Prognostic value of Poincare plot as nonlinear parameter of chaos theory in patients with myocardial infarction

Abstract

INTRODUCTION: There are different proofs about association of autonomic nervous system dysfunction, especially nonlinear parameters, with higher mortality after myocardial infarction. OBJECTIVE: The objective of the study was to determine predictive value of Poincaré plot as nonlinear parameter and other significant standard risk predictors: ejection fraction of the left ventricle, late potentials, ventricular arrhythmias, and QT interval. METHOD: The study included 1081 patients with mean follow-up of 28 months (ranging from 0-80 months). End-point of the study was cardiovascular mortality. The following diagnostic methods were used during the second week: ECG with commercial software Schiller AT-10: short time spectral analysis of RR variability with analysis of Poincaré plot as nonlinear parameter and late potentials; 24-hour ambulatory ECG monitoring: QT interval, RR interval, QT/RR slope, ventricular arrhythmias (Lown > II); echocardiography examinations: systolic disorder (defined as EF < 40%). RESULTS: There were 103 (9.52%) cardiovascular deaths during the follow-up. In univariate analysis, the following parameters were significantly correlated with mortality: mean RR interval < 800 ms, QT and RR interval space relationship as mean RR interval < 800 ms and QT interval > 350 ms, positive late potentials, systolic dysfunction, Poincaré plot as a point, ventricular arrhythmias (Lown > II). In multivariate analysis, the significant risk predictors were: Poincaré plot as a point and mean RR interval lower than 800 ms. CONCLUSION: Mean RR interval lower than 800 ms and nonlinear and space presentation of RR interval as a point Poincaré plot were multivariate risk predictors.