Relationship between heart rate variability and subclinical thyroid disorders of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

The association between subclinical thyroid dysfunctions and autonomic modulation changes has been described by many studies with conflicting results. We aimed to analyze the association between subclinical hyperthyroidism (SCHyper), subclinical hypothyroidism (SCHypo), and heart rate variability (HRV) using the baseline from ELSA-Brasil. SCHyper and SCHypo were classified by use of medication to treat thyroid disorders, thyrotropin levels respectively above and under the reference range, and normal free thyroxine levels. For HRV, the participants underwent 10 min in supine position and the R-R intervals of the final 5 min were selected for analysis. We first used linear regression models to report crude data and then, multivariate adjustment for sociodemographic (age, sex, and race) and cardiovascular risk factors (hypertension, dyslipidemia, diabetes, smoking, body mass index, use of alcohol, and leisure physical activity) using the euthyroid group as reference. From 9270 subjects (median age, 50; interquartile range: 44-56), 8623 (93.0%) were classified as euthyroid, 136 (1.5%) as SCHyper, and 511 (5.5%) as SCHypo. Compared to euthyroid subjects, SCHyper participants presented significantly higher heart rate (68.8 vs 66.5 for euthyroidism, P=0.007) and shorter R-R intervals (871.4 vs 901.6, P=0.007). Although SCHyper was associated with lower standard deviation of NN interval (SDNN) (β: -0.070; 95% confidence interval (95%CI): -0.014 to -0.009) and low-frequency (LF) (β: -0.242, 95%CI: -0.426 to -0.058) compared to the euthyroid group, these differences lost significance after multivariate adjustment for confounders. No significant differences were found for HRV in SCHypo. No association was found between HRV and SCHyper or SCHypo compared to euthyroid subjects in this sample of apparently healthy subjects.

Correlação entre classe funcional e qualidade de vida em usuários de marcapasso cardíaco / Correlation between functional class and quality of life among cardiac pacemaker users

INTRODUÇÃO: Os crescentes avanços tecnológicos desenvolvidos para o tratamento de distúrbios de condução cardíaca vêm proporcionando aos pacientes melhores condições de vida. As escalas de classificação funcional e questionários de qualidade de vida (QV) constituem uma forma suplementar de avaliação dos aspectos físicos, emocionais e funcionais dos pacientes. Entretanto, permanece a seguinte questão: existe correlação entre a classe funcional (CF) e a percepção da QV em usuários de marcapasso (MP)? OBJETIVO: O objetivo do estudo foi avaliar se existe correlação entre classe funcional (CF) e QV em portadores de MP cardíaco definitivo. MÉTODOS: Foram avaliados 14 usuários de MP. Para avaliar CF, foi utilizada a escala de atividade específica proposta por Goldman, e, com objetivo de avaliação da QV, foi aplicado o questionário Aquarel associado ao SF-36. Com o objetivo de verificar se existe correlação entre as variáveis, foi aplicado o teste de correlação de Spearman, considerando como significativo a< 0,05. Para a análise dos dados, foi utilizado Software SPSS for Windows versão 10.0. RESULTADOS: A CF correlacionou-se inversa e significativamente com a QV avaliada pelo Aquarel em seus três domínios: desconforto no peito (r= -0,666; p= 0,009); dispnéia (r= -0,604; p= 0,022) e arritmia (r= -0,550; p= 0,041). Já em relação ao SF-36, dos seus oito domínios, três estabeleceram uma correlação significativa com a CF: capacidade funcional (r= -0,745; p= 0,002); dor (r= -0,667; p= 0,009) e vitalidade (r= -0,591; p= 0,026). CONCLUSÃO: No presente estudo, encontrou-se correlação significativa entre CF e QV, sugerindo que as escalas de classificação funcional podem refletir aspectos da QV de portadores de MP.

INTRODUCTION: Growing technological progress in treating patients with heart conduction disturbances has provided such patients with better life conditions. Functional classification (FC) scales and quality of life (QOL) questionnaires are additional means for evaluating patients' physical, emotional and functional characteristics. However, the question remains as to whether there is any association between FC and perception of QOL among pacemaker users. OBJECTIVE: To evaluate whether there is any correlation between FC and QOL among definitive cardiac pacemaker users. METHOD: Fourteen pacemaker users were evaluated. To assess FC, the specific activity scale proposed by Goldman was used. To evaluate QOL, the Aquarel questionnaire was used in association with SF-36. The Spearman correlation test was applied to investigate whether there was any association between the variables, considering p< 0.05 to be significant. The SPSS for Windows software, version 10.0, was used for the data analysis. RESULTS: There was a significant negative correlation between FC and QOL through evaluation by Aquarel questionnaire in its three domains: chest discomfort (r= -0.666; p= 0.009); dyspnea (r= -0.604; p= 0.022); and arrhythmia (r= -0.550; p= 0.041). Among the eight domains of SF-36, three showed a significant correlation with FC: physical functioning (r= -0.745; p= 0.002); pain (r= -0.667; p= 0.009); and vitality (r= -0.591; p= 0.026). CONCLUSION: In the present study, a significant correlation was found between FC and QOL, thus suggesting that functional classification scales may reflect aspects of QOL among pacemaker users.

Electrocardiographic changes during low-dose, short-term therapy of cutaneous leishmaniasis with the pentavalent antimonial meglumine

The pentavalent antimonial (Sb5+) meglumine is the drug of choice for the treatment of cutaneous leishmaniasis (CL) in Brazil. Although the cardiotoxicity of high-dose, long-term Sb5+ therapy is well known, the use of low-dose, short-term meglumine has been considered to be safe and relatively free from significant cardiac effects. In order to investigate the cardiotoxicity of low-dose, short-term therapy with meglumine in cutaneous leishmaniasis, 62 CL patients treated with meglumine were studied. A standard ECG was obtained before and immediately after the first cycle of treatment (15 mg Sb5+ kg-1 day-1). The electrocardiographic interpretation was carried out blindly by two investigators using the Minnesota Code. There were no significant differences in qualitative ECG variables before and after meglumine treatment. However, the corrected QT interval was clearly prolonged after antimonial therapy (420.0 vs 429.3 ms, P<10-6). QTc augmentation exceeded 40 ms in 12 patients, 7 of whom developed marked QTc interval enlargement (500 ms) after meglumine therapy. This previously unrecognized cardiac toxicity induced by short-term, low-dose antimonial therapy has potentially important clinical implications. Since sudden death has been related to QTc prolongation over 500 ms induced by high-dose antimonial therapy, routine electrocardiographic monitoring is probably indicated even in CL patients treated with short-term, low-dose meglumine schedules. Until further studies are conducted to establish the interactions between pentavalent antimonials and other drugs, special care is recommended when using meglumine in combination with other medications, in particular with drugs that also increase the QTc interval