction of arrhythmias in such children.

MATERIALS AND METHODS

We included 40 children with PAH-CHD as Group I. Forty other children with CHD and no PAH were included as Group II. Forty healthy children of matched age and sex served as a Control group. Electrocardiography was performed to determine PWD and QTd. Furthermore, 24-hour Holter monitoring was performed to detect the presence of arrhythmias. Echocardiographic evaluation was also performed.

RESULTS

QTd and PWD were significantly higher in Group I than in Group II and Control group. A significant positive correlation was present between both QTd and PWD and mean pulmonary artery pressure, right ventricular diameter, pulmonary vascular resistance (PVR), and PVR to systemic vascular resistance ratio. QTd showed 93% sensitivity, 80% specificity, and 85% accuracy for prediction of occurrence of arrhythmias in patients with PAH-CHD at a cutoff point of 61 ms, whereas PWD showed 87% sensitivity, 80% specificity, and 85% accuracy for prediction of arrhythmias at a cutoff point of 32.5 ms in such patients. Logistic regression analysis showed that both QTd and PWD were good predictors for the occurrence of arrhythmias in children with PAH-CHD (p = 0.003 and p = 0.01, respectively).

CONCLUSIONS

PWD and QTd were good predictors for the occurrence of various arrhythmias in children with PAH-CHD.

Increased QT and P-wave dispersion during attack-free period in pediatric patients with migraine attacks

INTRODUCTION

Migraine is a common neurovascular disease characterised with recurrent attacks by pain-free periods. It has been suggested that both sympathetic and parasympathetic dysfunctions play a role in its pathophysiology.

AIM

The aim of our study was to investigate the ECG changes during attack-free period in children with migraine, in terms of QTc interval, QTc, and P-wave dispersion to evaluate the autonomic nervous system disturbance.

METHODS

Sixty children who were diagnosed with migraine were included as patient group and 50 healthy, age- and body mass index-matched children who were examined for innocent murmur were included as control group. The patients' routine ECG records were screened from the outpatient clinic files. The durations of P-wave, QT, and QTc intervals and dispersion values and heart rates (beats/minute) were compared between the patient and control groups.

RESULTS

P maximum and P dispersion were significantly higher, and P minimum was significantly lower in the migraine group compared with the control group. QT-QTc maximum and QT-QTc dispersion were significantly higher and QT-QTc minimum was significantly lower in the migraine group compared with the control group.

CONCLUSION

According to our findings, although migraine patients were asymptomatic and no arrhythmia was detected in the surface ECG, sympathovagal balance in the sympathetic system, which may be disrupted in favour of the sympathetic system, should continue even in the attack-free period, and we should be careful in terms of serious arrhythmias that may develop in these patients.

P-wave vector magnitude predicts recurrence of atrial fibrillation after catheter ablation in patients with persistent atrial fibrillation

BACKGROUND

The predictive efficacies of parameters related to P-wave amplitude (PWA) for atrial fibrillation (AF) recurrence after catheter ablation are unclear.

METHODS

We measured multiple PWA parameters using an automated system in 126 consecutive patients with persistent and long-standing persistent AF who underwent catheter ablation. The relationships between AF recurrence and various PWA parameters were examined, including the association with P-wave vector magnitude (calculated as the square root of the sum of lead II PWA squared, lead V6 PWA squared, and a one-half lead V2 PWA squared).

RESULTS

Atrial fibrillation did not recur in 87 patients (69%) during 32 ± 15 months of follow-up. The maximum PWA, mean PWA, and P-wave vector magnitude were lower in patients with AF recurrence than those without (maximum PWA, 0.14 ± 0.05 mV vs. 0.16 ± 0.05 mV, p = 0.017; mean PWA, 0.05 ± 0.02 mV vs. 0.06 ± 0.02 mV, p = 0.003; P-wave vector magnitude, 0.09 ± 0.03 mV vs. 0.13 ± 0.04 mV, p < 0.001). A multivariate Cox regression analysis revealed that the predictive ability of P-wave vector magnitude for AF recurrence was independent of other clinical properties (hazard ratio: 0.153, 95% confidence interval: 0.046-0.507, p = 0.002). Atrial fibrillation freedom rates of patients with P-wave vector magnitude higher and lower than 0.13 mV were 93% and 57%, respectively. P-wave vector magnitude weakly correlated with left atrial dimension (R = -0.280, p = 0.004).

CONCLUSIONS

P-wave vector magnitude can predict AF recurrence after catheter ablation in patients with persistent AF.

Atrioventricular block can be used as a risk predictor of clinical atrial fibrillation

Background

Atrial fibrillation (AF) is the most common cardiac arrhythmia, with its incidence making up nearly one‐third of all hospital admissions. Atrioventricular block (AVB) is a conduction abnormality along the atrioventricular node or the His‐Purkinje system. The relationship between atrioventricular conduction block and AF is controversial.

Hypothesis

This study is designed to observe whether there is a correlation between AVB and AF, and which type of AVB has the most obvious correlation with AF.

Methods

This study retrospectively reviewed 1345 patients. We classified the AVB according to the AVB classification criteria. One hundred and two patients were excluded, and the final total sample size was 1243 patients, including 679 patients in the AF group (378, 55.7% males) and 564 patients in the non‐AF group (287, 50.8% males). AF group and non‐AF group were compared to observe the relationship between AVB and AF.

Results

The I AVB have a relative statistical risk of 1.927 (95% confidence interval [CI]: 1.160‐3.203, P < 0.05) with the occurrence of AF. II AVB occupied the largest proportion, accounting for 67 cases (9.87%), and the statistical risk of II AVB in AF is 16.845 (95% CI: 6.099‐46.524, P < 0.000). III AVB has a comparative statistical risk of 17.599 (95% CI: 4.212‐73.541, P < 0.000).

Conclusions

The three types of AVB in the AF group were significantly higher than that in the non‐AF group. II AVB has the highest incidence rate compared with other types of AVB in the AF group. AVB can be used as a risk factor for AF occurrence.

Evaluating the effect of nasal septoplasty on atrial electromechanical features

BACKGROUND

Recent studies have demonstrated that right ventricular (RV) dysfunction and increased pulmonary artery pressure may be frequent in patients with upper airway obstruction. In this study, we evaluated atrial conduction delays in patients with upper airway obstruction secondary to nasal septum deviation (NSD).

METHODS

A total of 32 patients with upper airway obstruction secondary to NSD undergoing a septoplasty procedure were enrolled in this study. Preoperative electrocardiography and transthoracic echocardiography were performed in all patients who underwent surgery. The mean pulmonary artery pressure (mPAP) and atrial conduction time (ACT) were recorded before and 6 months after the surgical procedures.

RESULTS

The PAP was significantly lower postoperatively than preoperatively (20.75 ± 4.83 vs. 24.68 ± 5.26; P < 0.001). The postoperative Electromechanical Delay of Mitral septal wall (EMD-MS) value was significantly lower than that preoperatively (46.20 ± 8.5 vs. 40.5 ± 9.9; P < 0.001). The postoperative Electromechanical Delay of Mitral lateral wall (EMD-ML) value decreased significantly compared to the preoperative period (46.3 ± 7.4 vs. 40.6 ± 9.3; P < 0.001). The postoperative Electromechanical Delay of Tricuspit lateral wall (EMD-TL) value was significantly lower than that preoperatively (43.8 ± 7.0 vs. 38.1 ± 9.1; P < 0.001). There was no significant change in pre- or postoperative measurements of inter- and intra-atrial conduction delays.

CONCLUSIONS

We demonstrated that upper airway obstruction secondary to NSD causes a significant increase in mPAP and a significant delay in ACT, which improved after nasal septoplasty. According to these results, we conclude that upper airway obstruction may be an important risk factor for pulmonary arterial hypertension, RV dysfunction, and atrial arrhythmias, especially in unoperated cases.

QT interval and P wave dispersion in slow coronary flow phenomenon

BACKGROUND

Slow coronary flow (SCF) phenomenon is an angiographic finding which is defined as slow contrast passage through coronary arteries which may predispose patients to serious cardiac complications such as fatal arrhythmias. P-wave and QT-interval dispersion are electrocardiographic findings which are related to atrial fibrillation and ventricular tachyarrhythmias. In the present study, the relation between SCF and presence of P-wave and QT-interval dispersion in electrocardiography has been evaluated.

METHODS

47 patients with normal coronary arteries and SCF and 40 patients with normal coronary artery flow without SCF were enrolled in this case control study. Standard electrocardiogram (ECG) was analyzed for P-wave and QT-interval dispersion. SCF was identified in normal coronary vessels by use of Thrombolysis in Myocardial Infarction (TIMI) frame count (TFC) method (TFC > 27). Corrected TIMI frame count (CTFC) of coronary vessels as well as mean CTFC along with QT-interval and P-wave dispersion were compared between 2 groups. The study data were analyzed by SPSS software and P value less than 0.050 was considered to be significant.

RESULTS

QT-interval [76.17 (35.23) ms versus 39.25 (19.26) ms] and P-wave [39.74 (17.48) ms versus 19.50 (8.54) ms] dispersion were significantly higher among patients with SCF phenomenon (P < 0.050). In addition, there was a positive significant linear correlation between TFC and P-wave and QT-dispersion (r = 0.857, r = 0.861, respectively, P < 0.050).

CONCLUSION

According to the results, increasing TFC among patients with SCF will result in P wave and QT interval dispersion and therefore this finding can be considered as an indicative marker for cardiac events.

Protecting the esophagus from thermal injury during radiofrequency ablation with an esophageal cooling device

PURPOSE

We sought to quantify the capabilities of a commercially available cooling device to protect the esophagus from RF injury in an animal model and develop a mathematical model to describe the system and provide a framework from which to advance this technology.

METHODS

A series of ablations (10 W, duration 30-45 seconds) were performed directly on exposed swine esophagus. Control ablations were performed with static 37°C water, and treatment ablations were performed with water (range 5°C-37°C) circulating within the device. Mucosal lesions were evaluated visually and with target tissue histology. A mathematical model was then developed and compared against the experimental data.

RESULTS

All 23 ablations (100%) performed under control conditions produced visible external esophageal lesions; 12 of these (52%) were transmural. Under treatment conditions, only 5 of 23 ablations (22%) produced visible external lesions; none (0%) were transmural. Transmurality of lesions decreased as circulating water temperature decreased, with absolute reduction ranging from 5.1% with the use of 37°C water (p=0.7) to 44.5% with the use of 5°C water (p<0.001). Comparison to the mathematical model showed an R^2 of 0.75, representing good agreement.

CONCLUSION

Under worst-case conditions, with RF energy applied directly to the adventitial side of the esophagus, internal esophageal cooling with an esophageal cooling device provides significant protective effect from thermal injury. A mathematical model of the process provides a means to further investigate this approach to preventing esophageal injury during RF ablation and can serve to guide ongoing clinical investigations currently in progress.

Coefficient of variation of P-wave duration measured using an automated measurement system predicts recurrence of atrial fibrillation

BACKGROUND

P-wave parameters representing atrial conduction heterogeneity are associated with recurrence of atrial fibrillation (AF) after catheter ablation. However, intra- and inter-observer variabilities are unavoidable during manual measurement of P-wave parameters.

METHODS

The study included 201 patients with paroxysmal AF who underwent catheter ablation. P-wave duration (PWD) was measured using a computerized automated measurement system with a surface 12-lead electrocardiogram. The coefficient of variation of PWD (CV-PWD) across the 12 electrocardiographic leads was determined as an index of atrial conduction heterogeneity.

RESULTS

AF did not recur in 157 (78%) patients during a 12-month follow-up period. CV-PWD assessed before catheter ablation was not different between the AF-recurrent and AF-free groups (0.069 ± 0.023 vs. 0.069 ± 0.023, P = 0.090). However, CV-PWD measured after catheter ablation was significantly larger in the AF-recurrent group than in the AF-free group (0.090 ± 0.037 vs. 0.073 ± 0.024, P < 0.001). In receiver operating curve analysis, CV-PWD assessed after catheter ablation achieved an area under the curve of 0.702; the sensitivity, specificity, and positive and negative predictive values were 68%, 69%, 38%, and 88%, respectively, for the cut-off value of 0.080. During the follow-up period, AF freedom rates of high CV-PWD patients (CV-PWD ≥ 0.080) and low CV-PWD patients (CV-PWD < 0.080) were 65% and 88%, respectively.

CONCLUSIONS

CV-PWD determined using an automated measurement system was associated with AF recurrence after catheter ablation in patients with paroxysmal AF.

Association of vitamin D deficiency with electrocardiographic markers of left atrial abnormalities

OBJECTIVE

Electrocardiographic markers of left atrial (LA) abnormalities are linked to increased risk of cardiovascular disease (CVD). We examined the relationship of vitamin D deficiency with prolonged P wave duration and PR interval as markers of LA abnormalities.

METHODS

This analysis included 5,894 participants (58.12 ± 12.9 years; 54.7% women; 49.8% non-Hispanic Whites) without clinical CVD from NHANES III. A multivariable logistic regression model was used to examine the association of vitamin D categories (<20 ng/ml, 20-29 ng/ml and >30 ng/ml (reference) with prolonged P wave duration (≥120 ms) and PR interval (≥200 ms).

RESULTS

There was an incremental increase in the prevalence of prolonged P wave duration and PR interval across vitamin D categories with the highest prevalence in study participants with vitamin D levels <20 ng/ml, followed by 20-29 ng/ml and then >30 ng/ml (trend p-value < 0.0001). Vitamin D deficiency (<20 ng/ml) was associated with prolonged P wave duration (OR [95% CI]: 1.22 [1.03-1.45], p = 0.02) and prolonged PR interval (OR [95% CI]: 1.48 [1.12-1.97], p = 0.006) in multivariable logistic regression models adjusted for demographics, CVD risk factors, and other potential confounders. These associations were consistent across subgroups stratified by age, sex, and race.

CONCLUSIONS

Vitamin D deficiency is associated with an increased risk of LA abnormalities. This association elucidates an alternate pathway through which vitamin D deficiency may increase CVD risk. Whether vitamin D supplementation would improve LA abnormalities requires further investigation.

P-wave dispersion as a simple tool for screening childhood obstructive sleep apnea syndrome

INTRODUCTION

The gold standard for the diagnosis of childhood obstructive sleep apnea syndrome (OSAS) diagnosis is polysomnography; however, electrocardiography (ECG) may provide a simpler alternative. P-wave dispersion (PWD), the difference between the maximum and minimum P-wave duration measured by 12-lead ECG, is increased in adult OSAS but has not been researched in childhood OSAS. The aims of this study were to determine the PWD and cut-off value for the diagnosis of childhood OSAS and its association with severity.

METHODS

A total of 77 children with confirmed OSAS and 44 control participants underwent surface 12-lead ECG. P-wave duration was measured using a digital caliper by a researcher blinded to the groups.

RESULTS

Median (interquartile range) PWD in children with OSAS (median age = 82.8 months, range = 24-194 months) was significantly higher than that in the control group (median age = 73.4 months, range = 12-156 months): 38.3 (29.7-50.5) vs 25.5 (20.5-30.5) milliseconds, respectively (p < 0.0001). Subgroup analysis according to OSAS severity categorized by the apnea-hypopnea index from polysomnography demonstrated that PWD in the severe OSAS group (n = 24) was significantly higher than that in the mild-to-moderate OSAS group (n = 53): 48.5 (34.7-67.4) vs 35.5 (28.2-47.8) milliseconds, respectively (p = 0.006). A cut-off value of PWD at 26.5 ms from the receiver operating characteristic curve for the diagnosis showed the area under the curve to be 0.839, with a sensitivity of 89.6% and a specificity of 61.4%.

CONCLUSION

PWD was significantly increased in children with OSAS, particularly in severe cases. PWD could be a useful tool for screening childhood OSAS.

A Real Time and Lossless Encoding Scheme for Patch Electrocardiogram Monitors

Cardiovascular diseases are the leading cause of death worldwide. Due to advancements facilitating the integration of electric and adhesive technologies, long-term patch electrocardiogram (ECG) monitors (PEMs) are currently used to conduct daily continuous cardiac function assessments. This paper presents an ECG encoding scheme for joint lossless data compression and heartbeat detection to minimize the circuit footprint size and power consumption of a PEM. The proposed encoding scheme supports two operation modes: fixed-block mode and dynamic-block mode. Both modes compress ECG data losslessly, but only dynamic-block mode supports the heartbeat detection feature. The whole encoding scheme was implemented on a C-platform and tested with ECG data from MIT/BIH arrhythmia databases. A compression ratio of 2.1 could be achieved with a normal heartbeat. Dynamic-block mode provides heartbeat detection accuracy at a rate higher than 98%. Fixed-block mode was also implemented on the field-programmable gate array, and could be used as a chip for using analog-to-digital convertor-ready signals as an operation clock.

Efficient QRS complex detection algorithm based on Fast Fourier Transform

An ECG signal, generally filled with noise, when de-noised, enables a physician to effectively determine and predict the condition and health of the heart. This paper aims to address the issue of denoising a noisy ECG signal using the Fast Fourier Transform based bandpass filter. Multi-stage adaptive peak detection is then applied to identify the R-peak in the QRS complex of the ECG signal. The result of test simulations using the MIT/BIH Arrhythmia database shows high sensitivity and positive predictivity (P_P) of 99.98 and 99.96% respectively, confirming the accuracy and reliability of proposed algorithm for detecting R-peaks in the ECG signal.

Evaluation of Atrial Electromechanical Delay to Predict Atrial Fibrillation in Hemodialysis Patients

Background and objective: Prevalence of atrial fibrillation is higher in hemodialysis patients as compared to the general population. Atrial electromechanical delay is known as a significant predictor of atrial fibrillation. In this study, we aimed to reveal the relationship between atrial electromechanical delay and attacks of atrial fibrillation. Materials and methods: The study included 77 hemodialysis patients over 18 years of age giving written consent to participate in the study. The patients were divided into two groups based on the results of 24-h Holter Electrocardiogram (Holter ECG) as the ones having attacks of atrial fibrillation and the others without any attack of atrial fibrillation. Standard echocardiographic measurements were taken from all patients. Additionally, atrial conduction times were measured by tissue Doppler technique and atrial electromechanical delays were calculated. Results: Intra- and interatrial electromechanical delay were found as significantly lengthened in the group of patients with attacks of atrial fibrillation (p = 0.03 and p < 0.001 respectively). The optimal cut-off time for interatrial electromechanical delay to predict atrial fibrillation was >21 ms with a specificity of 79.3% and a sensitivity of 73.7% (area under the curve 0.820; 95% confidence interval (CI), 0.716⁻0.898). In the multivariate logistic regression model, interatrial electromechanical delay (odds ratio = 1.230; 95% CI, 1.104⁻1.370; p < 0.001) and hypertension (odds ratio = 4.525; 95% CI, 1.042⁻19.651; p = 0.044) were also associated with atrial fibrillation after adjustment for variables found to be statistically significant in univariate analysis and correlated with interatrial electromechanical delay. Conclusions: Interatrial electromechanical delay is independently related with the attacks of atrial fibrillation detected on Holter ECG records in hemodialysis patients.

Prediction of paroxysmal Atrial Fibrillation: A machine learning based approach using combined feature vector and mixture of expert classification on HRV signal

BACKGROUND AND OBJECTIVE

Paroxysmal Atrial Fibrillation (PAF) is one of the most common major cardiac arrhythmia. Unless treated timely, PAF might transform into permanent Atrial Fibrillation leading to a high rate of morbidity and mortality. Therefore, increasing attention has been directed towards prediction of PAF, to enable early detection and prevent further progression of the disease. Notwithstanding the pharmacological and electrical treatments, a validated method to predict the onset of PAF is yet to be developed. We aim to address this issue through integrating classical and modern methods.

METHODS

To increase the predictivity, we have made use of a combination of features extracted through linear, time-frequency, and nonlinear analyses performed on heart rate variability. We then apply a novel approach to local feature selection using meticulous methodologies, developed in our previous works, to reduce the dimensionality of the feature space. Subsequently, the Mixture of Experts classification is employed to ensure a precise decision-making on the output of different processes. In the current study, we analyzed 106 signals from 53 pairs of ECG recordings obtained from the standard database called Atrial Fibrillation Prediction Database (AFPDB). Each pair of data contains one 30-min ECG segment that ends just before the onset of PAF event and another 30-min ECG segment at least 45 min distant from the onset.

RESULTS

Combining the features that are extracted using both classical and modern analyses was found to be significantly more effective in predicting the onset of PAF, compared to using either analyses independently. Also, the Mixture of Experts classification yielded more precise class discrimination than other well-known classifiers. The performance of the proposed method was evaluated using the Atrial Fibrillation Prediction Database (AFPDB) which led to sensitivity, specificity, and accuracy of 100%, 95.55%, and 98.21% respectively.

CONCLUSION

Prediction of PAF has been a matter of clinical and theoretical importance. We demonstrated that utilising an optimized combination of - as opposed to being restricted to - linear, time-frequency, and nonlinear features, along with applying the Mixture of Experts, contribute greatly to an early detection of PAF, thus, the proposed method is shown to be superior to those mentioned in similar studies in the literature.

The assessment of P-wave dispersion and myocardial repolarization parameters in patients with chronic kidney disease

Objective: The risks of sudden death and cardiac arrhythmia are increased in patients with chronic kidney disease (CKD). Here, we aimed to evaluate the indicators of arrhythmias, such as p-wave dispersion (P-WD), QTc dispersion, Tp-e and Tp-e/QT ratio in patients with CKD stages 3–5 on no renal replacement therapy (RRT).

Material and methods: One-hundred and thirty three patients with CKD stages 3–5 and 32 healthy controls were enrolled into the study. No patients received RRT. QTc dispersion, P-WD and Tp-e interval were measured using electrocardiogram and Tp-e/QT ratio was also calculated.

Results: Mean age rates were found similar in patients and controls (60.8 ± 14.2 and 61 ± 12.9 y, p = .937, respectively). Compared patients with controls, P-WD (45.85 ± 12.42 vs. 21.17 ± 6.6 msec, p < .001), QTc-min (366.99 ± 42.31 vs. 387.15 ± 20.5 msec, p < .001), QTc dispersion (71.13 ± 27.95 vs. 41.25 ± 14.55 msec, p < .001), Tp-e maximum (81.04 ± 10.34 vs. 75.49 ± 10.9 msec, p < .001), Tp-e minimum (62.25 ± 7.58 vs. 54.8 ± 6.72 msec, p < .001) and Tp-e/QTc ratio (0.19 ± 0.02 vs. 0.18 ± 0.01, p = .001) were found to be different. QTc-max and Tp-e interval were found to be similar in both groups.

Conclusion: P-WD and QTc dispersion, Tp-e interval and Tp-e/QTc ratio were found to be increased in with CKD stages 3–5 on no RRT.

Coronary Artery Dominance May Predict Future Risk of Atrial Fibrillation

Background

Ischemia of the atria and conductive system of the heart results in greater atrial electrophysiological changes and propensity for atrial fibrillation. P wave duration and dispersion have been proposed to be useful for the prediction of paroxysmal atrial fibrillation (PAF). This study aimed to investigate the effect of coronary artery dominance on P wave duration and dispersion.

Methods

The study population included 194 patients with left dominant circulation (LDC) and 200 age- and gender-matched controls with right dominant circulation (RDC) and without coronary artery disease based on invasive coronary angiography findings. P wave dispersion (PWD) was defined as the difference between the maximum and minimum P wave duration. Arrhythmias were identified by 24-hour Holter electrocardiogram at 3 years of follow-up.

Results

PWD was significantly prolonged in the patients with LDC compared to the controls with RDC (p = 0.001). There were positive correlations between PWD and age (r: 0.502, p = 0.009), left ventricular mass (LVM) (r: 0.614, p = 0.001), LVM index (r: 0.727, p < 0.001) and left atrium (LA) diameter (r: 0.558, p = 0.003) in the LDC group. Multivariate logistic regression analysis showed that age, LVM index, LA diameter and LDC were independent predictors of prolonged PWD. At 3 years of follow-up, 7 (3.9%) patients with LDC and 1 (0.5%) patient with RDC had PAF in Holter electrocardiogram (p < 0.001).

Conclusions

LDC could lead to an increased risk of atrial fibrillation through prolonged PWD. We recommend following up these patients to assess the development of atrial fibrillation.

Advanced interatrial block is an electrocardiographic marker for recurrence of atrial fibrillation after electrical cardioversion

BACKGROUND

Early recurrence of atrial fibrillation (AF) is common following a successful electrical cardioversion (ECV). The purpose of this study was to investigate the hypothesis that AF recurrence is related to atrial electrical inhomogeneity, which may influence the P wave characteristics.

METHODS

Two hundred ninety-one consecutive persistent AF patients who underwent ECV were enrolled, and evaluated for AF recurrences one month after the ECV. Patients with open-heart surgery, a history of catheter ablation, and an unsuccessful ECV were excluded. The P wave duration, dispersion and P wave morphology were evaluated by 12‑lead ECGs 30 min after the ECV.

RESULTS

In total, 141 patients were investigated. One month after the ECV, 60 (43%) patients maintained sinus rhythm. The advanced interatrial block (aIAB; P wave duration >120 ms and biphasic P waves in the inferior leads) (Hazard ratio [HR], 4.51; 95% confidence interval [CI] 1.45-14.01, P = 0.009), P wave dispersion (HR, 1.06; 95%CI 1.02-1.09, P = 0.001), and duration of AF per month (HR, 1.03; 95%CI 1.01-1.04, P = 0.004) were independent predictors of AF recurrence. An aIAB was not associated with structural parameters such as the left atrial volume index or right atrial area. There were no differences in the serum BNP level and frequency of administering anti-arrhythmic drugs between the patients with and without recurrence.

CONCLUSIONS

The risk of AF recurrence after the ECV can be predicted by the P wave characteristics. A longer P wave dispersion and the duration of AF also had a tendency for recurrence.

Are P Wave and QT Dispersions Related to Severe Peripheral Artery Disease?

Background

The aim of this study was to evaluate the relationship between P wave and QT dispersions (PWD and QTD) during the course of severe peripheral artery disease (PAD).

Material/Methods

We recruited 163 patients who underwent peripheral angiography (PA) between August 2011 and March 2017, and they were divided into 2 groups according to the severity of PAD on PA. PWD and QTD were investigated using 12-lead electrocardiograms. Group One consisted of patients diagnosed with <70% stenosis on PA, who eventually received medical treatment; Group Two consisted of patients diagnosed with ≥70% stenosis on PA, who eventually underwent surgery.

Results

ROC curve analysis of the 2 groups demonstrated that PWD was significantly higher in Group Two (AUC: 0.913505; 95% confidence interval (CI): 0.859365 to 0.951788; p<0.0001). The Youden index showed that a cut-off PWD value of >35 msn predicted a peripheral artery stenosis of ≥70% with a sensitivity of 88.89% and a specificity of 85.37% (+LR: 6.07, −LR: 0.13). Moreover, QTD was significantly higher in Group Two (AUC: 0.884749; 95% CI: 0.825489 to 0.929391; p<0.0001). Youden index showed that a cut-off QTD value of >75 msn predicted a peripheral artery stenosis of ≥70% with a sensitivity of 76.54% and a specificity of 85.37% (+LR: 5.23, −LR: 0.27). Comparison of ROC curves showed no difference in terms of predicting peripheral artery stenosis of ≥70% between PWD and QTD (p=0.3308).

Conclusions

Interpreting PWD and QTD offers a non-invasive and cost-effective assessment method for detecting patients at high risk for coronary artery disease in the context of severe PAD.

Assessment of Atrial Conduction Times in Patients with Newly Diagnosed Parkinson's Disease

Background

An increased risk of ischemic stroke has been reported in patients with Parkinson's disease (PD). Atrial fibrillation (AF) is strongly associated with ischemic stroke. Prolonged atrial electromechanical delay (EMD) is an independent predictor for the development of AF.

Aims

The aim of the present study was to evaluate the atrial conduction parameters in patients with PD and to assess their relation with the severity of PD.

Study design

We prospectively enrolled 51 consecutive patients with newly diagnosed PD and 31 age- and sex-matched non-PD subjects.

Methods

To assess atrial electromechanical coupling (PA), the time intervals from the onset of p wave on ECG to the late diastolic wave at the septal (PAs) and lateral (PAl) mitral annulus and lateral tricuspid annulus (PAt) were measured on Tissue Doppler Echocardiography (TDE). The difference between PAs-PAl, PAs-PAt, and PAl-PAt were defined as left intra-atrial, right intra-atrial, and interatrial EMD, respectively. P-wave dispersion (PWD) was calculated from the 12-lead ECG.

Results

PWD, PAs, PAl, and PAt durations were significantly prolonged in the PD group (all p < 0.001). Interatrial, right, and left intra-atrial EMD were also significantly longer in PD patients (p < 0.001, p < 0.001 and p=0.002, resp.). There were significant positive correlations between disease severity (UPDRS score) and PWD (r=0.34, p=0.041), left intra-atrial (r=0.39, p=0.005), and interatrial EMD (r=0.35, p=0.012). By multivariate analysis, PWD (OR: 1.13, 95% CI: 1.02–1.25; p=0.017), LA volume index (OR: 1.19, 95% CI: 1.02–1.37; p=0.021), left intra-atrial (OR: 1.12, 95% CI: 1.01–1.24; p=0.041), and interatrial EMD (OR: 1.08, 95% CI: 1.01–1.16; p=0.026) were found as independent predictors of PD.

Conclusion

Atrial conduction times were longer and correlated with the severity of disease in PD patients. Prolonged inter- and intra-atrial-EMD intervals were also found as independent correlates of PD. These findings may suggest an increased predisposition to atrial fibrillation in PD.