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Chang-Wook Nam - Top 30 Publications

Comparison of Fractional FLow Reserve And Intravascular ultrasound-guided Intervention Strategy for Clinical OUtcomes in Patients with InteRmediate Stenosis (FLAVOUR): Rationale and design of a randomized clinical trial.

Coronary angiography has limitations in defining the ischemia-causing stenotic lesion, especially in cases with intermediate coronary stenosis. Fractional flow reserve (FFR) is a current standard method to define the presence of ischemia, and intravascular ultrasound (IVUS) is the most commonly used invasive imaging tool that can provide the lesion geometry and can provide the information on plaque vulnerability. The primary aim of this study is to compare the safety and efficacy of FFR-guided and IVUS-guided percutaneous coronary intervention (PCI) strategies in patients with intermediate coronary stenosis.

Paclitaxel-coated balloon treatment for functionally nonsignificant residual coronary lesions after balloon angioplasty.

There is limited data on the efficacy of paclitaxel-coated balloon (PCB) compared to stents for de novo coronary lesions. The purpose of this study was to compare the efficacy of PCB treatment with stent implantation for de novo coronary lesions after successful plain old balloon angioplasty (POBA) guided by fractional flow reserve (FFR). In 200 patients scheduled for elective percutaneous coronary intervention (PCI) for de novo lesions, FFR was measured after POBA (POBA-FFR). If POBA-FFR was ≥ 0.75, patients were treated with PCB (PCB group, n = 78) or stent (Stent group, n = 73). If POBA-FFR was < 0.75, stent was implanted as planned (Reference group, n = 42). The primary endpoint was late lumen loss at 9 months and the secondary endpoint was adverse cardiac events (cardiac death, myocardial infarction, target lesion thrombosis, or repeat revascularization) at 12 months follow-up. There was no between-group differences in the POBA-FFR (0.87 ± 0.05 in PCB, 0.89 ± 0.06 in stent, p = 0.101). At 9 months, late lumen loss was significantly lower in the PCB group compared to the Stent group (0.05 ± 0.33 vs. 0.59 ± 0.76 mm, p < 0.001). Adverse cardiac events were not different between the PCB, Stent and Reference groups (2.6, 5.5, and 9.5% respectively; p = 0.430 for PCB vs. Stent group; p = 0.229 for the reference vs. both other groups). PCB treatment guided by POBA-FFR showed excellent 9 months angiographic and functional results, as well as comparable 12 months clinical outcomes, compared with stent implantation for de novo coronary lesions.

Prognostic implication of thermodilution coronary flow reserve in patients with indeterminate pressure-bounded coronary flow reserve.

Recently, the concept of pressure-bounded coronary flow reserve (PB-CFR) has been introduced. However, using pressure-only data, a substantial proportion of patients could not be classified into high or low PB-CFR and remained as indeterminate PB-CFR. The current study evaluated the prognostic implication of thermodilution-based CFR (thermo-CFR) in patients with indeterminate PB-CFR.

Influence of Local Myocardial Damage on Index of Microcirculatory Resistance and Fractional Flow Reserve in Target and Nontarget Vascular Territories in a Porcine Microvascular Injury Model.

The aim of this study was to investigate the influence of microvascular damage in one vessel territory on invasively measured physiological parameters in the other vessel, using a porcine microvascular damage model.

Prognostic Usefulness of Tricuspid Annular Diameter for Cardiovascular Events in Patients With Tricuspid Regurgitation of Moderate to Severe Degree.

Functional tricuspid regurgitation (TR) is frequently encountered. Current guidelines recommend the surgical correction of severe TR only at the time of left valve surgery despite emphasizing the enlarged tricuspid annulus (TA) dimension. We attempted to evaluate the relation between TA dimension and clinical outcomes of moderate or severe TR. A total of 213 patients (mean age 68 years, women 68%) with moderate or severe TR secondary to left-sided valve surgery, nonvalvular disease, or isolated primary TR were retrospectively identified and classified into tertiles of TA dimension. Cardiovascular (CV) outcomes were defined as a composite of hospitalization for worsening heart failure (HF), stroke, and CV death over a median follow-up of 3.4 years. Upper and lower tertiles of TA dimension had high frequencies of left-sided valve surgery and isolated primary TR, respectively. TA dimension was correlated with TR severity assigned as color Doppler grade and systolic tissue Doppler imaging of the tricuspid valve (TDI s'). During follow-up, there were 87 (41%) occurrences of primary outcomes: 65 HFs (31%), 13 CV deaths (6%), and 9 strokes (4%). There was a high frequency of adverse outcomes in the upper tertile. TA dimension and TDI s' were independently related to outcomes. An enlarged TA dimension was associated with outcomes irrespective of subgroups according to type or severity of TR and TDI s' (p = 0.21, p = 0.77, p = 0.15 for interaction). A cut-off value of 4.0 cm for TA dimension was best for CV event occurrence. When assessing clinical CV outcomes, TA dimension should be considered, even in moderate TR.

Functional Approach for Coronary Artery Disease: Filling the Gap Between Evidence and Practice.

The presence of myocardial ischemia is the most important prognostic factor in patients with coronary artery disease, and ischemia-directed revascularization has been a standard of care. Fractional flow reserve (FFR) is an invasive method used to detect the functionally significant epicardial coronary stenosis, and FFR-guided revascularization strategy has been proven to be superior to angiography-guided strategy. Recently, a hyperemia-free index, instantaneous wave free ratio (iFR), was developed and showed its non-inferiority for clinical outcomes compared with FFR-guided strategy. While evidence supporting the benefit of pressure wire assessment exists, there remain several unresolved issues, such as the mechanism of discordance between resting and hyperemic physiologic indices, clinical outcomes of patient/lesions with discordant results among the physiologic indices, role of physiologic indices beyond per-vessel decision tool, and the role of microvascular dysfunction in patient prognosis. The current article will review the recent studies performed to address these questions.

Percutaneous coronary intervention in patients with multi-vessel coronary artery disease: a focus on physiology.

Multi-vessel coronary artery disease (MVD) frequently features ambiguous or intermediate lesions that may be both serial and complex, suggesting that multiple regions require revascularization. Percutaneous coronary intervention (PCI) is associated with various challenges such as appropriate identification of lesions that should be treated, the choice of an optimum revascularization method, and limitations of long-term outcomes. Optimal patient selection and careful targeting of lesions are key when planning treatment. Physiology-guided decision-making (based on the fractional flow reserve) can overcome the current limitations of PCI used to treat MVD regardless of clinical presentation or disease subtype, as confirmed in recent clinical trials. Here, we review the use of physiology-guided PCI for patients with MVD, and their early and late outcomes.

Identification of High-Risk Plaques Destined to Cause Acute Coronary Syndrome Using Coronary Computed Tomographic Angiography and Computational Fluid Dynamics.

We investigated the utility of noninvasive hemodynamic assessment in the identification of high-risk plaques that caused subsequent acute coronary syndrome (ACS).

Implications of prescribing a fixed-dose combination in clinical cardiology practice: a retrospective observational study using a single medical centre database in Korea.

Fixed-dose combination (FDC) prescribing enhances adherence to medication. However, there are limited data regarding the usefulness of FDC drugs across different risk groups. The aim of this study was to explore the relationship between FDC discontinuation and clinical outcomes.

Clinical Relevance of Functionally Insignificant Moderate Coronary Artery Stenosis Assessed by 3-Vessel Fractional Flow Reserve Measurement.

Understanding of the risk conferred by functionally insignificant lesions in multiple coronary vessels is limited. We investigated the prognostic implications of coronary artery disease (CAD) based on 3-vessel fractional flow reserve (FFR).

Comparison of drug-eluting stents and drug-coated balloon for the treatment of drug-eluting coronary stent restenosis: A randomized RESTORE trial.

This study sought to evaluate the optimal treatment for in-stent restenosis (ISR) of drug-eluting stents (DESs).

Response by Kobayashi et al to Letter Regarding Article, "Three-Vessel Assessment of Coronary Microvascular Dysfunction in Patients with Clinical Suspicion of Ischemia: Prospective Observation Study With the Index of Microcirculatory Resistance".

Prognostic Implication of Functional Incomplete Revascularization and Residual Functional SYNTAX Score in Patients With Coronary Artery Disease.

The aim of this study was to investigate the prognostic implication of functional incomplete revascularization (IR) and residual functional SYNTAX (Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery) score (rFSS) in comparison with 3-vessel fractional flow reserve (FFR) and residual SYNTAX score.

Comparison of 1-Year Outcomes of Triple (Aspirin + Clopidogrel + Cilostazol) Versus Dual Antiplatelet Therapy (Aspirin + Clopidogrel + Placebo) After Implantation of Second-Generation Drug-Eluting Stents into One or More Coronary Arteries: from the DECREASE-PCI Trial.

This study sought to evaluate the impact of triple antiplatelet therapy on clinical outcomes in patients treated with second-generation drug-eluting stents (DES) for coronary artery disease. There are limited data regarding the impact of triple antiplatelet therapy in patients who underwent implantation of second-generation DES. We planned to randomly assign 2,110 patients treated with second-generation DES to triple (aspirin, clopidogrel, and cilostazol) and dual (aspirin, clopidogrel, and placebo) antiplatelet therapy groups. The primary end point was a composite of death, myocardial infarction, ischemic stroke, or target vessel revascularization (TVR) at 1 year since randomization. The study was stopped early owing to slow enrollment. In total, 404 patients (202 patients each in the triple and dual antiplatelet therapy groups) were finally enrolled. At 1 year, the primary end point had occurred in 3.6% and 9.4% of patients in the triple and dual antiplatelet therapy groups, respectively (hazard ratio [HR] of the triple group 0.396; 95% confidence interval [CI] 0.166 to 0.949; p = 0.038). There was no significant difference between the 2 groups regarding the occurrence of a composite of all-cause death, myocardial infarction, or ischemic stroke (HR 0.583; 95% CI 0.229 to 1.481; p = 0.256). However, the rates of TVR were significantly lower in the triple antiplatelet therapy group than in the dual antiplatelet therapy group (HR 0.118; 95% CI 0.015 to 0.930; p = 0.043). In conclusion, triple antiplatelet therapy with cilostazol after implantation of second-generation DES improved clinical outcomes, mainly by reducing TVR.

Efficacy and Tolerability of Telmisartan/Amlodipine + Hydrochlorothiazide Versus Telmisartan/Amlodipine Combination Therapy for Essential Hypertension Uncontrolled With Telmisartan/Amlodipine: The Phase III, Multicenter, Randomized, Double-blind TAHYTI Study.

This 8-week study in Korea aimed to evaluate the efficacy and tolerability of a telmisartan/amlodipine + hydrochlorothiazide (TAH) combination versus telmisartan/amlodipine (TA) combination in patients with essential hypertension that did not respond appropriately to 4-week treatment with TA.

Clinical Outcomes According to Fractional Flow Reserve or Instantaneous Wave-Free Ratio in Deferred Lesions.

The authors investigated 2-year clinical outcomes according to fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) values in deferred lesions.

Heart rate at first postdischarge visit and outcomes in patients with heart failure.

Heart rate control is important to prevent adverse outcomes in patients with heart failure (HF). However, postdischarge activity may worsen heart rate control, resulting in readmission. This study aimed to explore the implications of the heart rate differences between discharge and the first outpatient visit (D-O diff).

Bioresorbable Vascular Scaffold Korean Expert Panel Report.

Bioresorbable vascular scaffold (BRS) is an innovative device that provides structural support and drug release to prevent early recoil or restenosis, and then degrades into nontoxic compounds to avoid late complications related with metallic drug-eluting stents (DESs). BRS has several putative advantages. However, recent randomized trials and registry studies raised clinical concerns about the safety and efficacy of first generation BRS. In addition, the general guidance for the optimal practice with BRS has not been suggested due to limited long-term clinical data in Korea. To address the safety and efficacy of BRS, we reviewed the clinical evidence of BRS implantation, and suggested the appropriate criteria for patient and lesion selection, scaffold implantation technique, and management.

Plaque Characteristics and Ruptured Plaque Location according to Lesion Geometry in Culprit Lesions of ST-Segment Elevation Myocardial Infarction.

The correlations between plaque characteristics and plaque rupture location according to segmental lesion analysis have not been well defined. The aim of this study was to assess those characteristics of ST-segment elevation myocardial infarction (STEMI) culprit lesions according to segmental lesion geometry using virtual histology intravascular ultrasound (VH-IVUS).

A randomized trial evaluating the efficacy and safety of alirocumab in South Korea and Taiwan (ODYSSEY KT).

Alirocumab, a fully human monoclonal antibody to proprotein convertase subtilisin/kexin type 9, has been shown to provide significant reductions in low-density lipoprotein cholesterol (LDL-C). Data about its efficacy and safety in patients from South Korea and Taiwan are limited.

Three-Vessel Assessment of Coronary Microvascular Dysfunction in Patients With Clinical Suspicion of Ischemia: Prospective Observational Study With the Index of Microcirculatory Resistance.

Difficulty directly visualizing the coronary microvasculature as opposed to the epicardial coronary artery makes its assessment challenging. The goal of this study is to measure the index of microcirculatory resistance (IMR) in all 3 major coronary vessels to identify the clinical and angiographic predictors of an abnormal IMR.

Similarity and Difference of Resting Distal to Aortic Coronary Pressure and Instantaneous Wave-Free Ratio.

Instantaneous wave-free ratio (iFR) has been used in clinical practice to identify functionally significant stenosis and to guide treatment strategy. However, there are limited clinical data regarding another resting pressure-derived index, resting distal to aortic coronary pressure (Pd/Pa), and similarities and differences between resting Pd/Pa and iFR.

Clinical implications of three-vessel fractional flow reserve measurement in patients with coronary artery disease.

There are limited data on the clinical implications of total physiologic atherosclerotic burden assessed by invasive physiologic studies in patients with coronary artery disease. We investigated the prognostic implications of total physiologic atherosclerotic burden assessed by total sum of fractional flow reserve (FFR) in three vessels (3V-FFR).

Comparison of long-term mortality according to obesity in patients with successful percutaneous chronic total occlusion interventions using drug-eluting stents.

To evaluate the long-term mortality according to obesity in patients with chronic total occlusion (CTO) lesions after successful percutaneous coronary intervention (PCI).

Clinical Outcomes of Deferred Lesions With Angiographically Insignificant Stenosis But Low Fractional Flow Reserve.

Data are limited regarding outcomes of deferred lesions in patients with angiographically insignificant stenosis but low fractional flow reserve (FFR). We investigated the natural history of angiographically insignificant stenosis with low FFR among patients who underwent routine 3-vessel FFR measurement.

Evaluation of the impact of statin therapy on the obesity paradox in patients with acute myocardial infarction: A propensity score matching analysis from the Korea Acute Myocardial Infarction Registry.

The phenomenon of obesity paradox after acute myocardial infarction (AMI) has been reported under strong recommendation of statin therapy. However, the impact of statin therapy on this paradox has not been investigated. This study investigated the impact of statin therapy on 1-year mortality according to obesity after AMI. A total of 2745 AMI patients were included from the Korea Acute Myocardial Infarction Registry after 1:4 propensity score matching analysis (n = 549 for nonstatin group and n = 2196 for statin group). Primary and secondary outcomes were all-cause and cardiac death, respectively. During 1-year follow-up, the incidence of all-cause (8.4% vs 3.7%) and cardiac (6.2% vs 2.3%) death was higher in nonstatin group than in statin (P < .001, respectively). In nonstatin group, the incidence of all-cause (7.2% vs 9.0%) and cardiac (5.5% vs 6.5%) death did not differ significantly between obese and nonobese patients. However, in statin group, obese patients had lower 1-year rate of all-cause (1.7% vs 4.8%) and cardiac (1.2% vs 2.9%) death (P < .05, respectively), and lower cumulative rates by Kaplan-Meier analysis of all-cause and cardiac death compared with nonobese patients (log-rank P < .05, respectively). The overall risk of all-cause death was significantly lower in obese than in nonobese patients only in statin group (hazard ratio: 0.35; P = .001). After adjusting for confounding factors, obesity was independently associated with decreased risk of all-cause death in statin group. In conclusion, the greater benefit of statin therapy for survival in obese patients is further confirmation of the obesity paradox after AMI.

Discrepancy between fractional flow reserve and instantaneous wave-free ratio: Clinical and angiographic characteristics.

The invasive physiologic index such as fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR) is used in clinical practice to identify ischemia-causing stenosis and to guide treatment strategy. We investigated clinical and angiographic characteristics of lesions with discrepancy between FFR and iFR.

Efficacy and Tolerability of Combination Therapy Versus Monotherapy with Candesartan and/or Amlodipine for Dose Finding in Essential Hypertension: A Phase II Multicenter, Randomized, Double-blind Clinical Trial.

Intensive blood pressure (BP) lowering is important for the treatment of hypertension; however, it has been a challenge to achieve target BP in many patients. The purpose of this study was to explore the optimal dosage of a fixed-dose combination of candesartan cilexetil (CAN) and amlodipine besylate (AML), by examining the tolerability and efficacy of CAN/AML combination therapy compared with those of monotherapy with either drug in patients with essential hypertension.

Prognosis of deferred non-culprit lesions according to fractional flow reserve in patients with acute coronary syndrome.

There are limited data on the prognosis of deferred non-culprit lesions in patients with acute coronary syndrome (ACS) based on fractional flow reserve (FFR). We aimed to investigate the prognosis of deferred non-culprit lesions in ACS patients, compared with deferred lesions in patients with stable coronary artery disease (SCAD), on the basis of FFR.

Diagnostic Performance of a Novel Method for Fractional Flow Reserve Computed from Noninvasive Computed Tomography Angiography (NOVEL-FLOW Study).

Coronary computed tomography angiography (CCTA)-derived fractional flow reserve from computed tomography (CT-FFR) may provide better diagnostic performance over CCTA alone, but the complexity of its method limits the use in clinical environment. The aim of the present study is to validate a newly developed vessel-length based computational fluid dynamics scheme for the computation of FFR based on CCTA data, compare them with invasively measured FFR, and evaluate its diagnostic performance with that of CCTA. One hundred seventeen patients from 4 medical institutions who had clinically indicated invasive coronary angiography for suspected coronary artery disease (CAD) were enrolled. Invasive FFR measurement was performed in 218 vessels and these measurements were regarded as the reference standard. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of CT-FFR on a per-vessel basis were 85.8%, 86.2%, 85.5%, 79.8%, and 90.3%, respectively, for CT-FFR ≤0.80, and 66.1%, 75.9%, 59.5%, 55.5%, and 78.8%, respectively, for CCTA ≥50%. A higher area under the receiver operating characteristic curve for CT-FFR was observed compared with CCTA (0.93 vs 0.74, p <0.0001). The CT-FFR and FFR correlated well (r = 0.76, p <0.001) with slight underestimation by CT-FFR (0.014 ± 0.077, p = 0.007). With a novel method of vessel-length based computational fluid dynamics scheme, CT-FFR can be performed at a personal computer enhancing its applicability in clinical situation. The diagnostic accuracy of CT-FFR for the detection of functionally significant CAD was good and was superior to that of CCTA within a population of suspected CAD.