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Publications (7)13.19 Total impact

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    ABSTRACT: The aim of this study is to identify the extent of initial malapposition using optical coherence tomography (OCT) in ST-elevation myocardial infarctions (STEMI) treated with different types of drug-eluting stents (DES). Twenty four STEMI patients that underwent primary percutaneous coronary intervention (PCI) were enrolled. The OCT and intravascular ultrasound (IVUS) were performed within 72 hours after the primary PCI. Distances between the endo-luminal surface of the strut reflection and the vessel wall and the extent of malapposition were measured and analyzed. Sirolimus-eluting stents (SES), paclitaxel-eluting stents (PES) and zotarolimus-eluting stents (ZES) were deployed in 7 patients (29%), 7 patients (29%) and 10 patients (42%). In total, 4951 struts in 620 mm single-stent segments were analyzed (1463 struts in SES, 1522 in PES, and 1966 in ZES). In strut analysis by OCT, the incidence of malapposition was 17 % (860/4951) and in stent analysis by IVUS, malapposition rate was 21% (5/24). The malapposition rate of strut level using OCT in 5 patients who had malapposition in IVUS was significantly higher than the 19 of those who had not (32 +/- 5% vs. 12 +/- 6%, p = 0.001). In addition, the frequency of malapposition was also significantly different (28% in SES, 11% in PES, 10% in ZES, p = 0.001). The use of SES was an independent predictor of malapposed struts. The incidence of malapposition using OCT was quite prevalent in STEMI after primary PCI with DES implantation and SES has especially higher rates of malapposition compared to other DESs.
    Yonsei medical journal 05/2010; 51(3):332-8. · 0.77 Impact Factor
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    ABSTRACT: This study sought to determine the efficacy of high-dose atorvastatin in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI). Previous randomized trials have demonstrated that statin pre-treatment reduced major adverse cardiac events (MACEs) in patients with stable angina pectoris and acute coronary syndrome. However, no randomized studies have been carried out with STEMI patients in a primary PCI setting. A total 171 patients with STEMI were randomized to 80-mg atorvastatin (n = 86) or 10-mg atorvastatin (n = 85) arms for pre-treatment before PCI. All patients were prescribed clopidogrel (600 mg) before PCI. After PCI, both groups were treated with atorvastatin (10 mg). The primary end point was 30-day incidence of MACE including death, nonfatal MI, and target vessel revascularization. Secondary end points included corrected thrombolysis in myocardial infarction frame count, myocardial blush grade, and ST-segment resolution at 90 min after PCI. MACE occurred in 5 (5.8%) and 9 (10.6%) patients in the 80-mg and 10-mg atorvastatin pre-treatment arms, respectively (p = 0.26). Corrected thrombolysis in myocardial infarction frame count was lower in the 80-mg atorvastatin arm (26.9 +/- 12.3 vs. 34.1 +/- 19.0, p = 0.01). Myocardial blush grade and ST-segment resolution were also higher in the 80-mg atorvastatin arm (2.2 +/- 0.8 vs. 1.9 +/- 0.8, p = 0.02 and 61.8 +/- 26.2 vs. 50.6 +/- 25.8%, p = 0.01). High-dose atorvastatin pre-treatment before PCI did not show a significant reduction of MACEs compared with low-dose atorvastatin but did show improved immediate coronary flow after primary PCI. High-dose atorvastatin may produce an optimal result for STEMI patients undergoing PCI by improving microvascular myocardial perfusion. (Efficacy of High-Dose AtorvaSTATIN Loading Before Primary Percutaneous Coronary Intervention in ST-Elevation Myocardial Infarction [STATIN STEMI]; NCT00808717).
    JACC. Cardiovascular Interventions 03/2010; 3(3):332-9. · 1.07 Impact Factor
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    ABSTRACT: A lot of conventional algorithms have tried to cancel the residual frame synchronization error (RFSE), which causes the performance degradation of channel estimation when using interpolation between pilot sub-carriers in comb-type pilot-aided OFDM systems. Among them, a tracking method has been attractive to provide good performance by eliminating the effects of RFSE. However, it requires high computational complexity because of its compensation process including many complex multiplications. In this paper, we propose a new method which significantly reduces computational costs by adjusting the starting point of FFT window in order to compensate for the RFSE. For the performance verification, we apply the proposed method to the IEEE 802.16e mobile WiMAX system and estimate its computational power compared to the tracking method. Simulation and implementation results show that the proposed algorithm has the performance similar to the tracking method and is very efficient for low power implementation in comb-type pilot-aided OFDM systems because it consumes only 40.5% of the tracking method's power.
    IEEE Transactions on Consumer Electronics 12/2009; · 1.09 Impact Factor
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    ABSTRACT: Inflammation is frequently associated with the development of atrial fibrillation (AF). This study was performed to investigate whether the high sensitivity C-reactive protein (hsCRP) present during acute inflammation could predict early AF and its relationship to left atrial (LA) enlargement in acute myocardial infarction (AMI). In 401 consecutive AMI patients, AF predictors were compared between those with and without early AF. Early AF was defined as AF developing within 24 h after AMI. In order to identify the difference in the AF predictors according to LA enlargement, patients were subgrouped according to an LA volume index (LAVI) of <32 cm(3)/m(2) (group 1, n=321) and ≥32 cm(3)/m(2) (group 2, n=80). Thirty-three (8.2%) patients developed early AF including 17 (5.3%) and 16 (20%) patients in groups 1 and 2, respectively. The independent predictors of AF were multivessel involvement (OR=2.51, p=0.03), LAVI≥32 cm(3)/m(2) (OR=2.47, p=0.03), higher hsCRP (OR=2.24, p=0.05), and old age (OR=1.06, p=0.01) in all patients. In the subgroups divided by the LAVI, higher hsCRP was a predictor of early AF only in group 1 (OR=4.56, p=0.004). Our results suggest that multivessel involvement, enlarged LA, higher hsCRP, and old age are predictors of early AF after AMI. However, hsCRP could be strongly related to early AF only in AMI patients with less dilated LA.
    International journal of cardiology 07/2009; 146(1):28-31. · 6.18 Impact Factor
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    ABSTRACT: To assess mid- to long-term clinical results of stent-graft repair in patients with type B aortic dissection. Retrospective analysis was done on 72 patients (47 men; mean age 55+/-12 years) who were diagnosed with chronic type B aortic dissection and underwent stent-graft repair from June 1994 to December 2007. Two types of stent-grafts were employed. Prior to 2000, a custom-designed stent-graft composed of self-expanding Z-type stainless steel stents covered with woven polytetrafluoroethylene material was used. Thereafter, a separate-type (modular) manufactured stent-graft was used, consisting of proximal and distal nitinol stents with an unsupported Dacron tube graft in between; the unsupported graft was stented after deployment. Procedural success (completion of the stent-graft deployment at the target area without device failure) was obtained in 97% (70/72). The 2 failures were due to stent migration and tortuous anatomy, respectively. There were persistent type I endoleaks in 6 cases for a clinical success (entry tear exclusion) of 88% (64/72). There was no immediate postprocedural mortality or paraplegia. There was unintended partial left subclavian artery occlusion in 1 case, as well as postprocedural transient renal failure in 1 patient and 2 access-site pseudoaneurysms. Median follow-up was 43 months (range 5-97, mean 64.4+/-38.8) in 61 patients (3 patients lost to follow-up). Five patients died, 1 of probable aortic rupture in the setting of residual type I endoleak. Overall clinical success (no death, conversion, or endoleak) was achieved in 84% (47/56); of these, 35 (74%) showed complete resolution of the thoracic false lumen, while the other 12 (26%) had a decrease in false lumen diameter. Intermediate to long-term results of stent-graft implantation in patients with chronic type B aortic dissection seem acceptable and may justify the use of this minimally invasive approach as first line therapy in these patients.
    Journal of Endovascular Therapy 03/2009; 16(1):42-7. · 2.70 Impact Factor
  • Heart Lung and Circulation - HEART LUNG CIRC. 01/2008; 17.
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    ABSTRACT: BackgroundThe objective of this study was to investigate atrial myocardial properties through two-dimensional (2D) myocardial imaging in patients with atrial fibrillation (AF) and its predictive role for recurrence after catheter ablation. Methods and resultsEchocardiographic examinations were performed in 40 patients with paroxysmal AF before catheter ablation and 40 age- and gender-matched healthy control subjects. Using a software package, bidimensional acquisitions were analyzed to measure longitudinal strain and strain rate for the left atrium (LA). Systolic strain and strain rate in all eight segments, and its average values, were significantly reduced in AF patients compared to controls. During 9months of follow-up after catheter ablation for AF, 11 of 40 AF patients had AF recurrence. AF recurrence was associated with gender, LA volume index, and average values of systolic strain and strain rate. By multivariate analysis, only average strain was an independent predictor of AF recurrence (OR = 0.88, 95% CI 0.79-0.98, p = 0.018). ConclusionsLower systolic strain of LA was strongly associated with recurrence after catheter ablation. Thus, diverse adjunctive ablation strategies should be considered to reduce recurrence in patients with lower systolic strain.
    Journal of Interventional Cardiac Electrophysiology 26(2):127-132. · 1.39 Impact Factor