Independent susceptibility markers for atrial fibrillation on chromosome 4q25

Background-: Genetic variants on chromosome 4q25 are associated with atrial fibrillation (AF). We sought to determine whether there is more than 1 susceptibility signal at this locus. Methods and results-: Thirty-four haplotype-tagging single-nucleotide polymorphisms (SNPs) at the 4q25 locus were genotyped in 790 case and 1177 control subjects from Massachusetts General Hospital and tested for association with AF. We replicated SNPs associated with AF after adjustment for the most significantly associated SNP in 5066 case and 30 661 referent subjects from the German Competence Network for Atrial Fibrillation, Atherosclerosis Risk In Communities Study, Cleveland Clinic Lone AF Study, Cardiovascular Health Study, and Rotterdam Study. All subjects were of European ancestry. A multimarker risk score composed of SNPs that tagged distinct AF susceptibility signals was constructed and tested for association with AF, and all results were subjected to meta-analysis. The previously reported SNP, rs2200733, was most significantly associated with AF (minor allele odds ratio 1.80, 95% confidence interval 1.50 to 2.15, P=1.2×10) in the discovery sample. Adjustment for rs2200733 genotype revealed 2 additional susceptibility signals marked by rs17570669 and rs3853445. A graded risk of AF was observed with an increasing number of AF risk alleles at SNPs that tagged these 3 susceptibility signals. Conclusions-: We identified 2 novel AF susceptibility signals on chromosome 4q25. Consideration of multiple susceptibility signals at chromosome 4q25 identifies individuals with an increased risk of AF and may localize regulatory elements at the locus with biological relevance in the pathogenesis of AF

Four-year follow-up of treatment with intramyocardial skeletal myoblasts injection in patients with ischaemic cardiomyopathy

Aims: Studies reporting improved left ventricular (LV) function of percutaneous skeletal myoblast (SkM) injection in patients with ischaemic cardiomyopathy had follow-up not exceeding 12 months, and did not include a control group. Our group has reported evidence for myoblast efficacy in the first five out of the 14 treated patients. The objective of the present evaluation was to assess if these effects were sustained at long-term follow-up. We compared function of patients treated with SkM 4 years earlier with a matched control group. Secondary endpoints included mortality, NYHA class, N-terminal pro-B-natriuretic peptide levels, incidence of arrhythmias, and quality of life. Methods and results: Fourteen patients with ischaemic cardiomyopathy who underwent SkM injection were compared with 28 non-randomized control patients matched for age, sex, location, and extent of myocardial infarction. Contrast echocardiography and tissue Doppler imaging (TDI) was performed to compare global and regional LV function. At 4-year follow-up, three patients (21%) had died in the treated group and 11 patients (39%) in the control group (P = 0.8). In the survivors, LV ejection fraction (EF) was 35 ± 10% and 37 ± 9% in the SkM group and 36 ± 8% and 36 ± 6% in the controls at baseline and 4 years follow-up, respectively (P = 0.96 between groups at follow-up). TDI-derived systolic velocity in the injected sites was 5.4 ± 1.8 cm/s in the SkM group when compared with 5.1 ± 1.6 cm/s in corresponding sites in the control group (P = 0.47). None of the secondary endpoints showed a difference between the groups. However, in the patients fitted with an internal cardioverter defibrillator, more arrhythmias leading to interventions occurred in the treated group than in the control group, 87% and 13%, respectively (P = 0.015). Conclusion: Percutaneous intramyocardial SkM injection in ischaemic cardiomyopathy has no sustained positive effect on resting global or regional LV function, respectively, at 4-year follow-up. Moreover, the procedure may induce a higher risk of developing serious arrhythmias, but larger patient series are required before more precise characterization of the safety and efficacy profile of the procedure is possible