Yong-Seog Oh

Bio: Yong-Seog Oh is an academic researcher from Catholic University of Korea. The author has contributed to research in topics: Catheter ablation & Atrial fibrillation. The author has an hindex of 13, co-authored 65 publications receiving 485 citations. Previous affiliations of Yong-Seog Oh include St Mary's Hospital.

Proposal of pharmacogenetics-based warfarin dosing algorithm in Korean patients

Abstract: Warfarin is a commonly prescribed anticoagulant drug for the prevention of thromboembolic disorders. We investigated the contribution of genetic variations of four genes and clinical factors to warfarin dose requirement and provided a warfarin-dosing algorithm based on genetic and clinical variables in Korean patients. We recruited 564 Korean patients on stable anticoagulation. Single nucleotide polymorphisms (SNPs) for the VKORC1, CYP2C9, CYP4F2 and GGCX were analyzed. Using multiple regression analysis, we developed a model to predict the warfarin requirement. The SNPs of VKORC1, CYP2C9, CYP4F2 and GGCX showed significant correlation with warfarin dose. Patients with the 3730AA genotype received significantly higher doses of warfarin than those with the 3730GG (P=0.0001). For CYP2C9, the highest maintenance dose was observed in the patients with wild-type genotype compared with the variant allele carriers (P<0.0001). The multiple regression model including age, gender, body surface area (BSA), international normalized ratio (INR) and four genetic polymorphisms accounted for 35% of total variations in warfarin dose (R(2)=0.3499; P<0.0001). This study shows that age, gender, BSA, INR and VKORC1, CYP2C9 and CYP4F2 polymorphism affect warfarin dose requirements in Koreans. Translation of this knowledge into clinical guidelines for warfarin prescription may contribute to improve the efficacy and safety of warfarin treatment for Korean patients.

Comparison of magnetic navigation system and conventional method in catheter ablation of atrial fibrillation: is magnetic navigation system is more effective and safer than conventional method?

Abstract: Background and Objectives: Although there have been so many reports of catheter ablation of atrial fibrillation (AF) with magnetic navigation system (MNS), it is not necessarily obvious that MNS is more effective than conventional ablation. We performed AF ablation with MNS and compared the clinical outcomes and radiofrequency ablation parameters with those of conventional ablation. Subjects and Methods: One hundred eleven consecutive patients (conventional group, n=70 vs. MNS group, n=41) undergoing catheter ablation of AF were enrolled. We compared and analyzed the procedural parameters, namely fluoroscopic time, procedural time, acute procedural success and 3 months success rate of both groups. Results: The MNS group was associated with slightly larger left atrial size (43.7 ±6.3 mm vs. 41.2±6.3 mm, p=0.04), significantly longer total proce dure time (352±50 minutes vs. 283±75 minutes, p<0.0001), and shorter total fluoroscopic time (99 ±28 minutes vs. 238±45 minutes, p<0.0001) than the conventional group. The MNS and conventional group did not differ with respect to acute pro cedural success, AF recurrence, atrial flutter/atrial tachycardia recurrence, or total arrhythmia recurrence. While no compli cations were observed in the MNS group, eight cases of significant pericardial effusion occurred in the conventional group. Conclusion: The MNS system seems to be effective and safe in the catheter ablation of AF, particularly in the population of patients with persistent AF and slightly dilated left atria. (Korean Circ J 2011;41:248-252) KEY WORD: Atrial fibrillation.

Passive Smoking in Never-Smokers Is Associated With Increased Plasma Homocysteine Levels

Abstract: Smoking is associated with increased plasma homocysteine levels, and both are associated with an increased risk of cardiovascular disease. However, little information is available on the effects of passive smoking on the level of homocysteine in nonsmokers. We analyzed the data of self-reported never-smokers (aged ≥ 20 years, n = 3,232), who were from the Third National Health and Nutrition Examination Survey. We quantified the passive nicotine exposure by dividing the never-smokers into quartiles as based on the serum cotinine values. Multiple linear and logistic regression models were used to determine any independent relationships between serum cotinine concentration and levels of homocysteine, vitamin B12, and folate. An elevated homocysteine level was defined as a concentration greater than the 80th percentile. A reduced folate or vitamin B12 level was defined as a concentration less than the 20th percentile.After adjusting for age, gender, body mass index, race, folate and vitamin B12 levels, increased cotinine levels (quartile III and IV) were found to be associated with hyperhomocysteinemia. There was a strong nonlinear increase in the serum homocysteine levels across the quartiles of cotinine. Multivariate analysis showed that age, male gender, non-Caucasian, low levels of folate and vitamin B12, and increased serum cotinine (quartile II-IV) were independently associated with elevated homocysteine levels. In conclusion, these findings indicate that passive smoke exposure in never-smokers is positively and independently associated with plasma homocysteine levels in a dose-dependent manner. These findings may help further determine the link between passive smoking and cardiovascular events.

Computed tomographic analysis of the esophagus, left atrium, and pulmonary veins: implications for catheter ablation of atrial fibrillation.

Abstract: Purpose: The aim of this study was to investigate the anatomic relationship around the left atrium (LA) and to provide clinical information to help avoid the risk of an atrio-esophageal fistula during atrial fibrillation (AF) ablation.

2020 ESC Guidelines for the diagnosis and management of atrial fibrillation developed in collaboration with the European Association for Cardio-Thoracic Surgery (EACTS).

Abstract: Supplementary Table 9, column 'Edoxaban', row 'eGFR category', '95 mL/min' (page 15). The cell should be coloured green instead of yellow. It should also read "60 mg"instead of "60 mg (use with caution in 'supranormal' renal function)."In the above-indicated cell, a footnote has also been added to state: "Edoxaban should be used in patients with high creatinine clearance only after a careful evaluation of the individual thromboembolic and bleeding risk."Supplementary Table 9, column 'Edoxaban', row 'Dose reduction in selected patients' (page 16). The cell should read "Edoxaban 60 mg reduced to 30 mg once daily if any of the following: creatinine clearance 15-50 mL/min, body weight <60 kg, concomitant use of dronedarone, erythromycin, ciclosporine or ketokonazole"instead of "Edoxaban 60 mg reduced to 30 mg once daily, and edoxaban 30 mg reduced to 15mg once daily, if any of the following: creatinine clearance of 30-50 mL/min, body weight <60 kg, concomitant us of verapamil or quinidine or dronedarone."

Validation of clinical classification schemes for predicting stroke: results from the national registry of atrial fibrillation☆

Abstract: a c statistic of 0.82 (95% CI, 0.80-0.84), the CHADS2 index was the most accurate predictor of stroke. The stroke rate per 100 patient-years without antithrombotic therapy increased by a factor of 1.5 (95% CI, 1.3-1.7) for each 1-point increase in the CHADS2 score: 1.9 (95% CI, 1.2-3.0) for a score of 0; 2.8 (95% CI, 2.0-3.8) for 1; 4.0 (95% CI, 3.1-5.1) for 2; 5.9 (95% CI, 4.6-7.3) for 3; 8.5 (95% CI, 6.3-11.1) for 4; 12.5 (95% CI, 8.2-17.5) for 5; and 18.2 (95% CI, 10.5-27.4) for 6. Conclusion The 2 existing classification schemes and especially a new stroke risk index, CHADS2, can quantify risk of stroke for patients who have AF and may aid in selection of antithrombotic therapy.