ABC | Volume 110, Nº2, February 2018

Original Article Rabelo et al The Presence and Extension of Myocardial Fibrosis in the Undetermined Form of Chagas’ Disease Arq Bras Cardiol. 2018; 110(2):124-131 Figure 2 – Myocardial fibrosis in the different clinical forms of Chagas’ disease. LV: left ventricular. 100 90 80 70 60 50 40 30 20 10 0 Percentage of fibrosis (%) p = 0.001 p = 0.18 Indeterminate form Cardiac form without LV dysfunction Cardiac form with LV dysfunction Indeterminate form Cardiac form without LV dysfunction Cardiac form with LV dysfunction Cardiac Magnetic Ressonance – area of fibrosis (%) 50.0 40.0 30.0 20.0 10.0 0.0 * * Figure 3 – Linear regression analysis: influence of fibrosis on the left ventricular ejection fraction. LV: left ventricular. 60.0 50.0 60.0 80.0 100.0 40.0 40.0 30.0 20.0 20.0 10.0 0.0 0.0 Cardiac magnetic ressonance – area of fibrosis (%) Cardiac magnetic ressonance –LV ejection fraction (%) n = 57 r = –0.565 p < 0.001 of those in the cardiac form without ventricular dysfunction, and 52.4% in those with ventricular dysfunction. 23 We found a percentage of fibrosis involvement similar to the previous study (64%), also showing progressive involvement in patients with LV dysfunction (92%). 17 However, in addition to previous research, our data demonstrate a prevalence of enhancement as well as the percentage of fibrosis-related area, which is similar between the indeterminate form and the non‑dysfunctional form of the LV. We found no difference in the subendocardial and transmural location of fibrosis. The description of the cardiac ultrastructural changes that occur in the indeterminate phase of Chagas' disease were initially reported in individuals with positive serology during necropsy after accidental death. 12 However, its designation as 128