Severe Coronary Obstruction Research Articles

Association of Calcium Index and Myocardial Blood Flow in Non-Obstructive Atherosclerotic Lesion of the Coronary Arteries

Background. Over the past few years, scientific data have demonstrated that patients with non-obstructive coronary artery disease can have high risk for adverse cardiovascular events (ACE) despite the absence of severe coronary obstruction. From this point of view, some patients require special monitoring and treatment; we have to find new methods for stratification of the risk of ACE. Aims to study the association of coronary artery calcification (CCA) with indicators of myocardial blood flow (MBF) and myocardial flow reserve (MFR) in patients with non-obstructive coronary artery disease (CAD). Methods. The study included patients (n = 52) with non-obstructive CAD ( 50%), identified by CCTA. All patients received dynamic myocardial SPECT according to the two-day rest-stress protocol with the radiopharmaceutical agent 99mTc-methoxy-isobutyl-isotnitrile and the pharmacological stress-test (adenosine triphosphate 160 mcg/kg/min) to determine quantitative indicators of MBF and MFR. Depending on the calcium index (CI), three groups of patients were formed: 1 without CCA (CI = 0 Agatston units), 19 patients; 2 Mild CCA (CI = 1100 Agatston units), 21 patients; 3 Moderate CCA (CI = 101400 Agatston units), 12 patients. Results. The study included 52 patients (age 55.0 9.8 years, 36 men). The groups differed statistically significantly (p 0.05) in terms of quantitative scintigraphic parameters: stress-MBF, MFR and MBF. When analyzing the groups in pairs, it was found that stress-MBF and MBF were significantly lower in the group with moderate CCA compared to the group without CCA, and MFR was lower in the group with moderate CCA compared to the groups without CCA and with mild CCA. Correlation analysis revealed significant relationships between CI and scintigraphic parameters: stress-MBF ( = 0.46; p = 0.003), MFR ( = 0.48; p = 0.001), MBF ( = 0.48; p = 0.0008), SSS ( = 0.34; p = 0.02) and SDS ( = 0.28; p = 0.046). Conclusions. Even with non-obstructive CAD, identified by CCTA, there is a decrease in MBF and MFR inversely proportional to the level of CI, which can be considered as an early marker of impaired vasodilation reserve of the vascular wall, which develops in atherosclerosis of the coronary artery.

Abstract P577: Demographic Disparities in the Distribution and Severity of Coronary Artery Disease- An Urban-Suburban Comparative Study

Background: Some small powered studies have suggested a paradoxical finding of less severe coronary artery obstruction in African American (AA) males as compared to Caucasian male patients despite a higher prevalence of CVD mortality in AAs. We performed a retrospective study to further identify the difference in the extent of coronary artery obstruction and the prevalence of multivessel disease between an urban hospital and a suburban hospital. Methods: A chart review of cardiac catheterization reports was performed on 3,579 patients from 2 different hospitals (1 urban and 1 suburban center). Statistical analysis was done using R and Stata. Results: Analyzing the main characteristics of the patient population we found that the suburban patient population (SPP) was 7 years older than the urban patient population (UPP) (P-valve= <0.001), 78.4% of the suburban population were Caucasian while 79.7% of the urban center patient population were African Americans (P value= <0.001). 96% of the patient population at the suburban center were insured while 85% of patients at the urban center were insured (P= <0.001). Comorbidity burden was overall higher in the SPP ( P-Value= < 0.001). SPPs were found to have a higher prevalence of severe CAD than UPP (Table 1). However, no significant difference was noted when comparing the prevalence of multivessel disease (Table 2). Conclusion: SPPs are more likely to have severe CAD than UPPs but with a similar level of CAD distribution.

Fundamental Pathobiology of Coronary Atherosclerosis and Clinical Implications for Chronic Ischemic Heart Disease Management—The Plaque Hypothesis

Recent clinical and imaging studies underscore that major adverse cardiac events (MACE) outcomes are associated not solely with severe coronary obstructions (ischemia hypothesis or stenosis hypothesis), but with the plaque burden along the entire coronary tree. New research clarifies the pathobiologic mechanisms responsible for plaque development/progression/destabilization leading to MACE (plaque hypothesis), but the translation of these insights to clinical management strategies has lagged. This narrative review elaborates the plaque hypothesis and explicates the current understanding of underlying pathobiologic mechanisms, the provocative destabilizing influences, the diagnostic and therapeutic implications, and their actionable clinical management approaches to optimize the management of patients with chronic coronary disease. Clinical trials of management strategies for patients with chronic coronary artery disease demonstrate that while MACE rate increases progressively with the anatomic extent of coronary disease, revascularization of the ischemia-producing obstruction does not forestall MACE. Most severely obstructive coronary lesions often remain quiescent and seldom destabilize to cause a MACE. Coronary lesions that later provoke acute myocardial infarction often do not narrow the lumen critically. Invasive and noninvasive imaging can identify the plaque anatomic characteristics (plaque burden, plaque topography, lipid content) and local hemodynamic/biomechanical characteristics (endothelial shear stress, plaque structural stress, axial plaque stress) that can indicate the propensity of individual plaques to provoke a MACE. The pathobiologic construct concerning the culprit region of a plaque most likely to cause a MACE (plaque hypothesis), which incorporates multiple convergent plaque features, informs the evolution of a new management strategy capable of identifying the high-risk portion of plaque wherever it is located along the course of the coronary artery. Ongoing investigations of high-risk plaque features, coupled with technical advances to enable prognostic characterization in real time and at the point of care, will soon enable evaluation of the entire length of the atheromatous coronary artery and broaden the target(s) of our therapeutic intervention to include all regions of the plaque (both flow limiting and nonflow limiting).

Coexistent coronary artery disease in Indian patients undergoing permanent pacemaker implantation (PPI) for symptomatic bradyarrhythmia

BackgroundThe cause-effect of conduction disturbance in chronic lesion of coronary arteries is complicated. This study was designed to evaluate coexistent CAD in patients with symptomatic bradyarrhythmia to find common anatomic basis for conduction disturbances and its relationship to conventional coronary risk factors. MethodsIn this prospective observational study, 929 patients who admitted for symptomatic bradyarrhythmia requiring permanent pacemaker implantation were included. All included patients underwent coronary angiography and were divided into groups based on angiographic findings. Association between conduction disturbances and these groups were analyzed. ResultsA total of 929 patients with mean age of 63.1 years were included in our study. We found age ≥50 years, male sex, presence of diabetes and hypertension as statistically significant predictors of abnormal coronary angiography. Obstructive CAD (≥50% stenosis) was found in 34.4% patients. Prevalence of single vessel disease, double vessel disease and triple vessel disease was 15.3%, 10.2% and 8.9% respectively. Severe coronary obstruction (≥90% obstruction) was found in 16.25% patients. Revascularization was advised in three fourth of cases of obstructive CAD. Approximately two third of patients didn’t have significant obstruction in coronaries supplying the conduction system. Type 4 was the commonest anatomy in obstructive CAD. SA Nodal artery was found more diseased in patients of SSS with p value of 0.01. ConclusionObstructive CAD was found in one third of patients undergoing PPI. Age ≥50 years, male sex, diabetes and hypertension were found significantly correlated with presence of CAD and may act as important markers for the judgment of further coronary evaluation.

Comparative analysis of adrenergic reactivity of erythrocytes in patients with myocardial infarction depending on the severity of coronary obstruction

Aim. To study the parameters of beta-adrenergic reactivity of membrane (p-ARM) of erythrocytes in patients with myocardial infarction with nonobstructive coronary arteries (MINOCA) and single-vessel CAD. Material and methods . The study included 40 patients with MI (experimental group — 19 patients; control group — 21 patients). Three patients (15,7%) with diagnosed acute myocarditis were excluded from the analysis. Levels of β -ARM were determined upon admission, on the 2 nd , 4 th and 7 th day after MI. The normal range of β -ARM were <20 CU. Results. In a significant proportion of patients, p-ARM values were two times higher than normal values. The median β -ARM in the experimental group at admission was 41,7 (29,0;61,5) CU, on the day 1 — 48,6 (38,5;57,3) CU, day 4 — 49,4 (39,0;63,3) CU, day 7 — 53,5 (35,2;67,7) CU. In the control group, the median p-ARM at admission was 52,5 (25,4;64,5) CU, day 1 — 51,6 (28,3;56,9) CU, day 4 — 48,5 (34,9;61,2) CU, day 7 — 45,1 (32,2;68,9) CU. Static analysis of p-ARM at all followup periods did not show differences between the groups by median level (p>0,05). The curves of β -ARM median changes show its multidirectional dynamics in the studied groups. During the hospitalization, in the group of patients with MINOCA there was a downward trend in β -ARM. In the control group, there was a tendency to increase of β -ARM. A statistically significant correlation of β -ARM with the ejection fraction (r=0,83, p=0,0007) and a moderate correlation between the p-ARM level on the 4 th day and GRACE risk (r=0,55, p=0,03) in patients of the control group were revealed. Conclusion. β-ARM values in patients with MINOCA were doubled, and this increase was comparable to levels in patients with obstructive CAD. During the hospitalization, the β -ARM levels did not significantly change, despite the use of beta-blockers.

Nonalcoholic Fatty Liver Disease and Coronary Artery Disease: Big Brothers in Patients with Acute Coronary Syndrome.

Background The prevalence of nonalcoholic fatty liver disease (NAFLD) has been increasing. This study aimed to evaluate the prevalence of NAFLD, as diagnosed by ultrasound, in patients with acute coronary syndrome (ACS) and to assess whether NAFLD is associated with the severity of coronary obstruction as diagnosed by coronary angiography. Methods We performed a prospective single-center study in patients hospitalized due to acute coronary syndrome who underwent diagnostic coronary angiography. Consecutive patients who presented to the emergency room were diagnosed with acute coronary syndrome and were included. All patients underwent ultrasonography of the upper abdomen to determine the presence or absence of NAFLD; NAFLD severity was graded from 0 to 3 based on a previously validated scale. All patients underwent diagnostic coronary angiography in the same hospital, with the same team of interventional cardiologists, who were blinded to the patients' clinical and ultrasonographic data. CAD was then angiographically graded from none to severe based on well-established angiographic criteria. Results This study included 139 patients, of whom 83 (59.7%) were male, with a mean age of 59.7 years. Of the included patients, 107 (77%) patients had CAD, 63 (45%) with serious injury. Regarding the presence of NAFLD, 76 (55.2%) had NAFLD including 18 (23.6%) with grade III disease. In severe CAD, 47 (60.5%) are associated with NAFLD, and 15 (83.3%) of the patients had severe CAD and NAFLD grade III. Conclusions NAFLD is common in patients with ACS. The intensity of NAFLD detected by ultrasonography is strongly associated with the severity of coronary artery obstruction on angiography.

Diagnostic Accuracy of Perfusional Computed Tomography in Moderate Coronary Stenosis: Comparison With Fractional Flow Reserve.

Coronary computed tomography with myocardial perfusion imaging (CCTA-MPI) provides data on coronary anatomy and perfusion and may be useful in the assessment of ischemic coronary artery disease (CAD). Management of angiographically intermediate coronary lesions is challenging, and coronary fractional flow reserve (FFR) evaluation is recommended to assess whether these lesions are functionally significant. Our aim was to evaluate the diagnostic accuracy of CCTA-MPI in patients with stable CAD and at least 1 angiographically intermediate coronary lesion submitted to FFR. In this single-center prospective study, patients with stable CAD and at least 1 moderate coronary stenosis (50%-70% by visual estimation) were referred for CCTA-MPI (64-row multidetector) assessment before coronary FFR evaluation. Patients with severe coronary obstructions (≥70%) were excluded. The significance level adopted for all tests was 5%. Twenty-eight patients (mean age 60 ± SD years, 54% women) with 33 intermediate coronary obstructions were enrolled. Ten patients (30%) had functionally significant coronary obstructions characterized by FFR ≤0.8. The sensitivity, specificity, and accuracy of CCTA-MPI for the detection of functionally significant coronary obstructions were 30%, 100%, and 78.8%, respectively. CCTA-MPI positive predictive value was 100%, whereas negative predictive value was 76.7%. Correlation coefficient between tests was 0.48 (P = 0.005). On a novel approach to evaluate intermediate coronary lesions, accuracy of CCTA-MPI was 78.8%. The positive predictive value of an abnormal CCTA-MPI on this population was 100%, suggesting that CCTA-MPI may have a role in the assessment of patients with anatomically identified intermediate coronary lesions.

Left Ventricular Longitudinal Global Strain to Predict Severe Coronary Disease in Patients with Precordial Pain Suggestive of Non-ST-Segment Elevation Acute Coronary Syndrome.

Background:Diagnosing non-ST-segment elevation acute coronary syndrome (NSTE-ACS) is not always straightforward. Left ventricular global longitudinal strain (LVGLS) is an echocardiographic method capable of detecting subclinical regional and global ventricular contractile dysfunction due to myocardial ischemia. The objectives of this study were to evaluate the efficacy of LVGLS in diagnosing severe coronary disease in patients with chest pain suggestive of NSTE-ACS and to assess the relationships between LVGLS reduction and ultrasensitive troponin T (UsTnT) elevation, electrocardiographic changes suggestive of ischemia, and the number of vessels with severe obstructions.Methods:This prospective, observational study evaluated hospitalized patients with chest pain of presumed coronary etiology. All patients underwent electrocardiography (ECG), UsTnT measurement, Doppler echocardiography, LVGLS measurement, and coronary angiography Coronary angiogram (CA) within 48 h of hospitalization.Results:A total of 75 patients with a mean age of 58 ± 17 years were included, of whom 84% (63 patients) were men. An LVGLS value of <-16.5, as determined by the Youden index proved to be useful for the detection of severe coronary obstructions (lesions >70%). The sensitivity, specificity, and positive and negative predictive values were 96%, 88%, 92%, and 92%, respectively. The number of coronary arteries involved had a direct relationship with the degree of LVGLS reduction (P < 0.001). Elevated UsTnT levels occurred more frequently in patients with reduced LVGLS than in those with normal LVGLS (83% vs. 17%, P < 0.0001). Abnormal strain was not associated with electrocardiographic changes suggestive of ischemia.Conclusions:LVGLS measurement in patients with presumed NSTE-ACS is efficient in predicting the presence of severe coronary disease. The number of coronary arteries involved has a direct relationship with the degree of LVGLS reduction. Abnormal strain is associated with UsTnT elevations but not with electrocardiographic changes suggestive of ischemia.

Predictive Value of Biomarkers in Patients with Suspected Coronary Heart Disease Regarding Severity of Coronary Obstruction and Mortality – LIFE-Heart Study

Predictive Value of Biomarkers in Patients with Suspected Coronary Heart Disease Regarding Severity of Coronary Obstruction and Mortality – LIFE-Heart Study

Relationship between Myocardial Performance Index and Severity of Coronary Artery Disease in patients with Stable Coronary Artery Disease.

Objectives: To investigate the relationship between severity of coronary artery disease (CAD) assessed with SYNTAX score (SS) and myocardial performance index (MPI) in stable CAD. Methods: The study included 100 patients who were candidate for coronary angiography. All subjects underwent full history taking, complete clinical examination, echocardiographic examination for calculation of MPI, EF and E/A ratio, and coronary angiography for calculation of syntax score. Results: Among study population 49 female (49.0%) and 51 male (51.0%) with mean age (48.96±7.30), 80 patients (80.0%) were had angiographically proven obstructive CAD, whereas 20 (20.0%) patients were had normal coronary angiography. There is statistically significant positive correlation between MPI and SS in patients with obstructive CAD (P-value < 0.001). Conclusion: MPI showed the ability of being a sensitive marker of LV function in SCAD as its value was impaired in proportion to severity of coronary obstruction and it is correlated well with Syntax score as it is the most recent quantitative and qualitative tool that can characterizes angiographically obstructive lesions, risk stratification and prognostication of patients with CAD.

Intra-aortic balloon pump for high-risk percutaneous coronary intervention.

The intra-aortic balloon pump (IABP) was first introduced into clinical practice in 1968.1 Early experimental and clinical trials suggested that intra-aortic balloon counterpulsation could provide circulatory assistance to a failing left ventricle.2,3 Counterpulsation—balloon inflation during diastole and deflation in systole—augments the intrinsic Windkessel effect, whereby potential energy stored in the aortic root during systole is converted to kinetic energy with the elastic recoil of the aortic root. Counterpulsation leads to a decline in afterload, a reduction in cardiac work, and therefore myocardial oxygen requirements of the ventricle. Augmentation of diastolic pressure when the balloon is fully inflated together with reduction in left ventricular (LV) filling pressures contribute to improved coronary perfusion (Figures 1 and 2).4 This proposed improvement in myocardial energetics has been further supported by a significant reduction in systemic lactate.5 These physiological enhancements are thought to be of particular benefit after acute myocardial infarction (AMI), supported by animal studies, which have shown a reduction in infarct size when counterpulsation is used.6,7 Figure 1. Coronary perfusion. Coronary flow is predominantly diastolic and further enhanced by counterpulsation, which augments diastolic blood flow and thus coronary perfusion. In addition, aortic recoil during diastole further improves efficiency of the left ventricle. Figure 2. Systemic arterial pressure waveform on introduction of intra-aortic balloon pump–assisted diastolic augmentation. The intra-aortic balloon pump inflates at the dicrotic notch, leading to peak-augmented diastolic pressure. As the balloon deflates, assisted end diastolic pressure is seen to be lower than unassisted end diastolic pressure and assisted systolic pressure is lower than unassisted systolic pressure. Peak diastolic augmentation should be greater than the unassisted systolic pressure and both assisted pressures should be less than the unassisted pressures. Intra-aortic balloon counterpulsation was initially used as a means of supporting patients undergoing surgical revascularization. Percutaneous delivery …

Relation of High-Density Lipoprotein Cholesterol and Apoprotein A1 Levels with Presence and Severity of Coronary Obstruction

The aim of this work was to investigate the relationship between different lipids parameters with presence and severity of coronary obstruction angiographically evaluated. 897 patients (629 men and 268 women) underwent an angiography and blood extraction to determine concentrations of lipid markers: total cholesterol (TC), HDL cholesterol (HDLc), triglycerides, LDL cholesterol (LDLc), apolipoprotein A1 (apoA1), apolipoprotein B100 (apoB), non-HDL cholesterol and total cholesterol/HDLc, apoB100/apoA1 and LDLc/HDLc ratios. Multivariate analysis revealed that low HDLc levels were independently associated with the presence of coronary obstruction (OR: 0.982, 95% CI 0.969–0.996). In relation to severity of coronary stenosis, only apoA1 levels (OR: 0.990, 95% CI 0.980–1.000) and apoB/apoA1 ratio (OR: 3.243, 95% CI 1.095–9.608) were independent predictors. Our study demonstrated that HDLc was the only lipid parameter negatively and significantly associated with the presence of coronary obstruction, whereas apoA1 levels and apoB/apoA1 ratio were independent predictors of stenosis severity.

The relationship between perceived discrimination and coronary artery obstruction

Chronic stressors such as perceived discrimination might underlie race disparities in cardiovascular disease. This study focused on the relationship between perceived discrimination and risk of severe coronary obstruction while also accounting for multiple psychosocial variables and clinical factors. Data from 793 (629 white and 164 black) male veterans with positive nuclear imaging studies were analyzed. Participants were categorized as being at low/moderate or high risk for severe coronary obstruction based on results of their nuclear imaging studies. Hierarchical logistic regression models were tested separately for blacks and whites. The first step of the models included clinical factors. The second step included the psychosocial variables of optimism, religiosity, negative affect, and social support. The final step included perceived discrimination. Perceived discrimination was positively related to risk of severe obstruction among blacks but not among whites after controlling for clinical and psychosocial variables. Similar results were found in patients who underwent coronary angiography (n = 311). Perceived discrimination was associated with risk of severe coronary obstruction among black male veterans and could be an important target for future interventions.

Multifocal Severe Coronary Artery Vasospasm Mistaken for Diffuse Atherosclerosis: A Case Report

Spontaneous severe multivessel coronary artery vasospasm is a rare but important cause of morbidity. One-third of patients have normal coronary vasculature, and these pose a significant therapeutic dilemma as lack of clinical suspicion might potentially lead to unnecessary revascularization therapies. A patient with resting chest pain and ischaemic electrocardiography demonstrated severe coronary obstruction at catheter angiography. Preangioplasty further information highlighted spasm as the likely cause and the angiographic abnormalities resolved post intracoronary nitrate. This paper emphasises thorough history-taking and judicious use of nitrates during diagnostic coronary angiography in such patients. This may negate the need for more complex cardiac interventions.

Identifying which patients with diabetes should be tested for the presence of coronary artery disease – The importance of baseline electrocardiogram and exercise testing

Numerous studies have reported that diabetic patients should not always be considered to be coronary artery disease (CAD)-equivalent as was previously suggested. Exercise testing is widely available at a relatively low cost, and even among patients in whom the diagnosis of CAD is highly probable on the basis of age, sex, description of chest pain and history of prior myocardial infarction, exercise testing is often a clinical requirement for risk or prognosis assessment to determine the need for possible coronary angiography or revascularization. Nevertheless, because of either the presence of atypical symptoms or the absence of symptoms often encountered, the screening approach may differ in patients with diabetes mellitus. Because CAD is the major cause of mortality in patients with diabetes, its early detection is important to improve medical interventions and outcomes. This is critical because the available evidence suggests that occult CAD is common among asymptomatic patients with diabetes. Therefore, noninvasive testing for asymptomatic CAD may be helpful for the identification of diabetic patients with severe coronary obstruction in whom revascularization therapy may be considered the first manifestation of silent CAD in patients with diabetes is a fatal cardiac event in approximately one-half of the patients. The present paper reviews some clinical markers that may be helpful to the clinician to increase the yield of finding significant occult CAD while screening patients with diabetes.

Monitoring of right-sided heart function

Because the right side of the heart supplies blood to the pulmonary circulation, its integrity is required for both adequate respiratory and circulatory function. By reducing pulmonary perfusion, right-sided heart failure may compromise arterial oxygenation and left ventricular filling, and monitoring of right-sided heart function at the bedside in critically ill patients is fundamental. Two recent clinical commentaries have focused on the invaluable help provided by echocardiography for this purpose. Bedside echocardiography has supplanted invasive procedures as the best tool to evaluate right-sided heart function. Although not recent, this technique, previously reserved for cardiologists, has recently gained a larger acceptance in respiratory intensive care units. Echocardiographic examination detects excessive right ventricular afterload, visualized by septal dyskinesia, and its usual consequence, right ventricular enlargement, which impairs left ventricular filling. Monitoring of right-sided heart function is essential in a clinical setting associated with hemodynamic instability, such as severe sepsis or acute coronary artery obstruction, and also in that it is associated with increased pulmonary vascular resistance, as in massive pulmonary embolism or acute respiratory failure. Moreover, use of mechanical ventilation requires regular evaluation of its effects on the right side of the heart.

Síndrome da disfunção apical reversível (Takotsubo)

The patient was a male with myasthenia gravis, hospitalized with acute respiratory failure due to decompensation of the underlying disease. He evolved with findings suggestive of acute myocardial infarction, with electrocardiographic and enzymatic alterations compatible with that diagnosis. The patient underwent emergency coronary angiography, which showed no severe coronary obstruction, although his left ventricle had significant systolic dysfunction with characteristic alterations, on ventriculography, of the syndrome described as transient ventricular dysfunction or Takotsubo syndrome. On evolution, complete recovery of the electrocardiographic alterations and systolic ventricular function assessed on echocardiography occurred, confirming the syndrome.

Exercise tolerance testing to screen for coronary heart disease: a systematic review for the technical support for the U.S. Preventive Services Task Force.

Coronary heart disease is the leading cause of morbidity and mortality in the United States. Exercise tolerance testing has been proposed as a means of better identifying asymptomatic patients at high risk for coronary heart disease events. To review the evidence on the use of exercise tolerance testing to screen adults with no history of cardiovascular disease for coronary heart disease. The MEDLINE database from 1966 through February 2003, hand-searching of bibliographies, and expert input. Eligible studies evaluated the benefits or harms of exercise tolerance testing when added to traditional risk assessment for adults with no known history of cardiovascular events. One reviewer extracted information from eligible articles into evidence tables, and another reviewer checked the tables. Disagreements were resolved by consensus. No study has directly examined the effect of screening asymptomatic patients with exercise tolerance testing on coronary heart disease outcomes or risk-reducing behaviors or therapies. Multiple cohort studies demonstrate that screening exercise tolerance testing identifies a small proportion of asymptomatic persons (up to 2.7% of those screened) with severe coronary artery obstruction who may benefit from revascularization. Several large prospective cohort studies, conducted principally in middle-aged men, suggest that exercise tolerance testing can provide independent prognostic information about the risk for future coronary heart disease events (relative risk with abnormal exercise tolerance testing, 2.0 to 5.0). However, when the risk for coronary heart disease events is low, most positive findings will be false and may result in unnecessary further testing or worry. The risk level at which the benefits of additional prognostic information outweigh the harms of false-positive results is unclear and requires further study. Although screening exercise tolerance testing detects severe coronary artery obstruction in a small proportion of persons screened and can provide independent prognostic information about the risk for coronary heart disease events, the effect of this information on clinical management and disease outcomes in asymptomatic patients is unclear.

Acute Coronary Syndrome

Acute coronary syndrome consists of acute myocardial infarction associated with electrocardiographic ST segment elevation (STEMI) and unstable angina/non-ST segment elevation myocardial infarction (UA/NSTEMI). Theses three conditions are differentiated primarily by clinical, electrocardiographic, and laboratory presentations correlating with the duration and extent of thrombotic occlusion as a consequence of plaque rupture. Acute coronary syndrome is now the most prevalent presentation of ischemic heart disease in Korea as well as developed countries. Q-wave acute myocardial infarction is the most easily identified syndrome ; persistent angina and ST-segment elevation are characteristic of sudden total or near-total thrombotic arterial occlusion. Urgent reperfusion is the mainstay of therapy, whereas UA/NSTEMI is usually associated with severe coronary obstruction but not total occlusion of the culprit coronary artery. The distinction between unstable angina and non-Q wave, non-ST segment elevation myocardial infarction is often not clear at the initial presentation of patients. Unstable angina is defined as angina pectoris with at least one of the following three features : ① It occurs at rest usually lasting more than 20 minutes. ② It is severe and described as frank pain and of new onset within 1 month. ③ It occurs with a crescendo pattern (more severe, prolonged, or frequent than previously). Some patients with this pattern of ischemic discomfort, especially those with prolonged rest pain, develop evidence of myocardial necrosis on the basis of the release of cardiac markers and thus have a diagnosis of NSTEMI. This diagnosis has been based on the elevation of serum creatine kinase (CK)-MB, level but recently troponin T and I assays are used to define ischemic myocardial damage based on their higher sensitivity for myocardial necrosis and prognostic implication. Troponin has become the standard myocardial marker. A certain number of patients have elevated levels of troponins in the absence of significant CK elevation. Several studies have shown that despite nondiagnostic CK levels, an elevated troponin level often indicates a poor prognosis.Successful treatment strategies for acute coronary syndrome that improve survival include anticoagulant, antiplatelet, thrombolytic, and interventional approaches.

Elective intraaortic balloon counterpulsation for high-risk off-pump coronary artery bypass operations

Background. Dislocations of the heart required for exposure and construction of distal anastomoses often produce hemodynamic instability when performing coronary artery revascularization without using cardiopulmonary perfusion (OPCAB). We report our early experience with elective intraaortic balloon counterpulsation (IABP) to enable and facilitate selected high-risk patients to undergo OPCAB. Methods. Sixteen high-risk patients undergoing multivessel OPCAB using elective IABP are reported. The patients were believed to be at increased risk because of the presence of severe proximal multivessel coronary artery obstruction, ventricular dysfunction, recent acute myocardial infarction, cardiomegaly–cardiomyopathy, and documented cerebral vascular disease. The presence of significant comorbid disease also made the avoidance of cardiopulmonary bypass desirable, if at all possible, in all patients. Results. The IABP appeared to facilitate the intraoperative management of our series of patients. This was evidenced by improved hemodynamic stability and virtual elimination of the need for inotropic support during the dislocations of the heart needed for exposure and construction of distal anastomoses. There were no complications related to use of IABP. There was one death. Conclusions. We believe this strategy to use IABP selectively can allow surgeons to safely extend the benefits of OPCAB procedures to high-risk patients and avoid dangerous hemodynamic instability that otherwise, often occurs.