Effects of Nardostachys chinensis on spontaneous ventricular arrhythmias in rats with acute myocardial infarction.

OBJECTIVES: To investigate the effects and mechanisms of Nardostachys chinensis (NC) on spontaneous ventricular arrhythmias in rats with hyper-acute myocardial infarction (AMI). METHODS: Seventy-two rats were randomly divided into the control group (n = 24), metoprolol group (n = 24), and the NC group (n = 24). Premature ventricular contractions (PVCs), ventricular tachycardias (VTs), ventricular fibrillations (VFs), and blood pressure were monitored for 4 hours after coronary artery ligation. The connexin 43 (Cx43) expression in ventricular myocardium was measured by immunohistochemistry, Western blot, and real-time RT-PCR. RESULTS: Compared with the control, metoprolol and NC decreased the VF incidence (50% vs. 4.2%, P < 0.001, and 50% vs. 12.5%, P = 0.005, respectively). There was a steady decrease in the cumulative number of PVCs and VTs within 4 hours from ligating in 3 groups. Compared with the control, metoprolol and NC reduced the cumulative number of VTs and PVCs. Compared with control, metoprolol and NC decreased the infarct size of the left ventricular tissue (55.98% ± 6.20% vs. 39.13% ± 4.53%, P < 0.001, and 55.98% ± 6.20% vs. 42.39% ± 3.44%, P < 0.001, respectively). The results from immunohistochemistry, Western blot, and real-time RT-PCR showed that the protein expression of Cx43 in the control group was significantly lower than that in the metoprolol and NC groups in the infarcted zone. CONCLUSIONS: NC decreased the incidence of spontaneous ventricular arrhythmias (especially VF), reduced Cx43 degradation, and improved Cx43 redistribution in myocardial infarcted zone in rats with hyper-AMI. The data of the present study indicated that NC may be a promising drug in the future to prevent patients with AMI from lethal ventricular arrhythmias in prehospital setting.

Early repolarization pattern and risk for arrhythmia death: a meta-analysis.

OBJECTIVES: A meta-analysis was performed to determine the risk and incidence rate of arrhythmia death, cardiac death, and all-cause death in the general population with the early repolarization pattern (ERP). BACKGROUND: The ERP has recently been associated with vulnerability to ventricular fibrillation in case-control studies. However, the prognostic significance of the ERP in the general population is controversial. METHODS: Relevant studies published through July 31, 2012, were searched and identified in the MEDLINE and Embase databases. Studies that reported risk ratio estimates with 95% confidence intervals (CIs) for the associations of interest were included. Data were extracted, and summary estimates of association were obtained using a random-effects model. RESULTS: Of the 9 studies included, 3 studies reported on arrhythmia death (31,981 subjects, 1,108 incident cases during 726,741 person-years of follow-up), 6 studies reported on cardiac death (126,583 subjects, 10,010 incident cases during 2,054,674 person-years of follow-up), and 6 studies reported on all-cause death (112,443 subjects, 22,165 incident cases during 2,089,535 person-years of follow-up). The risk ratios of the ERP were 1.70 (95% CI: 1.19 to 2.42; p = 0.003) for arrhythmia death, 0.78 (95% CI: 0.27 to 2.25; p = 0.63) for cardiac death, and 1.06 (95% CI: 0.87 to 1.28; p = 0.57) for all-cause death. The estimated absolute risk differences of subjects with the ERP were 70 cases of arrhythmia death per 100,000 subjects per year. J-point elevation ≥ 0.1 mV in the inferior leads and notching configuration had an increased risk for arrhythmia death in subgroup studies. CONCLUSIONS: The ERP was associated with increased risk and a low to intermediate absolute incidence rate of arrhythmia death. Further study is needed to clarify which subgroups of subjects with the ERP are at higher risk for arrhythmia death.