Preoperative risk stratification for endovascular surgery using pharmacologic stress myocardial imaging

To stratify perioperative cardiac risk for endovascular surgery, pharmacologic stress single-photon emission computed tomography (SPECT) was performed in 206 patients. Of 8 patients who had cardiac events, 7 occurred in 67 patients with positive SPECT results, whereas only 1 occurred in 139 patients with negative SPECT results (7 of 67 vs 1 of 139, p <0.002). Furthermore, a scintigraphic marker of a summed stress score >/=14 was the most important factor identifying patients who subsequently had cardiac events by multivariate analysis.     

Value of pharmacologic stress myocardial perfusion imaging for preoperative risk stratification for aortic surgery.

BACKGROUND: Aortic surgery is an invasive, high-risk noncardiac procedure and the patients who require it have a high prevalence of coronary artery disease. Therefore, preoperative risk stratification for this subset is essential. METHODS AND RESULTS: To assess the perioperative risk for aortic surgery, pharmacologic stress single-photon emission computed tomography (SPECT) was performed in 302 patients: aortic dissection in 56, thoracic aortic aneurysm in 124, and abdominal aortic aneurysm in 122. Not only was the presence or absence of perfusion defects analyzed, but also the 20-segment model. Pharmacologic thallium SPECT revealed negative findings in 210 patients and positives in 92. Perioperative cardiac events occurred in 9 patients: 7 occurred in patients with positive SPECT, and in only 2 of those with negative SPECT (2/210 vs 7/92; p<0.05). Multivariate analysis using logistic regression model revealed that a summed stress score>or=14 was the most important factor to identify patients who subsequently had perioperative cardiac events. CONCLUSIONS: Pharmacologic stress SPECT has significant value in the risk stratification of patients before aortic surgery. In patients with positive SPECT, an aggressive approach to reduce the preoperative risk is necessary, whereas aortic surgery can be performed safely in patients with negative SPECT.     

Utility of myocardial perfusion imaging in patients with low-risk treadmill scores

OBJECTIVES: The purpose of this study was to determine whether a previously validated clinical score (CS) could identify patients with a low-risk Duke treadmill score who had a higher risk of adverse events and, therefore, in whom myocardial perfusion imaging would be valuable for risk stratification. BACKGROUND: Current American College of Cardiology/American Heart Association guidelines recommend using a standard exercise test without imaging as the initial test in patients who have an interpretable electrocardiogram and are able to exercise. METHOD: We studied 1,461 symptomatic patients with low-risk Duke treadmill scores (> or =5) who underwent myocardial perfusion imaging. The CS was derived by assigning one point to each of the following variables: typical angina, history of myocardial infarction, diabetes, insulin use, male gender, and each decade of age over 40 years. A CS cutoff > or =5 or <5 was used to categorize patients as high risk (n = 303 [21%]) or low risk (n = 1,158 [79%]). Perfusion scans were categorized as low, intermediate, or high risk on the basis of the global stress score (GSS). RESULTS: High-risk scans were more common in patients with a high-risk CS (26.4% vs. 9.5%, p < 0.0001). The CS and GSS were significant independent predictors of cardiac death. However, in patients with a low CS, seven-year cardiac survival was excellent, regardless of the GSS (99% for normal scans, 99% for mildly abnormal scans, and 99% for severely abnormal scans). In contrast, patients with a high CS had a lower seven-year survival rate (92%), which varied with GSS (94% for normal scans, 94% for mildly abnormal scans, and 84% for severely abnormal scans; p < 0.001). CONCLUSIONS: In symptomatic patients with low-risk Duke treadmill scores and low clinical risk, myocardial perfusion imaging is of limited prognostic value. In patients with low-risk Duke treadmill scores and high clinical risk, annual cardiac mortality (>1%) is not low, and myocardial perfusion imaging has independent prognostic value.     

Role of myocardial perfusion imaging for risk stratification in suspected or known coronary artery disease

Nuclear cardiology is an evolving specialty that has recently benefited from technological and radiopharmaceutical advances. As a result there has been an increase in the accuracy of myocardial perfusion imaging (MPI) with gated single photon emission computed tomography (SPECT) for assessing the diagnosis and prognosis of coronary artery disease. Moreover, ECG gated SPECT allows the simultaneous assessment of both myocardial perfusion and left ventricular function, which provides additional prognostic value. With increasing concern over early detection of coronary artery disease and its effective treatment, myocardial perfusion imaging is ideally placed to provide a full "one stop" functional assessment for any patient, irrespective of their exercise capacity. This applies not only to patients with chest pain but also to those with myocardial infarction, revascularisation, and heart failure, and those being assessed for non-cardiac surgery. The focus of this review is the use of myocardial perfusion imaging in risk stratification for coronary artery disease.     

Preoperative cardiac risk assessment and perioperative cardiac management in non-cardiac surgery. The 2009 ESC guidelines

In November 2009 the first European guidelines were presented regarding preoperative risk assessment and perioperative management in non-cardiac surgery. They were designed by the European Society of Cardiology (ESC) and endorsed by the European Society of Anesthesiology.In a standardized manner, patient-specific clinical variables, their exercise capacity and surgery-specific risk factors are summarized to a recommendation concerning medication and preoperative cardiac evaluation. These guidelines are straightforward and feasible for cardiologists as well as specialists in internal medicine and general practicioners. Nevertheless, some points still lack evidence.     

A metaanalysis of predischarge risk stratification after acute myocardial infarction with stress electrocardiographic, myocardial perfusion, and ventricular function imaging

We assessed the relation of abnormal predischarge noninvasive test results to outcomes in postmyocardial infarction patients. We included series published from 1980 to 1995 containing only myocardial infarction patients, enrolling most patients after 1980, testing within 6 weeks of infarction, having follow-up rates > 80%, and having 2 × 2 frequency outcome rates for test results, that were the latest of multiple reports. Sensitivity, specificity, and predictive values were calculated for test results for 1-year outcomes (cardiac death, cardiac death or reinfarction). Univariable and summary odds were calculated for test results. Reports (n = 54) included a total of 19,874 patients and were primarily retrospective (76%) and small series (35% of reports included < 5 deaths). One-year mortality ranged from 2.5% for pharmacologic stress echocardiography to 9.3% for exercise radionuclide angiography. Positive predictive values for most noninvasive risk markers were < 0.10 for cardiac death and 0.20 for death or reinfarction. Electrocardiographic, symptomatic, and scintigraphic risk markers of ischemia (ST-segment depression, angina, a reversible defect) were less sensitive (≤44%) for identifying morbid and fatal outcomes than markers of left ventricular dysfunction or heart failure (exercise duration, impaired systolic blood pressure response, and peak left ventricular ejection fraction). The positive predictive value of predischarge noninvasive testing is low. Markers of left ventricular dysfunction appear to be better predictors than markers of ischemia. Limitations of the literature—small samples and widely varying event rates—impede our ability to discern the accuracy of predischarge noninvasive testing. More rigorous, controlled trials are required to elucidate the relative value of these tests for risk stratification.     

Managing patients undergoing non-cardiac surgery: need to shift emphasis from risk stratification to risk modification

Many patients undergo non-invasive testing for the detection of coronary artery disease before non-cardiac surgery. This is despite the low predictive value of positive tests in this population and the lack of any evidence of benefit of coronary revascularisation before non-cardiac surgical procedures. Further, this strategy often triggers a clinical cascade exposing the patient to progressively riskier testing and intervention and results in increased costs and unnecessary delays. On the other hand, administration of beta blockers, and more recently statins, has been shown to reduce the occurrence of perioperative ischaemic events. Therefore, there is a need for a shift in emphasis from risk stratification by non-invasive testing to risk modification by the application of interventions, which prevent perioperative ischaemia--principally, perioperative beta adrenergic blockade and perhaps treatment with statins. Clinical risk stratification tools reliably identify patients at high risk of perioperative ischaemic events and can guide in the appropriate use of perioperative medical treatment.     

About cardiovascular risk in non-cardiac surgery

The perioperative management of patients at risk for cardiovascular diseases who undergo non-cardiac surgery has been subject of debate over the past few decades and is still of great interest. An adequate perioperative management may modify postoperative mortality and morbidity and may improve the long-term prognosis. The purpose of this review is to examine the present day knowledge regarding the preoperative evaluation and perioperative and postoperative management. In spite of the available guidelines (the American College of Cardiology and the American Heart Association of 1996) and of several studies on this subject, many controversies still persist. The main questions are: 1) the preoperative cardiovascular evaluation through non-invasive tests (and the true predictive value of the increased cardiovascular risk) and 2) the real benefit of coronary revascularization before non-cardiac surgery. The last part of this review highlights many recent clinical observations and experimental studies regarding the efficacy of the extensive use of beta-adrenergic receptor blockers and optimized anti-ischemic pharmacological therapy in reducing the cardiovascular risk of non-cardiac surgery and in improving the long-term prognosis.     

Application of support vector machine classifiers to preoperative risk stratification with myocardial perfusion scintigraphy

BACKGROUND: Myocardial perfusion single-photon emission computed tomography (SPECT) has been used for risk stratification before non-cardiac surgery. However, few authors have used mathematical models for evaluating the likelihood of perioperative cardiac events. METHODS AND RESULTS: This retrospective cohort study collected data of 1,351 patients referred for SPECT before non-cardiac surgery. We generated binary classifiers using support vector machine (SVM) and conventional linear models for predicting perioperative cardiac events. We used clinical and surgical risk, and SPECT findings as input data, and the occurrence of all and hard cardiac events as output data. The area under the receiver-operating characteristic curve (AUC) was calculated for assessing the prediction accuracy. The AUC values were 0.884 and 0.748 in the SVM and linear models, respectively in predicting all cardiac events with clinical and surgical risk, and SPECT variables. The values were 0.861 (SVM) and 0.677 (linear) when not using SPECT data as input. In hard events, the AUC values were 0.892 (SVM) and 0.864 (linear) with SPECT, and 0.867 (SVM) and 0.768 (linear) without SPECT. CONCLUSION: The SVM was superior to the linear model in risk stratification. We also found an incremental prognostic value of SPECT results over information about clinical and surgical risk.     

The potential of myocardial perfusion scintigraphy for risk stratification of asymptomatic patients with type 2 diabetes.

Patients with diabetes, in particular patients with type 2 diabetes, are at a 2- to 4-fold higher risk of cardiovascular mortality compared with their nondiabetic peers. Patients with diabetes are also more likely to have silent ischemia and less likely to survive a myocardial infarction than nondiabetic patients. Recent studies with electron beam computed tomography (EBCT) have shown that subclinical atherosclerosis is common in patients with diabetes, and studies with myocardial perfusion scintigraphy (with single-photon emission computed tomography) or stress echocardiography have demonstrated that between 25% and 50% of asymptomatic diabetic patients have ischemia during exercise or pharmacological stress and that a substantial proportion of these patients go on to develop major cardiovascular events within several years. Clearly, asymptomatic diabetic patients include a subset of individuals at high risk of cardiovascular disease who would benefit from improved risk stratification beyond that possible with risk factor scoring systems alone. Single-photon emission computed tomography, stress echocardiography, and possibly EBCT or multi-slice computed tomography, are emerging as valuable diagnostic tools for identifying asymptomatic diabetic patients who might require early and aggressive intervention to manage their cardiovascular risk.     

Perioperative myocardial infarction in non-cardiac surgery. Pathophysiology and clinical implications

Advances in surgical and anaesthetic techniques and an aging patient population have resulted in more complex procedures being performed in greater numbers of aged subjects and in patients with a high likelihood of significant cardiovascular disease. Nearly one fourth of non-cardiac surgical procedures (major intra-abdominal, thoracic, vascular, and orthopaedic procedures) performed in persons older than 65 years have been found to be associated with significant perioperative cardiovascular morbidity and mortality. During previous years the main attempt was to define strategies to accurately estimate perioperative cardiovascular risk based either on the characteristics of surgery and on patient characteristics. More recently preventive medical strategies have been proposed. Therefore, the physician has to be aware of the key elements useful to calculate the perioperative cardiovascular risk, and of the medical preventive treatment or further interventions to adopt in patients candidate to surgery.     

Prediction of cardiac risk in non-cardiac surgery

This prospective study was carried out to develop a model forthe prediction of cardiac risk in non-cardiac surgery. Detaileddata were collected concerning the preoperative status of 2609consecutive patients, who were followed closely during the postoperativecourse. Fatal or life-threatening cardiac complications occurredin 68 patients (2.6%). By utilizing logistic regression, a model for prediction ofcardiac risk was developed. The model contained six significantpreoperative predictor variables: Congestive heart failure (with3 degrees of severity); ischaemic heart disease (with 2 degreesof severity); diabetes mellitus; serumcreatinine above 013 mmoll^–lemergency operation; and the type of operation (twocategories) With this model it seems possible to discriminate between patientswith very different levels of cardiac risk.     

冠状动脉CT造影指标对老年中或高危险度非心脏手术计划的影响

目的:探讨冠状动脉CT造影(CCTA)指标对老年中高危险度非心脏手术计划的影响。方法:回顾性分析我院2012年1月到2013年12月,连续入组的非心脏手术术前怀疑冠心病而行CCTA的患者冠状动脉粥样硬化特征资料,包括冠状动脉狭窄的严重程度(MSS)、冠状动脉粥样硬化病变累及支数(N)、节段累及积分(SIS)、节段狭窄积分(SSS);记录推迟或放弃手术的原因、分析CCTA结果对非心脏手术计划的影响。应用Logistic回归分析患者冠状动脉MSS、N、SIS及SSS与非心脏手术计划改变之间的关系,计算优势比(OR),作受试者工作特征曲线(ROC)并计算曲线下面积。结果:本研究共398例患者,其中76例(19.1%)冠状动脉无异常表现;220例(55.3%)表现为轻度冠状动脉粥样硬化征象;102例(25.6%)显示重度冠状动脉粥样硬化征象;参考CCTA结果,340例(85.4%)患者如期进行了手术,26例(6.5%)患者干预后择期进行手术,32例(9.2%)放弃手术;Logistic回归分析表明:个体冠心病的MSS、N、SIS及SSS是老年非心脏手术计划改变的危险因素,OR值分别为:2.07,2.89,1.17及1.16(均P0.05)。个体冠心病的MSS、N、SIS及SSS的ROC曲线下面积依次为:0.613,0.615及0.624,0.648,SIS及SSS的最佳截断点分别为3.50和3.50。结论:应用CCTA评价术前怀疑冠心病的老年中高危险度非心脏手术患者,冠状动脉粥样硬化指标均会影响手术计划。