Kyu-Bo Choi

Visualization of Coronary Atherosclerotic Plaques in Patients Using Optical Coherence Tomography: Comparison With Intravascular Ultrasound

OBJECTIVES The aim of this study was to evaluate the feasibility and the ability of intravascular optical coherence tomography (OCT) to visualize the components of coronary plaques in living patients. BACKGROUND Disruption of a vulnerable coronary plaque with subsequent thrombosis is currently recognized as the primary mechanism for acute myocardial infarction. Although such plaques are considered to have a thin fibrous cap overlying a lipid pool, imaging modalities in current clinical practice do not have sufficient resolution to identify thin (< 65 microm) fibrous caps. Optical coherence tomography is a new imaging modality capable of obtaining cross-sectional images of coronary vessels at a resolution of approximately 10 microm. METHODS The OCT images and corresponding histology of 42 coronary plaques were compared to establish OCT criteria for different types of plaques. Atherosclerotic lesions with mild to moderate stenosis were identified on angiograms in 10 patients undergoing cardiac catheterization. Optical coherence tomography and intravascular ultrasound (IVUS) images of these sites were obtained in all patients without complication. RESULTS Comparison between OCT and histology demonstrated that lipid-rich plaques and fibrous plaques have distinct OCT characteristics. A total of 17 IVUS and OCT image pairs obtained from patients were compared. Axial resolution measured 13 +/- 3 microm with OCT and 98 +/- 19 microm with IVUS. All fibrous plaques, macrocalcifications and echolucent regions identified by IVUS were visualized in corresponding OCT images. Intimal hyperplasia and echolucent regions, which may correspond to lipid pools, were identified more frequently by OCT than by IVUS. CONCLUSIONS Intracoronary OCT appears to be feasible and safe. Optical coherence tomography identified most architectural features detected by IVUS and may provide additional detailed structural information.

The Glu298Asp polymorphism in the endothelial nitric oxide synthase gene is strongly associated with coronary spasm.

Background Coronary spasm seems to be associated with coronary nitric oxide deficiency. Objectives We investigated whether the Glu298Asp polymorphism in the endothelial nitric oxide synthase (eNOS) gene is a definite risk factor for coronary spasm and whether diffuse spasm involving normal‐looking coronary artery correlates significantly with the Glu298Asp polymorphism, in contrast with focal spasm superimposed on an atherosclerotic plaque. Methods A polymerase chain reaction followed by restriction fragment length polymorphism analysis was performed in 118 control participants and in 102 patients with variant angina and a similar degree of atherosclerotic burden. Patients with coronary spasm were divided into diffuse spasm and focal spasm subgroups according to morphological criteria. Results There was a significantly higher incidence of the Glu298Asp polymorphism in the coronary spasm group than in the control group (21.5% compared with 8.5%, P =0.006). Multiple logistic regression analysis using risk factors and the Glu298Asp polymorphism showed that the most important predictive factor for coronary spasm was the Glu298Asp polymorphism (odds ratio 2.83, 95% confidence interval 1.25‐6.41, P = 0.009). The diffuse spasm subgroup had a significantly higher frequency of the Glu298Asp polymorphism than the control group (25.9% compared with 8.5%, P = 0.002). However, the focal spasm subgroup did not differ from the control group in the frequency of Glu298Asp polymorphism. Conclusion The Glu298Asp polymorphism in the eNOS gene is a definite risk factor for coronary spasm, especially for diffuse coronary spasm. This result supports the notion that diffuse coronary spasm is significantly associated with endothelial dysfunction, in contrast to focal spasm. Coron Artery Dis 14:293‐299

Prognosis of Large, Symptomatic Pericardial Effusion Treated by Echo-guided Percutaneous Pericardiocentesis

The causes and prognosis of pericardial effusion (PE) may be different according to time, region, economy, and hospital. This study was performed to evaluate the etiology, clinical outcome, and prognosis of patients with large, symptomatic PE treated by echo‐guided pericardiocentesis at Kangnam St. Marys Hopital (the Catholic University of Korea, Seoul, Korea).

The Effect of Cilostazol on Stent Thrombosis After Drug-Eluting Stent Implantation

Background and Objectives Placement of drug-eluting stents (DES) can be complicated by stent thrombosis; prophylactic antiplatelet therapy has been used to prevent such events. We evaluated the efficacy of cilostazol with regard to stent thrombosis as adjunctive antiplatelet therapy. Subjects and Methods A total of 1,315 patients (846 males, 469 females) were prospectively enrolled and analyzed for the frequency of stent thrombosis. Patients with known risk factors for stent thrombosis, except diabetes and acute coronary syndrome, were excluded from the study. All patients maintained antiplatelet therapy for at least six months. To evaluate the effects of cilostazol as another option for antiplatelet therapy, triple antiplatelet therapy (aspirin+clopidogrel+cilostazol, n=502) was compared to dual antiplatelet therapy (aspirin+clopidogrel, n=813). Six months after stent placement, all patients received only two antiplatelet drugs: treatment either with cilostazol+aspirin (cilostazol group) or clopidogrel+aspirin (clopidogrel group). There were 1,033 patients (396 in cilostazol group and 637 in clopidogrel group) that maintained antiplatelet therapy for at least 12 months and were included in this study. Stent thrombosis was defined and classified according to the definition reported by the Academic Research Consortium (ARC). Results defined and classified according to the definition reported by the Academic Research Consortium (ARC). Results: During follow-up (561.7±251.4 days), 15 patients (1.14%) developed stent thrombosis between day 1 to day 657. Stent thrombosis occurred in seven patients (1.39%) on triple antiplatelet therapy and four patients (0.49%) on dual antiplatelet therapy (p=NS) within the first six months after stenting. Six months and later, after stent implantation, one patient (0.25%) developed stent thrombosis in the cilostazol group, and three (0.47%) in the clopidogrel group (p=NS). Conclusion During the first six months after DES triple antiplatelet therapy may be more effective than dual antiplatelet therapy for the prevention of stent thrombosis. However, after the first six months, dual antiplatelet treatment, with aspirin and cilostazol, may have a better cost benefit ratio for the prevention of stent thrombosis.

The Relationship Between the Acute Changes of the Systolic Blood Pressure and the Brachial-Ankle Pulse Wave Velocity

Background The brachial-ankle pulse wave velocity (baPWV) is a useful parameter to assess arterial stiffness. However, it is difficult to evaluate arterial stiffness in hypertensive patients because the baPWV is affected by the blood pressure itself. This study was designed to estimate the relationship between the change of the blood pressure parameters and the baPWV (ΔbaPWV) when hypertensive patients were subjected to an acute reduction of blood pressure. Methods Thirty patients with essential hypertension and whose blood pressure was higher than 140/90 mmHg were enrolled. In all the patients, the blood pressure and baPWV were measured using an automatic waveform analyzer with the patients at a resting state. When the reduction of blood pressure was more than 10 mmHg after sublingual administration of nifedipine 10 mg, then the blood pressure and baPWV were measured again in the same manner and then they were compared with the baseline values. Spearmans correlation and multiple linear regression tests were performed to estimate the relationship between the change of the blood pressure parameters (ΔSBP, ΔDBP, ΔMAP and ΔPP) and the ΔbaPWV. Results The baPWV was significantly decreased shortly after the administration of nifedipine (1903.6±305.2 cm/sec vs. 1716±252.0 cm/sec, respectively, p<0.01). The ΔbaPWV was correlated with the ΔSBP (r=0.550, p<0.01), ΔDBP (r=0.386, p<0.05), ΔMAP (r=0.441, p<0.05), and ΔPP (r=0.442. p<0.05). On the multiple regression analysis, the ΔSBP was the only significant variable for predicting the ΔbaPWV, and the linear equation was ΔbaPWV=8.7×SBP-48. Conclusions The baPWV is affected by the systolic blood pressure level to a large degree and careful attention must be paid to the blood pressure level when evaluating arterial stiffness with using the baPWV.

Cardiac myxoma: clinical experiences with twenty-five patients in Korea.

Cardiac myxomas are histologically benign but and pulmonary edema in seventeen (68%) patients. may be lethal because of their strategic position. It Sixteen (64%) patients had abnormal electrocarmay mimic every cardiovascular or systemic disease, diographic findings that included sinus tachycardia, and can be missed without a high index of suspicion nonspecific ST-T wave change, left atrial enlarge[1]. Rapid advances have been made in cardiovascument, right bundle branch block, atrial fibrillation. In lar imaging, particularly in echocardiography, which laboratory findings, anemia was observed in eighteen is the most important modality in the preoperative (72%) patients, and leukocytosis was noted in six diagnosis of cardiac myxomas. We reviewed twenty(24%) patients. An erythrocyte sedimentation rate five patients with cardiac myxoma who underwent was found to be elevated in twelve of fifteen(80%) excision of the tumor at Catholic University Medical patients. In all of the patients, preoperative diagnosis Center between 1984 and 1999. The patients’ medical was confirmed by echocardiography, and surgical records were reviewed retrospectively, and special excision of the myxoma was performed as soon as attention was given to clinical presentation, physical possible without further diagnosis. The tumor size examination, chest X-ray, electrocardiogram, laborawas from 131.732.7 to 3.536.538 cm and from 18 tory findings, echocardiographic findings, operative to 200 g in weight. The stalk of tumors was found in findings, and postoperative course. The study group 18 (72%) patients, and hemorrhage and calcification consisted of six male (24%) and nineteen female of tumors in twenty (80%) and nine (36%) patients, (76%) patients. The patients’ ages ranged from 23 to respectively. Most myxomas in the left atrium were 64 years (mean 48) at the time of diagnosis. There located at the border of the oval fossa [sixteen (64%) were twenty-three (92%) left atrial and two (8%) patients] and the others at the base of interatrial right atrial myxomas. The most common symptoms septum, posterior atrial wall, and anterior atrial wall were associated with mitral obstruction in nineteen in descending order of frequency. There was no (76%) patients such as dyspnea on exertion, palpitaperioperative mortality. Early postoperative complition, and recurrent syncope. Embolic episodes cations controlled with medical treatment occurred in occurred in five (20%) patients. Twenty (80%) five patients: wound infection in two; Torsades de patients had abnormal findings at their cardiac aupointes in one; atrial fibrillation in one and acute scultation, systolic murmur in twelve, diastolic murrenal failure in one patient. Most patients were mur in eight, and tumor plop in four patients. Chest discharged within 2 weeks of the operation. In X-ray showed cardiomegaly, left atrial enlargement, sixteen (64%) patients who could be reevaluated, follow-up ranged from 4 months to 15 years. One *Corresponding author. Cardiology Department, St. Mary’s Hospital, patient who underwent tricuspid annuloplasty for No. 62 Yoido-dong, Youngdungpo-Ku 150-713, Seoul, South Korea. Tel.: severe tricuspid valve regurgitation died of intractable 182-2-3779-1325; fax: 182-2-3779-1374. E-mail address: younhj@cmc.cuk.ac.kr (H.-J. Youn). right heart failure and pulmonary hypertension 5

Aortic Valve Sclerosis on Echocardiography is a Good Predictor of Coronary Artery Disease in Patients With an Inconclusive Treadmill Exercise Test

Background and Objectives The treadmill exercise test (TMT) is used as a first-line test for diagnosing coronary artery disease (CAD). However, the findings of a TMT can be inconclusive, such as incomplete or equivocal results. Aortic valve sclerosis (AVS) is known to be a good predictor of CAD. We determined the usefulness of assessing AVS on 2-dimensional (2D) echocardiography for making the diagnosis of CAD in patients with inconclusive results on a TMT. Subjects and Methods This prospective study involved 165 consecutive patients who underwent a TMT that resulted in inconclusive findings, 2D echocardiography to detect AVS, and coronary angiography to detect CAD. Following echocardiography, AVS was classified as none, mild, or severe. CAD was defined as ≥70% narrowing of the luminal diameter on coronary angiography. Results CAD was more common in patients with AVS than in patients without AVS (75% vs. 47%, respectively, p<0.01). Multiple logistic regression analysis showed that AVS was the only independent predictor of CAD {odds ratio=8.576; 95% confidence interval (CI), 3.739-19.672}. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the presence of AVS for predicting CAD in a patient with an inconclusive TMT were 62%, 67%, 64%, 75%, and 53%, respectively. During a 1-year clinical follow-up, patients with and without AVS were similar in terms of event-free survival rates. Conclusion If the results of TMT for patients with chest pain on exertion are inconclusive, the presence of AVS on echocardiography is a good predictor of CAD.

Takayasu's arteritis treated by percutaneous transluminal angioplasty with stenting in the descending aorta.

A 17-yr-old young woman was referred to our hospital with a 2-yr history of claudication of the lower extremities and severe arterial hypertension. Physical examination revealed significantly different blood pressures between both arms (160/92 and 180/95 mmHg) and legs (92/61 and 82/57 mmHg). The hematological and biochemical values were within their normal ranges, except for the increased erythrocyte sedimentation rate (83 mm/hr) and C-reactive protein (6.19 mg/L). On 3-dimensional computed tomographic angiography, the ascending aorta, the aortic arch and its branches, and the thoracic and, descending aorta, but not the renal artery, were shown to be stenotic. The diagnosis of type IIb Takayasus arteritis was made according to the new angiographic classification of Takayasus arteritis, Takyasu conference 1994. Percutaneous transluminal angioplasty with stenting was performed on the thoracic and abdominal aorta. After the interventional procedures, the upper extremity blood pressure improved from 162/101 mmHg to 132/85 mmHg, respectively. She has been free of claudication and there have been no cardiac events during 2-yr of clinical follow-up.

A Transthoracic Echocardiographic Follow-Up Study After Catheter Ablation of Atrial Fibrillation: Can We Detect Pulmonary Vein Stenosis by Transthoracic Echocardiography?

Background and Objectives While pulmonary vein isolation (PVI) is an effective curative procedure for patients with atrial fibrillation (AF), pulmonary vein (PV) stenosis is a potential complication which may lead to symptoms that are often unrecognized. The aim of this study was to compare differences between ablation sites in pulmonary venous flow (PVF) measured by transthoracic Doppler echocardiography (TTE) before and after PVI. Subjects and Methods One hundred five patients (M : F=64 : 41; mean age 56±10 years) with paroxysmal AF (n=78) or chronic, persistent AF (n=27) were enrolled. PVI strategies consisted of ostial ablation (n=75; OA group) and antral ablation using an electroanatomic mapping system (n=30; AA group). The ostial diameter was estimated by magnetic resonance imaging (MRI) in patients with PVF ≥110 cm/sec by TTE after PVI. Results No patient complained of PV stenosis-related symptoms. Changes in mean peak right PV systolic (-6.7±28.1 vs. 10.9±25.9 cm/sec, p=0.038) and diastolic (-4.1±17.0 vs. 9.9±25.9 cm/sec, p=0.021) flow velocities were lower in the AA group than in the OA group. Although the change in mean peak systolic flow velocity of the left PV before and after PVI in the AA group was significantly lower than the change in the OA group (-13.4±25.1 vs. 9.2±22.3 cm/sec, p=0.016), there was no difference in peak diastolic flow velocity. Two patients in the OA group had high PVF velocities (118 cm/sec and 133 cm/sec) on TTE, and their maximum PV stenoses measured by MRI were 62.5% and 50.0%, respectively. Conclusion PV stenosis after PVI could be detected by TTE, and PVI by antral ablation using an electroanatomic mapping system might be safer and more useful for the prevention of PV stenosis.

SU‐GG‐T‐163: Discrepancy of IMRT Dose Delivery Due to Dynamic MLC Gravity Effect

Purpose: The aim of the present study was to investigate the MLC gravity effect on IMRT dose dynamic delivery at different gantry angles. Method and Materials: To investigate the DMLC gravity effect on IMRT dose fluence, 2D ion‐chamber matrix (MatriXX) was mounted to Varian 21EX Linac. One individual IMRT dynamic segments were applied by MSS and SW for 6 MV photon beam at five different gantry angles, which were 0° (neutral gravity), 45° (semi‐along gravity), 90° (vertical‐along gravity), 315° (semi‐against gravity) and 270° (against gravity). To test the correlation of leaf speed and gravity, the half MUs for planned dose were delivered for a relative comparison. Strict γ‐index (dose difference: 2%, distance to agreement: 2 mm) histogram was used for a quantitative analysis of the discrepancy. The dose distribution by MSS under neutral gravity (gantry 0°) with 137 MUs at prescribed dose (45 cGy) point was used as a reference to compare other results. Results: The γ‐index histograms showed the increased tendency of the dose discrepancy toward the gravity‐along direction rather than against directions. The acceptable proportional ranges below 1 of γ‐index were 96.2–99.6% (mean: 97.6%), 92.6–93.5% (mean: 93.0%), 90.4–92.6% (mean: 91.3%), 94.6–98.0% (mean: 96.4%), 92.9–96.8% (mean: 95.0%) for neutral, semi‐along, vertical‐along, semi‐against, and vertical‐against gravity of MLC positions respectively. It was observed that MSS deliveries were more stable than SW data (unacceptable γ‐index range 1.0–2.0: mean 3.6% for MSS, 5.4% for SW). For dose measurement on the prescribed dose point, all measurements showed a good agreement within 1%. Conclusion: Our experiment conclusively reveals that the DMLC gravity definitely affects IMRT dose distribution. The effect may impact more severe in gravity along direction and SW, while leaf speed does not influence so much. Conflict of Interest: This work was supported by a grant of Seoul R&BD Program (10550).