Left atrial dimension and new-onset atrial fibrillation in chronic Chagas disease: A competing-risk analysis of the SEARCH-Rio cohort

BACKGROUND: Atrial cardiomyopathy and atrial fibrillation (AF) complicate chronic Chagas disease (CCD). We assessed whether baseline left atrial (LA) diameter predicts new-onset AF during long-term follow-up, relates to ventricular remodeling, and whether P-wave signal-averaged ECG (P-SAECG) adds predictive value. METHODS: Fifty patients from the SEARCH-Rio study, in sinus rhythm at enrolment (age; 51 ± 9 years; 70% female), were followed for up to 25 years. AF incidence was estimated with death as a competing event and strata compared by log-rank test. Correlation analysis linked LV mass and LA diameter changes; baseline P-SAECG was tested for incident AF. RESULTS: Eleven patients (22%) developed AF over 25 years. Patients with AF had larger LA diameter compared to the non-AF group, at baseline (4.01 ± 0.51 vs. 3.47 ± 0.58 cm; p = 0.008) and at 25 years (4.75 ± 0.35 vs. 3.60 ± 0.63 cm; p = 0.028). AF incidence above vs. below baseline LA 4.0 cm was 39% vs. 18% (HR 5.81; log-rank p = 0.024). From LA crossing 4.0 cm, incidence was 42.5% in crossers vs. 13.6% in non-crossers (p = 0.026). LV mass and LA diameter changes correlated (r = 0.505, p = 0.002). P-SAECG predicted neither AF nor LA diameter. CONCLUSIONS: In CCD, baseline LA diameter predicts new-onset AF over 25 years, with 4.0 cm acting as a dynamic threshold. LA enlargement correlates only moderately with ventricular remodeling, and acts as a manifestation of independent atrial cardiomyopathy. P-SAECG is unrelated to LA size and poorly predicts AF.