T-wave Amplitude Research Articles

Natural Course of Electrocardiographic Features in Arrhythmogenic Right Ventricular Cardiomyopathy and Their Relation to Ventricular Arrhythmic Events.

Electrocardiographic abnormalities are common in arrhythmogenic right ventricular cardiomyopathy and are included in the 2010 Task Force Criteria. Their time course, however, remains uncertain. In this retrospective observational study, we aimed to assess the long-term evolution of electrocardiographic characteristics and their relation to ventricular arrhythmias. Three hundred fifty-three patients with arrhythmogenic right ventricular cardiomyopathy as per the 2010 Task Force Criteria with 6871 automatically processed 12-lead digital ECGs were included. The relationship between the electrocardiographic parameters and the risk of ventricular arrhythmias was assessed at 10 years from the first ECG. Electrocardiographic parameters were compared between the first contact ECG, the ECG at diagnosis, and the most recent ECG. Median time between the first and the latest ECG was 6 [interquartile range, 1-14] years. Reductions of QRS voltage, R- and T-wave amplitudes between the first, diagnostic, and the latest ECGs were observed across precordial and extremity leads. Mean QRS duration increased from 96 to 102 ms (P<0.001), terminal activation duration (V1) from 47 to 52 ms (P<0.001), and QTc from 419 to 432 ms (P<0.001). T-wave inversions in leads V3 to V6 and aVF at first ECG were associated with ventricular arrhythmias (adjusted hazard ratio [HRadj][V3], 2.03 [95% CI, 1.23-3.34] and HRadj[aVF], 1.87 [95% CI, 1.13-3.08]). Depolarization and repolarization parameters evolved over time in patients with arrhythmogenic right ventricular cardiomyopathy, supporting the progressive nature of arrhythmogenic right ventricular cardiomyopathy. Electrocardiographic abnormalities may be detected before diagnosis and might, although not fulfilling the 2010 Task Force Criteria, be markers of early disease. T-wave inversion in leads V3 or aVF before diagnosis was associated with ventricular arrhythmias during follow-up.

Abstract Mo125: Translating ECG responses to drugs across sexes: model development and validation in the clinic

Background: Sex-based differences in cardiac electrophysiology and their potential to impact susceptibility to cardiac arrhythmia and response to treatment are widely recognized. For example, female sex is an independent risk factor for drug-induced Long QT syndrome, Torsade de Pointes, and sudden cardiac death. However, arrhythmia studies have been predominantly performed in males, thus limiting our understanding of sex-specific arrhythmia mechanisms and the development of sex-specific metrics for arrhythmia risk. Computational tools are a powerful approach for integrating sex differences across scales and studying such multi-level phenomena, accelerating challenging and costly human and animal experiments. Aim: To develop a quantitative tool that predicts drug-induced responses in female electrocardiogram (ECG) features based on ECG data collected in males (and vice versa). Methods: Male and female 1D cable models of ventricular cardiomyocytes were constructed by incorporating transmural heterogeneity and sex-specific parameterizations. We constructed populations of male and female models by randomly perturbing baseline parameters, and derived pseudo-ECGs from computed extracellular potentials. We then utilized lasso regression to map ECG features (QRS duration, QT interval, T-peak-end duration, and T-wave amplitude) extracted from the male pseudo-ECG onto the female ECG features (and vice versa) ( Fig 1 ). Results: Our simulated data-driven translator accurately predicted female pseudo-ECG features from male data in an independent simulated test set (R 2 &gt;0.95). This predictive capability was further assessed in an independent dataset simulating the effects of 95 drugs at different concentrations ( Fig 2A ), exhibiting an average translation error &lt;1% for the QT interval ( Fig 2B ). Proof-of-concept application to ECG data sourced from publicly available FDA-approved datasets, in patients of both sexes under various anti-arrhythmic drugs and drug combinations, demonstrates high accuracy ( Fig 3 ) and validates the translator's applicability to the clinic. Conclusions: Our findings underscore the translator's potential in conducting sex-specific cardiac safety and efficacy assessments, enhancing the precision of evaluations in females. We plan to expand our translator capability to predict sex-specific effects of perturbations, including physiological and pathophysiological stressors.

Exploring the impact of electrocardiographic parameters on the risk of common arrhythmias: a two-sample Mendelian randomization study.

Observational studies have shown that heart rate (HR), heart rate variability (HRV), P-wave terminal force, P-wave duration, T-wave amplitude and PR interval are associated with risk factors for atrial fibrillation (AF) or bradycardia. Arrhythmias are associated with many causes of hospitalization. However, observational studies are susceptible to confounding factors that have not yet been identified. The objective of this study was to clarify the causal relationships by Mendelian randomization analysis. We conducted a two-sample and multivariate Mendelian randomization (MVMR) analysis using genome-wide association study (GWAS) data from a European population to assess the total and direct causal effects of HR, three HRV traits, P-wave terminal force, P-wave duration, T-wave top amplitude in five-lead modes, and the PR interval on the risk of AF (N=191,205), bradycardia (N=463,010), and supraventricular tachycardia (SVT) (N=463,010). The results of the univariate MR analysis revealed the following significant causal effects: the higher the genetically predicted PR interval, the lower the risk of AF; the higher the HR and T-wave top amplitude (aVR leads and V3 + V4 + aVL leads), the lower the risk of bradycardia; and the higher HR and the lower PR interval, the higher the risk of SVT. The multivariate MR results indicated that the HRV_standard deviation of the normal-to-normal (SDNN) interval had an independent causal effect on the risk of AF [odds ratio (OR): 0.515; 95% confidence interval (CI): 0.278-0.954; P=0.03], and the T-wave top amplitude in the aVR leads (OR: 0.998; 95% CI: 0.996-0.999; P<0.001) and the HRV_SDNN (OR: 0.988; 95% CI: 0.976-1.000; P=0.045) had independent causal effects on the risk of bradycardia. The HRV_SDNN had an independent causal effect on AF, while the HRV_SDNN and T-wave top amplitude in the aVR leads had independent causal effects on bradycardia, which suggests that some of the electrocardiographic parameters have preventive effects on the incidence of AF and bradycardia.

Hypoxaemic load in sleep apnoea is associated with acute changes in T-wave amplitude.

Obstructive sleep apnoea (OSA) imposes significant stress on the cardiovascular system and the heart. While long-term cardiac effects are understood, the immediate impact of hypoxaemia on the heart's electrophysiology lacks understanding. Our study aims to explore desaturation severity on cardiovascular repolarisation. We retrospectively analysed ECGs from full diagnostic polysomnographies from 492 patients with suspected OSA. The analyses were conducted before, during and after 9137 nocturnal apnoea- or hypopnoea-related desaturations. The mean and sd of T-wave amplitude change from the baseline level to the level during and after desaturations (ΔTamp_mean and ΔTamp_SD) were calculated. To investigate the modulatory effects of desaturation severity, the data were divided into subgroups based on the desaturation duration (Tdes; 10 s≤Tdes<20 s, 20 s≤Tdes<30 s, 30 s≤Tdes<45 s and Tdes≥45 s) and magnitude of blood oxygen saturation drop (change in peripheral oxygen saturation (ΔS pO2 ); 3%≤ΔS pO2 <4.5%, 4.5%≤ΔS pO2 <6%, 6%≤ΔS pO2 <7.5% and ΔS pO2 ≥7.5%) for men and women. Desaturations caused significant (p<0.01) changes in ΔTamp_mean during and after desaturations. In men, the median ΔTamp_mean during and after deep (ΔS pO2 ≥7.5%) desaturations were 21 µV and 24 µV, respectively. In women, the median ΔTamp_mean in deep desaturations was 15 µV during and 21 µV after desaturations. Similarly, the ΔTamp_SD increased during and after deep desaturations. In regression analysis, the desaturation depth was an independent predictor for ventricular repolarisation instability. We found an association between the severity of nocturnal desaturations and cardiac repolarisation instability. These findings hold particular importance, as repolarisation instability has been linked with cardiovascular morbidity and could potentially serve as a trigger for arrhythmias and sudden cardiac death.

A Clinical Diagnostic Test for Calcium Release Deficiency Syndrome

Sudden death and cardiac arrest frequently occur without explanation, even after a thorough clinical evaluation. Calcium release deficiency syndrome (CRDS), a life-threatening genetic arrhythmia syndrome, is undetectable with standard testing and leads to unexplained cardiac arrest. To explore the cardiac repolarization response on an electrocardiogram after brief tachycardia and a pause as a clinical diagnostic test for CRDS. An international, multicenter, case-control study including individual cases of CRDS, 3 patient control groups (individuals with suspected supraventricular tachycardia; survivors of unexplained cardiac arrest [UCA]; and individuals with genotype-positive catecholaminergic polymorphic ventricular tachycardia [CPVT]), and genetic mouse models (CRDS, wild type, and CPVT were used to define the cellular mechanism) conducted at 10 centers in 7 countries. Patient tracings were recorded between June 2005 and December 2023, and the analyses were performed from April 2023 to December 2023. Brief tachycardia and a subsequent pause (either spontaneous or mediated through cardiac pacing). Change in QT interval and change in T-wave amplitude (defined as the difference between their absolute values on the postpause sinus beat and the last beat prior to tachycardia). Among 10 case patients with CRDS, 45 control patients with suspected supraventricular tachycardia, 10 control patients who experienced UCA, and 3 control patients with genotype-positive CPVT, the median change in T-wave amplitude on the postpause sinus beat (after brief ventricular tachycardia at ≥150 beats/min) was higher in patients with CRDS (P < .001). The smallest change in T-wave amplitude was 0.250 mV for a CRDS case patient compared with the largest change in T-wave amplitude of 0.160 mV for a control patient, indicating 100% discrimination. Although the median change in QT interval was longer in CRDS cases (P = .002), an overlap between the cases and controls was present. The genetic mouse models recapitulated the findings observed in humans and suggested the repolarization response was secondary to a pathologically large systolic release of calcium from the sarcoplasmic reticulum. There is a unique repolarization response on an electrocardiogram after provocation with brief tachycardia and a subsequent pause in CRDS cases and mouse models, which is absent from the controls. If these findings are confirmed in larger studies, this easy to perform maneuver may serve as an effective clinical diagnostic test for CRDS and become an important part of the evaluation of cardiac arrest.

Cold pressor stress effects on cardiac repolarization

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

The ECG abnormalities in persons with chronic disorders of consciousness.

We aimed to investigate the electrocardiogram (ECG) features in persons with chronic disorders of consciousness (DOC, ≥ 29days since injury, DSI) resulted from the most severe brain damages. The ECG data from 30 patients with chronic DOC and 18 healthy controls (HCs) were recorded during resting wakefulness state for about five minutes. The patients were classified into vegetative state (VS) and minimally conscious state (MCS). Eight ECG metrics were extracted for comparisons between the subject subgroups, and regression analysis of the metrics were conducted on the DSI (29-593days). The DOC patients exhibit a significantly higher heart rate (HR, p = 0.009) and lower values for SDNN (p = 0.001), CVRR (p = 0.009), and T-wave amplitude (p < 0.001) compared to the HCs. However, there're no significant differences in QRS, QT, QTc, or ST amplitude between the two groups (p > 0.05). Three ECG metrics of the DOC patients-HR, SDNN, and CVRR-are significantly correlated with the DSI. The ECG abnormalities persist in chronic DOC patients. The abnormalities are mainly manifested in the rhythm features HR, SDNN and CVRR, but not the waveform features such as QRS width, QT, QTc, ST and T-wave amplitudes.

Electrocardiographic markers in patients with type 2 diabetes and the role of diabetes duration

BackgroundThe association between type 2 diabetes and electrocardiographic (ECG) markers are incompletely explored and the dependence on diabetes duration is largely unknown. We aimed to investigate the electrocardiographic (ECG) changes associated with type 2 diabetes over time. MethodsIn this cross-sectional study, we matched people with type 2 diabetes 1:1 on sex, age, and body mass index with people without diabetes from the general population. We regressed ECG markers with the presence of diabetes and the duration of clinical diabetes, respectively, adjusted for sex, age, body mass index, smoking, heart rate, diabetes medication, renal function, hypertension, and myocardial infarction. ResultsWe matched 988 people with type 2 diabetes (332, 34% females) with as many controls. Heart rate was 8 bpm higher (p < 0.001) in people with vs. without type 2 diabetes, but the difference declined with increasing diabetes duration. For most depolarization markers, the difference between people with and without type 2 diabetes increased progressively with diabetes duration. On average, R-wave amplitude was 6 mm lower in lead V5 (p < 0.001), P-wave duration was 5 ms shorter (p < 0.001) and QRS duration was 3 ms (p = 0.03). Among repolarization markers, T-wave amplitude (measured in V5) was lower in patients with type 2 diabetes (1 mm lower, p < 0.001) and the QRS-T angle was 10 degrees wider (p = 0.002). We observed no association between diabetes duration and repolarization markers. ConclusionsType 2 diabetes was independently associated with electrocardiographic depolarization and repolarization changes. Differences in depolarization markers, but not repolarization markers, increased with increasing diabetes duration.

Cardiovascular and Vector-Cardiographic Effects of Articaine Anesthesia with Epinephrine.

The aim was to investigate the vector-cardiographic effects in patients submitted to dental extraction under local anesthesia. Twenty-one patients aged 36.6 ± 12.4 years with a clinical and radiographic indication of mandibular or maxillary tooth extraction were enrolled. The intervention was a local or mandibular nerve block anesthesia with 4% articaine hydrochloride containing epinephrine (1 : 100,000; 40 mg/ml + 10 μg/ml). Blood pressure (BP), heart rate (HR), pulse wave transit time, and vector-cardiography data were recorded throughout 3 min before and 5 min after injection. QRS- and T-wave area under the curve (QRS AUC/T AUC) were calculated from the X/Y/Z QRS-vector or T-vector. T-wave amplitude (T AM), T AUC values, and diastolic BP decreased, and HR significantly increased 4 min after injection. A transient moderate HR drop and a corresponding small increase in T AM and T AUC immediately after the injection procedure may be explained by a decreased sympathetic tone due to psychological relief. In dental anesthesia, the systemic epinephrine effects are represented by a decrease in T AUC. These effects are most pronounced in the X- and Y-leads. The 3D determination of vector planes or amplitudes is a simple method to register the sympathetic tone in local anesthesia independently of possible effects on T-wave characteristics in single leads. In conclusion, T-wave determination may help to detect even small increases in systemic adrenaline concentration in case of accidental intravascular injection. At the same time, full rhythm and spatial ischemia control is provided.

Monitoring the electrophysiological effects of hydroquinidine non-invasively in patients with Brugada syndrome

Abstract Background Quinidine and it’s derivative hydroquinidine are the only drugs shown to reduce arrhythmic events in patients with Brugada syndrome (BrS). There is currently no standardised approach to monitoring the effect of pharmacotherapy in BrS to guide dosing and evaluate an individual’s response to therapy. Purpose To investigate if the electrophysiological effects of Hydroquinidine can be detected on non-invasive testing and identify parameters that may be used to study a non-invasive strategy for monitoring pharmacotherapy in BrS. Methods Patients with a diagnosis of BrS underwent multimodality non-invasive assessment with electrocardiogram (ECG), signal averaged ECG, 24 hour 12-lead Holter monitor and electrocardiographic imaging (ECGi – a method of non-invasive electroanatomical mapping), at baseline and "on treatment" with hydroquinidine (300mg BD) therapy. A medication survey was used to recorded adverse drug reactions and serum hydroquinidine levels were determined using liquid chromatography mass spectrometry. Results Twelve patients with BrS (11 male, mean age 47.6±10.9 years) with spontaneous type 1 BrS pattern or drug inducible type 1 BrS pattern and resuscitated cardiac arrest participated in the study. The mean Shanghai score was 4.6±1.4 and two patients had disease-causing SCN5A variants. During hydroquinidine therapy, there was a significant increase in QRS duration (110.7msec vs 117.8msec, p=0.004) and in mean activation time in the area of late activation in the right ventricular outflow tract (RVOT, 90.9ms to 97.7ms, p=0.020). In nine (75%) patients, the area of late activation (defined as &amp;gt;80ms after initial activation) in the RVOT also increased with hydroquinidine. Repolarisation parameters were also affected by hydroquinidine with an increase in QT interval corrected for heart rate (369.5msec vs 434.8msec, p&amp;lt;0.0001) and T-wave width (232.8msec to 271.2msec p=0.003) and a significant reduction in T-wave amplitude (0.4mV to 0.2mV p=0.001) on treatment. The reduction in T-wave amplitude precluded computation of repolarisation time in the RVOT by ECGi on treatment. No difference in the burden of type 1 BrS ECG pattern over 24 hours was seen on 12-lead Holter monitor between baseline and on treatment assessment. No significant difference in serum hydroquinidine level was detected between those who experienced side effects and those who did not (2.9µmol vs 3.1µmol, p=0.790). Conclusion Hydroquinidine affects both ventricular activation and repolarisation in patients with BrS and these effects can be detected non-invasively. Further work is required to determine clinical significance of these observed effects and investigate the feasibility of non-invasive monitoring strategy of pharmacotherapy in BrS.ECGi activation maps

Risk prediction of inappropriate implantable cardioverter-defibrillator therapy using machine learning

Abstract Background Inappropriate shock from implantable cardioverter-defibrillators (ICDs) undermines quality of life and increases all-cause mortality risk. Various predictors of inappropriate ICD shock have also been indicated in previous studies. Nevertheless, no prediction model by machine learning has been reported. Purpose We developed ML models for evaluating the risk of inappropriate ICD therapy, and proposed easily calculable risk scoring. Methods In total, 182 consecutive cases implanted with ICD were enrolled. The predictive models were based on 16 statistically significant factors out of 189 items including electrocardiogram parameters and clinical features after ICD implantation. Statistical analysis and 14 ensemble learning methods were performed. Shapley additive explanation (SHAP) method was performed to extract important features in the best ML model, and easily calculable score was established from the features. Results Twenty-five patients (13.7%) underwent inappropriate therapy. The extra-trees classifier demonstrated the highest area under the receiver operating characteristic curve (AUROC; 0.839). The top six features were history of atrial arrhythmia, ischemic cardiomyopathy (ICM), no diabetes mellitus (DM), cardiac resynchronization therapy (CRT), and V4- and V5 R-wave amplitudes. From the six features, the Cardi45 score was developed (+6.5 points for history of atrial arrhythmia, -2.0 points for ICM, -1.0 points for DM, -0.5 points for CRT, and +0.5 points for V4 T-wave amplitude ≥1200 μV and V5 R-wave amplitude ≥1400 μV). The AUROC for the Cardi45 score was 0.886, which was higher than that of extra-trees classifier. Conclusion Our study demonstrates that the ML approach can provide a good prediction model and Cardi45 score was powerful predictors for inappropriate ICD therapy. Cardi45 score, derived from this model, may be used to judge whether an aggressive rhythm control strategy should be implemented or ICD implantation should be avoided in some patients.Picture 1Picture 2

Comparison of historical criterion and artificial intelligence in patients with left ventricular hypertrophy

Abstract Backgrounds Diagnostic criterion of left ventricular hypertrophy (LVH) on 12-leads electrocardiogram (ECG) were historically established. However, there was no study to evaluate the criterion comparing with machine learning methods. Purpose To verify the historical criterion of LVH on ECG, and to compare them with diagnosis by machine learning. Methods First, consecutive 60 patients with LVH were recruited, and one to one matching with age and sex to patients with normal cardiac function was performed. Finally, 120 patients (69.6 ± 12.6years, 38men per group) were enrolled. LVH was defined as at least one LV wall (septum, posterior wall, apex) showed thickness over 15mm on ultrasound echocardiography. No sinus rhythm, and wide QRS cases were excluded. The accuracy of historical criterion and ECG predictors were calculated by an assessment of whether a predictor was higher/lower than the cut-off value of receivor operating characteristics curve analysis (ROC). Ten machine learning methods were built using the significant predictors of logistic regression with 10-times cross validation. Results By logistic regression analysis, 77 significant predictors were extracted, and 22 predictors showed their area under ROC (AUROC) over 0.700. Among historical criterion, Cornell voltage showed high accuracy (0.783) and AUROC (0.808). Conversely, among AI methods, light gradient boosting machine demonstrated higher accuracy (0.843) and random forest method higher AUROC (0.882). Shapley additive explanation method (SHAP) demonstrated that V2/V2 S-wave amplitude and I/V5 T-wave amplitude played essential roles to build the AI models. Conclusions AI diagnosis on ECG for LVH showed powerful diagnostic performance comparing historical criterion.

Abstract 11663: T Wave Alternans: A Clue in Plain Sight

Introduction: T-wave alternans (TWA) refers to the beat-to-beat variability in T-wave amplitudes or polarity on surface ECGs, and can signify susceptibility to malignant ventricular arrhythmias (VA). Aims: We present a case to emphasize the pathophysiology and clinical significance of this ECG finding. Case description: A 52 year-old female with history of HIV presents with shortness of breath and is treated for heart failure. In the ED, she has witnessed syncope and is found to have VT that progresses to VF. Resuscitation efforts are successful and include amiodarone loading. Figure 1A demonstrates baseline ECG on admission with a QTc of 495 ms. A few days later, an ECG reveals QTc of 696 ms with TWA (figure 1B). Shortly after, she develops polymorphic VT in the setting of long-short sequences and an R on T trigger (figure 1C) that is terminated with cardioversion. Review of pre-admission ECGs reveals that QTc prolongation occurred after initiation of a retroviral regimen that included rilpivirine and worsened with amiodarone. Both medications are discontinued, and she is eventually discharged with a QTc of 450 ms. Early theories for TWA's mechanism hypothesized that dispersion of refractoriness resulted in depolarization through alternating pathways and thus this phenomenon. Recent understanding further suggests that TWA occurs as a result of cellular alternans and variation in action potential duration due to dysregulation of repolarization. If discordant repolarization alternans ensues, whereby neighboring cells repolarize in opposite phases (long-short, short-long), the resultant repolarization gradient and heterogeneity in cellular repolarization serves as the substrate for VA; if a premature beat encounters refractory myocardium and unidirectional block occurs, a re-entrant excitation tachycardia can be initiated. Conclusions: TWA on ECG suggests myocardial electrical instability as a result of cellular repolarization inhomogeneity.

Abstract 13690: Diagnosis of Left Ventricular Hypertrophy on 12-leads Electrocardiogram by Historical Criterion and Machine Learning Models

Introduction: Diagnostic criterion of left ventricular hypertrophy (LVH) on 12-leads electrocardiogram (ECG) were established. We verified them comparing with artificial intelligence (AI) method. Hypothesis: Machine learning on 12-leads ECG show higher diagnostic performance comparing with historical criterion. Methods: First, consecutive 60 patients with LVH were recruited, and one to one matching with age and sex to patients with normal cardiac function was performed. Finally, 120 patients (69.6 ± 12.6years, 38men per group) were enrolled. LVH was defined as at least one LV wall (septum, posterior wall, apex) showed thickness over 15mm on ultrasound echocardiography. No sinus rhythm, and wide QRS cases were excluded. Results: By logistic regression analysis, 77 significant predictors were extracted. Among historical criterion, Cornell voltage showed high accuracy (0.783) and area under receiver operating characteristics curve analysis (AUROC; 0.808). Conversely, among AI methods, light gradient boosting machine demonstrated higher accuracy (0.843) and random forest method higher AUROC (0.882). V2/V2 S-wave amplitude and I/V5 T-wave amplitude played essential roles to build the AI models. Conclusions: AI diagnosis on ECG for LVH showed powerful diagnostic performance comparing historical criterion.

Prognostic significance of the Holter-derived T-wave variability in patients with ventricular tachyarrhythmias complicating acute coronary syndrome-TWIST study.

We aimed to investigate the association between ventricular repolarization instability and sustained ventricular tachycardia and ventricular fibrillation (VT/VF) occurring within 48 h (acute-phase VT/VF) after the onset of acute coronary syndrome (ACS) and the prognostic role of repolarization instability and heart rate variability (HRV) after discharge from the hospital. We studied 572 ACS patients with a left ventricular ejection fraction >35%. The ventricular repolarization instability was assessed by the beat-to-beat T-wave amplitude variability (TAV) using high-resolution 24-h Holter ECGs recorded at a median of 11 days from the date of admission. We calculated the HRV parameters including the deceleration capacity (DC) and non-Gaussian index calculated on a 25 s timescale (λ25s). The DC and λ25s were dichotomized based on previous studies' thresholds. Acute-phase VT/VF developed in 43 (7.5%) patients. In-hospital mortality was significantly higher among VT/VF patients (4.7% vs. 0.9%, p = .03). An adjusted logistic model showed that the maximum TAV (odds ratio 1.02, 95% confidence interval [CI] 1.00-1.29, p = .04) was associated with acute-phase VT/VF. During a median follow-up period of 2.1 years, 19 (3.3%) patients had cardiac deaths or resuscitated cardiac arrest. Acute-phase VT/VF (p = .12) and TAV (p = .72) were not significant predictors of survival. An age and sex-adjusted Cox model showed that the DC (p < .01), λ25s (p < .01), and emergency coronary intervention (p < .01) were independent predictors. T-wave amplitude variability was associated with acute-phase VT/VF, but the TAV was not predictive of survival post-discharge. The DC, λ25s, and emergency coronary intervention were independent predictors of survival.

Investigating the Radiation Dose Received by the Heart and Its Electrocardiographic Changes after Three-dimensional Conformal Radiation Therapy in Patients with Left Breast Cancer

Background and Objective: Breast cancer is one of the most common cancers and the fifth leading cause of cancer deaths in Iran. The present study aimed to investigate the absorbed dose received by the heart and its relationship with cardiac complications in radiotherapy of patients with left breast cancer using a three-dimensional conformal radiotherapy technique. Materials and Methods: A total of 181 women with left breast cancer who received radiotherapy after surgery were included in the study. Dosimetric parameters were obtained using dose-volume histograms for the heart, whole lung, left lung, and clinical target volume. Electrocardiography tests were performed for all patients before and one year after the radiotherapy. Results: The mean doses of heart, left lung, whole lung, and clinical target volume were 6.3±3.1, 13.3±4.5, 6.9±3.7, and 47.3±6.4 Gray (Gy), respectively. A significant reduction in T-wave amplitude was observed in 57% of patients three months after radiotherapy. T-wave amplitude decreased from 3.03±0.92 mm to 1.56±0.83 mm. The reduction in the T-wave amplitude displayed a significant relationship with the mean dose of the heart (β = 2.653; P= 0.019). Conclusion: In women with left-sided breast cancer, cardiac complications are frequent, for which electrocardiographic tests can be used for cardiac evaluation after radiotherapy. Based on the obtained results, the most frequent side effect caused by radiotherapy in these patients was an abnormality in T-wave

Hyperacute T Wave in the Early Diagnosis of Acute Myocardial Infarction.

The diagnostic performance of T-wave amplitudes for the detection of myocardial infarction is largely unknown. We aimed to address this knowledge gap. T-wave amplitudes were automatically measured in 12-lead ECGs of patients presenting with acute chest discomfort to the emergency department within a prospective diagnostic multicenter study. The final diagnosis was centrally adjudicated by 2 independent cardiologists. Patients with left ventricular hypertrophy, complete left bundle branch block, or paced ventricular depolarization were excluded. The performance for lead-specific 95th-percentile thresholds were reported as likelihood ratios (lr), specificity, and sensitivity. Myocardial infarction was the final diagnosis in 445 (18%) of 2457 patients. In most leads, T-wave amplitudes tended to be greater in patients without myocardial infarction than those with myocardial infarction, and T-wave amplitude exceeding the 95th percentile had positive and negative lr close to 1 or with confidence intervals (CIs) crossing 1. The exceptions were leads III, aVR, and V1, which had positive lrs of 3.8 (95% CI, 2.7 to 5.3), 4.3 (95% CI, 3.1 to 6.0) and 2.0 (95% CI, 1.4 to 2.9), respectively. These leads normally have inverted T waves, so T-wave amplitude exceeding the 95th percentile reflects upright rather than increased-amplitude hyperacute T waves. Hyperacute T waves, when defined as increased T-wave amplitude exceeding the 95th percentile, did not provide useful information in diagnosing myocardial infarction in this sample.

Prevalence and diagnostic significance of de-novo 12-lead electrocardiogram patterns following covid-19 infection in elite soccer players

Abstract Funding Acknowledgements Type of funding sources: None. Background Considering that myocarditis is implicated in 5-15% of all exercise related sudden cardiac deaths in athletes, following a novel viral pandemic, the identification and risk-stratification of affected athletes remains an important priority. Given its widespread availability, the inclusion of a 12-lead electrocardiogram (ECG) is common to all consensus-based protocols from North America and Europe. However, a single cross-sectional ECG is problematic because several physiological repolarisation changes are also common manifestations in individuals with myopericarditis. Purpose The aim of our study was to report on the prevalence and diagnostic significance of de-novo ECG patterns following COVID-19 infection in a well-defined cohort of elite soccer players in the English, Dutch and Brazilian leagues. Methods In this multicentre observational study, between March 2020–May 2022, we evaluated consecutive athletes with COVID-19 infection. ECGs were reported in accordance with the International recommendations for ECG interpretation in athletes. The following patterns were also considered abnormal if they were not detected on the pre-COVID-19 infection ECG: PR-segment depression, new J-point and ST segment elevation, low QRS voltages, QRS fragmentation, new ST-segment depression, new T-wave inversion, biphasic T-waves and a reduction in the T-wave amplitude by 50% or T-wave flattening. Athletes exhibiting de-novo ECG changes underwent cardiovascular magnetic resonance (CMR) scans. One club mandated CMR scans for all players (n=30) following COVID-19 infection, despite the absence of cardiac symptoms or de-novo ECG changes. Results 511 soccer players (median age 21-years, IQR:18-26-years) were included, of which 88% were male and 58% white. 17 (3%) athletes demonstrated de-novo ECG changes, which included, a reduction in T-wave amplitude in the inferior and lateral leads (n=5), inferior leads (n=4) and lateral leads (n=4); inferior T-wave inversion (n=7), and ST-segment depression (n=2). 15 (88%) athletes with de-novo ECG changes revealed CMR evidence of inflammatory cardiac sequalae. All athletes who underwent a mandatory CMR irrespective of illness severity or ECG findings, had normal findings. Athletes revealing de-novo ECG changes, had a higher prevalence of cardiac symptoms (71% v 12%; p&amp;lt;0.0001) and longer median symptom duration (5-days, IQR:3-10) compared with athletes without de-novo ECG changes (2-days, IQR:1-3; p&amp;lt;0.001). Among athletes without cardiac symptoms, the additional yield of de-novo ECG changes to detect cardiac inflammation was 17%. Conclusions 3% of athletes demonstrated de-novo ECG changes post COVID-19 infection, of which 88% were diagnosed with inflammatory cardiac sequalae. Most affected athletes exhibited cardiac symptoms; however de-novo ECG changes contributed to a diagnosis of cardiac inflammation in 17% of athletes without cardiac symptoms.

Using a smartwatch to record precordial electrocardiograms: a validation study

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This work received financial support from the French Government as part of the “Investments of the Future” program managed by the National Research Agency (ANR) Background Smartwatches which support recording of a single-lead electrocardiogram (ECG) are increasingly being used worldwide, mainly for detection of atrial fibrillation. Recordings beyond the wrist are anecdotal as their reliability remains unknown. Aim This clinical validation study assessed the reliability of an Apple Watch (AW) to obtain frontal and precordial leads as compared with standard 12-lead ECGs in both healthy subjects and patients with underlying heart disease. Methods In 100 subjects (80 with ECG anomalies), a standard 12-lead ECG was performed, followed by AW recordings of the standard Einthoven leads (leads I, II, and III) and precordial leads V1, V3, and V6. Seven parameters (P, QRS, ST and T-wave amplitudes, PR, QRS, and QT intervals) were compared through a Bland-Altman analysis including bias (mean difference), absolute offset (mean absolute difference), and 95% limits of agreement. Results No significant differences were observed for any parameter across any lead, except for R-wave measured across precordial leads V1, V3, and V6 where significantly greater amplitudes were measured by the AW, (0.20 mV; 0.19mV; 0.49 mV respectively; p = 9x10-7; p = 7x10-4; p = 6x10-14, respectively), indicating overestimation by the AW. There were no significant differences in absolute offset or bias for any parameters of any leads (p &amp;gt; 0.05). Conclusion ECGs recorded with the AW on the wrist but also on other positions had comparable durations and amplitudes compared to standard 12-lead ECG. The AW can be used to record frontal and precordial leads, paving the way for broader clinical applications.

T-wave amplitude on presenting 12-lead ECG is associated with coronary occlusion in NSTEMI

Las complicaciones en los pacientes hospitalizados en sala convencional suelen ser frecuentes y estar asociadas a mayor mortalidad, aumento de la estancia hospitalaria e incremento del coste sanitario. Las constantes fisiológicas monitorizadas habitualmente en los pacientes pueden predecir el riesgo de presentar estas complicaciones. Los sistemas de respuesta rápida son dispositivos de atención a pacientes en riesgo de descompensación en sala de hospitalización que se han creado con el objetivo de detectar estos episodios de forma temprana e instaurar un tratamiento precoz. Para identificar estas situaciones de riesgo están disponibles diferentes escalas de valoración basadas en los parámetros fisiológicos monitorizados. Funcionan mediante un sumatorio de puntos donde a mayor puntuación el paciente presenta un riesgo más alto de descompensación, facilitando la decisión de en qué momento activar el sistema de respuesta. La monitorización remota en sala juega un papel fundamental a modo de nexo entre la detección de estos pacientes y la activación de los sistemas. Actualmente los aparatos y sistemas de monitorización, tales como dispositivos portátiles, sensores inteligentes o dispositivos contactless están disponibles, permitiendo medir estas variables de forma simple, fiable y fácilmente exportable, disminuyendo así el error de transcripción y la carga de trabajo. Además, muchos de estos sistemas de monitorización permiten calcular de manera automática estas diferentes escalas e incluso activar directamente a los sistemas de respuesta rápida, permitiéndoles dar una respuesta proporcional al grado de alteración. En vista de los beneficios descritos sobre la implantación de estos sistemas, el presente artículo realiza una revision de sus componentes y de las herramientas actuales con las que cuenta para optimizar su utilidad.Patients admitted in hospital wards often present complications which are associated with an increase in mortality, length of stay and healthcare costs. The rapid response systems are basically organizations of care to inward patients who potentially can present these events with the objective of an early detection. In order to provide complementary monitoring, proper treatment or intensive care unit transfer if needed. The risk of developing adverse events could be predicted through the vital signs routinely monitored in hospitalized patients. Remote monitoring of the physiological parameters in the ward plays a fundamental role as a link between the detection of these patients and the activation of the rapid response system. Based on the information obtained there are available different assessment scales to identify risk situations. They work through a punctuation system, understanding that a higher score means higher risk of deteriorating; this information will support the decision process which finally activates the response system. Currently, monitoring devices and systems such as portable devices, smart sensors, contactless devices are widely available, allowing these variables to be measured in a simple, reliable and easily exportable way, reducing transcription error and workload. In addition, many of these monitoring systems allow these different scales to be calculated automatically and even directly activating the rapid response systems, allowing them to give a response proportional to the degree of alteration. In view of the benefits described with the implementation of these systems, this article reviews their components and the current tools that we have in order to optimize their usefulness.