Symptomatic response to antiarrhythmic drug therapy is modulated by a common single nucleotide polymorphism in atrial fibrillation.
OBJECTIVE
This study tested the hypothesis that response to antiarrhythmic drugs (AADs) is modulated by 3 common loci associated with atrial fibrillation (AF).


BACKGROUND
Recent genome-wide association studies have identified 3 loci, on chromosomes 4q25 (near PITX2), 16q22 (in ZFHX3), and 1q21 (in KCNN3), that associate with either typical or lone AF. These findings indicate that variable mechanisms contribute to AF susceptibility, and suggest that response to therapy may be genotype dependent.


METHODS
We studied 478 and 198 Caucasian patients in the discovery cohort and validation cohort, respectively, who were prospectively enrolled in the Vanderbilt AF registry. Response was defined prospectively as successful rhythm control if the patient remained on the same AAD therapy for a minimum of 6 months with ≥75% reduction in symptomatic AF burden. We also evaluated AF recurrence by 12-lead electrocardiogram (ECG) at 3, 6, and 12 months. Symptomatic patients were also given a 24- to 48-h Holter monitor or 30-day event recorder when AF recurrence was not captured by 12-lead ECG.


RESULTS
In the discovery cohort, 399 (83%) patients were successfully rhythm controlled. Multiple clinical variables (including age, hypertension, lone AF) failed to significantly predict response to AADs; however, single nucleotide polymorphism (SNP) rs10033464 at 4q25 was an independent predictor of successful rhythm control in patients with typical AF carrying the ancestral allele (wild type) versus carriers of variant allele (odds ratio [OR]: 4.7, 95% confidence interval [CI]: 1.83 to 12, p = 0.0013. In the validation cohort, 143 (72%) patients met the criteria for successful rhythm control, and rs10033464 was again an independent predictor of successful rhythm control, OR: 1.5, 95% CI: 1.02 to 3.06, p = 0.04. This SNP (rs10033464) was an independent predictor of AF recurrence in the discovery (39% AF recurrence) and validation (38% AF recurrence) cohorts; OR: 3.27, 95% CI: 1.7 to 6, p < 0.001 and OR: 4.3, 95% CI: 1.98 to 9.4, p < 0.001, respectively.


CONCLUSIONS
These results suggest that a common SNP on chromosome 4q25 associated with AF modulates response to AAD therapy and points to a potential role for stratification of therapeutic approaches by genotype.
Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37323-6602, USA.
Babar
B
Parvez
Joseph
J
Vaglio
Shane
S
Rowan
Raafia
R
Muhammad
Gayle
G
Kucera
Tanya
T
Stubblefield
Shannon
S
Carter
Dan
D
Roden
Dawood
D
Darbar
D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000235:genetics*; D002894:Chromosomes, Human, Pair 4 / Q000235:genetics*; D015331:Cohort Studies; D004562:Electrocardiography; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D012008:Recurrence; D012042:Registries; D044465:White People
D000889:Anti-Arrhythmia Agents