Analysis of Conduction Intervals in Normal Electrophysiological Studies: Establishment of Reference Values the Brazilian Population

Abstract Background In the investigation of cardiac rhythm disorders, a normal electrophysiological (EPS) study is associated with a favorable prognosis. One of the normality criteria is established by conduction intervals within expected range. Objective To establish reference values in EPS for the intracavitary conduction intervals (PA, AH and HV) in a Brazilian population. Methods A retrospective cohort study of the first 1,500 patients submitted to EPS ablation was performed at Instituto de Cardiologia do Rio Grande do Sul, Brazil. The EPS was considered normal if the test was performed for diagnostic purpose; absence of induced arrhythmias; and conduction intervals within the expected range. The REDCap software was used for data collection and management, and the SPSS Statistics 22.0 used for data analysis. Continuous variables were compared with Student's t-test for independent samples and categorical variables with the chi-square test (X 2 ). Values of p ≤ 0.05 were considered significant. Results A total of 124 (8.3%) with EPS considered normal were included; mean age was 52 ± 21 years, and 63 were male. The mean values in milliseconds of PA, AH and HV were 23 ± 9, 88 ± 25 and 44 ± 7, respectively. The PA, AH, and HV percentile ranges were 13 - 25, 81-107 and 40 - 52, respectively. When the patients were divided into three age groups (1 to 18 years, 19 to 64 years and 65 or more), we observed that the group of older patients had significantly higher values of PA, AH and HV compared with younger patients. Conclusion This study showed that intracavitary conduction intervals in a sample of the Brazilian population were similar to previously published studies. Elderly patients tend to have higher values of intracavitary conduction intervals in EPS. Future studies including broader age ranges could enable the acquisition of more reliable and reproducible reference values. (Int J Cardiovasc Sci. 2020; [online].ahead print, PP.0-0)

Atrial flutter and embolic risk: The relationship between atrial flutter cycle length and left atrial appendage function.

BACKGROUND: The potential for thromboembolism in atrial flutter (AFL) is different from atrial fibrillation. AFL cycle length (AFL-CL) may be related to reduced left atrial appendage (LAA) function. Very rapid AFL-CL can lead to mechanical and electrophysiological disorders that contribute to lower LAA emptying velocity (LAEV). The aim of this study is to relate atrial flutter cycle length with LAEV and its role in thrombogenesis. METHODS: Cross-sectional study of patients with atrial flutter AFL who underwent transoesophageal echocardiography (TEE) before catheter ablation or electric cardioversion. AFL-CL in milliseconds was measured with a 12-lead EKG or in intracardiac records. RESULTS: We included 123 patients. There was correlation between AFL-CL and LAEV (r = 0.34; p = 0.003) in typical AFL. Cycle length, LA size and atypical flutter were predictors of low LAEV on multivariate analysis. An index multiplying atrial rate (bpm) during the arrhythmia versus left atrial size(mm) >11,728 was associated with spontaneous echogenic contrast and/or left atrial thrombus on TEE (C-statistic = 0.71; CI95%0.60-0.81). CONCLUSIONS: There was a significant relationship between the AFL-CL and LAEV. The LAEV was affected by the LA size, the type of atrial flutter and the AFL-CL. A new index, relating the atrial rate with the left atrial size, was able to identify a higher occurrence of spontaneous echogenic contrast and/or left atrial thrombus.

CHA2 DS2 VASc Score as a Predictor of Cardiovascular Events in Ambulatory Patients without Atrial Fibrillation.

BACKGROUND: New evidence suggests that the CHA(2)DS(2)VASc (congestive heart failure, hypertension [HTN], age, diabetes, stroke, vascular disease, and female gender) score may be a reliable tool to predict the risk of thromboembolic events in patients without documented atrial fibrillation (AF). METHODS: We performed a prospective cohort study of outpatients without AF or flutter, who were not using oral anticoagulation. Clinical characteristics were assessed and patients were stratified according to the CHA(2)DS(2)VASc score. We evaluated the incidence of major adverse cardiac outcomes and its relation to the CHA(2)DS(2)VASc score during the follow-up. RESULTS: Four hundred sixty-eight patients without AF were enrolled with a mean follow-up of 12 ± 6 months. Age was 64.9 ± 11.3 years. The prevalence of HTN was 88.4%, diabetes 37.6%, heart failure 26.3%, and vascular disease 61.7%. Overall, CHA(2)DS(2)VASc score was 3.4 ± 1.4. There were 15 major adverse cardiac outcomes during 12.2 months of follow-up (overall incidence of 3.2 per 100 person-years). We found significant differences in relation to gender, age, previous stroke, and follow-up length in patients with and without adverse outcomes. The CHA(2)DS(2)VASc score was higher in those with adverse outcomes (4.2 ± 1.7 vs 3.4 ± 1.4; P = 0.035). Patients with a CHA(2)DS(2)VASc ≥6 had a relative risk for adverse outcomes of 4.2 (95% confidence interval: 1.27-13.90). CONCLUSIONS: In our population, CHA(2)DS(2)VASc score predicts major adverse cardiac outcomes, including stroke and death, in a cohort of patients without AF.

Clinical Differences between Subtypes of Atrial Fibrillation and Flutter: Cross-Sectional Registry of 407 Patients / Diferenças Clínicas entre Subtipos de Fibrilação Atrial e Flutter: Registro Transversal de 407 Pacientes

Atrial fibrillation and atrial flutter account for one third of hospitalizations due to arrhythmias, determining great social and economic impacts. In Brazil, data on hospital care of these patients is scarce.

Clinical Differences between Subtypes of Atrial Fibrillation and Flutter: Cross-Sectional Registry of 407 Patients.

INTRODUCTION: Atrial fibrillation and atrial flutter account for one third of hospitalizations due to arrhythmias, determining great social and economic impacts. In Brazil, data on hospital care of these patients is scarce. OBJECTIVE: To investigate the arrhythmia subtype of atrial fibrillation and flutter patients in the emergency setting and compare the clinical profile, thromboembolic risk and anticoagulants use. METHODS: Cross-sectional retrospective study, with data collection from medical records of every patient treated for atrial fibrillation and flutter in the emergency department of Instituto de Cardiologia do Rio Grande do Sul during the first trimester of 2012. RESULTS: We included 407 patients (356 had atrial fibrillation and 51 had flutter). Patients with paroxysmal atrial fibrillation were in average 5 years younger than those with persistent atrial fibrillation. Compared to paroxysmal atrial fibrillation patients, those with persistent atrial fibrillation and flutter had larger atrial diameter (48.6 ± 7.2 vs. 47.2 ± 6.2 vs. 42.3 ± 6.4; p < 0.01) and lower left ventricular ejection fraction (66.8 ± 11 vs. 53.9 ± 17 vs. 57.4 ± 16; p < 0.01). The prevalence of stroke and heart failure was higher in persistent atrial fibrillation and flutter patients. Those with paroxysmal atrial fibrillation and flutter had higher prevalence of CHADS2 score of zero when compared to those with persistent atrial fibrillation (27.8% vs. 18% vs. 4.9%; p < 0.01). The prevalence of anticoagulation in patients with CHA2DS2-Vasc ≤ 2 was 40%. CONCLUSIONS: The population in our registry was similar in its comorbidities and demographic profile to those of North American and European registries. Despite the high thromboembolic risk, the use of anticoagulants was low, revealing difficulties for incorporating guideline recommendations. Public health strategies should be adopted in order to improve these rates.

Electrophysiological Studies and Radiofrequency Ablations in Children and Adolescents with Arrhythmia / Estudos Eletrofisiológicos e Ablações com Radiofrequência em Crianças e Adolescentes com Arritmia

Background: Radiofrequency ablation is the standard non-pharmacological treatment for arrhythmias in pediatric patients. However, arrhythmias and their associated causes have particular features in this population. Objective: To analyze the epidemiological characteristics and findings of electrophysiological diagnostic studies and radiofrequency ablations in pediatric patients referred to the Electrophysiology Unit at Instituto de Cardiologia do Rio Grande do Sul, in order to characterize the particularities of this population. Methods: Cross-sectional study with 330 electrophysiological procedures performed in patients aged less than 20 years between June 1997 and August 2013. Results: In total, 330 procedures (9.6% of the overall procedures) were performed in patients aged less than 20 years (14.33 ± 3.25 years, age range 3 months to 19 years), 201 of which were males (60.9%). A total of 108 (32.7%) electrophysiological diagnostic studies were performed and of these, 48.1% showed abnormal findings. Overall, 219 radiofrequency ablations were performed (66.3%) with a success rate of 84.8%. The presence of an accessory pathway was the most prevalent finding, occurring in 158 cases (72.1%), followed by atrioventricular nodal reentrant tachycardia (16.8%), typical atrial flutter (3.1%) and extrasystoles originating from the right ventricular outflow tract (2.7%). Three patients developed complications during ablation (1.4%). Among congenital heart diseases, which occurred in 51 (15.4%) patients, atrial sept defect was the most frequent (27.4%), followed by ventricular sept defect (25.4%) and Ebstein's anomaly (17.6%). Conclusion: Electrophysiological study and radiofrequency ablation are effective tools for diagnosis and treatment of arrhythmias in the pediatric population. .

Fundamento: A ablação com radiofrequência é o tratamento não farmacológico de eleição para arritmias na população pediátrica. Porém, as arritmias e suas causas apresentam características particulares nesta população. Objetivos: Analisar as características epidemiológicas e os achados de estudo eletrofisiológico diagnóstico e ablação com radiofrequência na população pediátrica encaminhada à Eletrofisiologia do Instituto de Cardiologia do Rio Grande do Sul, a fim de caracterizar as suas particularidades. Resultados: Foram realizados 330 procedimentos (9,6% do total de procedimentos) em pacientes com idade inferior a 20 anos (14,33 ± 3,25 anos, variação entre 3 meses e 19 anos), dos quais 201 eram do sexo masculino (60,9%). Foram realizados 108 (32,7%) exames eletrofisiológicos diagnósticos e destes, 48,1% apresentaram anormalidades em seus achados. Ao todo, 219 ablações com radiofrequência foram realizadas (66,3%), obtendo-se sucesso em 84,8%. A presença de feixe acessório foi o achado mais prevalente, responsável por 158 casos (72,1%), seguida de taquicardia por reentrada nodal atrioventricular (16,8%), flutter atrial típico (3,1%) e extrassístole de via de saída de ventrículo direito (2,7%). Três pacientes apresentaram complicações durante a ablação (1,4%). Cardiopatia congênita esteve presente em 51 (15,4%) casos, sendo a comunicação interatrial a mais encontrada (27,4%), seguida de comunicação interventricular (25,4%) e anomalia de Ebstein (17,6%). Conclusão: Estudo eletrofisiológico e ablação com radiofrequência constituem ferramentas eficazes no diagnóstico e tratamento das arritmias na população pediátrica. .

Electrophysiological studies and radiofrequency ablations in children and adolescents with arrhythmia.

BACKGROUND: Radiofrequency ablation is the standard non-pharmacological treatment for arrhythmias in pediatric patients. However, arrhythmias and their associated causes have particular features in this population. OBJECTIVE: To analyze the epidemiological characteristics and findings of electrophysiological diagnostic studies and radiofrequency ablations in pediatric patients referred to the Electrophysiology Unit at Instituto de Cardiologia do Rio Grande do Sul, in order to characterize the particularities of this population. METHODS: Cross-sectional study with 330 electrophysiological procedures performed in patients aged less than 20 years between June 1997 and August 2013. RESULTS: In total, 330 procedures (9.6% of the overall procedures) were performed in patients aged less than 20 years (14.33 ± 3.25 years, age range 3 months to 19 years), 201 of which were males (60.9%). A total of 108 (32.7%) electrophysiological diagnostic studies were performed and of these, 48.1% showed abnormal findings. Overall, 219 radiofrequency ablations were performed (66.3%) with a success rate of 84.8%. The presence of an accessory pathway was the most prevalent finding, occurring in 158 cases (72.1%), followed by atrioventricular nodal reentrant tachycardia (16.8%), typical atrial flutter (3.1%) and extrasystoles originating from the right ventricular outflow tract (2.7%). Three patients developed complications during ablation (1.4%). Among congenital heart diseases, which occurred in 51 (15.4%) patients, atrial sept defect was the most frequent (27.4%), followed by ventricular sept defect (25.4%) and Ebstein's anomaly (17.6%). CONCLUSION: Electrophysiological study and radiofrequency ablation are effective tools for diagnosis and treatment of arrhythmias in the pediatric population.