ABSTRACT
Fundamentos: A fibrilação atrial (FA) apresenta alta taxa de recorrência que pode ser explicada por dois mecanismos: o primeiro diz respeito à capacidade dessa arritmia se perpetuar através da autoindução de alterações eletrofisiológicas, denominadas de remodelagem elétrica. O segundo mecanismo está relacionado a condições cardiovasculares subjacentes que podem estar presentes com alterações estruturais do coração, mesmo que de forma subclínica, por um longo período de tempo até o primeiro episódio de FA. Objetivo: Investigar a importância do eletrocardiograma de alta resolução da onda P (ECGAR-P) na avaliação da remodelagem elétrica atrial e na predição de recorrência da fibrilação atrial. Métodos: Foram realizados dois estudos, o ECGAR-P foi aplicado em ambos. No primeiro avaliaram-se os padrões evolutivos da ativação elétrica atrial durante um mês em 31 pacientes com FA idiopática de longa duração e submetidos à cardioversão. No segundo, investigou-se o ECGAR-P e outros preditores clínicos de não resposta à amiodarona em baixa dose, após a cardioversão do primeiro episódio persistente e altamente sintomático de FA não valvar. O segundo estudo incluiu 87 pacientes e teve seguimento mínimo de 24 meses. Ao final do seguimento, a resposta à terapia antiarrítmica (TA) foi considerada como não responsiva quando ocorreram duas ou mais recorrências de FA ou insucesso em nova cardioversão. Obteve-se de todos os participantes, de ambos os estudos, o Consentimento Livre e Esclarecido, tendo sido o estudo aprovado pelo Comitê de Ética da instituição. Resultados: O primeiro estudo mostrou que entre 31 indivíduos, 9 tiveram recorrência precoce da arritmia, todos nos primeiros sete dias após a cardioversão, e 22 permaneceram em ritmo sinusal por pelo menos um mês. Nesses pacientes a duração da onda P diminuiu progressivamente do primeiro para o terceiro ECGAR. Na análise no domínio da frequência, a turbulência espectral se mostrou inaparente no ECGAR imediato...
Background: Atrial fibrillation is frequently disabling and drug resistant. The high rate of recurrence of AF is represented by two separate mechanisms: the first can be summarized as atrial fibrillation (AF) itself promotes electrophysiological changes, termed "electrical remodeling", facilitationg its recurrence and maintenance. There are evidences that the remodeling process is reversible after restoration of sinus rhythm. However, the timing for recovery of electrophysiological properties is characterized by marked vulnerability to early recurrence of the arrhythmia and still undefined. The second mechanism relates to underlying cardiovascular conditions and cardiac structural changes, which may be hidden for a long time until AF emerges. Objective: In the first article we evaluated the atrial electrical activation by using P-wave signal-averaged electrocardiogram (P-SAECG) post-cardioversion of long-standing lone AF, focusing on the reversal remodeling process to identify the timing of stabilization of the process. The objective of the second article was evaluated the follow-up of patients after cardioversion of the first persistent AF episode, with poorly symptoms and without structural cardiopathy. Methods: In the first study with 31 patients, P-SAECG was performed immediately after cardioversion and repeated on days seven and thirty. The second article included 87 patients with highly symptomatic first-detected persistent AF. After successful electrical cardioversion, echocardiogram and P-SAECG were obtained. During the segment, for all patients were prescribed low-dose of amiodarone and each one were followed-up at least for 24 months. At the end of the follow-up, antiarrythmic therapy (AT) outcome was defined as nonresponse if there were >- 2 recurrences of symptomatic AF or unsuccessful in sequential cardioversion. Results: the results of the first study shows that among 31 subjets, nine underwent early recurrence of AF, all of then...
Subject(s)
Humans , Male , Female , Amiodarone/therapeutic use , Anti-Arrhythmia Agents/therapeutic use , Electric Countershock , Electrophysiologic Techniques, Cardiac , Electrocardiography/methods , Atrial Fibrillation/diagnosis , Atrial Fibrillation/physiopathology , Atrial Fibrillation/therapy , Recurrence/prevention & control , Signal Processing, Computer-Assisted , Age FactorsABSTRACT
PURPOSE--To study by using the signal-averaged P wave, the atrial activation of patients with documented episodes of paroxysmal atrial fibrillation (PAF). METHODS--This study enrolled a total of 20 patients with documented episodes of paroxysmal atrial fibrillation (males 14; mean age 58.4 +/- 10.6 years). The signal-averaged P wave was recorded with a Corazonix Predictor II system. The total P wave duration was determined from the combined filtered x,y,z vector-magnitude and used for analysis. The results were compared with a normal group of 10 patients, matched in age. RESULTS--In the control group, the total P wave duration ranged from 120.0 to 135.0 (mean = 128.3 +/- 5.8) ms. In the group of PAF, the total P wave duration ranged from 118.0 to 168.5 (mean = 151.5 +/- 13.7) ms (p < 0.000). Sixteen (80) of this patients showed a P wave duration > 140.0 ms. With a cut < 140.0 ms for the normal atrial activation, the sensitivity was 76, specificity was 100, positive and negative predictive value were 100 and 60 respectively for the method detected patients with PAF. CONCLUSION--Patients with PAF showed a prolonged signal-averaged P wave duration and should be differentiated by this method from the normal population.
Subject(s)
Humans , Male , Female , Adult , Middle Aged , Electrocardiography , Atrial Fibrillation/physiopathology , Tachycardia, Paroxysmal/physiopathology , Atrial Flutter , Predictive Value of Tests , Sensitivity and Specificity , Atrial Fibrillation/diagnosis , Tachycardia, Paroxysmal/diagnosisABSTRACT
PURPOSE--To evaluate by the signal averaged-ECG (SAECG) the initial portion of the activation of the sustained ventricular tachycardia (SVT) and monomorphic repetitive ventricular tachycardia (MRVT), correlating the findings with those obtained during sinus rhythm (SR). METHODS--Ten patients was studied; five with SVT and five with MRVT. Patients with SVT presented a positive SAECG while patients with MRVT the test was negative, during SR. The findings of this two populations were compared with those obtained in a group of ten patients with advanced bundle branch block (ABBB--five RBBB and five LBBB). We analyzed in the vector-magnitude obtained during VT and ABBB, the root mean square of the initial 40 ms portion of the activation (RMS40) and the duration of the low amplitude signals < 40 microV from the beginning of the filtered QRS (LAS). To define the positiveness of the test in SR, we analyzed the final RMS40 (normal > 20 microV), the duration of the LAS < 40 microV at the end of the activation (normal < 38 ms) and the total QRS duration (QRSD-normal < 114 ms). RESULTS--(mean)-SVT in SR: RMS40 = 11.2 +/- 6.2 microV; LAS = 47.4 +/- 5.8 ms; QRSD = 131.2 +/- 8.7 ms. SVT during VT: RMS40 = 6.9 +/- 4.5 microV; LAS = 54.5 +/- 9.1 ms. RMVT in SR: RMS40 = 59.7 +/- 49.0 microV; LAS = 28.3 +/- 8.5 ms; QRSD = 93.1 +/- 13.0 ms. MRVT during VT: RMS = 25.2 +/- 8.8 microV; LAS = 28.9 +/- 11.1 ms. RBBB: RMS = 53.3 +/- 34.2 microV; LAS = 22.6 +/- 9.8 ms. LBBB: RMS = 54.7 +/- 37.3 microV; LAS = 11.4 +/- 4.6 ms. The comparison between the data from SVT and MRVT/ABBB showed p < 0.01. CONCLUSION--In the studied population, the SAECG was able to identify abnormal LAS initiating SVT, that were not present in MRVT and ABBB. This signals probably represents intra-myocardial slow conduction, as a portion of a re-entry circuit. There was an excellent correlation between the findings during SVT and MRVT with those obtained in SR