OBJECTIVES: To perform a meta-analysis of studies using the Valsalva ratio (VR) in Chagas disease (ChD) patients without cardiopathy in comparison to control subjects in order to determine if vagal heart modulation is impaired in early forms of ChD. METHODS: The medical literature was systematically searched and reviewed for cross-sectional studies in humans in which the Valsalva maneuver was used to evaluate the autonomic modulation of the heart in ChD patients without cardiopathy. The Hedges g statistic (software Medcalc v.9.4.0.0) was used to combine the results of all studies through the calculation of the summary standardized mean difference (SMD): the mean VR in controls minus the mean VR in ChD patients, divided by the pooled and adjusted standard deviation. The sample size necessary to detect this SMD with 80% of power was calculated using the G*Power software v.3.0. RESULTS: The meta-analysis included 396 patients in 7 studies. Summary mean VRs were 1.87 +/- 0.39 ms in controls versus 1.74 +/- 0.40 ms in ChD without cardiopathy, leading to a statistically significant summary SMD of -0.310 (95% CI -0.513 to -0.106). Considering the summary SMD of -0.31, an alpha error of 0.05 and a 1:1 ratio of ChD and control patients, the estimated total sample size for a study with 80% power was 330 patients. INTERPRETATION: ChD patients without cardiopathy have reduced VR values compared to healthy controls, indicating early vagal dysfunction. Most previous studies could not detect this impairment due to small study samples and insufficient statistical power.
OBJECTIVES: To perform a meta-analysis of studies using the Valsalva ratio (VR) in Chagas disease (ChD) patients without cardiopathy in comparison to control subjects in order to determine if vagal heart modulation is impaired in early forms of ChD. METHODS: The medical literature was systematically searched and reviewed for cross-sectional studies in humans in which the Valsalva maneuver was used to evaluate the autonomic modulation of the heart in ChD patients without cardiopathy. The Hedges g statistic (software Medcalc v.9.4.0.0) was used to combine the results of all studies through the calculation of the summary standardized mean difference (SMD): the mean VR in controls minus the mean VR in ChD patients, divided by the pooled and adjusted standard deviation. The sample size necessary to detect this SMD with 80% of power was calculated using the G*Power software v.3.0. RESULTS: The meta-analysis included 396 patients in 7 studies. Summary mean VRs were 1.87 +/- 0.39 ms in controls versus 1.74 +/- 0.40 ms in ChD without cardiopathy, leading to a statistically significant summary SMD of -0.310 (95% CI -0.513 to -0.106). Considering the summary SMD of -0.31, an alpha error of 0.05 and a 1:1 ratio of ChD and control patients, the estimated total sample size for a study with 80% power was 330 patients. INTERPRETATION: ChD patients without cardiopathy have reduced VR values compared to healthy controls, indicating early vagal dysfunction. Most previous studies could not detect this impairment due to small study samples and insufficient statistical power.
Authors: Luiz Antonio Pertili R de Resende; Aldo César de Freitas Carneiro; Bruno Doriguetto Couto Ferreira; Raphael Antônio Gomes da Silva; Valdo José Dias da Silva; Aluízio Prata; Dalmo Correia Journal: Rev Soc Bras Med Trop Date: 2003 Nov-Dec Impact factor: 1.581
Authors: Luiz Antônio Pertili Rodrigues de Resende; Rodrigo Juliano Molina; Bruno Doriguetto Couto Ferreira; Aldo César Carneiro; Luiz Alberto Andrade Ferreira; Valdo José Dias da Silva; Aluízio Prata; Dalmo Correia Journal: Auton Neurosci Date: 2006-06-27 Impact factor: 3.145
Authors: Antonio Luiz Pinho Ribeiro; Luis Eduardo Díaz Giménez; Ciria Carolina Quintero Hernández; Antonio Carlos Campos de Carvalho; Mauro Martins Teixeira; Valesca Costa Guedes; Márcio Vinícius Lins Barros; Federico Lombardi; Manoel Otávio da Costa Rocha Journal: Int J Cardiol Date: 2006-07-21 Impact factor: 4.164
Authors: Anthony Halperin; Monica Pajuelo; Jeffrey A Tornheim; Nancy Vu; Andrés M Carnero; Gerson Galdos-Cardenas; Lisbeth Ferrufino; Marilyn Camacho; Juan Justiniano; Rony Colanzi; Natalie M Bowman; Tiffany Morris; Hamish MacDougall; Caryn Bern; Steven T Moore; Robert H Gilman Journal: Am J Trop Med Hyg Date: 2016-04-04 Impact factor: 2.345