Nonlinear Dynamics of Left Ventricular Mass Remodeling in Chagas Cardiomyopathy

AbstractO_ST_ABSBackgroundC_ST_ABSLeft ventricular (LV) remodeling in chronic Chagas cardiomyopathy (CCC) is progressive, but whether population-level LV mass dynamics follow nonlinear patterns and whether the loss of dynamic complexity tracks mortality is unknown. MethodsFifty outpatients from SEARCH-Rio cohort were followed-up for 10 years. Serial echocardiography provided paired LV mass measurements fitted to the logistic equation x = {middle dot}x{middle dot}(1-{gamma}{middle dot}x). Lyapunov exponents (LE) were computed from consecutive inter-patient derivatives. A clinical risk score was developed using Firth penalized logistic regression with bootstrap validation (B = 1,000) and Cox-Firth sensitivity analysis. ResultsLV mass remodeling adjusted the logistic equation with = 3.91 {+/-} 0.18 and {gamma} = 1.27 {+/-} 0.06, which was compatible with dynamics near the complexity threshold ( {approx} 3.57). Survivors showed positive LE (+0.339 {+/-} 0.543), and nonsurvivors showed negative LE (-0.825 {+/-} 0.972; p = 0.015). The fixed-point equilibrium of {approx} 280 g was approached by 63 % of patients at follow-up (p = 0.0003), a pattern indistinguishable from regression to the mean in the present design. Firth regression identified EF < 51.7 % and maximum heart rate < 109 bpm as independent predictors (optimism-corrected AUC = 0.959); the derived score showed a monotonic mortality gradient accompanied by lower LE across strata (Spearman {rho} = -0.369, p = 0.004). ConclusionsThese exploratory findings are compatible with nonlinear LV mass remodeling in Chagas disease and the association between loss of dynamic complexity and mortality. Replication in larger cohorts, formal model comparisons, and prospective validation of the score are warranted. Nonstandard Abbreviations and AcronymsASE, American Society of Echocardiography; AUC, area under the receiver operating characteristic curve; CCC, chronic Chagas cardiomyopathy; CHF, congestive heart failure; CI, confidence interval; EF, ejection fraction; HRV, heart rate variability; IQR, interquartile range; IVS, interventricular septum; LA, left atrial; LAHB, left anterior hemiblock; LBBB, left bundle branch block; LE, Lyapunov exponent; LV, left ventricular; LVEDD, left ventricular end-diastolic diameter; LVESD, left ventricular end-systolic diameter; NSVT, nonsustained ventricular tachycardia; NYHA, New York Heart Association; OR, odds ratio; PSVT, paroxysmal supraventricular tachycardia; PVC, premature ventricular complex; PW, posterior wall; RBBB, right bundle branch block; ROC, receiver operating characteristic; SAECG, signal-averaged electrocardiogram; SD, standard deviation; SDNN, standard deviation of normal-to-normal intervals; SEM, standard error of the mean; SVE, supraventricular ectopy