Effect of flecainide on heart rate variability in subjects without coronary artery disease or congestive heart failure

Heart rate variability is a noninvasive indicator of autonomic nervous syst em activity. The role of the autonomic nervous system in the genesis of atr ial or ventricular arrhythmias is now well established. Little is known abo ut the effects of flecainide on heart rate variability in patients with nor mal heart structure, the main population receiving flecainide. This study w as designed to evaluate the effects of flecainide on heart rate variability in patients without coronary artery disease or congestive heart failure. T ime and frequency domain analysis of heart rate variability on 24-hour elec trocardiogram recording were assessed in 40 patients with normal echocardio graphy and without evidence of coronary artery disease before and after 2 m onths of oral treatment with flecainide (321 +/- 57 mg/day) prescribed for Wolff Parkinson White syndrome with circus movement tachycardia. Flecainide significantly decreased all parameters of heart rate variability in the ti me domain (median Delta% -10% to -25%) and in the frequency domain (median Delta% -27% to -38%), including the markers of vagal activity. There was no correlation between plasma concentrations of flecainide and reduction in h eart rate variability. It was concluded that in subjects without coronary a rtery disease or congestive heart failure, flecainide decreases all the mea surements of heart rate variability and this decrease is not related to pla sma concentrations of flecainide.