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 Table 1 – Demographic and clinical characteristics Variables Subjects (n = 61) Indeterminate form (n = 17) Cardiac form without ventricular dysfunction (n = 16) Cardiac form with ventricular dysfunction (n = 28) Demographic characteristics Age (years), mean ± standard deviation 58 ± 8 59 ± 11 59 ± 9 58 ± 7 Female, n (%) 36 (59) 12 (70) 12 (75) 12 (43) Lived in a mud house, n (%) 50 (82) 15 (88) 15 (94) 20 (71) Family members with positive serology, n (%) 39 (64) 11 (65) 14 (88) 14 (50) Digestive form, n (%) 4 (6.6) – 2 (12) 2 (7) Body mass index (kg/m 2 ), mean ± standard deviation 25 ± 4 26 ± 4 27 ± 4 26 ± 3 Comorbidities, n (%) Arterial hypertension 44 (72) 14 (82) 12 (75) 18 (64) Diabetes mellitus 9 (15) 4 (23) – 5 (18) Syncope 6 (7) 1 (6) 1 (6) 2 (7) Smoking 16 (26) 3 (18) 3 (18) 10 (36) Congestive heart failure NYHA III/IV 16 (26) – – 16 (57)* Laboratory characteristics Creatinine (mg/dL) 0.88 (0.7 – 0.99) 0.84 (0.7 – 0.98) 0.78 (0.6 – 0.91) 0.94 (0.7 – 1.0) Sodium (mmoL/dL) 140 ± 3 138 ± 2 139 ± 2 139 ± 2 Hemoglobin (g/dL) 13.9 ± 0.9 14.2 ± 1.3 13.4 ± 0.7 14.2 ± 1.0 Total Cholesterol (mg/dL) 193 ± 38 202 ± 40 194 ± 42 200 ± 45 Reactive C protein (mg/dL) 1.15 (0.63 – 4.02) 1.71 (0.35 – 6.54) 1.24 (0.51 – 4.74) 1.09 (0.73 – 3.62) NT-ProBNP (pg/mL) 686 (66 – 816) 60.5 (34 – 108) 96.0 (73 – 181) 839.5** (189 – 2271) Troponin I (ng/mL) 0.684 (0.012 – 0.04) 0.012 (0.012 – 0.012) 0.012 (0.012 – 0.028) 0.038 (0.019 – 0.06) LVEF (%) 54 ± 15 64 ± 3 64 ± 4 43 ± 10* METS 9 ± 2.5 12 ± 3 9 ± 2 8 ± 2 NYHA: New York Heart Association; NT-ProBNP: N-terminal pro B-type natriuretic peptide; LVEF: left ventricular ejection fraction; METS: metabolic equivalent of task. Data expressed as mean ± standard deviation or percentage (%) for discrete variables and median and interquartile range for continuous variables with non-normal distribution. *p < 0.001, Fisher’s exact text. **p < 0.001, Kruskal-Wallis one-way analysis of variance. Results Clinical characteristics A total of 61 individuals with Chagas' disease, 56% female, with a mean age of 58 ± 9 years old were evaluated. Seventeen of them were in the indeterminate form, sixteen were in the cardiac form without left ventricular (LV) dysfunction and twenty eight were in the cardiac form with LV dysfunction. The majority of the subjects (74%) were in the NYHA functional class I or II, and 4 (6.6%) had concurrent gastrointestinal involvement. 82% were from urban areas, 50 individuals had previously lived in a mud house, and 44 reported contact with triatomine bugs. 64% of the relatives of patients with Chagas' disease reported a testimony. Eight patients used benzonidazole as an etiological treatment. The prevalence of hypertension, diabetes mellitus, dyslipidemia and smoking was similar among the three groups. The median Rassi score was 5 (IIQ: 0 - 11), and was distributed as follows: 36 individuals were classified as low risk (59%), 10 were classified as intermediate risk (16%) and 15 as high risk (25%). Other clinical and demographic characteristics are described in Table 1 and in Figure 1. The presence and extent of miocardial fibrose Late enhancement was found in 37 of the 58 subjects submitted to a CMR (64%). The percentage of the total area of ​myocardium affected by fibrosis was 9.4% (IIQ: 2.4 - 18.4), and was located most frequently in the inferolateral and apical LV segments. The location of the fibrosis in the subnedocardial and transmural areas were the most prevalent (72%); however, transmural fibrosis occured more frequently in those with ventricular dysfunction; p = 0.001. Myocardial fibrosis was identified in 6 of the 17 individuals in the indeterminate form (41%; 95% CI: 23-66), which is a proportion similar to that observed in the cardiac form without LV dysfunction (44%, 7 of 16 individuals); p = 1.0. Among the individuals with fibrosis, the total area of the affected myocardium was 4.1% (IIQ: 2.1 - 10.7) in the indeterminate form versus 2.3% 126