Extent of jeopardized viable myocardium determined by myocardial perfusion imaging best predicts perioperative cardiac events in patients undergoing noncardiac surgery

The association of preoperative cardiac stress testing with 30-day death and myocardial infarction among patients undergoing kidney transplantation

BACKGROUND

Although periodic cardiac stress testing is commonly used to screen patients on the waiting list for kidney transplantation for ischemic heart disease, there is little evidence to support this practice. We hypothesized that cardiac stress testing in the 18 months prior to kidney transplantation would not reduce postoperative death, total myocardial infarction (MI) or fatal MI.

METHODS

Using the United States Renal Data System, we identified ESRD patients ≥40 years old with primary Medicare insurance who received their first kidney transplant between 7/1/2006 and 11/31/2013. Propensity matching created a 1:1 matched sample of patients with and without stress testing in the 18 months prior to kidney transplantation. The outcomes of interest were death, total (fatal and nonfatal) MI or fatal MI within 30 days of kidney transplantation.

RESULTS

In the propensity-matched cohort of 17,304 patients, death within 30 days occurred in 72 of 8,652 (0.83%) patients who underwent stress testing and in 65 of 8,652 (0.75%) patients who did not (OR 1.07; 95% CI: 0.79-1.45; P = 0.66). MI within 30 days occurred in 339 (3.9%) patients who had a stress test and in 333 (3.8%) patients who did not (OR 1.03; 95% CI: 0.89-1.21; P = 0.68). Fatal MI occurred in 17 (0.20%) patients who underwent stress testing and 15 (0.17%) patients who did not (OR 0.97; 95% CI: 0.71-1.32; P = 0.84).

CONCLUSION

Stress testing in the 18 months prior to kidney transplantation is not associated with a reduction in death, total MI or fatal MI within 30 days of kidney transplantation.

Nuclear Myocardial Perfusion Imaging Versus Stress Echocardiography in the Preoperative Evaluation of Patients for Kidney Transplantation

The goal of this study was to evaluate the diagnostic accuracy, cost-effectiveness, and appropriate use of SPECT myocardial perfusion imaging (SMPI) versus stress echocardiography in the preoperative evaluation of patients for kidney transplantation.

METHODS

A single-institution, retrospective study was performed. SMPI was performed with regadenoson and stress echocardiography predominantly with dobutamine. Findings on subsequent coronary angiography were correlated. A cost analysis for SMPI versus stress echocardiography was modeled using reimbursements from the Center for Medicare Services.

RESULTS

One hundred thirteen patients underwent imaging (53 SMPI and 60 stress echocardiography). One hundred percent of SMPI studies were diagnostic, compared with only 80% (48/60) in the stress echocardiography group, and this result was statistically significant (χ(2) = 7.96, P < 0.01). The most common reason for a nondiagnostic test was not reaching the target heart rate. In the SMPI group, 15% (8/53) of patients had ischemia on imaging and all underwent subsequent coronary angiography, which confirmed obstructive coronary lesions. One patient with a negative SMPI result underwent a subsequent angiogram that was negative. In the stress echocardiography group, 5% (3/60) of patients had ischemia on imaging and 2 underwent subsequent angiography, which was negative. Three of 12 patients with nondiagnostic examinations underwent further testing. One patient underwent a follow-up positive SMPI scan but no subsequent coronary angiography. The other 2 patients underwent coronary angiography, which was negative. Of the 45 negative stress echocardiography patients, 6 (13%) underwent angiography, with a positive result for obstructive coronary artery disease in 3 of 6. For the modeling of cost analysis, rates of $1,173 and $1,521 (Center for Medicare Services) were used for SMPI and stress echocardiography, respectively. The model assumed that all nondiagnostic imaging would be referred for further stress testing (i.e., nondiagnostic stress echocardiography would be referred for SMPI). This model estimated that initial noninvasive testing with stress echocardiography versus SMPI resulted in a 50% greater cost.

CONCLUSION

For the preoperative evaluation of kidney transplantation, SMPI is more often diagnostic than stress echocardiography. A cost model estimates that initial noninvasive diagnostic testing with stress echocardiography would result in an approximately 50% greater cost than SMPI. Our data also suggest that SMPI has greater diagnostic accuracy than stress echocardiography. Therefore, this single-institution experience supports SMPI as the more appropriate test.

Prognostic capabilities of coronary computed tomographic angiography before non-cardiac surgery: prospective cohort study

OBJECTIVES

To determine if coronary computed tomographic angiography enhances prediction of perioperative risk in patients before non-cardiac surgery and to assess the preoperative coronary anatomy in patients who experience a myocardial infarction after non-cardiac surgery.

DESIGN

Prospective cohort study.

SETTING

12 centers in eight countries.

PARTICIPANTS

955 patients with, or at risk of, atherosclerotic disease who underwent non-cardiac surgery.

INTERVENTIONS

Coronary computed tomographic angiography was performed preoperatively; clinicians were blinded to the results unless left main disease was suspected. Results were classified as normal, non-obstructive (<50% stenosis), obstructive (one or two vessels with ≥ 50% stenosis), or extensive obstructive (≥ 50% stenosis in two vessels including the proximal left anterior descending artery, three vessels, or left main).

MAIN OUTCOME MEASURE

Composite of cardiovascular death and non-fatal myocardial infarction within 30 days after surgery (primary outcome). This was the dependent variable in Cox regression. The independent variables were scores on the revised cardiac risk index and findings on coronary computed tomographic angiography.

RESULTS

The primary outcome occurred in 74 patients (8%). The model that included both scores on the revised cardiac risk index and findings on coronary computed tomographic angiography showed that coronary computed tomographic angiography provided independent prognostic information (P=0.014; C index=0.66). The adjusted hazard ratios were 1.51 (95% confidence interval 0.45 to 5.10) for non-obstructive disease; 2.05 (0.62 to 6.74) for obstructive disease; and 3.76 (1.12 to 12.62) for extensive obstructive disease. For the model with coronary computed tomographic angiography compared with the model based on the revised cardiac risk index alone, with 30 day risk categories of <5%, 5-15%, and >15% for the primary outcome, the results of risk reclassification indicate that in a sample of 1000 patients that coronary computed tomographic angiography would have resulted appropriately in 17 net patients receiving a higher risk estimation among the 77 patients who would have experienced the primary outcome (P<0.001). Coronary computed tomographic angiography, however, would have resulted inappropriately in 98 net patients receiving a higher risk estimation, among the 923 patients who would not have experienced the primary outcome (P<0.001). Among patients who had a perioperative myocardial infarction, preoperative coronary anatomy showed extensive obstructive disease in 31% (22/71), obstructive disease in 41% (29/71), non-obstructive disease in 24% (17/71), and normal findings in 4% (3/71).

CONCLUSIONS

Though findings on coronary computed tomographic angiography can improve estimation of risk for patients who will experience perioperative cardiovascular death or myocardial infarction, findings are more than five times as likely to lead to an inappropriate overestimation of risk among patients who will not experience these outcomes. Perioperative myocardial infarction occurs across the spectrum of coronary artery disease, suggesting that there could be several pathophysiologic mechanisms.

Current practice and recommendation for presurgical cardiac evaluation in patients undergoing noncardiac surgeries

The increasing number of patients with coronary artery disease (CAD) undergoing major noncardiac surgery justifies guidelines concerning preoperative cardiac evaluation. This is compounded by increasing chances for a volatile perioperative period if the underlying cardiac problems are left uncorrected prior to major noncardiac surgeries. Preoperative cardiac evaluation requires the clinician to assess the patient's probability to have CAD, severity and stability of CAD, placing these in perspective regarding the likelihood of a perioperative cardiac complication based on the planned surgical procedure. Coronary events like new onset ischemia, infarction, or revascularization, induce a high-risk period of 6 weeks, and an intermediate-risk period of 3 months before performing noncardiac surgery. This delay is unwarranted in cases where surgery is the mainstay of treatment. The objective of this review is to offer a comprehensive algorithm in the preoperative assessment of patients undergoing noncardiac surgery and highlight the importance of myocardial perfusion imaging in risk stratifying these patients.

The utility and prognostic value of dipyridamole technetium-99m sestamibi myocardial perfusion imaging SPECT in predicting perioperative cardiac events following non-cardiac surgery

OBJECTIVE

A perioperative cardiac events is one of the most important medical concerns for both surgeons and patients. The purpose of the current study was to determine the prognostic value of myocardial perfusion imaging (MPI), using dipyridamole 99m Tc-MIBI, for the prediction of perioperative cardiac events.

MATERIALS AND METHODS

This study included 253 patients who were candidates for non-cardiac elective surgery and underwent scanning with dipyridamole 99m Tc-MIBI. Based on normal or abnormal MPI, patients were divided into two groups and all preoperative cardiac events were recorded. Risk factors, including diabetes mellitus, dyslipidemia, hypertension, smoking and age ≥70 years, were compared between patients with normal and abnormal MPI and, also, in patients with or without cardiac events.

RESULTS

There were 197 patients with normal and 56 patients with abnormal MPI. In total, 14 patients had perioperative cardiac events, which included myocardial infarction (MI), hypotension, arrhythmia and death; of the 14 patients with perioperative cardiac events, 12 had abnormal and two had normal MPI. There were statistically meaningful differences between the two groups (p<0.001). Based on these findings, we determined that MPI had a sensitivity of 85.7%, a specificity of 81.6%, an accuracy of 81.8%, a positive predictive value of 21.4 % and a negative predictive value of 98.9%.

CONCLUSION

The incidence of perioperative cardiac events is higher in patients with abnormal MPI. Dipyridamole 99m Tc-MIBI myocardial perfusion imaging can accurately detect the preoperative cardiac risk of patients undergoing major non-cardiac surgery. Based on these findings, the occurrence of perioperative cardiac events in patients with abnormal MPI should be considered, especially in the older age population (age ≥70).

The coronary CT angiography vision protocol: a prospective observational imaging cohort study in patients undergoing non-cardiac surgery

INTRODUCTION

At present, physicians have a limited ability to predict major cardiovascular complications after non-cardiac surgery and little is known about the anatomy of coronary arteries associated with perioperative myocardial infarction. We have initiated the Coronary CT Angiography (CTA) VISION Study to (1) establish the predictive value of coronary CTA for perioperative myocardial infarction and death and (2) describe the coronary anatomy of patients that have a perioperative myocardial infarction.

METHODS AND ANALYSIS

The Coronary CTA VISION Study is prospective observational study. Preoperative coronary CTA will be performed in 1000-1500 patients with a history of vascular disease or at least three cardiovascular risk factors who are undergoing major elective non-cardiac surgery. Serial troponin will be measured 6-12 h after surgery and daily for the first 3 days after surgery. Major vascular outcomes at 30 days and 1 year after surgery will be independently adjudicated.

ETHICS AND DISSEMINATION

Coronary CTA results in a measurable radiation exposure that is similar to a nuclear perfusion scan (10-12 mSV). Treating physicians will be blinded to the CTA results until 30 days after surgery in order to provide the most unbiased assessment of its prognostic capabilities. The only exception will be the presence of a left main stenosis >50%. This approach is supported by best available current evidence that, excluding left main disease, prophylatic revascularisation prior to non-cardiac surgery does not improve outcomes. An external safety and monitoring committee is overseeing the study and will review outcome data at regular intervals. Publications describing the results of the study will be submitted to major peer-reviewed journals and presented at international medical conferences.

Myocardial perfusion scintigraphy: techniques, interpretation, indications and reporting

Myocardial perfusion single photon emission-computed tomography (MPS) has been one of the most important and common non-invasive diagnostic cardiac test. Gated MPS provides simultaneous assessment of myocardial perfusion and function with only one study. With appropriate attention to the MPS techniques, appropriate clinical utilization and effective reporting, gated MPS will remain a useful diagnostic test for many years to come. The aim of this article is to review the basic techniques of MPS, a simplified systematic approach for study interpretation, current clinical indications and reporting. After reading this article the reader should develop an understanding of the techniques, interpretation, current clinical indications and reporting of MPS studies.

Assessment of cardiac risk before non-cardiac surgery: brain natriuretic peptide in 1590 patients

OBJECTIVE

To evaluate the predictive value of brain natriuretic peptide (BNP) for assessment of cardiac risk before non-cardiac surgery.

METHODS

Consecutively treated patients (947 men, 643 women) whose BNP was measured before non-cardiac surgery were studied. Clinical and ECG variables were evaluated to identify predictors of postoperative cardiac events.

RESULTS

Events occurred in 6% of patients: 21 cardiac deaths, 20 non-fatal myocardial infarctions, 41 episodes of pulmonary oedema and 14 patients with ventricular tachycardia. All of these patients had raised plasma BNP concentrations (best cut-off point 189 pg/ml). The only independent predictor of postoperative events was BNP (odds ratio 34.52, 95% confidence interval (CI) 17.08 to 68.62, p < 0.0001). Clinical variables of Goldman's multifactorial index identified 18% of patients in class I, 40% in class II, 24% in class III and 18% in class IV preoperatively; postoperative event rates were 2%, 3%, 7% and 14%, respectively. BNP identified 60% of patients as having zero risk (BNP 0-100 pg/ml), 22% low risk (101-200 pg/ml), 14% intermediate risk (201-300 pg/ml) and 4% high risk (> 300 pg/ml); postoperative event rates were 0%, 5%, 12% and 81%, respectively.

CONCLUSIONS

In this population of patients evaluated before non-cardiac surgery, BNP is an independent predictor of postoperative cardiac events. BNP > 189 pg/ml identified patients at highest 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.

The role of cardiopulmonary fitness and its genetic influences on surgical outcomes

Background

Outcome after major surgery remains poor in some patients. There is an increasing need to identify this cohort and develop strategies to reduce postsurgical morbidity and mortality. Central to outcome is the ability to mount cardiovascular output in response to the increased oxygen demand associated with major surgery.

Methods

A medline search was performed using keywords to identify factors that affect, and genetic influences in, disease and outcome from surgery, and all relevant English language articles published between 1980 and 2005 were retrieved. Secondary references were obtained from key articles.

Results

Preoperative cardiopulmonary exercise testing assesses patient fitness, highlights those at particular risk and, combined with triage to critical care, facilitates significant improvement in surgical outcome. However, genetic factors also influence responses to increased oxygen demand, and some patients are genetically predisposed to mounting increased inflammatory responses, which raise oxygen demand further. Polymorphisms in genes influencing fitness (angiotensin converting enzyme) and immune and inflammatory responses (such as interleukin 6) may associate with surgical outcome.

Conclusions

Development of preoperative screening methods like cardiopulmonary exercise testing and genotype analysis to identify index factors may permit better patient stratification, provide targets for future tailored treatments and so improve surgical outcome.

Complete myocardial revascularization: between myth and reality

Myocardial revascularization in patients with multi-vessel coronary artery disease may be accomplished, by percutaneous interventions or surgery, either on all diseased lesions or directed to selectively targeted coronary segments. The extent of planned revascularization is often a major determinant of treatment strategy. Revascularization of all diseased coronary segments-complete myocardial revascularization-has a potential long-term benefit, but is more complex and may increase in-hospital untoward events. Revascularization may otherwise be incomplete, either because of the operator's inability to treat all diseased coronary segments or by choice of deciding to selectively revascularize only large areas of myocardium at risk. Although incomplete revascularization may negatively affect long-term outcomes, it may be, when wisely chosen, the preferred treatment strategy in selected patient categories because of its lower immediate risks. The patient's clinical status, ventricular function, and the presence of co-morbidities may orient clinical decisions in favour of incomplete revascularization.

Advances in nuclear imaging for preoperative risk assessment

Myocardial perfusion imaging (MPI) is frequently utilized for preoperative risk assessment. Results are pertinent for long-term risk. MPI, though most frequently applied in intermediate-risk patients, may also be valuable in selected low- and high-risk individuals. Coronary stenting may alter the timing of noncardiac surgery, which should be considered when performing preoperative risk assessment.

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.

Cardiac Troponin After Major Vascular Surgery

OBJECTIVES

We sought to determine the role of preoperative predictors, particularly ischemia, on preoperative thallium scanning (PTS) and coronary revascularization on low-level and conventional troponin elevations after major vascular surgery.

BACKGROUND

Postoperative cardiac troponin (cTn) elevations have recently been shown to predict both short- and long-term mortality after vascular surgery.

METHODS

The perioperative data, including PTS and subsequent coronary revascularization, continuous perioperative 12-lead ST-segment trend monitoring, cTn-I and/or cTn-T, and creatine kinase-MB fraction in the first three postoperative days, were prospectively collected in 501 consecutive elective major vascular procedures.

RESULTS

Moderate to severe inducible ischemia on PTS was associated with a 49.0% incidence of low-level (cTn-I >0.6 and/or cTn-T >0.03 ng/ml) and 22.4% conventional (cTn-I >1.5 and/or cTn-T >0.1 ng/ml) troponin elevation. In contrast, patients with preoperative coronary revascularization had 23.4% and 6.4% low-level and conventional troponin elevations, respectively, similar to patients without ischemia on PTS. By multivariate logistic regression, ischemia on PTS was the most important predictor of both low-level and conventional troponin elevations (adjusted odds ratios [ORs] 2.5 and 2.7, p = 0.02 and 0.04, respectively), whereas preoperative coronary revascularization predicted less troponin elevations (adjusted ORs 0.35 and 0.16, p = 0.045 and 0.022, respectively). Postoperative ischemia (>10 min), the more so prolonged (>30 min) ischemia was the only independent predictor of troponin elevation if added with the preoperative predictors to the multivariate analysis (ORs 15.8 and 22.8, respectively, p < 0.001).

CONCLUSIONS

Troponin elevations occur frequently after vascular surgery. They are strongly associated with postoperative ischemia, predicted by inducible ischemia on PTS, and reduced by preoperative coronary revascularization.

QTc dispersion is prolonged in patients with early postoperative adverse cardiovascular events and those with silent myocardial ischemia

OBJECTIVE

To determine if increased QT interval dispersion (corrected and not corrected for heart rate) is associated with perioperative silent myocardial ischemia or postoperative adverse cardiovascular events.

DESIGN

Blinded retrospective observational study.

SETTING

University hospital.

PARTICIPANTS

One hundred eighty-one perioperative patients receiving general anesthesia for elective major vascular or orthopedic surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

QT dispersion, corrected and uncorrected for heart rate, was prolonged in patients suffering significant myocardial ischemia up to 48 hours assessed by Holter ECG monitoring, for early cardiac morbidity and all early cardiac events (including mortality) up to 1 month postoperatively. There were no significant changes in patients showing early cardiovascular mortality or late cardiac morbidity or mortality between 1 and 12 months postoperatively. Morbidity and mortality were determined from clinical notes, laboratory investigations, and autopsy when available. QT dispersion performed poorly as a screening test to identify those who subsequently developed early adverse cardiovascular outcomes.

CONCLUSIONS

QT dispersion is prolonged in those at risk of early adverse cardiovascular events but is a poor screening tool.

Perioperative risk stratification in non cardiac surgery: role of pharmacological stress echocardiography

Perioperative ischemia is a frequent event in patients undergoing major non-cardiac vascular or general surgery. This is in agreement with clinical, pathophysiological, and epidemiological evidence and constitutes an additional diagnostic therapeutic factor in the assessment of these patients. Form a clinical standpoint, it is well known that multidistrict disease, especially at the coronary level, is a severe aggravation of the operative risk. From a pathophysiological point of view, however, surgery creates conditions able to unmask coronary artery disease. Prolonged hypotension, hemorrhages, and haemodynamic stresses caused by aortic clamping and unclamping during major vascular surgery are the most relevant factors endangering the coronary circulation with critical stenoses. From the epidemiological standpoint, coronary disease is known to be the leading cause of perioperative mortality and morbidity following vascular and general surgery: The diagnostic therapeutic corollary of these considerations is that coronary artery disease - and therefore the perioperative risk - in these patients has to be identified in an effective way preoperatively.

Myocardial perfusion scintigraphy: the evidence

This review summarises the evidence for the role of myocardial perfusion scintigraphy (MPS) in patients with known or suspected coronary artery disease. It is the product of a consensus conference organised by the British Cardiac Society, the British Nuclear Cardiology Society and the British Nuclear Medicine Society and is endorsed by the Royal College of Physicians of London and the Royal College of Radiologists. It was used to inform the UK National Institute of Clinical Excellence in their appraisal of MPS in patients with chest pain and myocardial infarction. MPS is a well-established, non-invasive imaging technique with a large body of evidence to support its effectiveness in the diagnosis and management of angina and myocardial infarction. It is more accurate than the exercise ECG in detecting myocardial ischaemia and it is the single most powerful technique for predicting future coronary events. The high diagnostic accuracy of MPS allows reliable risk stratification and guides the selection of patients for further interventions, such as revascularisation. This in turn allows more appropriate utilisation of resources, with the potential for both improved clinical outcomes and greater cost-effectiveness. Evidence from modelling and observational studies supports the enhanced cost-effectiveness associated with MPS use. In patients presenting with stable or acute chest pain, strategies of investigation involving MPS are more cost-effective than those not using the technique. MPS also has particular advantages over alternative techniques in the management of a number of patient subgroups, including women, the elderly and those with diabetes, and its use will have a favourable impact on cost-effectiveness in these groups. MPS is already an integral part of many clinical guidelines for the investigation and management of angina and myocardial infarction. However, the technique is underutilised in the UK, as judged by the inappropriately long waiting times and by comparison with the numbers of revascularisations and coronary angiograms performed. Furthermore, MPS activity levels in this country fall far short of those in comparable European countries, with about half as many scans being undertaken per year. Currently, the number of MPS studies performed annually in the UK is 1,200/million population/year. We estimate the real need to be 4,000/million/year. The current average waiting time is 20 weeks and we recommend that clinically appropriate upper limits of waiting time are 6 weeks for routine studies and 1 week for urgent studies.

Preoperative thallium scanning, selective coronary revascularization, and long-term survival after major vascular surgery

BACKGROUND

Ischemia on thallium scanning is a strong predictor of long-term mortality in CAD patients. Whether coronary revascularization (CR) in patients with significant ischemia on preoperative thallium scanning (PTS) improves long-term survival after major vascular surgery has not been determined.

METHODS AND RESULTS

The perioperative data, including PTS and subsequent CR in patients with moderate to severe reversible ischemia on PTS, and long-term survival of 502 consecutive patients who underwent 578 major vascular procedures were analyzed retrospectively. Patients with PTS who ultimately did not undergo the planned vascular operation were also studied. Cox regression and propensity score analyses were used to analyze survival. A total of 407 patients (81.1%) had PTS: 221 (54.3%) had no or mild defects (group I); 50 (12.3%) had moderate-severe fixed defects (group II); 62 (15.2%) had moderate-severe reversible ischemia yet did not undergo CR (group III); and 74 (18.2%) had moderate-severe reversible ischemia and subsequent CR by CABG (36) or PTCA (38; group IV). Patients who sustained major complications as a result of the preoperative cardiac workup were included in group IV. By multivariate analysis, age, type of vascular surgery, presence of diabetes, previous myocardial infarction, and moderate-severe ischemia on PTS independently predicted mortality (P=0.001, 0.009, 0.039, 0.006, and 0.029, respectively), and preoperative CR predicted improved survival (OR 0.52, P=0.018). Group IV had better survival than group III even when subdivided according to normal and reduced left ventricular function (OR 0.40 and 0.41, P=0.035 and 0.021, respectively).

CONCLUSIONS

Long-term survival after major vascular surgery is significantly improved if patients with moderate-severe ischemia on PTS undergo selective CR.

Risk assessment by myocardial perfusion imaging for coronary revascularization, medical therapy, and noncardiac surgery

Stress myocardial perfusion imaging (MPI) has become an important tool in risk stratification of patients with known coronary artery disease. A normal myocardial perfusion scan has a high negative predictive value and is associated with low annual mortality rate (< 1%). Patients with extensive ischemia (> 20% of the left ventricle), defects in more than 1 coronary vascular territory, transient or persistent left ventricular cavity dilation, and ejection fraction less than 45% have a high annual mortality rate (> 3%). Those patients should undergo coronary revascularization whenever feasible, as the cardiac event rate increases in proportion to the magnitude of the jeopardized myocardium. Stress MPI can be used to demonstrate ischemia in patients with symptoms early after coronary artery bypass surgery (< 5 years) or in those without symptoms late (>/= 5 years) after coronary artery bypass surgery. With respect to patients who underwent percutaneous interventions, stress MPI can help detect in-stent restenosis early after the intervention (3-6 months) or assess the progression of native coronary disease afterward. Since preliminary data suggest that a reduction in the perfusion defect size may translate to a reduction of coronary events, stress MPI can help assess the efficacy of medical management of coronary disease. Finally, stress MPI is indicated for perioperative cardiac risk stratification for noncardiac surgery in patients with intermediate risk predictors (mild angina, prior myocardial infarction or heart failure symptoms, diabetes mellitus, renal insufficiency) and poor functional capacity or in those who undergo high-risk surgery with significant implications in further preoperative management.

Preoperative risk evaluation and perioperative management of patients with coronary artery disease

We have reviewed the methods of evaluating a patient's cardiac risk preoperatively using a careful history, physical examination, and EKG. Based on this information, various risk indices, guidelines, and algorithms can further assist the physician in deciding which patients can undergo surgery without further testing and which patients might benefit from further cardiac evaluation or medical therapy prior to surgery. The physician must keep in mind that a test should not be ordered if it is unlikely to alter the patient's management, and it is rarely necessary to perform a revascularization procedure with the sole purpose of getting a patient through surgery. Ongoing research is likely to lead to improvement in perioperative medical therapy.

Pharmacologic radionuclide myocardial perfusion imaging

Pharmacologic stress testing with myocardial perfusion imaging has enabled patients who cannot complete adequate exercise to undergo diagnostic and prognostic evaluation for coronary artery disease. Pharmacologic stress agents belong to two groups: vasodilators (such as adenosine and dipyridamole), and inotropes (such as dobutamine). All have similar sensitivity (89%-91%) and specificity (78%-86%) for the diagnosis of coronary disease. For risk stratification, the risk of future cardiac events is related to the extent and severity of perfusion abnormalities. Pharmacologic stress testing permits risk stratification as early as 1 to 4 days following an acute myocardial infarction, and is superior to exercise stress testing in this regard. Similarly, it identifies patients at high risk for perioperative cardiac events prior to noncardiac surgery. This review summarizes the current evidence available regarding the diagnostic and prognostic use of pharmacologic stress testing.

[Clinical predictors of the presence of perfusion defects in more than than one territory in myocardial scintigraphy with GATED-SPECT]

BACKGROUND AND OBJECTIVE

Extension of perfusion defects is associated with outcome in patients undergoing myocardial scintigraphy. The study aimed to identify the clinical characteristics that can predict the existence of perfusion defects in more than one territory in patients referred for myocardial scintigraphy with GATED-SPECT.

PATIENTS AND METHODS

A total of 193 patients undergoing myocardial scintigraphy with GATED-SPECT (99mTc-tetrofosmine) were studied. Clinical variables and scintigraphy results were studied to determine what clinical variables are associated with perfusion defects in more than one territory.

RESULTS

The number of territories with perfusion defects per patient was 1.1 0.8 and 29% had perfusion defects in > 1 territory. Patients with greater probability of having perfusion defects in > 1 territory were those with previous myocardial infarction (44% vs 21%, p = 0.030) and males (33% vs 10%, p = 0.006). In addition, patients with > 2 coronary risk factors had a statistical tendency to have defects in > 1 territory (47% vs 20%, p = 0.057). Only 15% of the patients with one of these three characteristics had perfusion defects in > 1 territory in comparison with 45% and 83% in those with 2 or 3 factors, respectively.

CONCLUSION

Considering 3 simple clinical characteristics (male gender, previous infarction and existence of > 2 coronary risk factors), it is possible to predict which patients are more likely to show perfusion defects in > 1 territory during GATED-SPECT myocardial scintigraphy.

Use of pharmaceuticals in noninvasive cardiovascular diagnosis

A number of pharmaceuticals are employed as diagnostic agents for cardiovascular diseases. Four groups of agents are reviewed here: 1) vasoactive substances employed as adjuncts to physical maneuvers in diagnosis of structural heart disease; 2) vasodilators used to produce heterogeneity of coronary flow; 3) sympathomimetic agents simulating the effects of exercise on the heart for the purpose of detection of coronary artery stenosis; and 4) ultrasonic contrast agents used to enhance myocardial imaging for the assessment of segmental wall motion. In the first group are amyl nitrate, a vasodilator, and methoxamine and phenylephrine, both vasopressors. The vasodilators of the second group are dipyridamole and adenosine. When combined with scintigraphic perfusion imaging or with echocardiographic assessment of segmental wall motion, these agents can detect single- or multiple-vessel coronary artery disease with sensitivity and specificity comparable to submaximal exercise. They are especially useful for preoperative risk assessment before noncardiac surgery. The sympathomimetic agents of the third group, dobutamine and arbutamine, increase myocardial contractility and heart rate, and dilate the peripheral vasculature. As with the vasodilators, when combined with nuclear or echocardiographic techniques they are equivalent to exercise in detection of coronary disease. They are especially useful in patients with bronchospastic disease and for assessment of myocardial viability. Agents from groups 2 and 3 have acceptable side-effect and safety profiles. The last group reviewed includes echocardiographic contrast agents that, in this investigative setting, are employed to enhance detection of segmental wall motion when used with agents from groups 2 and 3.

Which stress test is superior for perioperative cardiac risk stratification in patients undergoing major vascular surgery?

OBJECTIVE

to compare the additional prognostic value of Dobutamine Stress Echocardiography (DSE), Dipyridamole Stress Echocardiography (DiSE) and Perfusion Scintigraphy (DTS) on clinical risk factors in patients undergoing major vascular surgery.

DESIGN

retrospective analysis.

MATERIALS

2204 consecutive patients who underwent DSE (n=1093), DiSE (n=394), or DTS (n=717) testing before major vascular surgery were studied.

METHODS

primary endpoint was a composite of cardiac death and non-fatal myocardial infarction (MI). Logistic regression analysis was performed to evaluate the relation between cardiac risk factors, stress test results and the incidence of the composite endpoint.

RESULTS

there were 138 patients (6.3%) with cardiac death or MI. Patients with 0, 1-2, and 3 or more risk factors experienced respectively 3.0, 5.7 and 17.4% cardiac events. We found no statistically significant difference in the predictive value of a positive test result for DiSE and DSE (Odds ratio (OR) of 37.1 [95% CI, 8.1-170.1] vs 9.6 [95% CI, 4.9-18.4]; p=0.12), whereas a positive test result for DTS had significantly lower prognostic value (OR=1.95 [95% CI, 1.2-3.2]).

CONCLUSION

a result of stress echocardiography effectively stratified patients into low- and high-risk groups for cardiac complications, irrespective of clinical risk profile. In contrast, the prognostic value of DTS results was more likely to be dependent on patients' clinical risk profile.

Long-term prognostic value of stress-redistribution-reinjection Tl-201 imaging in patients with severe left ventricular dysfunction and coronary artery bypass surgery

OBJECTIVES

This study sought to evaluate the long-term prognostic significance of stress-redistribution-reinjection Tl-201 imaging in patients with severe left ventricular (LV) dysfunction and coronary artery bypass surgery.

BACKGROUND

Preoperative stress-redistribution-reinjection Tl-201 imaging detects viable but asynergic segments which show functional improvement postoperatively and is considered as a valuable noninvasive method in selection of patients with severe LV dysfunction for revascularization. The long-term prognostic value of the reinjection technique remains unclear.

METHODS

Fifty-two patients with severe LV dysfunction (mean ejection fraction (EF) 0.32+/-0.03) who underwent coronary artery bypass surgery in 1993-1994 were included in the study. Patients had follow-up 49+/-12 months. LV function was assessed by two-dimensional echocardiography. Perfusion was assessed by Tl-201 SPECT imaging and was graded on a four-point scale (0 = normal, 3 = absent uptake) using the 20 segment model. Perfusion index was derived by adding the score of all segments and dividing these by 20. Patients were divided into two groups. Group A comprised patients with seven and more dysfunctional viable myocardial segments. Group B included patients with less than seven dysfunctional but viable segments.

RESULTS

Mean EF increased from 0.32+/-0.03 to 0.46+/-0.04. Mean perfusion index did not show a significant difference as a whole during follow-up compared to the early postoperative values (0.9+/-0.4 and 1.1+/-0.4, p = NS). When adequacy of revascularization was considered, the predictive value of a positive preoperative viability test for functional improvement was 82%. Nineteen cardiac events occurred in group B patients and six in group A patients: six deaths (four from cardiac and two from noncardiac causes), 13 myocardial infarctions (MI). Multivariate Cox survival analysis identified the number of viable segments detected preoperatively (chi2 = 7.2, p = 0.002), postoperative improvement in Tl-uptake (chi2 = 6.6, p = 0.01) and functional improvement (chi2 = 5.3, p = 0.03) postoperatively as independent predictors of cardiac events. Preoperative EF and functional capacity were not associated with cardiac events in long-term prognosis.

CONCLUSION

These data suggest that preoperative stress-redistribution-reinjection Tl-201 imaging, specifically the number of viable segments detected preoperatively and postoperative improvement in Tl-201 uptake provide important long-term prognostic information in patients with severe LV dysfunction who had coronary artery bypass surgery.

The usefulness of dipyridamole thallium-201 single photon emission computed tomography for predicting perioperative cardiac events in patients undergoing non-cardiac vascular surgery

The aim of this study was to evaluate the usefulness of dipyridamole Tl-201 myocardium single photon emission computed tomography (201Tl-SPECT) for predicting perioperative cardiac events in patients with arteriosclerosis obliterans (ASO) and abdominal aortic aneurysm (AAA) undergoing non-cardiac vascular surgery.

METHODS

Preoperative dipyridamole 201Tl-SPECT imaging in association with clinical risk assessment was performed in 224 consecutive patients (97 ASO and 127 AAA).

RESULTS

The patients were classified into three groups, including low-risk (n = 173, 77%), intermediate-risk (n = 39, 18%), and high-risk (n = 12, 5%) groups according to the clinical risk stratification. The prevalence of reversible Tl-201 defect was significantly higher in the high-risk group than that in the low-risk group (83% vs. 14%, p < 0.001). In 180 patients who underwent vascular surgery, 9 patients (5.0%) had perioperative cardiac events, including heart failure (n = 1), unstable angina (n = 2), and other cardiac events such as arrhythmias (n = 6). The clinical variables including the clinical risk stratification did not significantly correlate with the perioperative cardiac events. In contrast, the reversible defect on 201Tl-SPECT was the only variable to predict perioperative cardiac events by a stepwise logistic regression analysis (odds ratio 7.0, 95% confidence interval 1.7-28.0, p = 0.007). It was also a significant predictor of perioperative cardiac events in a subgroup of low risk patients (odds ratio 11.6, 95% confidence interval 2.3-57.4, p = 0.004). The sensitivity and specificity of the reversible defect for predicting perioperative cardiac events were 55.6% and 84.8% in all operated patients, and 57.1% and 89.7% in low risk patients, respectively.

CONCLUSIONS

The preoperative dipyridamole 201Tl-SPECT was useful for predicting perioperative cardiac events in patients with vascular diseases, even in patients identified as having a low risk based on the clinical risk assessment.

The role of myocardial perfusion scanning, heart rate variability and D-dimers in predicting the risk of perioperative cardiac complications after peripheral vascular surgery

OBJECTIVES

To study the value of a number of proposed prognostic factors in prediction of the risk of perioperative cardiac events after vascular surgery.

DESIGN AND METHODS

Two hundred and ninety-seven patients undergoing peripheral vascular surgery were prospectively studied. Patients underwent preoperative 24 h ambulatory electrocardiography, measurement of haemostatic variables, myocardial assessment of perfusion by dipyridamole-thallium scintigraphy and radionuclide ventriculography. The primary endpoint was cardiac death or nonfatal myocardial infarction within 30 days of surgery. A combined endpoint included the primary endpoint plus occurrence of cardiac failure, unstable angina or serious arrhythmias.

RESULTS

The primary endpoint occurred in 21 (7%), and the combined endpoint in 41 (14%) of patients. On multivariate analysis, increased age, previous myocardial infarction, aortic surgery, impaired heart rate variability and a positive thallium scan were independent predictors of primary end-points. Preoperative atrial fibrillation and increased fibrin D-dimer were additional predictors of the combined endpoint. Construction of receiver-operator characteristic curves to examine the incremental value of predictive models showed that sensitivity and specificity of clinical data alone for primary endpoints was 71% and 72% respectively, while for the full model (incorporating heart rate variability and thallium data) this rose to 84% and 80% (p=0.0001).

CONCLUSIONS

Preliminary screening using clinical data has limited value in risk assessment prior to vascular surgery but preoperative heart rate variability, D-dimers and thallium scanning provide modest incremental predictive value.

Assessment of cardiac risk before peripheral vascular surgery: a comparison of myocardial perfusion imaging and long axis echocardiography at rest

OBJECTIVE

To compare resting long axis echocardiography with adenosine thallium-201 emission tomography in detecting myocardial ischaemic abnormalities and surgical related risk in patients before peripheral vascular surgery.

DESIGN

A prospective and blinded pre-operative examination of resting left ventricular minor and long axes and myocardial perfusion during adenosine vasodilation using thallium-201 emission tomography.

SETTING

A tertiary referral centre for cardiac and vascular disease equipped with invasive, non-invasive and surgical facilities.

SUBJECTS

65 patients (40 male) with significant peripheral vascular disease, mean age 63+/-10 (S.D.) years, and 21 normal subjects of similar age.

RESULTS

Thallium-201 myocardial perfusion tomography was abnormal in 50/65 patients; 27 had fixed, 23 reversible abnormalities (19 of whom had both). Long axis was considered abnormal if one or more of two systolic long axis disturbances, reduced extent of total excursion <1 cm at any of the three (left, septal and posterior left ventricular) sites or prolonged shortening >1 mm after A2, and two diastolic abnormalities, delayed onset of lengthening >80 ms after A2 or reduced peak lengthening velocity <4.5 cm/s, was present. Long axis score (maximum 12) was based on the presence or absence of these four disturbances at each of the three sites. Myocardial perfusion imaging with thallium-201 classified the patients into three different groups according to their liability to low, moderate or high surgical risk (summed stress perfusion score of 36). Thirteen of 50 patients were identified as subjects at high surgical risk, with a perfusion score of 22/36 and below. Twelve of these demonstrated significantly greater impairment of systolic and diastolic long axis function, compared to those at low surgical risk, with a total long axis echo score of 6/12 or more. Seventeen of 18 patients identified as being at low surgical risk, with a perfusion score of 32/36 and above, had total long axis score of less than 6/12. The remaining 19 moderate risk patients had a wide range of long axis scores. In the 65 patients studied there were two post-operative deaths, one post-discharge death due to cerebrovascular accident, and one due to renal failure.

CONCLUSION

The combination of both systolic and diastolic long axis disturbances in patients with peripheral vascular disease can be used to predict the thallium assessment of surgical risk. Long axis echocardiography may thus have value as a screening test before non-cardiac surgery as well as providing a means of monitoring myocardial perfusion.

Cardiac nuclear medicine in monitoring patients with coronary heart disease

Patient monitoring is a major indication for cardiac nuclear medicine procedures. Stress myocardial perfusion scintigraphy was initially used for diagnosis, but monitoring patients with coronary artery disease has become more common. Stress myocardial perfusion scintigraphy has been shown to provide a considerable amount of incremental prognostic information, which may be useful in selecting patients for therapy. In patients being considered for revascularization, fluorodeoxyglucose can be used to identify regions of dysfunctional but viable myocardium, even within regions that show fixed defects on stress perfusion imaging. It can be used to select a group of patients who will improve function with revascularization and who may have an improved outcome. Thus, cardiac nuclear medicine plays a pivotal role in monitoring patients with coronary artery disease.

Cardiac risk assessment in noncardiac thoracic surgery

Preoperative cardiac risk assessment for noncardiac thoracic surgery is limited by the lack of data specific to this type of surgery, especially prospective, controlled data. However, the value of clinical predictors in determining accurate postoperative cardiac outcomes is a reliable tool. Thus, the approach is similar to traditional cardiac risk assessment for noncardiac surgery. The essential elements of cardiovascular evaluation as it pertains to noncardiac thoracic surgery are reviewed with a specific focus on coronary artery disease, perioperative arrhythmias, and selected topics relevant to noncardiac thoracic surgery. The core recommendations of the clinical guidelines by the American College of Cardiology and American Heart Association are discussed in the context of noncardiac thoracic surgery.

Principal uses of myocardial perfusion scintigraphy in the management of patients with known or suspected coronary artery disease

The use of myocardial perfusion single photon emission computed tomography (SPECT) has undergone considerable expansion and evolution over the past 2 decades. Although myocardial perfusion imaging was first conceived as a noninvasive diagnostic tool for determining the presence or absence of coronary artery disease, its prognostic value is now well established. Thus, identification of patients at risk for future cardiac events has become a primary objective in the noninvasive evaluation of patients with chest pain syndromes and among patients with known coronary artery disease. In particular, the ability of myocardial perfusion SPECT to identify patients at low (< 1%), intermediate (1% to 5%) or high (> 5%) risk for future cardiac events is essential to patient management decisions. Moreover, previous studies have conclusively shown the incremental prognostic value of myocardial perfusion SPECT over clinical and treadmill exercise data in predicting future cardiac events. This report addresses the current role and new developments, with respect to the use of myocardial perfusion imaging, in determining patient risk for cardiac events and the cost-effective integration of such information into patient management decisions.