Association Between rs2200733 Polymorphism on Chromosome 4q25 and Atrial Fibrillation in a Greek Population.

INTRODUCTION: Atrial fibrillation (AF) is a common arrhythmia with evidence of genetic susceptibility. The rs2200733 single-nucleotide polymorphism (SNP) in a non-coding region on chromosome 4q25 has been associated with AF. The purpose of this case-control study was to examine the possible association of the rs2200733 polymorphism with AF in the Greek population. METHODS: A total of 295 individuals, 167 AF patients and 128 controls, were genotyped for the presence of the rs2200733 polymorphism using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLPs) method. RESULTS: The T/T genotype and the T allele were detected more frequently in patients with AF compared to controls (13.2% vs. 2.3%, p=0.001, and 29.6% vs. 17.9%, p=0.001), suggesting that the rs2200733 polymorphism increases susceptibility to AF in the Greek population. In a multivariate stepwise analysis that included many conventional precipitating factors for AF, T/T genotype and left atrium (LA) diameter were the only independent predictors of AF (OR 1.74, 95% CI: 1.40-2.98, p=0.005, and OR 2.88, 95% CI: 1.835.62, p<0.001, respectively). A trend of association was observed between the T/T genotype and lone AF (p=0.08). CONCLUSIONS: Our results suggest that SNP rs2200733 confers a significant risk of AF in the Greek population, providing further support to the previously reported association between AF and rs2200733 polymorphism on chromosome 4q25.

Ranolazine enhances the efficacy of amiodarone for conversion of recent-onset atrial fibrillation.

AIMS: Amiodarone is used commonly for pharmacological cardioversion of atrial fibrillation (AF), but it is limited by moderate efficacy and delayed action. Ranolazine and amiodarone are markedly synergistic in suppressing experimental AF in vitro, yet the clinical efficacy of ranolazine combined with amiodarone for AF conversion has only undergone minimal investigation. This prospective, single-blinded, randomized study compared the safety and efficacy of ranolazine added to amiodarone vs. amiodarone alone for conversion of recent-onset AF. METHODS AND RESULTS: We enroled 121 patients (64 ± 10 years, 45% male) with recent-onset (<48 h duration) AF who were eligible for pharmacological cardioversion. Patients received either 24 h amiodarone infusion (loading dose 5 mg/kg followed by maintenance dose of 50 mg/h; n = 60), or amiodarone infusion at the same dosage plus a single oral dose of ranolazine 1500 mg (n = 61). Patients in the amiodarone plus ranolazine group compared with the amiodarone-only group showed significantly higher conversion rates at 24 h (87 vs. 70%, respectively; P = 0.024) and at 12 h (52 vs. 32%; P = 0.021), and shorter time to conversion (10.2 ± 3.3 vs. 13.3 ± 4.1 h; P = 0.001). Subgroup analysis identified higher 24 h conversion in patients with left atrial (LA) diameter >46 mm who received the combination treatment vs. amiodarone alone (81 vs. 54%; P = 0.02), whereas the efficacy of the two interventions did not differ among patients with LA diameter ≤46 mm (P = 0.77). There was modest QT prolongation in both the groups, no serious adverse reactions, and no pro-arrhythmic events. CONCLUSION: Addition of ranolazine to amiodarone was safe and well tolerated in this study, and it demonstrated efficacy superior to amiodarone alone for conversion of recent-onset AF. These findings may have clinical implications by offering a simple therapeutic manoeuvre to enhance amiodarone's effectiveness for conversion of AF.