Association between typical electrocardiographic abnormalities and NT-proBNP elevation in a large cohort of patients with Chagas disease from endemic area

Highlights

• Describes electrocardiograms of a large cohort of patients with Chagas disease

• Typical ECG alterations of Chagas disease have greater odds of NT-proBNP elevation.

• Men had more major ECG abnormalities than women.

• The ECG is a simple and accurate method to predict Chagas disease severity.

Abstract

Chagas cardiomyopathy is the most harmful complication of Chagas disease. The electrocardiogram is a well-studied exam and has been considered an important tool for detection and evaluation of Chagas cardiomyopathy since the first years of its description. Many of its abnormalities have been described as associated with a worse prognosis. Serum BNP levels were described as inversely related to the left ventricular ejection fraction and as an independent predictor of death. It was not reported how electrocardiographic alterations correlate to NT-proBNP and its analog. The present study aims to describe the baseline electrocardiograms of a large cohort of patients with Chagas disease from endemic area and to establish an association between the number of electrocardiogram alterations and high levels of NT-ProBNP in Chagas disease patients. This study selected 1959 Chagas disease patients in 21 municipalities within a limited region in the northern part of the State of Minas Gerais (Brazil), 1084 of them had Chagas cardiomyopathy. NT-proBNP levels were suggestive of heart failure in 11.7% of this population. One or more electrocardiographic alterations have an Odds Ratio of 9.12 (CI 95% 5.62–14.80) to have NT-proBNP elevation. Considering the association between the number of 1, 2, and 3 or more alterations in electrocardiogram and NT-proBNP elevation, the ORs were 7.11 (CI 95% 4.33–11.67); 16.04 (CI 95% 9.27–27.77) and 47.82 (CI 95% 17.98–127.20), respectively. The presence and the number of typical electrocardiographic alterations of Chagas disease are independently associated with the severity of the cardiomyopathy.

Introduction

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and remains a health problem despite the partial control of its transmission. The World Health Organization estimates that approximately 8 million people have been infected, particularly in Latin America where the disease is endemic. In recent decades, the epidemiological profile has changed due to migratory movements, which has led to both the urbanization and globalization of the disease. There are nearly 300,000 infected people in USA, and 30,000 to 45,000 of these individuals have an unrecognized form of Chagas cardiomyopathy (ChCM) according to the Centers for Disease Control and Prevention [1,2].

ChCM is the most harmful complication of Chagas disease. Its annual incidence among the patients with indeterminate form is 1.85 per 100 people-years [3]. Many exams, which can easily be performed on outpatients, provide valuable information about both the prognosis of ChCM and the presence of left ventricular systolic dysfunction. Serum BNP levels were described as inversely related to the left ventricular ejection fraction, with a high positive predictive value of 80% and an even higher negative predictive value of 97% to identify those patients with low left ventricular ejection fraction [4]. The BNP, or its analog, NT-proBNP, was also described as a marker of ventricular arrhythmias [5], and diastolic dysfunction [6,7], as well as an independent predictor of death [8]. Therefore, considering these results, we assumed that high BNP levels are associated with heart failure (HF) and could be considered a surrogate marker of this condition.

The electrocardiogram (ECG) is a well-studied exam and has been considered an important tool for detection and evaluation of ChCM since the first years of its description [9]. Many of its abnormalities have been described as associated with a worse prognosis in ChCM and the need of further evaluation [[10], [11], [12], [13]]. However, it is not reported how electrocardiographic alterations correlate to BNP. Because the ECG has a low cost and is a widely available exam, it can be useful in identifying those patients with a higher probability for NT-ProBNP alterations. Therefore, the present study, aims to describe the baseline electrocardiograms of a large cohort of patients with Chagas disease from a endemic area, named São Paulo-Minas Gerais Tropical Medicine Research Center cohort (SaMi-Trop Study), and to establish an association between the number of ECG alterations evaluated according to the Minnesota Code and high levels of NT-ProBNP in T. cruzi chronically infected individuals [14].