Search

BackgroundPeriprocedural myocardial injury (PPMI) frequently occurs after transcatheter aortic valve implantation (TAVI), although its impact on long-term mortality is uncertain.MethodsWe performed a pooled analysis of Kaplan-Meier-derived individual patient data to compare survival in patients with and without PPMI after TAVI. Flexible parametric models with B-splines and landmark analyses were used to determine PPMI prognostic value. Subgroup analyses for VARC-2, troponin, and creatine kinase-MB (CK-MB)-defined PPMI were also performed.ResultsEighteen observational studies comprising 10,094 subjects were included. PPMI was associated with lower overall survival (OS) after two years (HR = 1.46, 95% CI 1.30–1.65, p

This paper presents a contribution to reviewing the most common seismic design procedures of CLT buildings and their implications on structural features and technological solutions. Attention is particularly focused on the overall seismic performance, damage tolerance, construction costs and environmental impact. It is intended as a baseline for a more comprehensive study, thus the assessment is made with reference to a real building, representative of a class of common buildings recently designed and erected in many Italian regions exposed to low and moderate seismic hazards. As usual, the analysis was carried out according to a two-dimensional model of the panels, assumed to be elastic, varying the type of connections at the base, the presence of pre-stressing steel bars for rocking control and dissipative devices. The main outcomes of the study can be summarized as follows: (i) the structural seismic behavior of CLT buildings is significantly influenced by the structural schemes adopted for walls and connections; (ii) construction costs and environmental impact decrease whenever damage tolerance is accounted for in design procedures.

Oral bacteria are implicated not only in oral diseases but also in gut dysbiosis and inflammatory conditions throughout the body. The periodontal pathogen Aggregatibacter actinomycetemcomitans (Aa) often occurs in complex oral biofilms with Streptococcus gordonii (Sg), and this interaction might influence the pathogenic potential of this pathogen. This study aims to assess the impact of oral inoculation with Aa, Sg, and their association (Aa+Sg) on alveolar bone loss, oral microbiome, and their potential effects on intestinal health in a murine model. Sg and/or Aa were orally administered to C57Bl/6 mice, three times per week, for 4 weeks. Aa was also injected into the gingiva three times during the initial experimental week. After 30 days, alveolar bone loss, expression of genes related to inflammation and mucosal permeability in the intestine, serum LPS levels, and the composition of oral and intestinal microbiomes were determined. Alveolar bone resorption was detected in Aa, Sg, and Aa+Sg groups, although Aa bone levels did not differ from that of the SHAM-inoculated group. Il-1β expression was upregulated in the Aa group relative to the other infected groups, while Il-6 expression was downregulated in infected groups. Aa or Sg downregulated the expression of tight junction genes Cldn 1, Cldn 2, Ocdn, and Zo-1 whereas infection with Aa+Sg led to their upregulation, except for Cldn 1. Aa was detected in the oral biofilm of the Aa+Sg group but not in the gut. Infections altered oral and gut microbiomes. The oral biofilm of the Aa group showed increased abundance of Gammaproteobacteria, Enterobacterales, and Alloprevotella, while Sg administration enhanced the abundance of Alloprevotella and Rothia. The gut microbiome of infected groups showed reduced abundance of Erysipelotrichaceae. Infection with Aa or Sg disrupts both oral and gut microbiomes, impacting oral and gut homeostasis. While the combination of Aa with Sg promotes Aa survival in the oral cavity, it mitigates the adverse effects of Aa in the gut, suggesting a beneficial role of Sg associations in gut health. [ABSTRACT FROM AUTHOR]

Several genera of Nyctaginaceae, currently merged under Pisonia, have been described for the Indo-Pacific region. Results from a recent molecular phylogenetic study of tribe Pisonieae showed that Pisonia is non-monophyletic and comprises three well-supported lineages: one including typical Pisonia and allies (Pisonia s.str.), a clade of species which corresponds to the original description of Ceodes and a third lineage whose single representative was formerly treated under the monotypic genus Rockia. Thus, as part of an effort to achieve a natural classification for tribe Pisonieae, this work proposes to re-establish Ceodes and Rockia to accommodate taxa with inconspicuous glands on anthocarps, recognising 21 species (20 for the former and one for the latter), of which 16 are new combinations: Ceodes amplifolia comb. nov., Ceodes artensis comb. nov., Ceodes austro-orientalis comb. nov., Ceodes brownii comb. nov., Ceodes cauliflora comb. nov., Ceodes coronata comb. nov., Ceodes diandra comb. nov., Ceodes gigantocarpa comb. nov., Ceodes gracilescens comb. nov., Ceodes lanceolata comb. nov., Ceodes merytifolia comb. nov., Ceodes muelleriana comb. nov., Ceodes rapaensis comb. nov., Ceodes sechellarum comb. nov., Ceodes taitensis comb. nov. and Ceodes wagneriana comb. nov. A general distribution of each species recognised in this work is also included, along with line drawings and colour pictures of representative species of Ceodes, Pisonia and Rockia and an updated dichotomous key based on reproductive characters for the nine genera (Ceodes, Cephalotomandra, Grajalesia, Guapira, Neea, Neeopsis, Pisonia, Pisoniella and Rockia) comprising the tribe Pisonieae. Résumé Plusieurs genres de Nyctaginaceae actuellement fusionnés sous Pisonia ont été décrits pour la région Indo-Pacifique. Les résultats d’une récente étude phylogénétique moléculaire de la tribu Pisonieae ont montré que Pisonia est non monophylétique et comprend trois lignées bien supportées: une comprenant Pisonia typique et ses alliés (Pisonia s.str.), un clade d’espèces qui correspond à la description originale de Ceodes et une troisième lignée dont l’unique représentant était auparavant traité sous le genre monotypique Rockia. Ainsi, dans le cadre d’un effort pour parvenir à une classification naturelle de la tribu Pisonieae, ce travail proposons de rétablir les Ceodes et Rockia pour accueillir des taxons avec des glandes discrètes sur les anthocarpes, reconnaissant 21 espèces (20 pour les premières et une pour les dernières), dont 16 sont de nouvelles combinaisons: Ceodes amplifolia comb. nov., Ceodes artensis comb. nov., Ceodes austro-orientalis comb. nov., Ceodes brownii comb. nov., Ceodes cauliflora comb. nov., Ceodes coronata comb. nov., Ceodes diandra comb. nov., Ceodes gigantocarpa comb. nov., Ceodes gracilescens comb. nov., Ceodes lanceolata comb. nov., Ceodes merytifolia comb. nov., Ceodes muelleriana comb. nov., Ceodes rapaensis comb. nov., Ceodes sechellarum comb. nov., Ceodes taitensis comb. nov. et Ceodes wagneriana comb. nov. Une distribution générale de chaque espèce reconnue dans ce travail est également incluse, ainsi que des dessins au trait et des images en couleur des espèces représentatives de Ceodes, Pisonia et Rockia, et préparé une clé dichotomique mise à jour basée sur les caractères reproductifs des neuf genres (Ceodes, Cephalotomandra, Grajalesia, Guapira, Neea, Neeopsis, Pisonia, Pisoniella et Rockia) comprenant la tribu Pisonieae.

The structural and seismic fragility assessment of minor historical centers of the Inner Peripheries of Italy is a key phase of the preservation process of the historical and cultural features of a portion of the Italian building stock, whose reuse is crucial for the reversal of shrinking trends and the stimulation of population growth. In this framework, the opportunities offered by digital crowd-sourcing technologies with respect to performing probabilistic structural safety assessment at a large scale are investigated herein. The objective of this research was to exploit data and information available on the web such that the key building features of an area of interest are collected through virtual inspections, historical databases, maps, urban plans, etc. Thus, homogeneous clusters of buildings identified in the area of interest are catalogued and associated with specific building classes (chosen among those available in the literature), and the buildings’ levels of seismic fragility are determined through the development of fragility curves. The research outcomes show that the proposed approach provides a satisfactory initial screening of the seismic fragility level of an area, thus allowing for the identification of priority zones that require further investigations or structural interventions to mitigate seismic risk.

Background No study has evaluated the impact of the additional manipulation demanded by multiple resheathing (MR) in patients undergoing transcatheter aortic valve replacement with repositionable self‐expanding valves. Methods and Results This study included a real‐world, multicenter registry involving 16 centers from Canada, Germany, Latin America, and Spain. All consecutive patients who underwent transcatheter aortic valve replacement with the Evolut R, Evolut PRO, and Portico valves were included. Patients were divided according to the number of resheathing: no resheathing, single resheathing (SR), and MR. The primary end point was device success. Secondary outcomes included procedural complications, early safety events, and 1‐year mortality. In 1026 patients, the proportion who required SR and MR was 23.9% and 9.3%, respectively. MR was predicted by the use of Portico and moderate/severe aortic regurgitation at baseline (both with P

Os parâmetros da variabilidade da frequência cardíaca (VRR) têm se demonstrado de grande valor prognóstico para eventos arrítmicos graves e para a morte súbita cardíaca. Está comprovada a importância da atividade vagai como protetora contra a induçao de arritmias ventriculares. Por outro lado, sabemos que a hiperatividade simpática é arritmogênica. Baixa VRR indica predomínio simpático e, portanto, maior facilidade para a ocorrência de arritmias.

Due to the increasing environmental degradation, the understanding of how reforestation and other restoration techniques function became fundamental to base the reestablishment of degraded ecosystems. The aim of this study was to perform a vegetation survey in a restoration site through three different techniques. The study site has 7.2 ha in a subtropical forest in Dois Vizinhos, Paraná state, Brazil and it is approximately 20 m from a secondary forest fragment. The experiment consisted of 12 plots with three treatments (T1-3) randomly distributed in four blocks. T1: natural regeneration through passive restoration. T2: set of nucleation techniques. T3: seedlings planted through filling and diversity lines (3x2 m). For sampling purposes, each plot was divided into 24 subplots. In order to evaluate plant presence, two years and eight months after the treatments implementation, a survey was conducted in three random subplots for each plot, where all plants taller than 50cm were identified and quantified. Native species richness was higher than 87% in all treatments, whereas the presence of herbaceous species was higher at passive restoration and woody species at plantation. The most common dispersal syndromes were anemochory and zoochory. By comparing planted and regenerated individuals for the three treatments, the plantation technique had the highest Shannon diversity index (3.017), with 148 individuals and 53 species sampled. However, there was no statistically significant difference. This higher diversity is related to the larger number of species planted, but it is still not facilitating regeneration species in its understory at this age. Considering only regenerated individuals, nucleation showed the highest Shannon diversity index (2.078) with a total of 908 individuals of 40 species, however, it wasn’t statistically significant different of passive restoration (Shannon = 1.965) which had 2,018 individuals of 40 species. The most floristic similar treatments were passive restoration and nucleation. Nucleation facilitated species natural regeneration (17 planted and 40 regenerated species) while passive restoration showed high resilience, therefore the use of passive restoration can be considered an effective alternative since its results did not differ statistically from nucleation, and the main advantage of this technique is the reduced cost.

Há alguns anos o assunto “aparelhos autoligados“, não é considerado novidade na Ortodontia. Muitos estudos e relatos de caso envolvendo a eficiência desses aparelhos vem sendo publicados e discutidos na literatura. No entanto, apesar desse fato, existe ainda muita discussão relacionada a esse tema, no que se refere a comparação do sistema autoligado com o sistema convencional. Dessa forma, este trabalho buscou por meio de uma revisão aprofundada da literatura atual, comparar e ressaltar os prós e os contras do sistema autoligado em relação ao sistema convencional.

Foram estudados 8 (oito) pacientes portadores de marcapasso Micropacer, cujas funções de porcentagem de batimentos totais, estimulados, sentidos, porcentagem de estimulação, função Holter simplificada e histograma foram ativados e analisados com eletrocardiografia dinâmica (E. C. G. D.). As diferenças obsevadas foram: batimentos totais (0,04% a 2,7%), batimentos estimulados (0,17% a 11,6%), batimentos sentidos (0,09% a 56%), porcentagem de estimulação (0% a 4%). Contagem telemétrica média em faixa de frequencia (Actual Holter values) fol semelhante em 3 (tres) casos e 0 histograma em 7 casos.

In this paper, an energy and exergy analysis is applied to the air dehumidification unit of a liquid desiccant system in an industrial gelatin conveyor dryer. The working fluid is a binary solution of lithium chloride (LiCl) in water. Dry air is used in order to decrease the amount of liquid in the gelatin. Therefore, the environmental air must have its absolute humidity reduced from about 12 g/kg to the project target, which is 5 g/kg. The process is a cycle using an absorption desiccant unit (LiCl in water), where the weak solution absorbs water vapor from the air. In the regenerator, condensation of the solution (desorption) from the moist air occurs. As a result, the steam consumption of the desorber and electrical power used for the vapor compression chiller (with ammonia, NH3, as working fluid) are the primary sources of cost for the factory. To improve the plant’s energy and exergy behaviors, the process is evaluated using a mathematical model of the system processes. In addition, we evaluate the substitution of the vapor compression chiller by an absorption unit (lithium bromide (LiBr) in water). The performance indicators of the compression vapor systems showed the best results. Even when using the condenser’s energy to pre-heat the solution, the installed system proved to be more effective.

Cross-laminated timber (CLT) buildings are recognized as a robust alternative to heavyweight constructions, because beneficial for seismic resistance and environmental sustainability, more than other construction materials. The lightness of material and the satisfactory dissipative response of the mechanical connections provide an excellent seismic response to multi-story CLT buildings, in spite of permanent damage to timber panels in the connection zones. Basically, CLT constructions are highly sustainable structures from extraction of raw material, to manufacturing process, up to usage, disposal and recycling. With respect to other constructions, the potential of CLT buildings is that their environmental sustainability in the phases of disposal and/or recycling can be further enhanced if the seismic damage in structural timber components is reduced or nullified. This paper reports a state-of-the art overview on seismic performance and sustainability aspects of CLT buildings in seismic prone regions. Technological issues and modelling approaches for traditional CLT buildings currently proposed in literature are discussed, focusing the attention on some research advancements and future trends devoted to enhance seismic performance and environmental sustainability of CLT buildings in seismic prone regions.

This paper deals with the influence of the rolling shear deformation on the flexural behavior of CLT (Cross-Laminated Timber) panels. The morphological configuration of the panels, which consist of orthogonal overlapped layers of boards, led to a particular shear behavior when subjected to out-of-plane loadings: the low value of the shear modulus in orthogonal to grain direction (i.e., rolling shear modulus) gives rise to significant shear deformations in the transverse layers of boards, whose grains direction is perpendicular with respect to the tangential stresses direction. This produces increases of deflections and vibrations under service loads, creating discomfort for the users. Different analytical methods accounting for this phenomenon have been already developed and presented in literature. Comparative analyses among the results provided by some of these methods have been carried out in the present paper and the influence of the rolling shear deformations, with reference to different span-to-depth (L/H) ratios investigated. Moreover, the analytical results have also been compared with those obtained by more accurate 2D finite element models. The results show that, at the service limit states, the influence of the rolling shear can be significant when the aspect ratios became less than L/H = 30, and the phenomenon must be accurately considered in both deflection and stress analysis of CLT floors. Contrariwise, in the case of higher aspect ratios (slender panels), the deflections and stresses can be evaluated neglecting the rolling shear influence, assuming the layers of boards as fully-connected.

Abstract Background: Transcatheter aortic valve implantation (TAVI) is a well-established procedure; however, atrioventricular block requiring permanent pacemaker implantation (PPI) is a common complication. Objectives: To determine the incidence, predictors and clinical outcomes of PPI after TAVI, focusing on how PPI affects left ventricular ejection fraction (LVEF) after TAVI. Methods: The Brazilian Multicenter TAVI Registry included 819 patients submitted to TAVI due to severe aortic stenosis from 22 centers from January/2008 to January/2015. After exclusions, the predictors of PPI were assessed in 670 patients by use of multivariate regression. Analysis of the ROC curve was used to measure the ability of the predictors; p < 0.05 was the significance level adopted. Results: Within 30 days from TAVI, 135 patients (20.1%) required PPI. Those patients were older (82.5 vs. 81.1 years; p = 0.047) and mainly of the male sex (59.3% vs 45%; p = 0.003). Hospital length of stay was longer in patients submitted to PPI (mean = 15.7 ± 25.7 vs. 11.8 ± 22.9 days; p < 0.001), but PPI affected neither all-cause death (26.7% vs. 25.6%; p = 0.80) nor cardiovascular death (14.1% vs. 14.8%; p = 0.84). By use of multivariate analysis, the previous presence of right bundle-branch block (RBBB) (OR, 6.19; 3.56-10.75; p ≤ 0.001), the use of CoreValve® prosthesis (OR, 3.16; 1.74-5.72; p ≤ 0.001) and baseline transaortic gradient > 50 mm Hg (OR, 1.86; 1.08-3.2; p = 0.025) were predictors of PPI. The estimated risk of PPI ranged from 4%, when none of those predictors was present, to 63%, in the presence of all of them. The model showed good ability to predict the need for PPI: 0.69 (95%CI: 0.64 - 0.74) in the ROC curve. The substudy of 287 echocardiograms during the 1-year follow-up showed worse LVEF course in patients submitted to PPI (p = 0.01). Conclusion: BRD prévio, gradiente aórtico médio > 50 mmHg e CoreValve® são preditores independentes de implante de MPD pós-TAVI. Ocorreu implante de MPD em aproximadamente 20% dos casos de TAVI, o que prolongou a internação hospitalar, mas não afetou a mortalidade. O implante de MPD afetou negativamente a FEVE pós-TAVI.

Abstract Background: Left atrial appendage closure (LAAC) is an effective alternative to oral anticoagulation (OA) for the prevention of stroke in patients with non-valvular atrial fibrillation (NVAF). Objective: To present the immediate results and late outcomes of patients submitted to LAAC and included in the Brazilian Registry of Percutaneous Left Atrial Appendage Closure. Methods: 91 patients with NVAF, high stroke risk (CHA2DS2VASc score = 4.5 ± 1.5) and restrictions to OAC (HAS-BLED score = 3.6 ± 1.0) underwent 92 LAAC procedures using either the Amplatzer cardiac plug or the Watchman device in 11 centers in Brazil, between late 2010 and mid 2016. Results: Ninety-six devices were used (1.04 device/procedure, including an additional non-dedicated device), with a procedural success rate of 97.8%. Associated procedures were performed in 8.7% of the patients. Complete LAAC was obtained in 93.3% of the successful cases. In cases of incomplete closure, no residual leak was larger than 2.5 mm. One patient needed simultaneous implantation of 2 devices. There were 7 periprocedural major (5 pericardial effusions requiring pericardiocentesis, 1 non-dedicated device embolization and 1 coronary air embolism without sequelae) and 4 minor complications. After 128.6 patient-years of follow-up there were 3 deaths unrelated to the procedure, 2 major bleedings (one of them in a patient with an unsuccessful LAAC), thrombus formation over the device in 2 cases (both resolved after resuming OAC for 3 months) and 2 strokes (2.2%). Conclusions: In this multicenter, real world registry, that included patients with NVAF and high thromboembolic and bleeding risks, LAAC effectively prevented stroke and bleeding when compared to the expected rates based on CHA2DS2VASc and HASBLED scores for this population. Complications rate of the procedure was acceptable considering the beginning of the learning curve of most of the involved operators.

Fundamentos: O implante por cateter de bioprótese valvar aórtica (TAVI) consolidou-se como alternativa para o tratamento de pacientes com estenose aórtica importante de alto risco cirúrgico. Contudo, há poucos dados na literatura com respeito à obstrução coronária que, apesar de rara, trata-se de grave complicação do TAVI. Objetivo: Avaliar, no contexto brasileiro, a presença dessa importante complicação. Métodos: Foram avaliados todos os casos de obstrução coronária incluídos no Registro Brasileiro de TAVI. Foram coletados dados clínicos, do procedimento, do manejo e de evolução intra-hospitalar. Resultados: Entre 418 pacientes consecutivos do registro, ocorreram três casos de obstrução coronária (incidência de 0,72%). Em sua totalidade, os pacientes eram do sexo feminino, sem cirurgia de revascularização miocárdica (CRM) prévia, com idade média de 85 ± 3 anos, EuroSCORE logístico de 15 ± 6% e STS de 9 ± 4%. Todos os casos foram realizados com a válvula balão-expansível Sapien XT. Em um dos pacientes, com dados de tomografia computadorizada pré-procedimento, verificaram-se origem das artérias coronárias baixa e seio de Valsalva estreito. Todos os pacientes apresentaram-se clinicamente com hipotensão importante e mantida, imediatamente após o implante da válvula, e, apesar de angioplastia com implante de stent, todos os pacientes foram a óbito, sendo dois periprocedimento e um durante hospitalização. Conclusão: A obstrução coronária como complicação do TAVI, apesar de rara, é potencialmente fatal, podendo ocorrer mais frequentemente em mulheres e com as próteses expansíveis por balão. Fatores anatômicos podem estar relacionados com sua ocorrência, ressaltando-se a importância de boa avaliação pré-procedimento no sentido de evitar essa grave complicação.

FUNDAMENTOS: Inúmeros indicadores são utilizados para assegurar a qualidade de um serviço; entretanto, a competência médica e o adequado fluxo de realização de um procedimento são determinantes da qualidade final. Nesse contexto, a Sociedade Brasileira de Arritmias Cardíacas pretende recomendar parâmetros mínimos necessários para garantir a excelência dos serviços de monitorização eletrocardiográfica ambulatorial. OBJETIVOS: Recomendar competências médicas mínimas e as informações necessárias para emissão do laudo de Holter. MÉTODOS: O documento foi fundamentado no conceito de medicina baseada em evidência, e nas circunstâncias em que a evidência não estava disponível a opinião de uma comissão de redação foi utilizada para a formulação da recomendação. Essa comissão foi formada por profissionais que apresentam vivência nas dificuldades do método e gestão na prestação de serviços nessa área. RESULTADOS: O profissional responsável pela análise de Holter deve conhecer as patologias cardiovasculares e ter formação consistente em eletrocardiografia, incluindo arritmias cardíacas e seus diagnósticos diferenciais. O laudo deve ser redigido de forma clara e objetiva. Os parâmetros mínimos que devem constar no laudo incluem as estatísticas do exame, assim como quantificação e análise dos distúrbios do ritmo observados durante a monitorização. CONCLUSÃO: A monitorização eletrocardiográfica ambulatorial deve ser realizada por profissionais com vivência em análise eletrocardiográfica e o laudo deve conter os parâmetros mínimos mencionados nesse documento.

FUNDAMENTO: Diversos mecanismos podem estar envolvidos no desencadeamento da síncope em pacientes com cardiomiopatia hipertrófica (CMH), incluindo colapsos hemodinâmicos que podem estar relacionados a um desequilíbrio autonômico. OBJETIVO: Avaliar e comparar a função autonômica de pacientes que apresentam CMH com síncope inexplicada (SI) com os que não apresentam síncope. MÉTODOS: Trinta e sete pacientes foram incluídos, sendo 16 com SI e 21 sem síncope. Sua função autonômica foi avaliada por sensibilidade barorreflexa (SB) espontânea e induzida por fenilefrina, pela variabilidade da frequência cardíaca (VFC) no domínio do tempo durante o Holter de 24 horas e no domínio da frequência (análise espectral), ambos em decúbito dorsal e no teste de inclinação (TI) a 70º. RESULTADOS: A SB espontânea mostrou-se semelhante em ambos os grupos (16,46 ± 12,99 vs. 18,31 ± 9,88 ms/mmHg, p = 0,464), assim como a SB induzida por fenilefrina (18,33 ± 9,31 vs. 15,83 ± 15,48 ms/mmHg, p = 0,521). Não foram observadas diferenças no SDNN (137,69 ± 36,62 vs . 145,95 ± 38,07 ms, p = 0,389). O grupo com síncope apresentou um RMSSD significativamente menor (24,88 ± 10,03 vs. 35,58 ± 16,43 ms, p = 0,042) e tendência a menor pNN50 (4,51 ± 3,78 vs . 8,83 ± 7,98%, p =0,085) e a menores valores do componente de alta frequência da análise espectral da VFC em repouso (637,59 ± 1.295,53 vs. 782,65 ± 1.264,14 ms2 , p = 0,075). Nenhuma diferença significativa foi observada em resposta ao TI (p = 0,053). A sensibilidade, especificidade e acurácia do TI na identificação da etiologia da SI em pacientes com CMH foram 6%, 66% e 40%, respectivamente. CONCLUSÃO: Observou-se tônus parassimpático mais baixo em pacientes com CMH e SI, mas a relevância clínica deste achado ainda não está clara. O TI não é uma ferramenta vantajosa para avaliar a origem da síncope em tais doentes, principalmente por causa da sua baixa especificidade.BACKGROUND: Several mechanisms may be involved in the trigger of syncope in patients with hypertrophic cardiomyopathy (HCM), including hemodynamic collapses that might be related to an autonomic imbalance. OBJECTIVE: To evaluate and compare the autonomic function of patients presenting HCM with unexplained syncope (US) to those without syncope. METHODS: Thirty-seven patients were included, 16 with US and 21 without syncope. Their autonomic function was assessed by spontaneous and phenylephrine induced baroreflex sensitivity (BRS), by heart rate variability (HRV) in time domain during 24-hour Holter and in frequency domain (spectral analysis), both in supine position and at 70º head-up tilt (HUT). RESULTS: The spontaneous BRS was similar in both groups (16,46 ± 12,99 vs. 18,31 ± 9,88 ms/mmHg, p = 0,464), as was phenylephrine-induced BRS (18,33 ± 9,31 vs. 15,83 ± 15,48 ms/mmHg, p = 0,521). No differences were observed in SDNN (137,69 ± 36,62 vs . 145,95 ± 38,07 ms, p=0,389). The group presenting syncope had a significantly lower RMSSD (24,88±10,03 vs. 35,58 ± 16,43 ms, p = 0,042) and a tendency to lower pNN50 (4,51 ± 3,78 vs . 8,83 ± 7,98%, p =0,085) and lower values of the high frequency component of HRV spectral analysis at rest (637,59±1.295,53 vs. 782,65±1.264,14ms2, p=0,075). No significant difference was observed in response to HUT (p = 0,053). HUT sensitivity, specificity and accuracy in identifying the etiology of US in HCM patients were 6%, 66% and 40%, respectively. CONCLUSIONS: A lower parasympathetic tone was observed in HCM patients with US, but the clinical relevance of this finding remains unclear. HUT is not a valuable tool for evaluating the origin of syncope in these patients, mainly because of its poor specificity.