Pilot study: Noninvasive monitoring of oral flecainide's effects on atrial electrophysiology during persistent human atrial fibrillation using the surface electrocardiogram.
BACKGROUND
The relation between flecainide's plasma level and its influence on human atrial electrophysiology during acute and maintenance therapy of atrial fibrillation (AF) is unknown. Therefore, this study determined flecainide plasma levels and atrial fibrillatory rate obtained from the surface ECG during initiation and early maintenance of oral flecainide in patients with persistent lone AF and assessed their relationship.


RESULTS
In 10 patients (5 males, mean age 63 +/- 14 years, left atrial diameter 46 +/- 3 mm) with persistent lone AF, flecainide was administered as a single oral bolus (day 1) followed by 200-400 mg/day (days 2-5). The initial 300 mg flecainide bolus resulted in therapeutic plasma levels in all patients (range 288-629 ng/ml) with no side effects. Flecainide plasma levels increased on day 3 and remained stable thereafter. Day 5 plasma levels were lower (508 +/- 135 vs 974 +/- 276 ng/ml, P = 0.009) in patients with daily mean flecainide doses of 200 mg compared to patients with higher maintenance doses. Fibrillatory rate obtained from the surface electrocardiogram measuring 378 +/- 17 fpm at baseline was reduced to 270 +/- 18 fpm (P < 0.001) after the flecainide bolus but remained stable thereafter. Fibrillatory rate reduction was independent of flecainide plasma levels or clinical variables.


CONCLUSIONS
A 300 mg oral flecainide bolus is associated with electrophysiologic effects that are not increased during early maintenance therapy in persistent human lone AF. In contrast to drug plasma levels, serial analysis of fibrillatory rate allows monitoring of individual drug effects on atrial electrophysiology.
Husser
Daniela
D
Department of Cardiology, University Hospital Magdeburg, Magdeburg, Germany.
Binias
Karl-Heinz
KH
Stridh
Martin
M
Sornmo
Leif
L
Olsson
S Bertil
SB
Molling
Jochen
J
Geller
Christoph
C
Klein
Helmut U
HU
Bollmann
Andreas
A
D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology* / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000188:drug therapy*; D016275:Atrial Function / Q000187:drug effects*; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D005424:Flecainide / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology* / Q000627:therapeutic use; D006325:Heart Atria / Q000187:drug effects; D006329:Heart Conduction System / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory; D010865:Pilot Projects
D000889:Anti-Arrhythmia Agents; D005424:Flecainide