Refining the deceleration capacity index in phase-rectified signal averaging to assess physical conditioning level.

BACKGROUND: Deceleration capacity (DC) of heart rate is a measure of cardiac vagal modulation. This study introduced a DC adaptation (Modified Index) that measured the velocity of change in the phase-rectified signal averaging curve, and assessed its ability to discriminate athletes from controls. MATERIALS AND METHODS: The Modified Index was compared to Standard DC approach in a prospective case-control study. Subjects were classified according to maximal metabolic equivalents as the control group (CG) and athlete group (AG). The Modified Index was compared to Standard DC and classical approaches (RMSSD and HF) by the area under receiver operating characteristic curve (AUC) using 10,000 bootstraps. RESULTS: In Standard DC and Modified Index bootstrap median values were (ms), respectively, 11.80 and 17.94 (p<0.01) in CG, and 25.98 and 45.62 in AG (p<0.01). AUC (mean±SD) was 0.70±0.12 for Standard DC and 0.96±0.04 for Modified Index (p<0.01). CONCLUSIONS: Modified Index appropriately discriminates athletes from healthy sedentary subjects.

Clinical and Laboratory Data Up on Hospital Admission are Predictors of New-Onset Atrial Fibrillation in Patients Hospitalized Due to COVID-19 Pneumonia. / Variáveis Clínicas e Laboratoriais na Admissão Hospitalar são Preditores de Fibrilação Atrial Nova em Pacientes Internados com Pneumonia por COVID-19.

BACKGROUND: New-onset atrial fibrillation (NOAF) occurs in patients hospitalized due to COVID-19. It is still unknown whether clinical and laboratory data assessed upon hospital admission have predictive value for NOAF. OBJECTIVES: To analyze, upon hospital admission, variables with predictive potential for the occurrence of NOAF in patients with COVID-19 pneumonia. METHODS: Observational, retrospective, case-control study. Electronic medical reports of consecutive patients, 60 years of age or older, hospitalized due to COVID-19 pneumonia between March 1st and July 15th, 2020, were reviewed. Non-paired Student or chi-squared tests compared variables. A Cox proportional hazard model was employed to identify independent predictors of NOAF. P value < 0.05 was considered statistically significant. RESULTS: Among 667 patients hospitalized due to COVID-19, 201 (30.1%) fulfilled the inclusion criteria. NOAF was documented in 29 patients (14.4%), composing group 1. Group 2 was composed of 162 patients without NOAF. Ten patients were excluded due to the AF rhythm upon hospital admission. In groups 1 and 2, there were differences in overall in-hospital survival rate (24.1 % vs. 67.9%; p<0.001), length of stay in ICU (11.1 ± 10.5 days vs. 4.9 ± 7.5 days; p=0.004) and need for mechanical ventilation rate (82.9% vs. 32.7%; p<0.001). In the Cox model, age > 71 y/o (HR=6.8; p<0.001), total leukocyte count ≤ 7,720 cels.µL-¹ (HR=6.6; p<0.001), serum [Na+] ≤ 137 mEq.L-¹ (HR=5.0; p=0.001), SAPS3 score > 55 (HR=5.6; p=0.002), and disorientation (HR=2.5; p=0.04) on admission were independent predictors of NOAF. CONCLUSION: NOAF is a common arrhythmia in elderly hospitalized patients with COVID-19 pneumonia. Clinical and laboratory parameters evaluated on admission have a predictive value for the occurrence of NOAF during hospitalization.

FUNDAMENTO: Fibrilação atrial nova (FAN) ocorre em pacientes internados por COVID-19. Há controvérsias quanto ao valor preditivo de dados clínicos e laboratoriais à admissão hospitalar para ocorrência de FAN. OBJETIVOS: Analisar, à admissão hospitalar, variáveis com potencial preditivo para ocorrência de FAN em pacientes com pneumonia por COVID-19. MÉTODO: Estudo observacional, retrospectivo, caso-controle. Foram avaliados prontuários eletrônicos de pacientes consecutivos ≥ 60 anos, hospitalizados com pneumonia por COVID-19 entre 1º de março e 15 de julho de 2020. Comparações feitas pelos testes `t' de Student ou qui-quadrado. Foi empregado modelo de risco proporcional de Cox para identificação de preditores de FAN. Considerou-se o valor de p < 0,05 como estatisticamente significativo. RESULTADOS: Entre 667 pacientes internados por COVID-19, 201 (30,1%) foram incluídos. FAN foi documentada em 29 pacientes (14,4%) (grupo 1). Grupo 2 foi composto por 162 pacientes que não apresentaram FAN. Dez pacientes excluídos por estarem em FA na admissão hospitalar. Houve diferenças entre os grupos 1 e 2, respectivamente, no tempo de permanência em UTI (11,1±10,5 dias vs. 4,9±7,5 dias; p=0,004), necessidade de ventilação invasiva (82,9% e 32,7%; p<0,001) e mortalidade hospitalar (75,9% vs. 32,1%; p<0,001). No modelo de Cox, idade > 71 anos (hazard ratio [HR]=6,8; p<0,001), leucometria ≤ 7.720 cels.µL-1 (HR=6,6; p<0,001), natremia ≤ 137 mEq.L-1 (HR=5,0; p=0,001), escore SAPS3 > 55 (HR=5,6; p=0,002) e desorientação (HR=2,5; p=0,04) foram preditores independentes de FAN. CONCLUSÕES: FAN é uma arritmia comum em idosos hospitalizados com pneumonia por COVID-19. Parâmetros clínicos e laboratoriais avaliados na admissão são preditores de FAN durante internação.

Predictive Model of All-Cause Death in Patients with Heart Failure using Heart Rate Variability. / Modelo Preditivo de Mortalidade por Todas as Causas em Pacientes com Insuficiência Cardíaca Usando a Variabilidade da Frequência Cardíaca.

BACKGROUND: Central Illustration : Predictive Model of All-Cause Death in Patients with Heart Failure using Heart Rate Variability. BACKGROUND: Short and long-duration heart rate variability (HRV) data from Holter monitoring could identify predictors of all-cause death in heart failure (HF) patients. OBJECTIVES: To build a predictive model of all-cause death in patients with HF using HRV. METHODS: Retrospective study including patients with suspected or confirmed HF who were admitted for decompensated HF or syncope that underwent Holter monitoring. In analysis of augmented sympathetic tonus, we evaluated the lowest HRV in nonoverlapping 10-minutes periods throughout 24h continuous electrocardiographic signal recording (short HRV variables). Variables with p<0.01 were included in a multivariate Cox regression model to determine the occurrence of the all-cause death. Variables with statistical significance in Cox regression were chosen to build the predictive model. P<0.05 was considered significant. RESULTS: A total of 116 patients were included, mean age of 71.9±16.3 years, 45.7% men, mean follow-up of 2.83±1.27 years. Thirty-nine deaths occurred (33.6%). By comparing survivors vs. non-survivors, the variables that showed statistical significance were lowest SDNN, lowest rMSSD, age and left ventricular ejection fraction (LVEF). In Cox regression, independent predictors of all-cause death were: age>69 years (HR 3.95, 95%CI 1.64-9.52); LVEF≤57% (HR 4.70, 95%CI 2.38-9.28) and lowest rMSSD≤12ms (HR 5.54, 95%CI 2.04-15.08). An integer value was assigned to each variable. Score<3 showed AUC=0.802 (95%CI 0.72-0.87). CONCLUSION: In HF patients hospitalized for decompensated HF or syncope, independent long-term predictors of all-cause death were age, LVEF, and 10-minutes rMSSD. These findings indicate that even brief moments of high sympathetic tone can impact survival, specifically in the elderly and patients with HF with reduced ejection fraction.

Influence of fetal respiratory movements on left atrial functional status.

OBJECTIVE: Because fetal respiratory movements increase left ventricular compliance, we hypothesized that the left atrial shortening fraction increases during fetal respiratory motions. METHODS: A group of 26 normal fetuses with gestational ages between 28 and 38 weeks were assessed in a prospective cross-sectional study. Left atrial telesystolic and presystolic diameters were measured during apnea and after five consecutive respiratory movements. Left atrial shortening fraction was obtained by the ratio: [maximal left atrium diameter (telesystolic) - minimal left atrium diameter (presystolic)]/maximal left atrium diameter (telesystolic). The mean of three measurements were considered. Two-tailed Student's t-test was used. RESULTS: Mean gestational age was (mean ± SD) 30.7 ± 2.8 weeks. Mean left atrial telesystolic diameter in apnea was 10.6 ± 0.7 mm and during respiratory movements it was 10.5 ± 1.1 mm (p = 0.98). Presystolic left atrial diameter was 5.2 ± 0.1 mm in apnea and 4.4 ± 1.3 mm during respiratory movements (p < 0.001). Left atrial shortening fraction was 0.50 ± 0.05 in apnea and 0.58 ± 0.13 during respiratory movements (p < 0.001). CONCLUSION: Left atrial shortening fraction is higher during respiratory movements as a result of increased left ventricular compliance and consequent optimization of left atrial functional status.

Assessing Dynamic Atrioventricular Conduction Time to RR-interval Coupling in Athletes and Sedentary Subjects. / Avaliação da Dinâmica do Acoplamento da Condução Atrioventricular à Variação dos Intervalos RR em Atletas e Indivíduos Sedentários.

Background Atrioventricular conduction time ( AVCT ) is influenced by autonomic input and subject to physiological remodeling. Objective To evaluate beat-by-beat AVCT and RR-interval variability in athletes and healthy sedentary subjects. Methods Twenty adults, including 10 healthy sedentary (Controls) and 10 elite long-distance runners (Athletes), age, weight and height-adjusted, underwent maximal metabolic equivalent (MET) assessment, and 15-min supine resting ECG recording seven days later. The interval between P-wave and R-wave peaks defined the AVCT . Mean (M) and standard deviation (SD) of consecutive RR-intervals (RR) and coupled AVCT were calculated, as well as regression lines of RR vs. AVCT (RR-AVCT) . Concordant AV conduction was defined as positive RR-AVCT slope and discordant otherwise. A multivariate linear regression model was developed to explain MET based on AVCT and RR-interval variability parameters. Significance-level: 5 %. Results In Athletes, M-RR and SD-RR values were higher than in Controls, whereas M-AVCT and SD-AVCT were not. RR-AVCT slopes were, respectively, 0.038 ± 0.022 and 0.0034 ± 0.017 (p < 0.05). Using a cut-off value of 0.0044 (AUC 0.92 ± 0.07; p < 0.001), RR-AVCT slope showed 100% specificity and 80% sensitivity. In a multivariate model, SD-RR and RR-AVCT slope were independent explanatory variables of MET (F-ratio: 17.2; p < 0.001), showing 100% specificity and 90% sensitivity (AUC 0.99 ± 0.02; p < 0.001). Conclusion In elite runners, AVCT to RR -interval dynamic coupling shows spontaneous discordant AV conduction, characterized by negative AVCT vs. RR -interval regression line slope. RR -intervals standard deviation and AVCT vs. RR -interval regression line slope are independent explanatory variables of MET (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0).

Experience in a Brazilian Center with Cryoablation for Electric Isolation of the Pulmonary Veins in Paroxysmal and Persistent Atrial Fibrillation - Preliminary Results in Brazil. / Experiência de um Centro Brasileiro com Crioablação para Isolamento Elétrico das Veias Pulmonares na Fibrilação Atrial Paroxística e Persistente ­ Resultados Preliminares no Brasil.

BACKGROUND: Electrical isolation of the pulmonary veins is recognized as the cornerstone of non-pharmacological treatment of Atrial Fibrillation (AF), and therefore, has been recommended as the first step in AF ablation according to all guidelines. Even though the cryoballoon technology is widely used in North America and Europe, this experience is still incipient in many developing countries such as Brazil. OBJECTIVE: To evaluate initial results regarding success and safety of the new technology in patients with persistent and paroxysmal AF. METHODS: One hundred and eight consecutive patients with symptomatic AF refractory to pharmacological treatment were submitted to cryoablation for isolation of the pulmonary veins. Patients were separated into two groups according to AF classification: persistent (AF for over one week); or paroxysmal (shorter episodes). Recurrence and procedural safety data were analyzed respectively as primary and secondary outcomes. The level of significance was 5%. RESULTS: One hundred and eight patients, with mean age 58±13 years, 84 males (77.8%), underwent cryoablation. Sixty-five patients had paroxysmal AF (60.2%) and 43 had persistent AF (39.2%). The mean time of the procedure was 96.5±29.3 minutes and the mean fluoroscopy time was 29.6±11.1 minutes. Five (4.6%) complications were observed, none fatal. Considering a blanking period of 3 months, 21 recurrences (19.4%) were observed in a one-year follow-up period. The recurrence-free survival rates of AF in the paroxysmal and persistent groups were 89.2% and 67.4%, respectively. CONCLUSION: Cryoablation for electrical isolation of the pulmonary veins is a safe and effective method for the treatment of AF. Our results are consistent with other studies suggesting that this technology can be used as an initial technique even in cases of persistent AF.

FUNDAMENTO: O isolamento elétrico das veias pulmonares é reconhecidamente base fundamental para o tratamento não farmacológico da fibrilação atrial (FA) e, portanto, tem sido recomendado como passo inicial na ablação de FA em todas as diretrizes. A técnica com balão de crioenergia, embora amplamente utilizada na América do Norte e Europa, ainda se encontra em fase inicial em muitos países em desenvolvimento, como o Brasil. OBJETIVO: Avaliar o sucesso e a segurança da técnica de crioablação em nosso serviço, em pacientes com FA paroxística e persistente. MÉTODOS: Cento e oito pacientes consecutivos com FA sintomática e refratária ao tratamento farmacológico foram submetidos à crioablação para isolamento das veias pulmonares. Os pacientes foram separados em dois grupos, de acordo com a classificação convencional da FA paroxística (duração de até sete dias) e persistente (FA por mais de sete dias). Dados de recorrência e segurança do procedimento foram analisados respectivamente como desfechos primário e secundário. O nível de significância adotado foi de 5%. RESULTADOS: Cento e oito pacientes, com idade média de 58±13 anos, 84 do sexo masculino (77,8%), foram submetidos ao procedimento de crioablação de FA. Sessenta e cinco pacientes apresentavam FA paroxística (60,2%) e 43, FA persistente (39,2%). O tempo médio do procedimento foi de 96,5±29,3 minutos e o tempo médio de fluoroscopia foi de 29,6±11,1 minutos. Foram observadas cinco (4,6%) complicações, nenhuma fatal. Considerando a evolução após os 3 meses iniciais, foram observadas 21 recorrências (19,4%) em período de um ano de seguimento. As taxas de sobrevivência livre de recorrência nos grupos paroxístico e persistente foram de 89,2% e 67,4%, respectivamente. CONCLUSÃO: A crioablação para isolamento elétrico das veias pulmonares é um método seguro e eficaz para tratamento da FA. Nossos resultados estão consoantes com demais estudos, que sugerem que a tecnologia pode ser utilizada como abordagem inicial, mesmo nos casos de FA persistente. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0).

Variáveis Clínicas e Laboratoriais na Admissão Hospitalar são Preditores de Fibrilação Atrial Nova em Pacientes Internados com Pneumonia por COVID-19 / Clinical and Laboratory Data Up on Hospital Admission are Predictors of New-Onset Atrial Fibrillation in Patients Hospitalized Due to COVID-19 Pneumonia

Resumo Fundamento Fibrilação atrial nova (FAN) ocorre em pacientes internados por COVID-19. Há controvérsias quanto ao valor preditivo de dados clínicos e laboratoriais à admissão hospitalar para ocorrência de FAN. Objetivos Analisar, à admissão hospitalar, variáveis com potencial preditivo para ocorrência de FAN em pacientes com pneumonia por COVID-19. Método Estudo observacional, retrospectivo, caso-controle. Foram avaliados prontuários eletrônicos de pacientes consecutivos ≥ 60 anos, hospitalizados com pneumonia por COVID-19 entre 1º de março e 15 de julho de 2020. Comparações feitas pelos testes `t' de Student ou qui-quadrado. Foi empregado modelo de risco proporcional de Cox para identificação de preditores de FAN. Considerou-se o valor de p < 0,05 como estatisticamente significativo. Resultados Entre 667 pacientes internados por COVID-19, 201 (30,1%) foram incluídos. FAN foi documentada em 29 pacientes (14,4%) (grupo 1). Grupo 2 foi composto por 162 pacientes que não apresentaram FAN. Dez pacientes excluídos por estarem em FA na admissão hospitalar. Houve diferenças entre os grupos 1 e 2, respectivamente, no tempo de permanência em UTI (11,1±10,5 dias vs. 4,9±7,5 dias; p=0,004), necessidade de ventilação invasiva (82,9% e 32,7%; p<0,001) e mortalidade hospitalar (75,9% vs. 32,1%; p<0,001). No modelo de Cox, idade > 71 anos (hazard ratio [HR]=6,8; p<0,001), leucometria ≤ 7.720 cels.μL-1 (HR=6,6; p<0,001), natremia ≤ 137 mEq.L-1 (HR=5,0; p=0,001), escore SAPS3 > 55 (HR=5,6; p=0,002) e desorientação (HR=2,5; p=0,04) foram preditores independentes de FAN. Conclusões FAN é uma arritmia comum em idosos hospitalizados com pneumonia por COVID-19. Parâmetros clínicos e laboratoriais avaliados na admissão são preditores de FAN durante internação.

Abstract Background New-onset atrial fibrillation (NOAF) occurs in patients hospitalized due to COVID-19. It is still unknown whether clinical and laboratory data assessed upon hospital admission have predictive value for NOAF. Objectives To analyze, upon hospital admission, variables with predictive potential for the occurrence of NOAF in patients with COVID-19 pneumonia. Methods Observational, retrospective, case-control study. Electronic medical reports of consecutive patients, 60 years of age or older, hospitalized due to COVID-19 pneumonia between March 1st and July 15th, 2020, were reviewed. Non-paired Student or chi-squared tests compared variables. A Cox proportional hazard model was employed to identify independent predictors of NOAF. P value < 0.05 was considered statistically significant. Results Among 667 patients hospitalized due to COVID-19, 201 (30.1%) fulfilled the inclusion criteria. NOAF was documented in 29 patients (14.4%), composing group 1. Group 2 was composed of 162 patients without NOAF. Ten patients were excluded due to the AF rhythm upon hospital admission. In groups 1 and 2, there were differences in overall in-hospital survival rate (24.1 % vs. 67.9%; p<0.001), length of stay in ICU (11.1 ± 10.5 days vs. 4.9 ± 7.5 days; p=0.004) and need for mechanical ventilation rate (82.9% vs. 32.7%; p<0.001). In the Cox model, age > 71 y/o (HR=6.8; p<0.001), total leukocyte count ≤ 7,720 cels.μL-¹ (HR=6.6; p<0.001), serum [Na+] ≤ 137 mEq.L-¹ (HR=5.0; p=0.001), SAPS3 score > 55 (HR=5.6; p=0.002), and disorientation (HR=2.5; p=0.04) on admission were independent predictors of NOAF. Conclusion NOAF is a common arrhythmia in elderly hospitalized patients with COVID-19 pneumonia. Clinical and laboratory parameters evaluated on admission have a predictive value for the occurrence of NOAF during hospitalization.

Modelo Preditivo de Mortalidade por Todas as Causas em Pacientes com Insuficiência Cardíaca Usando a Variabilidade da Frequência Cardíaca / Predictive Model of All-Cause Death in Patients with Heart Failure using Heart Rate Variability

Resumo Fundamento Dados de curto e de longo prazo da variabilidade da frequência cardíaca (VFC) poderiam identificar preditores de mortalidade por todas as causas em pacientes com insuficiência cardíaca (IC). Objetivos Construir um modelo preditivo de mortalidade por todas as causas em pacientes com IC usando a VFC. Métodos Estudo retrospectivo incluindo pacientes com suspeita ou diagnóstico confirmado de IC internados por IC descompensada ou síncope e que realizaram exame de Holter 24 horas. Na análise do tônus simpático aumentado, nós avaliamos a VFC mais baixa em períodos de 10 minutos não sobrepostos em um registro contínuo de sinal eletrocardiográfico por 24 horas (VFC de curta duração). As variáveis com p<0,01 foram incluídas no modelo de regressão multivariada de Cox para determinar a ocorrência da mortalidade por todas as causas. As variáveis com significância estatística na regressão de Cox foram escolhidas para construir o modelo preditivo. Um p<0,05 foi considerado estatisticamente significativo. Resultados Um total de 116 pacientes foram incluídos, com idade média de 71,9±16,3 anos, 45,7% eram do sexo masculino. O tempo médio de acompanhamento foi de 2,83 ± 1,27 anos. Trinta e nove (33,6%) óbitos ocorreram. Na comparação de sobreviventes e não sobreviventes, as variáveis que mostraram significância estatística foram menor SDNN, menor rMSSD, idade e fração de ejeção ventricular esquerda (FEVE). Na regressão Cox, os preditores independentes de mortalidade por todas as causas foram: idade > 69 anos (HR 3,95, IC95% 1,64-9,52); FEVE≤57% (HR 4,70, IC95% 2,38-9,28) e menor rMSSD ≤12ms (HR 5,54; IC 95% 2,04-15,08). Um valor inteiro foi atribuído para cada variável. Este escore < 3 apresentou uma área sob a curva de 0,802 (IC95% 0,72-0,87). Conclusão Em pacientes com IC internados por IC descompensada ou síncope, preditores de longo prazo de mortalidade por todas as causas foram idade, FEVE, e rMSSD em 10 minutos. Esses achados indicam que mesmo breves momentos de tônus simpático elevado podem ter impacto na sobrevida, principalmente em idosos e pacientes com IC e fração de ejeção reduzida.

Abstract Background Short and long-duration heart rate variability (HRV) data from Holter monitoring could identify predictors of all-cause death in heart failure (HF) patients. Objectives To build a predictive model of all-cause death in patients with HF using HRV. Methods Retrospective study including patients with suspected or confirmed HF who were admitted for decompensated HF or syncope that underwent Holter monitoring. In analysis of augmented sympathetic tonus, we evaluated the lowest HRV in nonoverlapping 10-minutes periods throughout 24h continuous electrocardiographic signal recording (short HRV variables). Variables with p<0.01 were included in a multivariate Cox regression model to determine the occurrence of the all-cause death. Variables with statistical significance in Cox regression were chosen to build the predictive model. P<0.05 was considered significant. Results A total of 116 patients were included, mean age of 71.9±16.3 years, 45.7% men, mean follow-up of 2.83±1.27 years. Thirty-nine deaths occurred (33.6%). By comparing survivors vs. non-survivors, the variables that showed statistical significance were lowest SDNN, lowest rMSSD, age and left ventricular ejection fraction (LVEF). In Cox regression, independent predictors of all-cause death were: age>69 years (HR 3.95, 95%CI 1.64-9.52); LVEF≤57% (HR 4.70, 95%CI 2.38-9.28) and lowest rMSSD≤12ms (HR 5.54, 95%CI 2.04-15.08). An integer value was assigned to each variable. Score<3 showed AUC=0.802 (95%CI 0.72-0.87). Conclusion In HF patients hospitalized for decompensated HF or syncope, independent long-term predictors of all-cause death were age, LVEF, and 10-minutes rMSSD. These findings indicate that even brief moments of high sympathetic tone can impact survival, specifically in the elderly and patients with HF with reduced ejection fraction.

The oral transmission of Chagas' disease: an acute form of infection responsible for regional outbreaks.

Orally transmitted Chagas' disease is an ordinarily rare form of Trypanosome cruzi transmission, and responsible for regional outbreaks. Ingestion of contaminated material is generally associated with massive parasitic transmission, ultimately leading to acute myocarditis, with more severe clinical presentation at younger ages, and high death rates. Close monitoring of regional outbreaks by health agencies is mandatory in order to prevent recrudescence of the disease.

Spectral turbulence analysis of the signal-averaged electrocardiogram of the atrial activation as predictor of recurrence of idiopathic and persistent atrial fibrillation.

The frequency domain analysis of the P-wave signal-averaged ECG (P-SAECG) is able to identify patients at risk for lone atrial fibrillation (AF) after cardioversion to sinus rhythm. The terminal portion of the P-wave of right precordial leads on 12-lead ECG is associated with electrical abnormalities in the atria. The aim of this study was to assess the spectral turbulence analysis (STA) of the P-SAECG as a predictor of recurrence of idiopathic AF. STA was performed in 41 patients with 2 or more symptomatic episodes of idiopathic and persistent AF after successful electrical cardioversion and drug-free state (Group A), and in 25 control individuals during sinus rhythm (Group B), matched by age, gender, and P-wave duration. The orientation of the terminal portion (positive or negative) of the Z-lead was assessed as representing right precordial leads potentials. After 6 months follow-up, Group A was divided into two groups according to recurrence: G-A1--at least one recurrence (21 patients), and G-A2--no recurrence (20 patients). Fragmented electrical activity (FEA) was observed in 19 patients of G-A1 and in 2 of G-A2 (odds ratio = 85.5; p<<0.001). STA showed 90.5% sensitivity and 90.0% specificity for early recurrence of AF. After 12 months, no patients of G-A2 and 15 of G-A1 developed >3 episodes of persistent AF, being FEA observed in 13 (odds ratio = 14.6, p = 0.002). No episodes of AF were observed in Group B. Average time for recurrence of FEA positive patients (4.3 +/- 0.7 months) was significantly shorter than of G-A2 (7.4+/-0.7 months), and log-rank analysis revealed significant difference of event-free rate over time (p = 0.004). In a logistic regression model FEA, use of amiodarone and a positive terminal portion of the Z-lead of the P-SAECG were independent predictors of recurrence of idiopathic and persistent AF.

[Assessing autonomic function in hypertrophic cardiomyopathy]. / Avaliação da função autonômica na cardiomiopatia hipertrófica.

OBJECTIVE: Assess the autonomic function in hypertrophic cardiomyopathy (HCM) through heart rate variability (HRV) and to correlate it to echocardiographic data. METHODS: Two groups were studied, and compared for gender, age and HR: A) Ten (10) patients reporting septal HCM (70% non-obstructive); B) Ten (10) healthy volunteers. HRV was analyzed along four successive stages: at rest, under controlled breathing, while bending, and controlled breathing associated to bending. Variables means were compared between groups and intra-groups in the different stages; in Group A, variables means were correlated to echocardiographic measurements (interventricular septum and left atrial diameter). RESULTS: No HRV difference was reported among groups in the first 3 stages. In the fourth stage vagal activity was shown to be higher in Group A [quadratic mean log between RR intervals (RMSSD) - 1.35+/-0.14 vs 1.17+/-0.16; p=0.019; high frequency component logarithm (LogHF)- 4.89+/-0.22 vs 4.62+/-0.26; p=0.032]. Along the stages, vagal measurements [rate of pairs of consecutive RR intervals whose difference is > or =50 ms (pNN50) and LogHF] also showed lower reduction in the third stage in Group A, while LogHF showed some increase in last stage (p=0.027), thus indicating marked parasympathetic activity in that group. Group A HRV analysis showed no difference among patients reporting larger hypertrophy or atrial diameter. CONCLUSION: 1) Parasympathetic prevalence was shown during autonomic stimulation in HCM patients; 2) No correlation was found between HRV and echocardiographic measurements under analysis.

Avaliação da Dinâmica do Acoplamento da Condução Atrioventricular à Variação dos Intervalos RR em Atletas e Indivíduos Sedentários / Assessing Dynamic Atrioventricular Conduction Time to RR-interval Coupling in Athletes and Sedentary Subjects

Resumo Fundamento O tempo de condução atrioventricular (TCAV) é influenciado pelo estímulo autonômico e sujeito a remodelação fisiológica. Objetivo Avaliar a variabilidade da TCAV batimento-a-batimento e o intervalo RR em atletas e indivíduos sedentários saudáveis. Métodos Vinte adultos, incluindo 10 indivíduos sedentários saudáveis (controles) e 10 corredores de elite de longa distância (atletas), com idade, peso e altura ajustados foram submetidos à avaliação do equivalente metabólico máximo (MET) e registro de ECG em repouso supino de 15 minutos sete dias depois. O intervalo entre os picos da onda P e da onda R definiu o TCAV. Foram calculadas a média (M) e o desvio padrão (DP) de intervalos RR consecutivos (RR) e TCAV acoplados, bem como as linhas de regressão de RR vs. TCAV (RR-TCAV). A condução AV concordante foi definida como o slope RR-AVCT positivo e, caso contrário, discordante. Um modelo de regressão linear multivariada foi desenvolvido para explicar o MET com base nos parâmetros de variabilidade do TCAV e intervalo RR. Nível de significância: 5%. Resultados Nos atletas, os valores de M-RR e DP-RR foram maiores que nos controles, enquanto M-TCAV e DP-TCAV não foram. Os slopes RR-TCAV foram, respectivamente, 0,038 ± 0,022 e 0,0034 ± 0,017 (p < 0,05). Utilizando um valor de corte de 0,0044 (AUC 0,92 ± 0,07; p < 0,001), o slope RR-TCAV mostrou 100% de especificidade e 80% de sensibilidade. Em um modelo multivariado, o slope DP-RR e RR-TCAV foram variáveis explicativas independentes do MET (razão F: 17,2; p < 0,001), apresentando especificidade de 100% e sensibilidade de 90% (AUC: 0,99 ± 0,02; p < 0,001). Conclusão Em corredores de elite, o acoplamento dinâmico de TCAV para intervalo RR apresenta condução AV discordante espontânea, caracterizada por slope na linha de regressão TCAV negativa vs. intervalo RR. O desvio padrão dos intervalos RR e o slope da linha de regressão do TCAV vs. intervalo RR são variáveis explicativas independentes do MET. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)

Abstract Background Atrioventricular conduction time ( AVCT ) is influenced by autonomic input and subject to physiological remodeling. Objective To evaluate beat-by-beat AVCT and RR-interval variability in athletes and healthy sedentary subjects. Methods Twenty adults, including 10 healthy sedentary (Controls) and 10 elite long-distance runners (Athletes), age, weight and height-adjusted, underwent maximal metabolic equivalent (MET) assessment, and 15-min supine resting ECG recording seven days later. The interval between P-wave and R-wave peaks defined the AVCT . Mean (M) and standard deviation (SD) of consecutive RR-intervals (RR) and coupled AVCT were calculated, as well as regression lines of RR vs. AVCT (RR-AVCT) . Concordant AV conduction was defined as positive RR-AVCT slope and discordant otherwise. A multivariate linear regression model was developed to explain MET based on AVCT and RR-interval variability parameters. Significance-level: 5 %. Results In Athletes, M-RR and SD-RR values were higher than in Controls, whereas M-AVCT and SD-AVCT were not. RR-AVCT slopes were, respectively, 0.038 ± 0.022 and 0.0034 ± 0.017 (p < 0.05). Using a cut-off value of 0.0044 (AUC 0.92 ± 0.07; p < 0.001), RR-AVCT slope showed 100% specificity and 80% sensitivity. In a multivariate model, SD-RR and RR-AVCT slope were independent explanatory variables of MET (F-ratio: 17.2; p < 0.001), showing 100% specificity and 90% sensitivity (AUC 0.99 ± 0.02; p < 0.001). Conclusion In elite runners, AVCT to RR -interval dynamic coupling shows spontaneous discordant AV conduction, characterized by negative AVCT vs. RR -interval regression line slope. RR -intervals standard deviation and AVCT vs. RR -interval regression line slope are independent explanatory variables of MET (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)

Assessment of Autonomic Function by Phase Rectification of RRInterval Histogram Analysis in Chagas Disease.

BACKGROUND: In chronic Chagas disease (ChD), impairment of cardiac autonomic function bears prognostic implications. Phase­rectification of RR-interval series isolates the sympathetic, acceleration phase (AC) and parasympathetic, deceleration phase (DC) influences on cardiac autonomic modulation. OBJECTIVE: This study investigated heart rate variability (HRV) as a function of RR-interval to assess autonomic function in healthy and ChD subjects. METHODS: Control (n = 20) and ChD (n = 20) groups were studied. All underwent 60-min head-up tilt table test under ECG recording. Histogram of RR-interval series was calculated, with 100 ms class, ranging from 600-1100 ms. In each class, mean RR-intervals (MNN) and root-mean-squared difference (RMSNN) of consecutive normal RR-intervals that suited a particular class were calculated. Average of all RMSNN values in each class was analyzed as function of MNN, in the whole series (RMSNNT), and in AC (RMSNNAC) and DC (RMSNNDC) phases. Slopes of linear regression lines were compared between groups using Student t-test. Correlation coefficients were tested before comparisons. RMSNN was log-transformed. (α < 0.05). RESULTS: Correlation coefficient was significant in all regressions (p < 0.05). In the control group, RMSNNT, RMSNNAC, and RMSNNDC significantly increased linearly with MNN (p < 0.05). In ChD, only RMSNNAC showed significant increase as a function of MNN, whereas RMSNNT and RMSNNDC did not. CONCLUSION: HRV increases in proportion with the RR-interval in healthy subjects. This behavior is lost in ChD, particularly in the DC phase, indicating cardiac vagal incompetence.

Experiência de um Centro Brasileiro com Crioablação para Isolamento Elétrico das Veias Pulmonares na Fibrilação Atrial Paroxística e Persistente - Resultados Preliminares no Brasil / Experience in a Brazilian Center with Cryoablation for Electric Isolation of the Pulmonary Veins in Paroxysmal and Persistent Atrial Fibrillation - Preliminary Results in Brazil

Resumo Fundamento O isolamento elétrico das veias pulmonares é reconhecidamente base fundamental para o tratamento não farmacológico da fibrilação atrial (FA) e, portanto, tem sido recomendado como passo inicial na ablação de FA em todas as diretrizes. A técnica com balão de crioenergia, embora amplamente utilizada na América do Norte e Europa, ainda se encontra em fase inicial em muitos países em desenvolvimento, como o Brasil. Objetivo Avaliar o sucesso e a segurança da técnica de crioablação em nosso serviço, em pacientes com FA paroxística e persistente. Métodos Cento e oito pacientes consecutivos com FA sintomática e refratária ao tratamento farmacológico foram submetidos à crioablação para isolamento das veias pulmonares. Os pacientes foram separados em dois grupos, de acordo com a classificação convencional da FA paroxística (duração de até sete dias) e persistente (FA por mais de sete dias). Dados de recorrência e segurança do procedimento foram analisados respectivamente como desfechos primário e secundário. O nível de significância adotado foi de 5%. Resultados Cento e oito pacientes, com idade média de 58±13 anos, 84 do sexo masculino (77,8%), foram submetidos ao procedimento de crioablação de FA. Sessenta e cinco pacientes apresentavam FA paroxística (60,2%) e 43, FA persistente (39,2%). O tempo médio do procedimento foi de 96,5±29,3 minutos e o tempo médio de fluoroscopia foi de 29,6±11,1 minutos. Foram observadas cinco (4,6%) complicações, nenhuma fatal. Considerando a evolução após os 3 meses iniciais, foram observadas 21 recorrências (19,4%) em período de um ano de seguimento. As taxas de sobrevivência livre de recorrência nos grupos paroxístico e persistente foram de 89,2% e 67,4%, respectivamente. Conclusão A crioablação para isolamento elétrico das veias pulmonares é um método seguro e eficaz para tratamento da FA. Nossos resultados estão consoantes com demais estudos, que sugerem que a tecnologia pode ser utilizada como abordagem inicial, mesmo nos casos de FA persistente. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)

Abstract Background Electrical isolation of the pulmonary veins is recognized as the cornerstone of non-pharmacological treatment of Atrial Fibrillation (AF), and therefore, has been recommended as the first step in AF ablation according to all guidelines. Even though the cryoballoon technology is widely used in North America and Europe, this experience is still incipient in many developing countries such as Brazil. Objective To evaluate initial results regarding success and safety of the new technology in patients with persistent and paroxysmal AF. Methods One hundred and eight consecutive patients with symptomatic AF refractory to pharmacological treatment were submitted to cryoablation for isolation of the pulmonary veins. Patients were separated into two groups according to AF classification: persistent (AF for over one week); or paroxysmal (shorter episodes). Recurrence and procedural safety data were analyzed respectively as primary and secondary outcomes. The level of significance was 5%. Results One hundred and eight patients, with mean age 58±13 years, 84 males (77.8%), underwent cryoablation. Sixty-five patients had paroxysmal AF (60.2%) and 43 had persistent AF (39.2%). The mean time of the procedure was 96.5±29.3 minutes and the mean fluoroscopy time was 29.6±11.1 minutes. Five (4.6%) complications were observed, none fatal. Considering a blanking period of 3 months, 21 recurrences (19.4%) were observed in a one-year follow-up period. The recurrence-free survival rates of AF in the paroxysmal and persistent groups were 89.2% and 67.4%, respectively. Conclusion Cryoablation for electrical isolation of the pulmonary veins is a safe and effective method for the treatment of AF. Our results are consistent with other studies suggesting that this technology can be used as an initial technique even in cases of persistent AF.

Effect of oscillatory breathing on the variability of the RR Intervals and its prognostic importance in individuals with left ventricular global systolic dysfunction.

OBJECTIVE: To assess the effect of the oscillatory breathing on the variability of RR intervals (VRR) and on prognostic significance after one year follow-up in subjects with left ventricular global systolic dysfunction. METHODS: We studied 76 subjects, whose age ranged from 40 to 80 years, paired for age and gender, divided into two groups: group I - 34 healthy subjects; group II - 42 subjects with left ventricular global systolic dysfunction (ejection fraction < or = 0.40). The ECG signals were acquired during 600s in supine position, and analyzed the variation of the thoracic amplitude and the VRR. Clinical and V-RR variables were applied into a logistic multivariate model to foretell survival after one year follow-up. RESULTS: Oscillatory breathing was detected in 35.7% of subjects in vigil state of group II, with a concentration of the spectral power in the very low frequency band, and was independent of the presence of diabetes, functional class, ejection fraction, cause of ventricular dysfunction and survival after one year follow-up. In the logistic regression model, ejection fraction was the only independent variable to predict survival. CONCLUSION: 1). Oscillatory breathing pattern is frequent during wakefulness in the left ventricular global systolic dysfunction and concentrates spectral power in the very low band of V-RR; 2). it does not relate to severity and cause of left ventricular dysfunction; 3). ejection fraction is the only independent predictive variable for survival in this group of subjects.

Analysis of the prevalence of ventricular late potentials in the late phase of myocardial infarction based on the site of infarction.

OBJECTIVE: The initial site of myocardial infarction (MI) may influence the prevalence of ventricular late potentials (VLP), high-frequency signals, due to the time course of ventricular activation. The prevalence of VLP in a period of more than 2 years after acute MI was assessed focusing on the initially injured wall. METHODS: The prevalence of VLP in a late phase after MI (median of 924 days) in anterior/antero-septal and inferior/infero-dorsal wall lesion was analyzed using signal-averaged electrocardiogram in time domain. The diagnostic performance of the filters employed for analysis on was tested at high-pass cut-off frequencies of 25 Hz, 40 Hz and 80 Hz. RESULTS: The duration of the ventricular activation and its terminal portion were larger in inferior than anterior infarction, at high-pass cut-off frequencies of 40 Hz and 80 Hz. In patients with ventricular tachycardia, these differences were more remarked. The prevalence of ventricular late potentials was three times greater in inferior than anterior infarction. CONCLUSION: Late after myocardial infarction, the prevalence and the duration of ventricular late potentials are greater in lesions of inferior/infero-dorsal than anterior/antero-septal wall confirming their temporal process, reflecting their high-frequency content.

Noninvasive cardiac assessment in children of women with systemic lupus erythematosus.

OBJECTIVE: Noninvasive cardiac assessment of newborns and infants of women with systemic lupus erythematosus. The children had no congenital total atrioventricular block and were compared with the children of healthy women. METHODS: We prospectively assessed 13 newborns and infants aged 1 to 60 days, children of women with systemic lupus erythematosus and without congenital total atrioventricular block. These children were compared with 30 children of women who had no lupus or anti-Ro/SSA antibodies, and no risk factors for congenital heart disease either. Their age groups matched. The following examinations were performed: cardiological physical examination, electrocardiography, echocardiography, and signal-averaged electrocardiography. RESULTS: The statistical analysis showed no significant difference in ventricular function or in the cardiac conduction system between the groups. CONCLUSION: In regard to the conduction system and ventricular function in the absence of total atrioventricular block, no statistically significant difference was observed between the children of women with systemic lupus erythematosus and children of healthy women.

Effects of age and aerobic fitness on heart rate recovery in adult men.

BACKGROUND: Physiological aging leads to cardiac autonomic dysfunction, which is associated with the onset and worsening of cardiovascular disease and an increased risk of death. Currently, physical exercise is considered a cardioprotective strategy and more research is needed on its benefit on cardiac autonomic function. OBJECTIVE: To evaluate the autonomic control of heart rate in healthy young and middle-aged volunteers with different levels of aerobic fitness. METHODS: The study included 68 volunteers, stratified for age and level of aerobic fitness. Based on aerobic fitness assessed by the submaximal exercise test, subjects were separated into two groups, good fitness and poor fitness. Assessment of cardiac autonomic control was performed based on measurements of heart rate variability at rest and heart rate recovery post-exercise. Analysis of variance with two factors was used to compare the variables investigated. RESULTS: The heart rate variability is significantly lower in middle-aged volunteers than in young individuals, regardless of the aerobic fitness level (p <0.01). Higher levels of aerobic fitness in middle-aged volunteers are associated with earlier post-effort vagal reentry - rate of HR decline after 1min30s: 39.6% good aerobic fitness vs. poor 28.4% (p < 0.01). CONCLUSION: Better levels of aerobic fitness act beneficially on the autonomic control of post-exercise heart rate, preserving the vagal reentry velocity in healthy middle-aged volunteers. However, it does not attenuate the decrease in heart rate variability due to the natural aging process.