Functional Angioplasty: Definitions, Historical Overview, and Future Perspectives

Percutaneous coronary intervention (PCI) is used to treat obstructive coronary artery disease (CAD). The role of PCI is well defined in acute coronary syndrome, but that for stable CAD remains debatable. Although PCI generally relieves angina in patients with stable CAD, it may not change its prognosis. The extent and severity of CAD are major determinants of prognosis, and complete revascularization (CR) of all ischemia-causing lesions might improve outcomes. Several studies have shown better outcomes with CR than with incomplete revascularization, emphasizing the importance of functional angioplasty. However, different definitions of inducible myocardial ischemia have been used across studies, making their comparison difficult. Various diagnostic tools have been used to estimate the presence, extent, and severity of inducible myocardial ischemia. However, to date, there are no agreed reference standards of inducible myocardial ischemia. The hallmarks of inducible myocardial ischemia such as electrocardiographic changes and regional wall motion abnormalities may be more clinically relevant as the reference standard to define ischemia-causing lesions. In this review, we summarize studies regarding myocardial ischemia, PCI guidance, and possible explanations for similar findings across studies. Also, we provide some insights into the ideal definition of inducible myocardial ischemia and highlight the appropriate PCI strategy.

Ischemic Burden Assessment Using Single Photon Emission Computed Tomography in Single Vessel Chronic Total Occlusion of Coronary Artery

Background and Objectives@#Studies evaluating the nature of ischemic burden of chronic total occlusion (CTO) vessels are still lacking. @*Methods@#A total of 165 patients with single vessel CTO >2.5 mm in an epicardial coronary artery who underwent single photon emission computed tomography (SPECT) were enrolled in the study. Ischemic burden was calculated with the use of semi-quantitative SPECT analysis, and was defined as the summed difference score (SDS) divided by the maximal limit of the score (=SDS/68). @*Results@#The mean age of the participants was 59.5 years and the CTO of the left anterior descending coronary artery (LAD), left circumplex coronary artery (LCX), and right coronary artery (RCA) accounted for 93 (56.4%), 18 (10.9%), and 54 (32.7%) patients, respectively. The median ischemic burden of the total population was 8.8%, and it was highest in the LAD CTO (10.3%) compared with the LCX (5.9%) and RCA CTO (5.9%, p10%) was observed in 66 patients (40.0%), and in 47 patients (50.5%) of the LAD CTO. Ischemic burden was different according to the CTO location only in LAD CTO. The statistically significant predictors for high-ischemic burden were hypertension, baseline ejection fraction >45%, LAD CTO, proximal CTO location, and de novo CTO. Japanese-CTO score and Rentrop scale collateral grade were not associated with high-ischemic burden. @*Conclusions@#Only 40% of patients with single vessel CTO had ischemic burden >10%. For CTO vessels, measurement of ischemic burden using SPECT prior to revascularization may be helpful in identifying beneficial subjects.

Coronary Arteriovenous Fistulas Mimicking Coronary Perforation After Chronic Total Occlusion Recanalization

No abstract available.

The Transradial Approach for Coronary Intervention: More Comfort, Better Outcome

No abstract available.

Early experience and favorable clinical outcomes of everolimus-eluting bioresorbable scaffolds for coronary artery disease in Korea

BACKGROUND/AIMS: Compared with metallic drug-eluting stents (DES), bioresorbable vascular scaffolds (BVS) may further improve long-term outcomes of percutaneous coronary intervention (PCI) in patients with coronary artery disease. We report our early experience with BVS in Korea. METHODS: We evaluated 105 consecutive patients with BVS implanted at Asan Medical Center, Korea between October 21, 2015 and June 3, 2016. Angiographic results, and in-hospital and 6-month clinical outcomes were assessed. RESULTS: A total of 134 BVS were implanted to treat 115 lesions. The mean age was 62 ± 10.5 years; 85 patients (81%) were males, 26 patients (25%) were presented with acute coronary syndrome. Among 115 lesions treated with BVS, 76 (66.1%) were B2/C type, 27 (23.5%) were bifurcation lesions, and four (3.5%) were chronic total occlusion. Pre-dilation and post-dilation using high-pressure non-compliant balloon was performed in 104 lesions (90.4%) and 113 lesions (98.2%), respectively. During the procedure, intravascular imaging was used for all patients (100%; intravascular ultrasound 89 and optical coherence tomography 40 patients). Device success rate was 100%. In-segment and in-scaffold acute again were 1.1 ± 0.6 and 1.3 ± 0.5 mm, respectively. Periprocedural myocardial infraction occurred in four patients (3.8%). No deaths, stent thrombosis, or urgent revascularizations occurred either during hospitalization or the follow-up period. CONCLUSIONS: In this single-center experience, implantation of BVS with intravascular imaging support was feasible and early clinical outcomes were excellent. Evaluation of long-term efficacy and safety of BVS and its feasibility in clinical use for a broader range of lesions is warranted.

Coronary Artery Bypass Grafting vs. Drug-Eluting Stent Implantation for Multivessel Disease in Patients with Chronic Kidney Disease

BACKGROUND AND OBJECTIVES: There is currently a limited amount of data that demonstrate the optimal revascularization strategy for chronic kidney disease (CKD) patients with multivessel coronary artery disease (CAD). We compared the long-term outcomes of percutaneous coronary intervention (PCI) with drug-eluting stents (DES) versus coronary artery bypass graft surgery (CABG) for multivessel CAD in patients with CKD. SUBJECTS AND METHODS: We analyzed 2108 CKD patients (estimated glomerular filtration rate <60 mL/min/1.73 m²) with multivessel CAD that were treated with PCI with DES (n=1165) or CABG (n=943). The primary outcome was a composite of all causes of mortality, myocardial infarction, or stroke. The mean age was 66.9±9.1 years. RESULTS: Median follow-up duration was 41.4 (interquartile range 12.1-75.5) months. The primary outcome occurred in 307 (26.4%) patients in the PCI group compared with 304 (32.2%) patients in the CABG group (adjusted hazard ratio [HR], 0.941; 95% confidence interval [CI], 0.79–1.12; p=0.493). The two groups exhibited similar rates of all-cause mortality (adjusted HR, 0.91; 95% CI, 0.77–1.09; p=0.295), myocardial infarction (adjusted HR, 1.86; 95% CI, 0.85–4.07; p=0.120) and stroke (3.2% vs. 4.8%; HR, 0.93; 95% CI, 0.57–1.61; p=0.758). However, PCI was associated with significantly increased rates of repeat revascularization (adjusted HR, 4.72; 95% CI, 3.20–6.96; p<0.001). CONCLUSION: Among patients with CKD and multivessel CAD, PCI with DES when compared with CABG resulted in similar rates of composite outcome of mortality from any cause, MI, or stroke; however, a higher risk of repeat revascularization was observed.

Impact of Follow-Up Ischemia on Myocardial Perfusion Single-Photon Emission Computed Tomography in Patients with Coronary Artery Disease

PURPOSE: Few studies have reported on predicting prognosis using myocardial perfusion single-photon emission computed tomography (SPECT) during coronary artery disease (CAD) treatment. Therefore, we aimed to assess the clinical implications of myocardial perfusion SPECT during follow-up for CAD treatment. MATERIALS AND METHODS: We enrolled 1153 patients who had abnormal results at index SPECT and underwent follow-up SPECT at intervals ≥6 months. Major adverse cardiac events (MACE) were compared in overall and 346 patient pairs after propensity-score (PS) matching. RESULTS: Abnormal SPECT was associated with a significantly higher risk of MACE in comparison with normal SPECT over the median of 6.3 years (32.3% vs. 19.8%; unadjusted p<0.001). After PS matching, abnormal SPECT posed a higher risk of MACE [32.1% vs. 19.1%; adjusted hazard ratio (HR)=1.73; 95% confidence interval (CI)=1.27–2.34; p<0.001] than normal SPECT. After PS matching, the risk of MACE was still higher in patients with abnormal follow-up SPECT in the revascularization group (30.2% vs. 17.9%; adjusted HR=1.73; 95% CI=1.15–2.59; p=0.008). Low ejection fraction [odds ratio (OR)=5.33; 95% CI=3.39–8.37; p<0.001] and medical treatment (OR=2.68; 95% CI=1.93–3.72; p<0.001) were independent clinical predictors of having an abnormal result on follow-up SPECT. CONCLUSION: Abnormal follow-up SPECT appears to be associated with a high risk of MACE during CAD treatment. Follow-up SPECT may play a potential role in identifying patients at high cardiovascular risk.

Role of Coronary Artery Calcium Scoring in Detection of Coronary Artery Disease according to Framingham Risk Score in Populations with Low to Intermediate Risks

Current guidelines recommend that coronary artery calcium (CAC) screening should only be used for intermediate risk groups (Framingham risk score [FRS] of 10%-20%). The CAC distributions and coronary artery disease (CAD) prevalence in various FRS strata were determined. The benefit to lower risk populations of CAC score-based screening was also assessed. In total, 1,854 participants (aged 40-79 years) without history of CAD, stroke, or diabetes were enrolled. CAC scores of > 0, ≥ 100, and ≥ 300 were present in 33.8%, 8.2%, and 2.9% of the participants, respectively. The CAC scores rose significantly as the FRS grew more severe (P 20% strata were 3.4%, 6.7%, 9.0%, and 11.6% (P 20%; P < 0.05). In conclusion, the yield of screening for significant CAC and occult CAD is low in the very low risk population but it rises in low and intermediate risk populations.

Two Cases of Immediate Stent Fracture after Zotarolimus-Eluting Stent Implantation

Drug-eluting stent (DES) implantation is currently the standard treatment for various types of coronary artery disease. However, previous reports indicate that stent fractures, which usually occur after a period of time from the initial DES implantation, have increased during the DES era; stent fractures can contribute to unfavorable events such as in-stent restenosis and stent thrombosis. In our present report, we describe two cases of zotarolimus-eluting stent fracture: one that was detected six hours after implementation, and the other case that was detected immediately after deployment. Both anatomical and technical risk factors contributed to these unusual cases of immediate stent fracture.

Deep Vein Thrombosis Due to Hematoma as a Rare Complication after Femoral Arterial Catheterization / 영남의대학술지

Hematoma is quite a common complication of femoral arterial catheterization. However, to the best of our knowledge, there have been no previous studies regarding deep vein thrombosis (DVT) caused by compression of a vein due to a hematoma. We report a case of a hematoma developing after femoral arterial catheterization and causing extensive symptomatic DVT. A 59-year-old male was seen in our Emergency Department with right lower leg swelling 15 days after coronary stent implantation performed using right femoral artery access. Computed tomographic (CT) scanning revealed a large hematoma (45 mm in its longest diameter) compressing the common femoral vein and with DVT from the right external iliac vein to the popliteal vein. Due to the extensive DVT involvement, we decided to release the compressed common femoral vein by surgical evacuation of the large hematoma. However, even following evacuation of the hematoma, as the DVT did not resolve soon, further mechanical thrombectomy and catheter-directed thrombolysis were performed. Angiography then showed nearly resolved DVT, and the leg swelling was improved. The patient was discharged with the anticoagulation medication, warfarin.

Transcatheter Aortic Valve Implantation: Early Experience in Korea

BACKGROUND AND OBJECTIVES: Transcatheter aortic valve implantation (TAVI) was recently introduced in Korea. The present report describes the experience of early TAVI cases. SUBJECTS AND METHODS: Between March, 2010 and October, 2011, 48 patients with severe symptomatic aortic stenosis (AS) were screened at the Asan Medical Center to determine their suitability for surgical intervention. Of these, 23 were considered unsuitable and underwent TAVI. Procedural success rates, procedure-related complications, and clinical outcomes were evaluated in the TAVI patients. RESULTS: Transfemoral (n=20) or transapical (n=3) TAVI was performed. The mean age of patients was 75.9+/-5.4 years and 57% were females. The mean logistic European System for Cardiac Operative Risk Evaluation was 25.6+/-5.1%. Implantation was successful in 22 patients (19 transfemoral, three transapical). After successful implantation, the mean aortic valve area increased from 0.68+/-0.14 cm2 to 1.45+/-0.33 cm2. There were no procedure-related complications or mortality. The patients showed no paravalvular aortic regurgitation with > or = moderate degree and remained stable without progression during follow-up. During follow-up (interquartile range, 1.1-12.9), all patients were alive without any occurrence of valve failure. CONCLUSION: TAVI procedure is feasible in patients with inoperative symptomatic AS leading to hemodynamic and clinical improvement. With accumulation of experience, proper patient selection and development of device technologies, TAVI should decrease adverse events and expand the indications in the near future.

Acute and Long-Term Angiographic Outcomes of Side Branch Stenosis after Randomized Treatment of Zotarolimus-, Sirolimus-, and Paclitaxel-Eluting Stent for Coronary Artery Stenosis

This was designed to assess the outcomes of side branch (SB) stenosis after implantation of three drug-eluting stents (DES). From 2,645 patients in the ZEST (Comparison of the Efficacy and Safety of Zotarolimus-Eluting Stent with Sirolimus-Eluting and PacliTaxel-Eluting Stent for Coronary Lesions) Trial, 788 patients had 923 bifurcation lesions with SB > or = 1.5 mm were included. SB was treated in 150 lesions, including 35 (3.8%) receiving SB stenting. Of untreated SB with baseline stenosis < 50%, the incidences of periprocedural SB compromise was similar in the zotarolimus (15.8%), sirolimus (17.2%), and paclitaxel (16.6%) stent groups (P = 0.92). At follow-up angiography, delayed SB compromise occurred in 13.9%, 3.2%, and 9.4% (P = 0.010) of these groups. When classified into four groups (< 50%, 50%-70%, 70%-99%, and 100%), 9.0% of untreated SB were worsened, whereas improvement and stationary were observed in 9.6% and 81.4%. In a multivariable logistic regression model, main branch (MB) stenosis at follow-up (%) was the only independent predictor of SB stenosis worsening (odds ratio, 1.03; 95% confidence interval, 1.01-1.04; P < 0.001). After MB stenting in bifurcation lesions, a minority of SB appears to worsen. DES with strong anti-restenotic efficacy may help maintain SB patency.

Clinical outcomes according to coronary calcium scores in asymptomatic individuals undergoing coronary CT angiography / 대한내과학회지

BACKGROUND/AIMS: In general, multidetector computed tomography (MDCT) is not recommended as a screening tool for asymptomatic individuals. However, the programs for general health evaluation at several hospitals in Korea include MDCT to detect cardiac disease. The objectives of this study were to evaluate the clinical outcomes of asymptomatic individuals according to the coronary artery calcium score (CACS) obtained from screening MDCT and to assess the eligibility of risk stratification in the NCEP-ATP III guidelines for predicting a significant stenosis on MDCT. METHODS: We reviewed the medical records of 845 asymptomatic subjects (age 53+/-9 years, 67% men) who underwent MDCT as part of a general health evaluation at Asan Medical Center, Seoul, Korea, from January to December 2008. RESULTS: Atherosclerotic plaques were identified in 332 (39.3%) subjects. Sixty (7.1%) individuals had significant stenosis (> or = 50% diameter stenosis). The prevalence of significant stenosis was higher in the group that had more than a 10% risk of coronary heart disease (CHD) at 10 years (p or = 110 was associated with a significantly higher rate of coronary revascularization in asymptomatic patients with significant stenosis on MDCT.

Clinical impact of aspirin resistance measured using the Ultegra Rapid Platelet Function Assay-ASA in patients undergoing percutaneous coronary intervention / 대한내과학회지

BACKGROUND/AIMS: Aspirin resistance is reported to be associated with myocardial infarction, stroke, and myonecrosis after percutaneous coronary intervention. However, aspirin resistance and its clinical implications in patients undergoing drug-eluting stent (DES) implantation have not been evaluated sufficiently. METHODS: The study enrolled 419 consecutive patients who underwent DES implantation. All of the patients took aspirin 100 mg (228 patients, 54.4%) or 200 mg (191 patients, 45.6%). Aspirin resistance was measured using the Ultegra Rapid Platelet Function Assay-ASA (Accumetrics, San Diego, CA, USA). The results were expressed as aspirin reaction units (ARU). Aspirin resistance was defined as ARU > or =550. We followed all patients for 9 months. RESULTS: Aspirin resistance was found in 33 patients (33/419, 7.9%). The aspirin dose (118.18+/-39.2 vs. 147.93+/-50.0 mg, p= 0.011) was lower in the aspirin-resistant (n=33) versus the aspirin-sensitive (n=386) group. There was no significant difference in the occurrence of myocardial necrosis (15.6% vs. 15.5%, p=0.988). On multivariate analysis, low-dose aspirin (odds ratio (OR) 4.714; 95% confidence interval (CI) 1.865-11.914; p=0.001), age (OR 1.048; 95% CI 1.005-0.092, p=0.029), platelet count (OR 1.007; 95% CI 1.001-1.014, p=0.011), and hypercholesterolemia (OR 2.937; 95% CI 1.310-6.583, p=0.009) were independent predictors of aspirin resistance. Over the 9 months, no stent thrombosis or death occurred; one acute myocardial infarction occurred in the aspirin-sensitive group. CONCLUSIONS: Low-dose aspirin, old age, a higher platelet count, and hypercholesterolemia were associated with a high incidence of aspirin resistance in patients who underwent DES implantation. However, no significant differences in clinical outcome were found between the aspirin-resistant and -sensitive groups during a 9-month follow-up.

Catastrophic Catecholamine-Induced Cardiomyopathy Mimicking Acute Myocardial Infarction, Rescued by Extracorporeal Membrane Oxygenation (ECMO) in Pheochromocytoma

Pheochromocytoma is a rare disorder and functioning tumor composed of chromaffin cells that secrete catecholamines. Patients with a pheochromocytoma 'crisis' have a high mortality in spite of aggressive therapy. We present a case with a severe acute catecholamine cardiomyopathy presenting ST segment elevation with cardiogenic shock after hemorrhage into a left suprarenal tumor. Intra-aortic balloon pump (IABP) support, combined with inotropic therapy, was performed. However, the patient deteriorated rapidly and was unresponsive to a full dose of inotropics and IABP. We decided to apply extracorporeal membrane oxygenation (ECMO) device for the patient. His clinical state began to improve 3 days after ECMO. After achieving hemodynamic stabilization, he underwent successful laparoscopic left adrenalectomy. He needed no further cardiac medication after discharge.

Different Gene Expression Patterns in the Lungs of Patients with Secondary Pulmonary Hypertension

BACKGROUND AND OBJECTIVES: Despite the similar degree of pressure or volume overloading, the development of secondary pulmonary hypertension (PH) shows diverse variability among individual patients. SUBJECTS AND METHODS: Using microarray technology, we compared the gene expression pattern of the lung tissues in 13 patients with secondary PH due to congenital shunt (pulmonary arterial hypertension, PAH, n=6) or valvular heart disease (pulmonary venous hypertension, PVH, n=7) with 5 normal subjects. RESULTS: As compared to the normal controls, secondary PH showed a decreased expression of genes encoding transcriptional factors (BHLHB2, EGR3, JUNB, KLF4, KLF6 and MAFF), cytoskeleton protein (VIL2 and XLKD1) and cell differentiation and viability (MCL1, SNF1LK and TNFAIP3). PVH showed an increased expression of genes encoding proliferation of pulmonary capillary endothelial cells (ESM1), cell proliferation (IGFBP2 and BMP6), collagen synthesis (COL4A2 and SERPINH1), and cytoskeleton (TMSL8) as compared with the normal controls. In patients with secondary PH, PVH showed an upregulated expression of proliferation of pulmonary capillary endothelial cells (ESM1), cell proliferation (EGR2, PLK2 and TNC) and collagen synthesis (COL4A1), and an down-regulated expression of inflammation (IL1RL1, IL7R, CCL5, CCL19, CXCR 6 and XCL1/XCL2) and immune response (IGHM and TRA@; TRAC), as compared with PAH. CONCLUSION: There were significant differences in the gene expression pattern in secondary PH patients according to the underlying mechanism. A future study is needed to determine the diagnostic and therapeutic implications of these findings.

Predictive Factors for Restenosis after Drug-Eluting Stent Implantation

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 post-intervention 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. Non-uniform 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.

Characteristics of Transplant Coronary Artery Disease after Heart Transplantation in Koreans: A Serial Intravascular UltraSound Analysis

BACKGROUND AND OBJECTIVES: Coronary artery disease (CAD) in a transplanted heart has been a major cause of morbidity and mortality for the transplantation patients who survive more than 1 year. The incidence and characteristic pattern of coronary artery disease after heart transplantation in Koreans are not known. The aim of this study is to determine the incidence and characteristics of significant CAD and the coronary arterial remodeling pattern after heart transplantation by using intravascular ultrasound (IVUS). SUBJECTS AND METHODS: We evaluated a total of 101 consecutive patients who had been examined via serial (over one year interval) IVUS and coronary angiogram. The patients were divided into two groups according to the period of the serial IVUS follow-up. The post-transplant early period (EP) group (n=58) was defined when IVUS was performed within the first month and at one year after heart transplantation, and the post-transplant late period (LP) group (n=43) was defined when IVUS was performed after one year and subsequently over another one year interval. RESULTS: The CAD-free survival rates, as assessed by coronary angiogram, were 99% at 5 years, 89% at 7 years and 71% at 9 years. In the EP group, 17 patients (29%) had donor lesions and 8 patients (14%) had de novo lesions. For the donor lesions, the diffuse and concentric lesions were 12%, respectively, and the remodeling index was 2.3+/-6.5, which represents a positive remodeling pattern. For the de novo lesion, the diffuse lesions were 25%, the concentric lesions were 13% and the remodeling index was -2.5+/-4.9, which represent a negative remodeling pattern. CONCLUSIONS: The incidence of significant CAD with diffuse and concentric lesions after heart transplantation was low in Koreans. The coronary arterial remodeling pattern was negative in the early period, and then it became positive during the late period.

Clinical Outcomes of Cobalt-Chromium Alloy ArthosPico Stent for Native Coronary Lesions

BACKGROUND AND OBJECTIVES: It has been reported that strut thickness is associated with the occurrence of in-stent restenosis. This prospective, multicenter, single-arm study was designed to evaluate the safety and efficacy of the ArthosPico stent manufactured with thin-strut cobalt-chromium alloy steel for simple de novo coronary lesions. SUBJECTS AND METHODS: A total of 150 coronary lesions that were > or =3.0 mm in diameter and < or =20 mm in length, which could be covered by a single stent, were enrolled. Clopidogrel was used for 1 month. RESULTS: Acute coronary syndrome was involved in 60.7% of patients. The right coronary artery (50.0%) was the most common target vessel. All stents were successfully deployed at the target lesions. Reference vessel diameter was 3.1+/-0.5 mm and lesion length was 13.6+/-4.6 mm. Minimal lumen diameter was increased from 1.03+/-0.48 to 3.04+/-0.49 mm after the procedure. Follow-up angiography was obtained in 117 lesions (78%). Binary restenosis was documented in 12.0% of stented segments and in 13.7% of analytic segments. Late luminal loss was found to be 0.78+/-0.75 mm in stented segments and 0.59+/-0.74 mm in analytic segments. During 7.0+/-2.8 months follow-up, cardiac death or non-fatal myocardial infarction occurred in 2 (1.3%) and 2 (1.3%) patients, respectively. Target lesion revascularization was performed in 11 (7.3%) patients. CONCLUSION: The cobalt-chromium alloy ArthosPico stent for relatively simple coronary lesions showed favorable acute and long-term outcomes in terms of very low incidence of death or myocardial infarction and a single digit rate of target lesion revascularization.

Aspirin for the Prevention of Cardiovascular Events

Plaque disruption and subsequent thrombotic occlusion is the primary mechanism by which atherosclerosis leads to acute coronary syndromes and ischemic stroke. Platelets are the key component of arterial thrombus formation in response to sudden fissuring or rupture of the atheromatous plaque. Low dose aspirin (100~300 mg/day) rapidly inhibits platelets through permanent inactivation of the key platelet enzyme, cyclooxygenase (COX). The efficacy and safety of aspirin have been extensively studied in several populations, ranging from healthy individuals to highrisk patients with acute myocardial infarction or ischemic stroke. It is well established that aspirin reduces the risk of serious vascular events (death, myocardial infarction, and stroke) by approximately 25% in patients with established vascular diseases. However, long-term therapy with aspirin approximately doubles the risk of major extracranial bleeding (mostly gastrointestinal bleeding) and also increases the risk of hemorrhagic stroke. In contrast to the clear benefit of aspirin in secondary prevention, its benefits in primary prevention are less clear. A meta-analysis of primary prevention trials in men demonstrated that aspirin reduces the risk of myocardial infarction by approximately 30% but has no effects on the risk of stroke. By contrast, the Women's Health Study showed that aspirin reduces the risk of stroke by 17% but has no effects on the risk of myocardial infarction. The reasons for this discrepancy remain unclear, requiring additional studies. Taken together, aspirin is recommended for primary prevention in healthy individuals with an annual risk of vascular events >1.5%. In conclusion, aspirin is recommended for secondary prevention in all patients, but its risk-benefit ratio should be carefully considered for primary prevention.