Nonlinear Dynamics of Left Ventricular Mass Remodeling in Chagas Cardiomyopathy
Left ventricular (LV) mass remodeling in chronic Chagas cardiomyopathy (CCC) is progressive, but whether its dynamics follow nonlinear patterns linked to all-cause mortality remains unexplored. In this SEARCH-Rio substudy, 50 outpatients were followed for 10 years (40 survivors, 10 nonsurvivors). Serial echocardiography provided paired LV mass measurements fitted to the logistic equation x = {middle dot}x{middle dot}(1-{gamma}{middle dot}x), yielding = 3.952 {+/-} 0.096 and {gamma} = 1.267 {+/-} 0.012, above the complexity threshold ( > 3.57). Lyapunov exponents (LE), computed from consecutive inter patient derivatives, were positive in survivors (+0.349 {+/-} 0.342) and negative in nonsurvivors (-0.459 {+/-} 0.377; p < 0.001), indicating preserved versus lost dynamical complexity, respectively. The fixed-point equilibrium ({approx} 179 g) is mathematically unstable for = 3.952, consistent, but not confirmatory, with sensitive dependence on initial conditions. Complex nonlinear dynamics were independently confirmed at the intra-patient level in a subgroup with extended longitudinal follow-up beyond the initial 10-year period. A Firth penalized regression risk score based on ejection fraction < 51.7% and maximum heart rate < 109 bpm (optimism-corrected AUC = 0.959, bootstrap B = 1,000) showed monotonic mortality gradient and progressively lower LE across strata (Spearman {rho} = -0.381, p = 0.003). These findings support nonlinear LV mass remodeling associated with all-cause mortality over the same observation window in CCC; replication in larger cohorts is warranted.