Objective:
Postmortem and animal experimental studies on Chagas disease (CD) have shown direct right ventricular damage on myocardial biopsies. CD clinically manifests with predominant right heart failure symptoms, and prior cardiac imaging studies have indicated early and isolated right ventricular dysfunction. However, there is a paucity of data regarding right heart involvement in CD. We aim to examine right ventricular (RV) size, volumes, and systolic function in a multiethnic cohort of patients with untreated seropositive CD using cardiac magnetic resonance imaging (cMRI).
Materials and Methods:
A retrospective cohort study of 105 patients with untreated seropositive CD who underwent cMRI at our institution from 2010 to 2017 was performed with an IRB-waiver. MRI was obtained on a 1.5 T Siemens Avanto scanner. Images were reviewed by 3 board certified radiologists with specialty training in cardiac imaging (10 - 20 years of experience). Images were reviewed on the Synapse PACS (Picture Archive and Communication System). The RV and left ventricle (LV) intracavitary diameter were measured at the maximum measurable distance from the endocardial borders and RV/LV ratio was obtained. Images were then transferred to Vitrea (Vital Images) software and endocardial borders of the ventricles were semi-automatically segmented over 20 phases of the cardiac cycle with volumetric analysis being provided by the software. Ejection fraction and volumetric analysis were recorded. Patient information was obtained through chart review of the electronic medical records (QuadraMed Affinity and Orchid) and correlations were made with age, sex, country of origin, and ECG findings.
Results:
This cohort included 34 men and 71 women with a mean age of 49.6 ± 13.6 years. Countries of origin include 53.3% (56/105) patients from El Salvador, 28.6% (30/105) from Mexico, 5.7% (6/105) from Guatemala, 3.8% (4/105) from Honduras, 2.9% (3/105) from Bolivia, 2.9% (3/105) from U.S., 1.9% (2/105) from Argentina, 1.0% (1/105) from Colombia. Of the 105 patients in the study, 33.3% (35/105) patients had a RV/LV ratio of greater than 0.9, including 54% (19/35) from El Salvador, 11.4% (4/35) from Mexico, 8.6% (3/35) from Guatemala, 8.6% (3/35) from Bolivia, 5.7% (2/35) from Honduras, 2.9% (1/35) from Colombia, and 2.9% (1/35) from the U.S. Of these 35 patients with RV enlargement, 6 had ECG abnormalities: 2 right bundle branch block (RBBB), a bifasicular block, a LBBB, a 1st degree AV block with incomplete RBBB, an incomplete RBBB, and a left anterior fascicular block. All but one patient with ECG abnormalities were from El Salvador. RV systolic dysfunction, defined as reduced RV ejection fraction based on predefined cutoffs accounting for age, was not seen in the majority of patients based on our preliminary analysis.
Conclusion:
Prior studies with cMRI have been focused on assessment of LV and there is limited data on RV. This study further characterizes RV involvement in a unique multiethnic cohort with untreated CD from the Center of Excellence for Chagas.
