The single nucleotide polymorphisms of Kir3.4 gene and their correlation with lone paroxysmal atrial fibrillation in Chinese Han population.

BACKGROUND: Acetylcholine induced inwardly rectifying current (I(KACh)) is a heteromultimeric complex formed by Kir3.1 and Kir3.4 subunits and plays important roles in the development of atrial fibrillation (AF). AF is a common disorder among Chinese, the frequency of AF is about 0.61%, and in patients with strokes it is 12.1%. We hypothesise that lone paroxysmal AF genetic variation in Kir3.4 may predispose the atria to fibrillation in the Chinese population. METHODS: We recruited 186 patients with lone paroxysmal AF, and 210 matched controls by age (49.61+/-8.04 years), sex, smoking habit, and left atrial dimension in Zhejiang Province, China. Genotype of Kir3.4 was determined with polymerase chain reaction (PCR) and direct sequencing. The SPSS statistical software was used for chi(2) test. LD and haplotypes were calculated using SHESIS software package. RESULTS: Three synonymous known single nucleotide polymorphisms (SNPs) in Kir3.4 were genotyped, including C171T (rs6590357), G810T (rs7118824) and C834T (rs7118833). We found low levels of linkage disequilibrium (LD) between C171T and G810T (D'=0.272), complete LD between SNPs G810T and C834T (D'=1) in AF patients and controls. The case-control analysis revealed that the frequency of genotype and allele in three SNPs are significantly different between lone paroxysmal AF patients than in control subjects. The odds ratio (OR) for AF 171T and 810T alleles were 1.546 (95% CI 1.015-2.355) and 1.520 (95% CI 1.012-2.284), respectively, when compared with patients without Kir3.4T alleles in these two loci. The OR for AF in patients with C-T genotype were 13.364 (95% CI 5.710-31.278) and 37.135 (95% CI 9.050-152.381) when comparing patients with T-G genotype. CONCLUSIONS: Our findings suggest that C171T and G810T SNPs in Kir3.4 gene might be risk factors for lone paroxysmal AF in Chinese population.

[Right ventricular desynchronization in patients with pacemaker syndrome].

OBJECTIVE: To observe the incidence of ventricular desynchronization in patients with or without pacemaker syndrome (PMS). METHODS: The systolic peak velocity, the acceleration and the time to peak velocity of the interventricular septum (IVS), left ventricular (LV) and right ventricular (RV) lateral wall were detected by tissue Doppler imaging (TDI) in 14 atrial fibrillation patients without pacemaker implantation (control), 18 atrial fibrillation patients without PMS and 16 atrial fibrillation patients with PMS. All patients were free of valve disease, myocardial infarction, severe pulmonary hypertension, low left ventricular eject fraction (< or = 50%), significant segmental hypokinesis of ventricular wall or complete bundle branch block. RESULTS: Compared to the control patients, the systolic peak velocity and the accelerations on lateral walls of the LV and RV reduced significantly in patients with implanted pacemakers (P < 0.05). The intervals to peak velocity of the IVS and LV lateral walls were significantly prolonged [PMS group (80.13 +/- 26.92) ms vs. (25.60 +/- 4.30) ms, P < 0.01; without PMS group (76.22 +/- 23.32) ms vs. (25.60 +/- 4.30) ms, P < 0.01] and the intervals to peak velocity of the IVS and RV lateral walls significantly shortened [PMS group (16.33 +/- 6.85) ms vs. (40.70 +/- 7.60) ms, P < 0.01; without PMS group (21.20 +/- 7.34) ms vs. (40.70 +/- 7.60) ms, P < 0.01]. The systolic peak velocities, the accelerations of the IVS and bilateral walls and the intervals to peak velocity of the IVS and LV lateral wall were similar in patients with and without PMS (P > 0.05), however, the intervals to peak velocity of the IVS and RV lateral wall was significant shorter in patients with PMS compared to that of patients without PMS [(16.33 +/- 6.85) ms vs. (21.20 +/- 7.34) ms, P < 0.01]. CONCLUSION: RV desynchronization but not LV desynchronization might play an important role in patients with PMS.