Heart Rate Variability Is Decreasing During Paroxysmal Atrial Fibrillation

Abstract

Background:The high R-R variability in permanent atrial fibrillation (AF) is stable. Its behavior in paroxysmal AF is unknown. The aim of this study was to examine heart rate variability behavior during paroxysmal AF and its relationship with clinical characteristics by using time-domain indices and scatterplot analysis.Methods: In 43 patients, R-R variability was assessed by time-domain indices and graphical measurements of scattering area (SA) on scatterplot for each sample of 150-second ventricular rhythms extracted at the onset, the middle, and before termination of AF episodes recorded on Holter monitoring. Results were compared between the three time periods, and a nested procedure assessed the components of the SA variance.Results: In 11 0 episodes lasting 89 rfr 130 minutes with a mean of 2.5 ? 3 (1 -1 2) per patient, mean R-R interval did not significantly change while time-domain indices and SA significantly decreased between the three time periods (P < 0.05 for SD and CV, P < 1 0-2 for rMSSD and pNN50, P < 1 0-4 for SA, ANOVA 1). The magnitude of the decrease in SA was not related to any episode characteristic; in addition, there was no variation from episode to episode within patient (lo% of SA variance), and the high variation between patients (To%, P < was not related to any clinical parameter. Conclusions: Heart rate variability decreases gradually during paroxysmal AF. This decrease is peculiar to each patient, unrelated to clinical status.A.N.E. 1999;4(2):144-151 atrial fibrillation; Holter monitoring; heart rate variability; scatterplot ~~ Address for reprints: