Angiotensin II is an octapeptide hormone of the renin-angiotensin system (RAS), and it regulates a wide variety of physiological responses including salt and water balance, the blood pressure and the vascular tone. Clinical trials with angiotensin-converting enzyme (ACE) inhibitors have demonstrated survival benefits in subjects with congestive heart failure and myocardial infarction, and this support the importance of angiotensin II in the pathogenesis of cardiovascular diseases. Through activation of small G proteins such as Ras, Rho, and Rac, angiotensin II induces remodeling of vascular smooth muscle cells (VSMC), including proliferation, migration, hypertrophy and inflammation. Angiotensin (1-7) appears to be the main effector peptide of ACE2 with vasodilatory, natriuretic and antiinflammatory properties. The cross-talk between the angiotensin II receptors may play an important role in maintaining cardiovascular homeostasis. (Korean Circulation J 2007;37:91-96)

Background and Objectives：Despite the dramatic reduction in restenosis conferred by drug-eluting stents (DES), restenosis remains a significant problem for real-world patients. Restenosis is a complex phenomenon, and a variety of stent-, drug-, patient- and lesion-related factors have been studied as the determinants of restenosis after DES implantation. Methods and Results：The stent delivery system, the polymer and the drug are integral components of DES, and these are the device-specific factors that can affect restenosis. While the sirolimuseluting Cypher stent appears to provide better outcomes than the paclitaxel-eluting Taxus stent in high-risk patient groups with complex lesions, such differences between the two DES are not apparent in the low-risk groups. Diabetic patients are generally prone to restenosis after percutaneous coronary intervention, but there are conflicting findings regarding the impact of diabetes mellitus on restenosis after DES implantation. The postintervention final lumen area continues to be the most important determinant of restenosis after DES implantation, indicating that a greater stented area contributes to a decreased rate of restenosis even in the DES era. Nonuniform strut distribution and stent fracture also contribute to the development of restenosis after DES implantation. In addition, the risk of restenosis increases linearly according to lesion length, and a “full metal jacket” approach in small vessels is related to a high risk of DES failure. Conclusion：Small vessel disease, diffuse disease and the type of DES are important predictors of restenosis after DES implantation. However, predicting restenosis remains difficult, and this indicates the need for further studies in order to ultimately identify those patients who are at high risk for DES failure. (Korean Circulation J 2007;37:97-102)

Background and Objectives：Increased carotid intima-media thickness (IMT) is known to be associated with adverse cardiovascular events in the patients with risk factors or established atherosclerosis. However, the prognostic importance of carotid IMT is uncertain in the patients who underwent percutaneous coronary intervention (PCI). We sought to evaluate the association of carotid IMT with major adverse cardiovascular events (MACE) and restenosis in the patients who underwent PCI. Subjects and Methods：The study population consisted of 308 consecutive patients who underwent PCI, and they were followed up for mean of 30.6±13.3 months. Base on the median values of carotid IMT, which was measured in the right common carotid artery at the time of PCI with using high-resolution ultrasound and a semiautomatic method, the subjects were divided into the thick (n=156, 1.003±0.14 mm) and thin IMT (n=152, 0.748±0.07 mm) groups, and they were followed up for at least 1 year. Results：Patients with thick carotid IMT were older (61±9 years vs. 57±10 years, respectively, p=0.001), had a higher body mass index (25.0±3.0 vs. 23.9±4.0, respectively, p=0.017), a history of previous myocardial infarction (20% vs. 9%, respectively, p=0.008), more multivessel disease and more restenosis (34.6% vs. 23.0%, respectively, p=0.025) than those patients with a thin carotid IMT. However other MACEs such as death, myocardial infarction, stroke, heart failure and target lesion revascularization did not show any significant differences between the two groups. Multivariate Cox regression analysis showed that carotid IMT was an independent predictor of restenosis (odds ratio: 1.754, 95% confidence interval: 1.1296 to 2.726, p=0.012). Conclusion：An increased carotid IMT is associated with restenosis, but it does not have clinical prognostic importance for the patients who underwent PCI during a mean follow up period of 31 months. (Korean Circulation J 2007;37:103-107)

Background and Objectives：Percutaneous coronary intervention (PCI) of unprotected left main coronary artery (LMCA) stenosis is a promising approach during this era of drug-eluting stents. However, there is no available hemodynamic data on these type patients during the performance of LMCA stenting. The purpose of this study was to determine the risk factors affecting hemodynamic stability during LMCA stenting, and to evaluate whether hemodynamic support such as inotropics or intra-aortic balloon pump (IABP) is needed, based on the risk factors. Subjects and Methods：From July 2003 to January 2006, we enrolled 92 study patients (Male=55) who had visited Yeungnam University Hospital, Keimyung University Dongsan Hospital and InJe University Baik Hospital in Busan and they were all were diagnosed with angiographically detected unprotected LMCA stenosis. Group 1 (n=69) included those patients who did not need hemodynamic support during PCI. Group 2 (n=23) included patients who needed hemodynamic support during PCI. All patients had stents deployed in the LMCA lesions without hemodynamic support; the clinical, angiographic and procedural outcomes were compared between the two groups after the procedure. Results：The baseline patient characteristics were not statistically different between the two groups. On univariate analysis, Group 2 had more patients diagnosed with acute myocardial infarction (AMI) than Group 1 (40% vs. 15%, respectively, p=0.014). Group 1 had a greater frequency of an increased left ventricular (LV) ejection fraction than Group 2 (60±10 vs. 47±11, respectively, p=0.01). Regarding the lesion location in the LMCA, Group 2 had relatively more lesions at bifurcated locations than Group 1 (44% vs. 78%, respectively, p=0.004). Group 2 required more complex techniques to repair lesions, such as kissing or crush stenting, than did Group 1 (19% vs. 48%, respectively, p=0.006). Multivariate logistic regression analysis showed that the presence of AMI (Odds Ratio (OR)=3.74, p=0.014), a complex stenting procedure such as kissing or crushing (OR=3.99, p=0.006), a bifurcated lesion (OR=4.58, p=0.004) and poor LV function (OR=9.95, p= 0.0001) were independent risk factors for hemodynamic instability during LMCA stenting. Conclusion：The most important risk factor for hemodynamic instability during LMCA stenting was LV function. Therefore, preparation for hemodynamic support, including IABP before the procedure, is necessary for the high risk patients. (Korean Circulation J 2007;37:108-112)

Background and Objectives：The left ventricular ejection fraction (LVEF) is known to be a significant prognostic factor for patients with acute myocardial infarction (AMI). The aim of this study was to investigate clinical or therapeutic factors associated with the recovery of a low LVEF for patients with AMI. Subjects and Methods： From January to December 2004, we enrolled 89 patients (mean age: 62.5±10.6 years, 43 males and 26 females) with AMI and who had a LVEF less than 50%. Forty five patients whose LVEF improved more than 10% were classified as group I (mean age: 62.4±10.4 years, 34 males and 11 females) and 44 patients whose LVEF was not changed or decreased were classified as group II (mean age: 62.3±10.9 years, 29 males and 15 females). The clinical variables, including risk factors and the pain-to-door time, the biochemical markers of myocardial injury, the coronary angiographic findings and the treatment-related variables, were compared between the two groups. Results：The cardiovascular risk factors were not different between the groups. The location of infarction, the success rate of percutaneous coronary intervention and the coronary angiographic lesion morphologies were not different between the groups. However, the pain-to-door time was significantly shorter in group I than in group Ⅱ (6.0±9.5 vs 22.4±7.5 hours, respectively, p=0.046). Improved control of risk factors was not associated with the recovery of LV function. The use of beta-blocker, statin, anti-platelet agents, vasodilators and diuretics were not different between the groups. However, the use of angiotensin converting enzyme inhibitor (ACEI) was more common in group Ⅰ than group Ⅱ (79.3% vs 47.4%, respectively, p=0.03). Conclusion：A shorter pain-to-door time and the use of ACEI were significant predictors of the recovery of LV dysfunction for patients with AMI. (Korean Circulation J 2007;37:113-118)

Background and Objectives：Heart failure (HF) may occur in atrial fibrillation (AF) patients with a normal left ventricular (LV) systolic function if the diastolic function is impaired. The association of new parameters from the relationship between the preceding RR interval (RR-1) and LV outflow peak ejection velocity (Vpe) with systolic function has been reported. The aim of this study was to observe whether these parameters were associated with HF in AF patients with a normal systolic function. Subjects and Methods：AF patients with a normal systolic function were divided into two groups according to the presence (n=16) or absence (n=30) of a history of HF. From the logarithmic equation between RR-1 and Vpe, the slope, Vpe at RR-1 second (Vpe-1), and Slope/Vpe- 1 were calculated. Results：Patients with a history of HF were older (p=0.037) and tended to more frequently have hypertension (p=0.063) than those with no history of HF. The ejection fractions were similar between the two groups. In the coordinates with RR-1 from 0.6 to 1 second, the slope tended to be steeper (p=0.074) and slope/ Vpe-1 was higher in patients with a history of HF (p=0.011). The Vpe-1 was similar between the two groups (p= 0.66). A multiple forward logistic regression analysis showed that slope/Vpe-1 was the only independent variable associated with the occurrence of HF. Slope/Vpe-1 was related with aortic regurgitation, HF history, and the interventricular septal thickness in a multiple stepwise regression analysis. Conclusion：New parameters from the relationship between the RR intervals and LV performances were associated with the occurrence of HF in AF patients with a normal systolic function. This finding suggests that these parameters may be related with the LV diastolic function. (Korean Circulation J 2007;37:119-126)

This report describes the case of a 26-year-old male diagnosed with angina on exertion. A diagnostic coronary angiography revealed significant luminal narrowing at the middle third of the left anterior descending artery and proximal circumflex artery. The patient underwent implantation of sirolimus-eluting stents. Eight months after implantation of the stents, a follow-up coronary angiography showed intrastent coronary artery aneurysms. We suggest that the implantation of the sirolimus-eluting stent caused late formation of a coronary artery aneurysm. (Korean Circulation J 2007;37:127-129)

A 29-year-old woman in her 8th week of pregnancy was referred to our hospital for swelling in the lower extremities, rapid onset of dyspnea (1 hr) and pre-syncope. Severe right ventricular dysfunction and moderate pulmonary hypertension were detected using 2-dimentional Doppler echocardiography. In addition, left calf vein and proximal thromboses were detected by venous compression ultrasound imaging. After successful thrombolytic treatment, the patient quickly recovered and was discharged from hospital on subcutaneous low-molecular-weight heparin. She delivered a normal, healthy infant at full-term (40 weeks). (Korean Circulation J 2007;37:130-133)