Refining ECG interpretation: From false assumptions to evidence-based precision.

INTRODUCTION: Electrocardiography (ECG) remains a fundamental tool in cardiovascular diagnostics, frequently relying on System 1 thinking-rapid, intuitive pattern recognition (PR). However, this approach can be insufficient when dealing with complex cases where diagnostic precision is essential. This article emphasizes the importance of integrating System 2 thinking-a more deliberate, evidence-based approach-into ECG interpretation to enhance diagnostic accuracy and avoid clinical errors. METHODS: This review examines the distinction between findings that can be adequately managed through System 1 PR and those requiring System 2 reasoning supported by diagnostic accuracy studies. RESULTS: While System 1 PR is effective for recognizing routine ECG findings and self-evident truths, it falls short in conditions where the ECG serves as a mere surrogate marker for underlying pathology. Examples such as false-negative acute coronary occlusions illustrate the need for System 2 reasoning to account for the limitations of ECG's diagnostic precision. Relying solely on System 1 in these contexts risks treating the ECG as an infallible diagnostic tool and as a false gold standard for many diseases, which it is not. CONCLUSION: To prevent diagnostic errors, ECG interpretation must distinguish between self-evident truths suited for PR and findings that require System 2 reasoning due to their association with actual pathology. Clinicians and educators should prioritize evidence-based methods, incorporating System 2 reasoning into practice to improve diagnostic precision and patient outcomes.

EPM algorithm: A stepwise approach to accessory pathway localization in ventricular pre-excitation.

BACKGROUND: Accurate estimation of accessory pathway (AP) localization in patients with ventricular pre-excitation or Wolff-Parkinson-White (WPW) syndrome remains a diagnostic challenge. Existing algorithms have contributed significantly to this area, but alternative algorithms can offer additional perspectives and approaches to AP localization. OBJECTIVE: This study introduces and evaluates the diagnostic accuracy of the EPM algorithm in AP localization, comparing it with established algorithms Arruda and EASY. METHODS: A retrospective analysis was conducted on 138 patients from Hospital São Paulo who underwent catheter ablation. Three blinded examiners assessed the EPM algorithm's diagnostic accuracy against the Arruda and EASY algorithms. The gold standard for comparison was the radioscopic position of the AP where radiofrequency ablation led to pre-excitation disappearance on the ECG. RESULTS: EPM showed a diagnostic accuracy of 51.45%, closely aligning with Arruda (53.29%) and EASY (44.69%). Adjacency accuracy for EPM was 70.67%, with Arruda at 66.18% and EASY at 72.22%. Sensitivity for EPM in distinguishing left vs. right APs was 95.73%, with a specificity of 74.33%. For identifying septal vs. lateral right APs, EPM sensitivity was 82.79% with a specificity of 46.15%. These measures were comparable to those of Arruda and EASY. Inter-observer variability was excellent for EPM, with Kappa statistics over 0.9. CONCLUSION: The EPM algorithm emerges as a reliable tool for AP localization, offering a systematic approach beneficial for therapeutic decision-making in electrophysiology. Its comparable diagnostic accuracy and excellent inter-observer variability underscore its potential clinical applicability. Future research may further validate its efficacy in a broader clinical setting.

Twelve-lead ambulatory ECG recording using a seven-electrode recorder: An alternative method for electrophysiological evaluation.

INTRODUCTION: Conventional three-lead ambulatory electrocardiogram recording (3L-AECG) is used for the quantitative diagnosis of arrhythmias. However, the lack of crucial information, such as QRS morphology and orientation, renders the 3L-AECG incomplete for planning electrophysiological interventions. The 12-lead AECG (12L-AECG) merges the temporal resolution 3L-AECG with the spatial resolution of the standard electrocardiogram (S-ECG). Although it provides more detail, it is not widely used. This study aimed to verify whether the seven-electrode 12L-AECG and S-ECG have similar waveforms. METHODS: A questionnaire consisting of 240 side-by-side comparisons (12 leads from 20 patients) was created. These consisted of a QRS registered using the 12L-AECG and a QRS from the same patient, registered using the S-ECG. The questionnaire was submitted to cardiologists trained in electrophysiology. For each comparison, the evaluator assigned "similar" or "different" depending on their own judgment. RESULTS: Five cardiologists completed the questionnaire, resulting in 1200 answers. The AECG-12 was similar to the ECG in 84.50 % of the instances (95 % confidence interval [CI] 83.20-86.50). The interobserver agreement was moderate (0.542, p < 0.001). The similarity between specific leads ranged up to 98 % (95 % CI 92.96-99.76). No significant differences were found among patients (p = 0.407). CONCLUSION: The seven-electrode 12L-AECG and S-ECG produced comparable waveforms. This similarity supports the use of 12L-AECG for accurate arrhythmia tracking and assists in planning electrophysiological procedures.

Long-term clinical outcomes of patients with nonsignificant transplanted renal artery stenosis.

BACKGROUND: Transplant renal artery stenosis (TRAS) is the main vascular complication of kidney transplantation. For research and treatment purposes, several authors consider critical renal artery stenosis to be greater than 50%, and percutaneous intervention is indicated in this scenario. However, there are no reports in the current literature on the evolution of patients with less than 50% stenosis. METHOD: This retrospective study included data from all patients who underwent kidney transplantation and were suspected of having TRAS after transplantation with stenosis under 50% independent of age and were referred for angiography at a single centre between January 2007 and December 2014. RESULTS: During this period, 6,829 kidney transplants were performed at Hospital do Rim, 313 of whom had a clinical suspicion of TRAS, and 54 of whom presented no significant stenosis. The average age was 35.93 years old, the predominant sex was male, and most individuals (94.4%) underwent dialysis before transplantation. In most cases in this group, transplants occurred from a deceased donor (66.7%). The time between transplantation and angiography was less than one year in 79.6% of patients, and all presented nonsignificant TRAS. Creatinine levels, systolic blood pressure, diastolic blood pressure and glomerular filtration rate improved over the long term. The outcomes found were death and allograft loss. CONCLUSION: Age, sex and ethnic group of patients were factors that did not interfere with the frequency of renal artery stenosis. The outcomes showed that in the long term, most patients evolve well and have improved quality of life and kidney function, although there are cases of death and kidney loss.

Pacemaker lead-related macroreentrant atrial tachycardia.

Macroreentrant atrial circuits are frequently associated with scarring. Previous reports have shown the possible development of scar tissue that is adjacent to pacemaker (PM) leads. However, reports of PM lead-related reentrant tachycardia are scarce. We report the case of a 63-year-old woman who presented with macroreentrant atrial tachycardia (MAT), related to the atrial trajectory of an old single-lead ventricular PM, that was successfully treated with radiofrequency ablation after a conventional electrophysiological study ruled out isthmus-dependent atrial flutter and provided sufficient data to confirm this diagnosis. This report presents a case of MAT originating around the trajectory of a PM lead, probably because of scar tissue that developed adjacent to the lead. Experimental studies have already shown that interstitial atrial fibrosis may develop adjacent to a ventricular single-lead. This finding suggests that MAT develops in patients with this specific condition. Recognizing this condition is important for managing these arrhythmias and performing safe ablation with the preservation of PM lead integrity.

Catheter entrapment in Chiari network: Extraction with radiofrequency.

We report a challenging case of a duodecapolar mapping catheter entrapment in Chiari network and its release by radiofrequency energy application with an ablation catheter.

Radiofrequency ablation of a middle cardiac vein inserted accessory pathway resulting in posterolateral coronary artery occlusion: A case report.

INTRODUCTION: Posteroseptal accessory pathways account for 34.5% of the total. Of these, 36% are located within the coronary sinus (CS). Its ablation requires technical alternatives to avoid damage to surrounding tissues, especially branches of the right coronary artery. CASE REPORT: A 22-year-old man was referred for re-do ablation of an accessory left septal-septal (PSE) pathway. Inside the CS, a precocity of 25 ms was found in the region of the median cardiac vein (VCM) (Fig. 2, panel A). Radiofrequency (RF) was administered with a non-irrigated bidirectional catheter within this vessel with resolution of the pre-excitation after 5 seconds. Immediately after, the patient presented chest pain and revealed a ST segment elevation of 1 mm in the inferior leads of ECG. Coronary angiography showed occlusion of the middle third of the posterior ventricular branch of the right coronary artery, with no signs of thrombus or dissection. Arterial angioplasty was performed with a bare metal stent, followed by TIMI III distal flow. Retrograde aortic mapping was performed and a precocity of 20 ms was found in the PSE region. The RF was applied followed by loss of pre-excitation after 1.5 seconds of application. CONCLUSION: This case demonstrates the risks involving delivering radiofrequency within the coronary sinus. We discuss some strategy that could help electrophysiologists in similar cases.

Objective Evaluation of Gastroesophageal Reflux Disease in Patients with Paroxysmal Atrial Fibrillation.

BACKGROUND: Atrial fibrillation (AF) is the most common cardiac arrhythmia. Some evidence shows that gastroesophageal reflux disease (GERD) may be a trigger for paroxysmal AF (PAF). Most of the previous studies that correlated GERD and AF used questionnaires to diagnose GERD, not an objective evaluation. This study aims to evaluate in patients with PAF: (a) accuracy of symptoms to diagnose GERD; (b) prevalence of GERD; and (c) temporal correlation between cardiac arrhythmia and reflux. METHODS: Twenty-two patients (59% females, mean age 68 years) with PAF underwent esophageal manometry followed by ambulatory pH monitoring and concurrent Holter. Eight (36%) patients had GERD symptoms. Patients were grouped as GERD+ or GERD- based on the DeMeester score. Temporal correlation between arrhythmia and reflux was recorded. RESULTS: Six (27%) patients were GERD+. Symptoms had sensitivity and specificity of 50 and 70%, respectively, for the diagnosis of GERD. Episodic AF occurred in one patient only (GERD-). There were 23 episodes of AF during the test with 14% correlation with reflux. Persistent AF during the period of the test was found in five patients (60% GERD+). CONCLUSIONS: Our results show: (a) Symptoms have a low accuracy for the diagnosis of GERD; (b) the prevalence of GERD in patients with PAF is low; and

Ventricular arrhythmias are not a short-term reproducible phenomenon--why long recording monitoring is necessary.

BACKGROUND: The variability of ventricular arrhythmias (VA) among different days of the week is not well detected by one-day Holter monitoring. AIMS: To evaluate whether there are differences in VA distribution pattern during long recording period. METHODS: The EKG was recorded for 14 h per day during 7 days by Holter system in 34 consecutive pat ventricular couplets and non-sustained ventricular tachycardia (NSVT) recording from patients provided graphic data. We applied the Hurst method (H Coefficient) which evaluates whether a repetitive phenomenon is random or not. When the H is >0.5 and <1 means it is not random and implies a long-term memory effect. Considering the arrhythmic variability, the data were also analyzed by repetitive ANOVA comparing incidence of arrhythmias among the days. RESULTS: Isolated PVCs and ventricular couplets during 98 h recording provided graphic of the occurrence. A trend of increasing and decreasing of arrhythmias was observed which looks erratic. The H coefficient, however, was significantly >0.5 for all patients. Repeated ANOVA showed statistic difference among days in 31 patients with isolated PVCs; in 26 with ventricular couplets and 19 with NSVT when analyzed per hour during week days (p < 0.05). CONCLUSION: PVCs, ventricular couplets and NSVT are not a random phenomenon. Our data suggest the occurrence of ventricular arrhythmias had no similarity among the days, making unlikely that a single Holter recording for 24h may capture this phenomenon.

Amiodarone or Implantable Cardioverter-Defibrillator in Chagas Cardiomyopathy: The CHAGASICS Randomized Clinical Trial.

Importance: Over 10 000 people with Chagas disease experience sudden cardiac death (SCD) annually, mostly caused by ventricular fibrillation. Amiodarone hydrochloride and the implantable cardioverter-defibrillator (ICD) have been empirically used to prevent SCD in patients with chronic Chagas cardiomyopathy. Objective: To test the hypothesis that ICD is more effective than amiodarone therapy for primary prevention of all-cause mortality in patients with chronic Chagas cardiomyopathy and moderate to high mortality risk, assessed by the Rassi score. Design, Setting, and Participants: CHAGASICS is an open-label, randomized clinical trial. The study enrolled patients from 13 centers in Brazil from May 30, 2014, to August 13, 2021, with the last follow-up November 8, 2021. Patients with serological findings positive for Chagas disease, a Rassi risk score of at least 10 points (intermediate to high risk), and at least 1 episode of nonsustained ventricular tachycardia were eligible to participate. Data were analyzed from May 3, 2022, to June 16, 2023. Interventions: Patients were randomized 1:1 to receive ICD or amiodarone (with a loading dose of 600 mg after randomization). Main Outcomes and Measures: The primary outcome was all-cause mortality, and secondary outcomes included SCD, hospitalization for heart failure, and necessity of a pacemaker during the entire follow-up. Results: The study was stopped prematurely for administrative reasons, with 323 patients randomized (166 in the amiodarone group and 157 in the ICD group), rather than the intended 1100 patients. Analysis was by intention to treat at a median follow-up of 3.6 (IQR, 1.8-4.4) years. Mean (SD) age was 57.4 (9.8) years, 185 patients (57.3%) were male, and the mean (SD) left ventricular ejection fraction was 37.0% (11.6%). There were 60 deaths (38.2%) in the ICD arm and 64 (38.6%) in the amiodarone group (hazard ratio [HR], 0.86 [95% CI, 0.60-1.22]; P = .40). The rates of SCD (6 [3.8%] vs 23 [13.9%]; HR, 0.25 [95% CI, 0.10-0.61]; P = .001), bradycardia requiring pacing (3 [1.9%] vs 27 [16.3%]; HR, 0.10 [95% CI, 0.03-0.34]; P < .001), and heart failure hospitalization (14 [8.9%] vs 28 [16.9%]; HR, 0.46 [95% CI, 0.24-0.87]; P = .01) were lower in the ICD group compared with the amiodarone arm. Conclusions and Relevance: In patients with chronic Chagas cardiomyopathy at moderate to high risk of mortality, ICD did not reduce the risk of all-cause mortality. However, ICD significantly reduced the risk of SCD, pacing need, and heart failure hospitalization compared with amiodarone therapy. Further studies are warranted to confirm the evidence generated by this trial. Trial Registration: ClinicalTrials.gov Identifier: NCT01722942.

CHronic use of Amiodarone aGAinSt Implantable cardioverter-defibrillator therapy for primary prevention of death in patients with Chagas cardiomyopathy Study: rationale and design of a randomized clinical trial.

BACKGROUND: The implantable cardioverter defibrillator (ICD) is better than antiarrhythmic drug therapy for the primary and secondary prevention of all-cause mortality and sudden cardiac death in patients with either coronary artery disease or idiopathic dilated cardiomyopathy. This study aims to assess whether the ICD also has this effect for primary prevention in chronic Chagas cardiomyopathy (CCC). METHODS: In this randomized (concealed allocation) open-label trial, we aim to enroll up to 1,100 patients with CCC, a Rassi risk score for death prediction of ≥10 points, and at least 1 episode of nonsustained ventricular tachycardia on a 24-hour Holter monitoring. Patients from 28 centers in Brazil will be randomly assigned in a 1:1 ratio to receive an ICD or amiodarone (600 mg/d for 10 days, then 200-400 mg/d until the end of the study). The randomization sequence will be generated by computer, and the members of the committees responsible for end point validation and data analysis will be blinded to study assignment. The primary end point is all-cause death, and enrolment will continue until 256 patients have reached this end point. Key secondary end points include cardiovascular death, sudden cardiac death, hospitalization for heart failure, and quality of life. We expect follow-up to last 3 to 6 years, and data analysis will be done on an intention-to-treat basis. This trial is registered with ClinicalTrials.gov number NCT01722942. CONCLUSION: CHAGASICS is the first large-scale trial to assess the benefit of ICD therapy for the primary prevention of death in patients with CCC and nonsustained ventricular tachycardia, who have a moderate to high risk of death.

Volume-time curve: an alternative for endotracheal tube cuff management.

BACKGROUND: Despite numerous studies on endotracheal tube cuff pressure (CP) management, the literature has yet to establish a technique capable of adequately filling the cuff with an appropriate volume of air while generating low CP in a less subjective way. The purpose of this prospective study was to evaluate and compare the CP levels and air volume required to fill the endotracheal tubes cuff using 2 different techniques (volume-time curve versus minimal occlusive volume) in the immediate postoperative period after coronary artery bypass grafting. METHODS: A total of 267 subjects were analyzed. After the surgery, the lungs were ventilated using pressure controlled continuous mandatory ventilation, and the same ventilatory parameters were adjusted. Upon arrival in the ICU, the cuff was completely deflated and re-inflated, and at this point the volume of air to fill the cuff was adjusted using one of 2 randomly selected techniques: volume-time curve and minimal occlusive volume. We measured the volume of air injected into the cuff, the CP, and the expired tidal volume of the mechanical ventilation after the application of each technique. RESULTS: The volume-time curve technique demonstrated a significantly lower CP and a lower volume of air injected into the cuff, compared to the minimal occlusive volume technique (P < .001). No significant difference was observed in the expired tidal volume between the 2 techniques (P = .052). However, when the subjects were submitted to the minimal occlusive volume technique, 17% (n = 47) experienced air leakage as observed by the volume-time graph. CONCLUSIONS: The volume-time curve technique was associated with a lower CP and a lower volume of air injected into the cuff, when compared to the minimal occlusive volume technique in the immediate postoperative period after coronary artery bypass grafting. Therefore, the volume-time curve may be a more reliable alternative for endotracheal tube cuff management.

Epicardial and Endocardial Ablation Based on Channel Mapping in Patients With Ventricular Tachycardia and Chronic Chagasic Cardiomyopathy: Importance of Late Potential Mapping During Sinus Rhythm to Recognize the Critical Substrate.

Background Ventricular tachycardia (VT) in patients with chronic chagasic cardiomyopathy (CCC) is associated with considerable morbidity and mortality. Catheter ablation of VT in patients with CCC is very complex and challenging. The main goal of this work was to assess the efficacy of VT catheter ablation guided by late potentials (LPs) in patients with CCC. Methods and Results Seventeen consecutive patients with refractory VT and CCC were prospectively included in the study. Combined endo-epicardial voltage and late activation mapping were obtained during baseline rhythm to define scarred and LP areas, respectively. The end point of the ablation procedure was the elimination of all identified LPs. Epicardial and endocardial dense scars (<0.5 mV) were detected in 17/17 and 15/17 patients, respectively. LPs were detected in the epicardial scars of 16/17 patients and in the endocardial scars of 14/15 patients. A total of 63 VTs were induced in 17 patients; 22/63 (33%) were stable and entrained, presenting LPs recorded in the isthmus sites. The end point of ablation was achieved in 15 of 17 patients. Ablation was not completed in 2 patients because of cardiac tamponade or vicinity of the phrenic nerve and circumflex artery. Three patients (2 with unsuccessful ablation) had VT recurrence during follow-up (39 months). Conclusions Endo-epicardial LP mapping allows us to identify the putative isthmuses of different VTs and effectively perform catheter ablation in patients with CCC and drug-refractory VTs.

Epicardial mapping complicated by multi-vessel coronary spasm and electrical storm.

The case report describes a severe multi-vessel coronary spasm complicating the epicardial mapping in a patient with chronic Chagas cardiomyopathy.

Prevalence of atrial fibrillation and stroke risk assessment based on telemedicine screening tools in a primary healthcare setting.

BACKGROUND: Worldwide atrial fibrillation (AF) prevalence varies between 0.1% and 4.0%, and has been increasing. Little is known about the prevalence of AF in Brazil. Our objective was to estimate the prevalence of AF in several regions of Brazil using recordings of long-distance electrocardiogram (ECG) transmission. METHODS: Patients from 125 outpatient general practitioner units covered by the telemedicine service of the Federal University of São Paulo were included. Only one ECG was considered per patient. A scripted telephone interview was also performed. We analyzed the data to project the prevalence of AF in the Brazilian population and estimate it for the year 2025. The overall AF prevalence was calculated based on ECGs from primary care units where patients went for routine visits. RESULTS: Based on 676,621 ECG exams from January 2009 through April 2016, the mean age (±SD) of patients was 51.38 (±19.05) years, with 57.5% being female. The 7-year period prevalence of AF was 2.2% (n = 14,968). The prevalence of AF countrywide was projected to be 1.5% in 2016 and 1.7% in 2025. In the subset of patients with AF who were interviewed (n = 301), 91 (30.2%) were not receiving any type of treatment for rate or rhythm control. Among patients interviewed, 189 (62.8%) were at high risk for stroke; only 28 (14.8%) were regular oral anticoagulant users. CONCLUSIONS: Our study highlights the importance of screening for AF in the primary care setting in Brazil and identifies important gaps in the treatment of AF in this population.

Amiodarone or implantable cardioverter-defibrillator in chagas cardiomyopathy: the CHAGASICS randomized clinical trial

IMPORTANCE: Over 10 000 people with Chagas disease experience sudden cardiac death (SCD) annually, mostly caused by ventricular fibrillation. Amiodarone hydrochloride and the implantable cardioverter-defibrillator (ICD) have been empirically used to prevent SCD in patients with chronic Chagas cardiomyopathy. OBJECTIVE: To test the hypothesis that ICD is more effective than amiodarone therapy for primary prevention of all-cause mortality in patients with chronic Chagas cardiomyopathy and moderate to high mortality risk, assessed by the Rassi score. DESIGN, SETTING, AND PARTICIPANTS: CHAGASICS is an open-label, randomized clinical trial. The study enrolled patients from 13 centers in Brazil from May 30, 2014, to August 13, 2021, with the last follow-up November 8, 2021. Patients with serological findings positive for Chagas disease, a Rassi risk score of at least 10 points (intermediate to high risk), and at least 1 episode of nonsustained ventricular tachycardia were eligible to participate. Data were analyzed from May 3, 2022, to June 16, 2023. INTERVENTIONS: Patients were randomized 1:1 to receive ICD or amiodarone (with a loading dose of 600 mg after randomization). MAIN OUTCOMES AND MEASURES: The primary outcome was all-cause mortality, and secondary outcomes included SCD, hospitalization for heart failure, and necessity of a pacemaker during the entire follow-up. RESULTS: The study was stopped prematurely for administrative reasons, with 323 patients randomized (166 in the amiodarone group and 157 in the ICD group), rather than the intended 1100 patients. Analysis was by intention to treat at a median follow-up of 3.6 (IQR, 1.8-4.4) years. Mean (SD) age was 57.4 (9.8) years, 185 patients (57.3%) were male, and the mean (SD) left ventricular ejection fraction was 37.0% (11.6%). There were 60 deaths (38.2%) in the ICD arm and 64 (38.6%) in the amiodarone group (hazard ratio [HR], 0.86 [95% CI, 0.60-1.22]; P = .40). The rates of SCD (6 [3.8%] vs 23 [13.9%]; HR, 0.25 [95% CI, 0.10-0.61]; P = .001), bradycardia requiring pacing (3 [1.9%] vs 27 [16.3%]; HR, 0.10 [95% CI, 0.03-0.34]; P < .001), and heart failure hospitalization (14 [8.9%] vs 28 [16.9%]; HR, 0.46 [95% CI, 0.24-0.87]; P = .01) were lower in the ICD group compared with the amiodarone arm. CONCLUSIONS AND RELEVANCE: In patients with chronic Chagas cardiomyopathy at moderate to high risk of mortality, ICD did not reduce the risk of all-cause mortality. However, ICD significantly reduced the risk of SCD, pacing need, and heart failure hospitalization compared with amiodarone therapy. Further studies are warranted to confirm the evidence generated by this trial.

Algoritmo EPM: uma abordagem passo a passo para localização de via acessória na pré-excitação ventricular / EPM algorithm: a step-by-step approach for accessory pathway localization in ventricular pre-excitation

INTRODUÇÃO: Aestimativa precisa da localização da via acessória (VA) em pacientes com pré-excitação ventricular ou síndrome de Wolff-Parkinson-White (WPW) continua sendo um desafio diagnóstico. Algoritmos existentes têm contribuído significativamente nessa área, mas abordagens alternativas podem oferecer novas perspectivas na localização da VA. OBJETIVO: Este estudo introduz e avalia a precisão diagnóstica do algoritmo EPM na localização da VA, comparando-o com os algoritmos consagrados Arruda e EASY. MÉTODOS: Foi realizada uma análise retrospectiva de 138 pacientes do Hospital São Paulo submetidos à ablação por cateter. Três examinadores cegos avaliaram a precisão diagnóstica do algoritmo EPM em comparação com os algoritmos Arruda e EASY. O padrão-ouro para comparação foi a posição radioscópica da VA onde a ablação por radiofrequência levou ao desaparecimento da pré-excitação no ECG. RESULTADOS: O EPM apresentou uma precisão diagnóstica de 51,45%, alinhando-se com Arruda (53,29%) e EASY (44,69%). Aprecisão de adjacência para o EPM foi de 70,67%, com Arruda em 66,18% e EASYem 72,22%. Asensibilidade do EPM para distinguir VAesquerda de direita foi de 95,73%, com uma especificidade de 74,33%. Na identificação de VAseptal versus lateral direita, a sensibilidade do EPM foi de 82,79% com especificidade de 46,15%. Esses resultados foram comparáveis aos dos algoritmos Arruda e EASY. A variabilidade interobservadores foi excelente para o EPM, com estatísticas Kappa superiores a 0,9. CONCLUSÃO: O algoritmo EPM se destaca como uma ferramenta confiável para localização da VA, oferecendo uma abordagem sistemática que pode ser útil na tomada de decisões terapêuticas em eletrofisiologia. Sua precisão diagnóstica comparável e excelente variabilidade interobservadores sublinham sua aplicabilidade clínica potencial. Pesquisas futuras podem validar ainda mais sua eficácia em cenários clínicos mais amplos.

EPM algorithm: a stepwise approach to accessory pathway localization in ventricular pre-excitation

BACKGROUND: Accurate estimation of accessory pathway (AP) localization in patients with ventricular pre-excitation or Wolff-Parkinson-White (WPW) syndrome remains a diagnostic challenge. Existing algorithms have contributed significantly to this area, but alternative algorithms can offer additional perspectives and approaches to AP localization. OBJECTIVE: This study introduces and evaluates the diagnostic accuracy of the EPM algorithm in AP localization, comparing it with established algorithms Arruda and EASY. METHODS: A retrospective analysis was conducted on 138 patients from Hospital São Paulo who underwent catheter ablation. Three blinded examiners assessed the EPM algorithm's diagnostic accuracy against the Arruda and EASY algorithms. The gold standard for comparison was the radioscopic position of the AP where radiofrequency ablation led to pre-excitation disappearance on the ECG. RESULTS: EPM showed a diagnostic accuracy of 51.45%, closely aligning with Arruda (53.29%) and EASY (44.69%). Adjacency accuracy for EPM was 70.67%, with Arruda at 66.18% and EASY at 72.22%. Sensitivity for EPM in distinguishing left vs. right APs was 95.73%, with a specificity of 74.33%. For identifying septal vs. lateral right APs, EPM sensitivity was 82.79% with a specificity of 46.15%. These measures were comparable to those of Arruda and EASY. Inter-observer variability was excellent for EPM, with Kappa statistics over 0.9. CONCLUSION: The EPM algorithm emerges as a reliable tool for AP localization, offering a systematic approach beneficial for therapeutic decision-making in electrophysiology. Its comparable diagnostic accuracy and excellent inter-observer variability underscore its potential clinical applicability. Future research may further validate its efficacy in a broader clinical setting.

Electroanatomic remodeling of the left atrium in patients undergoing repeat pulmonary vein ablation: mechanistic insights and implications for ablation.

INTRODUCTION: There is limited information describing late changes in the electroanatomic characteristics of the left atrium (LA) associated with recurrence after an anatomical circumferential pulmonary vein ablation (CPVA) for atrial fibrillation (AF). METHODS AND RESULTS: Forty-seven patients (57 +/- 8 years) undergoing a repeat ablation after CPVA were included. Using an electroanatomic mapping system, we measured the bipolar voltage by averaging points in the pulmonary vein (PV)-LA junction and four other LA sites. Conduction velocity and AF cycle length (AFCL) were also measured and the results are compared with the first procedure. After an initial decrease observed at the end of the first procedure, voltage and conduction velocity returned to intermediate values in all LA sites, with lower voltage at the LIPV antrum (P = 0.004), and lower conduction velocity across the LIPV and RSPV (P < 0.001). Conduction gaps were more prevalent at the septal aspect of the right PV encircling lines (85%), between the left atrial appendage (LAA) and the LSPV (70%) and lines at the posterior wall (71%). There was a nonsignificant increase in AFCL, with a more widespread distribution of organized electrograms (32.4% vs 46.6%). CONCLUSION: Recurrence after CPVA is associated with a reverse process of voltage and conduction velocity increase across ablated areas, especially the PV-LA junction, and is related to the presence of conduction gaps, which are distributed mostly at the septal aspect of the lines encircling the right PVs and at the LAA-LSPV area. Organization of atrial electrograms seen during AF ablation is maintained at a repeat procedure.

Effect of central hypothyroidism on Doppler-derived myocardial performance index.

BACKGROUND: Myocardial performance index (MPI) has been used to assess global ventricular function in different types of cardiac disease. Thyroid hormones influence cardiac performance directly and indirectly by changes in peripheral circulation. The aim of this study was to evaluate the possible effect of central hypothyroidism (CH) on MPI. METHODS: The study included 28 control subjects and 7 patients with CH without cardiac disease. MPI was defined as the sum of isovolumetric contraction time (ICT) and isovolumetric relaxation time divided by ejection time. Patients were submitted to hormonal therapy with thyroxin and the study was repeated after 35 to 42 days. RESULTS: MPI was significantly higher in patients with CH (0.54 +/- 0.08) than in control subjects (0.40 +/- 0.05) (P =.002). The increase in MPI was caused by the prolongation of ICT without a significant variation of isovolumetric relaxation time and ejection time. After hormonal therapy there was a significant reduction of MPI (0.54 +/- 0.08 vs 0.42 +/- 0.07; P =.028) and ICT. CONCLUSION: MPI was increased in patients with untreated CH. The increase was related to prolongation of ICT and reverted by hormonal therapy.