Effects of the Ikr-blocker almokalant and predictors of conversion of chronic atrial tachyarrhythmias to sinus rhythm. A prospective study.
OBJECTIVE
To assess the efficacy of the Ikr-blocker almokalant attempting to convert chronic atrial tachyarrhythmias, and to find predictors of conversion, to sinus rhythm.


METHODS
The electrophysiological effects of a 6-hour infusion of almokalant, to a total dose of 25 +/- 4 mg, were assessed by ECG and transesophageal atrial electrograms (TAE) in 100 consecutive patients with atrial fibrillation/flutter (n = 95/5) of 8 +/- 12 months' duration (range 1 to 99 months).


RESULTS
The conversion rate was 32%. The time to conversion was 3.5 +/- 2.2 hours. During infusion increases in QTtop (292 +/- 35 to 335 +/- 44 ms, p < 0.001, after 30 minutes), QT (387 +/- 40 to 446 +/- 60 ms, p < 0.001), corrected QT (425 +/- 30 to 487 +/- 44 ms, p < 0.001), and QT dispersion (21 +/- 12 to 29 +/- 31 ms, p = 0.02), were paralleled by decreases in T wave amplitude (0.31 +/- 0.19 to 0.23 +/- 0.16 mV, p < 0.001), and atrial rate (425 +/- 78 to 284 +/- 44 beats per minute (bpm) on ECG, and 396 +/- 72 to 309 +/- 44 bpm on TAE), with no differences between converters to sinus rhythm and non-converters. Patients with aberrantly conducted beats, and T wave variation, also increased. Calcium antagonists were more common among converters. A decreasing T wave amplitude predicted conversion. Four patients developed torsades de pointes.


CONCLUSIONS
This study demonstrates class III action of almokalant, with a conversion rate of 32% of long-standing, chronic atrial tachyarrhytmias. An early decrease in T wave amplitude was associated with conversion to sinus rhythm.
Houltz
B
B
Department of Medicine, Sahlgrenska University Hospital/Ostra, Göteborg, Sweden. birgitta.houltz@medfak.gu.se
Darpö
B
B
Swedberg
K
K
Blomström
P
P
Brachmann
J
J
Crijns
H J
HJ
Jensen
S M
SM
Svernhage
E
E
Vallin
H
H
Edvardsson
N
N
D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000188:drug therapy* / Q000235:genetics; D004562:Electrocardiography / Q000187:drug effects*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D011412:Propanolamines / Q000627:therapeutic use*; D013997:Time Factors; D016171:Torsades de Pointes / Q000209:etiology
D000889:Anti-Arrhythmia Agents; D011412:Propanolamines; C074334:almokalant