Statistical analysis: The primary study endpoint will be AF burden (the proportion of time a patient is in AF) and will be calculated for each patient while undergoing therapy with each study drug. The primary endpoint will be expressed for each study drug as median, 25th percentile, and 75th percentile. The difference in AF burden while on class I and class III AADs will be compared using the Wilcoxon signed-rank test for paired data. We will conduct an exploratory analysis using a linear regression model to detect an association between genotype and AF burden after adjustment for age and sex. First, we will analyze a model including separate terms for all three chr4q25 SNPs simultaneously with adjustment for age and sex. Then we will create a second model that replaces the separate chr4q25 SNP terms for a combined chr4q25 risk score calculated by adding the beta-coefficients for the genotypes at rs2200733, rs17570669, and rs3853445 found in the first model. If multivariable analysis demonstrates the combined chr4q25 risk score and study drug assignment are both significantly associated with AF burden, they will be tested for a statistical interaction to determine whether the chr4q25 AF susceptibility locus determines a differential response to class I and class III AADs. It should be emphasized that this analysis will be underpowered and over-fitted in this pilot/feasibility study.