Recurrence quantification analysis based on P-P intervals measurement in postinfarction patients with frequent ventricular ectopy

Frequent ventricular ectopy results a great problem of any heart rate variability analysis method, because the interpolation of the R-R intervals significantly disturbs the intrinsic rhythm's features. Recurrence quantification analysis (RQA) is a valuable tool for predicting serious cardiovascular events. Our ambulatory ECG (AECG) system (RhythmPattern, SzivLeso) processes the 1 kHz ECG recordings, calculates various non-linear heart rate parameters, and analyses the P- and R-waves The study population (age 61.9±8.6) consists of 89 postinfarction patients, where frequent (> 6000/24 hours) ventricular ectopic beats were found. The ambulatory ECG monitoring was repeated in every month; the mean follow-up was 38.8 months. The patients were divided into two groups: 72 pts were alive (Group_A), and 17 pts (Group_B) died at the end of the study. The P-P tachogram was determined instead of R-R intervals. The standard parameters of RQA were calculated. Significant (p<0.01) differences were found of the majority of RQA parameters, when the P-to-P wave tachograms were used instead of R-to-R wave ones.