Viroj Wiwanitkit
Wiwanitkit House, Bangkhae, Bangkok, Thailand
Dear Editor:
A recent report on electrocardiophysiology of chagasic cases was very interesting1. Gupta et al. concluded that “the indeterminate form of Chagas’ disease can present cardiac wall motion abnormality, demonstrating functional and electric damage compared with chagasic patients with normal echocardiogram1.” There were some concerns about this work. First, the few subjects might not be statistically acceptable for the comparison or correlation study. Second, without control of previous cardiological status of the patients, it could not exclude the confounding factors that affect the electrocardiophysiology of the patients.
REFERENCE
1. Barros ML, Ribeiro A, Nunes MD, Rocha MO. Association between left ventricular wall motion abnormalities and ventricular arrhythmia in the indeterminate form of Chagas disease. Rev Soc Bras Med Trop 2011; 44: 213-216.
Address to:
Dr. Viroj Wiwanitkit. Wiwanitkit House, Bangkhae, 10160 Bangkok Thailand.
Phone: 668 7097-0933
email: somsriwiwan@hotmail.com
Received in 28/04/2011
Accepted in 09/05/2011
Authors’ reply regarding the comments about the article Association between left ventricular wall motion abnormalities and ventricular arrhythmia in the indeterminate form of Chagas disease
Resposta do autor quanto aos comentários feitos sobre o artigo Associação entre dissinergia miocárdica e arritmia ventricular na forma indeterminada da doença de Chagas
Márcio Lins BarrosI, II; Antônio Luiz RibeiroI, II; Maria do Carmo NunesI, II; Manoel Otávio da Costa RochaI, II
IHospital das Clínicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG
IIPrograma de Pós-Graduação em Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG
We appreciate Wiwanitkit’s interest in our study and the opportunity to clarify several issues.
In relation to the size of the sample studied, the calculation of the statistic power test, considering the difference observed in the percentage of ectopic ventricular beats > 10 by Holter monitoring, was 88%1.
Regarding the patient selection, we described the exclusion criteria in the method’s section, with the purpose of avoiding confounding conditions that could induce ventricular ectopy.
The following were the excluding criteria: systemic arterial hypertension, defined as arterial pressure measured during physical examination > 160/95; suggestive history of coronary artery disease; previous episode suggesting rheumatic fever disease; diabetes mellitus or intolerance to glucose as defined by the National Diabetes Data Group; thyroid dysfunction, manifested by abnormal levels of thyroid stimulating hormone (TSH) and free thyroxine (T4); kidney failure, defined by the increase in creatinine and urea levels; chronic obstructive pulmonary disease based on suggestive radiologic and electrocardiographic clinical data; hydroelectrolytic disorders, based on sodium and potassium dosages; significant anemia, defined as hemoglobin below 10 g/dl; alcoholism, defined as an average consumption of 420 grams of ethanol per week; pregnancy; abnormal ECG and/or echocardiogram and Doppler studies; and impossibility of following the protocol.
REFERENCE
1. Dupont WD, Plummer WD: Power and Sample Size Calculations for Studies Involving Linear Regression. Controlled Clin Trials 1998; 19:589-601.
Address to:
Dr. Márcio Vinícius Lins Barros
HC/UFMG. Rua Carangola 57/1201 Santo Antônio
30330-240 Belo Horizonte, MG.
Tel: 55 31 3292-2207
e-mail: marciovlbarros@uol.com.br
Received in 07/05/2011
Accepted in 09/05/2011
