11 research outputs found

    Frequency analysis of surface electrocardiograms (ECGs) in patients with persistent atrial fibrillation: Correlation with the intracardiac ECGs and implications for radiofrequency catheter ablation

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    Background: The nature and significance of the frequency characteristics of the surface electrocardiogram (ECG) in patients with persistent atrial fibrillation (AF) undergoing radiofrequency ablation are unclear. Methods: Preablation surface and intracardiac ECGs were obtained using offline fast Fourier transform (FFT) analysis in 40 patients with persistent AF. For the FFT analysis of the surface f-wave, the QRS-T complex was canceled utilizing a template subtraction algorithm. The ablation procedure included isolation of the pulmonary veins (PV) and posterior left atrium and linear ablation of the mitral isthmus and additional lesions using a stepwise approach. Results: The dominant frequency (DF) of all the intracardiac signals, except for the left inferior PV, had a significant correlation with the DFs from the surface electrocardiogram. The strongest correlation was observed between the DFs of the left atrial appendage (LAA) and those on the limb leads (correlation coefficient, 0.802–0.882, P<0.001) and between the DFs on the right atrial appendage and those on lead V1 (correlation coefficient, 0.86, P<0.0001). After radiofrequency ablation, AF was terminated in 23 patients and persisted in the remaining 17. The best electrographic predictor of AF termination was the DFs in the LAA (DF<6.5 Hz, sensitivity 75%, specificity 86%) and lead II (DF<5.9 Hz, sensitivity 82%, specificity 78%), respectively. Conclusions: The frequency characteristics of the surface ECG correlated with those of the intracardiac signals, and the DF predicted termination of AF during radiofrequency ablation in patients with persistent AF

    PIK3CA mutation and methylation influences the outcome of colorectal cancer

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    Colorectal cancer (CRC) occurs through the accumulation of genetic and epigenetic alterations. The epigenetic abnormalities, in cooperation with genetic alterations, are capable of causing aberrant gene function that results in cancer. In the present study, we examined mutations and methylation status in 164 CRCs to determine whether the combination of genetic and epigenetic alterations may be used to classify CRC patients in relation to their clinicopathological characteristics and outcomes. Mutation analyses for the KRAS and PIK3CA genes were performed using direct sequencing, and the MethyLight method was used to determine the methylation status of BNIP3, p16 and hMLH1. The combination of the KRAS mutation with methylation status did not have any association with clinicopathological characteristics and outcomes. However, patients with the PIK3CA mutation and/or high methylation (2 or 3 methylated genes) had significantly poorer outcomes in disease-specific survival (DSS) compared with those with wild-type PIK3CA and 0 or 1 methylated genes (P=0.0059). Additionally, multivariate analysis revealed that the PIK3CA mutation and/or a high level of methylation predicts a poor DSS independently of clinicopathological characteristics. Our results suggest that a combination of genetic and epigenetic alterations is a potent biomarker for predicting the prognosis of CRC
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