Diagnostic electrocardiography in epidemiological studies of Chagas' disease: multicenter evaluation of a standardized method

Abstract

An electrocardiographic recording method with an associated reading guide, designed for epidemiological studies on Chagas' disease, was tested to assess its diagnostic reproducibility. Six cardiologists from five countries each read 100 electrocardiographic (ECG) tracings, including 30 from chronic chagasic patients, then reread them after an interval of 6 months. The readings were blind, with the tracings numbered randomly for the first reading and renumbered randomly for the second reading. The physicians, all experienced in interpreting ECGs from chagasic patients, followed printed instructions for reading the tracings. Reproducibility of the readings was evaluated using the kappa (kappa) index for concordance. The results showed a high degree of interobserver concordance with respect to the diagnosis of normal vs. abnormal tracings (kappa = 0.66; SE 0.02). While the interpretations of some categories of ECG abnormalities were highly reproducible, others, especially those having a low prevalence, showed lower levels of concordance. Intraobserver concordance was uniformly higher than interobserver concordance. The findings of this study justify the use by specialists of the recording of readings method proposed for epidemiological studies on Chagas' disease, but warrant caution in the interpretation of some categories of electrocardiographic alterations.

Health-related quality of life in patients with Chagas disease

“…The methodology used for these tests has been previously described by our research group 22,23 . The examinations were conducted and analyzed by experienced cardiologists who were blind to the serological profile of the patients and used the following classification parameters: I) electrocardiogram: abnormal in accordance with the ChD-specific Buenos Aires criterion 24,25 ; II) ventricular arrhythmia detected during Holter monitoring: presence of nonsustained ventricular tachycardia or more than ten ventricular extrasystoles per hour 25 ; III) abnormal Doppler echocardiogram considering the presence of one of the following abnormalities: left ventricular ejection fraction (LVEF) < 0.50, right ventricle (RV) > 56mm, left atrium (LA) > 40mm, presence of apical aneurysm or alteration in contractility; IV) abnormal autonomic function tests, considering the presence of one of the following abnormalities: heart rate variability with a standard deviation for normal cardiac intervals (SDNN) < 75ms on the 24h recordings, Valsalva ratio < 1.5 or respiratory sinus arrhythmia with a ratio of the greatest expiratory interval over the smallest inspiratory interval (mean of six respiratory cycles) < 1.1 22,23 . To evaluate HRQoL, interviews were conducted by trained professionals using the SF-36 generic multidimensional questionnaire 8 and the specific questionnaire MLWHFQ 10 .…”

Therapy, diagnosis and prognosis of chronic Chagas disease: insight gained in Argentina

“…Chagasic cardiac disease has been intensively studied in Argentina in both clinical and epidemiological studies (Rosenbaum & Cerisola 1961, Rosenbaum 1964, Chiale et al 1984, Lazzari et al 1998.…”

A Population-Based Study of the Association between <i>Trypanosoma cruzi</i> Infection and Cognitive Impairment in Old Age (The Bambuí Study)

“…Reading was performed via computer algorithm and by an independent cardiologist, using a standardized method developed for ChD [21] . ECG abnormalities are, by definition, always present in Chagas' cardiomyopathy [22] .…”