Preoperative Cardiac Risk Stratification Research Articles

Gated myocardial perfusion SPECT for preoperative risk stratification in patients with noncardiac vascular disease

Myocardial perfusion single photon emission computed tomography (SPECT) is useful for preoperative cardiac risk stratification. We investigated the value of preoperative pharmacologic stress electrocardiographic (ECG)-gated myocardial perfusion SPECT for noncardiac vascular surgery. To assess the perioperative cardiac risk for noncardiac vascular surgery, preoperative pharmacologic stress ECG-gated myocardial perfusion SPECT was performed in 211 consecutive patients who underwent noncardiac aortic surgery. We examined myocardial perfusion and left ventricular function by the quantitative gated SPECT (QGS), and the correlation with perioperative cardiac events was investigated. Perioperative cardiac events occurred in 9 of 211 patients (4.3%). On the basis of univariate analysis, significant predictors for preoperative cardiac risk stratification included history of heart failure (P < 0.05), history of coronary artery revascularization (P < 0.05), summed stress score (SSS) (P < 0.0001), summed rest score (SRS) (P < 0.005), SSS > or = 7 (P < 0.005), end-diastolic volume (EDV) > or = mean + 2 standard deviation (SD) (134 ml for men and 93 ml for women) (P < 0.005), end-systolic volume (ESV) > or = mean + 2 SD (60 ml for men and 37 ml for women) (p < 0.0001), left ventricular ejection fraction (EF) < or = mean - 2 SD (48% for men and 55% for women) (P < 0.005) and wall motion abnormality (P < 0.05). On the basis of multivariate analysis, ESV > or = mean + 2 SD was the only independent predictor for perioperative cardiac events (P < 0.005). Pharmacologic stress ECG-gated myocardial perfusion SPECT, which permits assessment of both myocardial perfusion and cardiac function, is useful for preoperative risk stratification of noncardiac vascular surgery.

Treatment recommendations to prevent myocardial ischemia and infarction in patients undergoing vascular surgery

During major vascular surgery (MVS), patients are at high risk for developing unrecognized myocardial infarction (MI) and myocardial ischemia. In reducing postoperative morbidity and mortality, preoperative cardiac risk stratification and adequate medical therapy play a pivotal role. Based on literature and current opinions, medical treatment should comprise at least a combination of beta-blockers, aspirin, and statins. beta-Blockers exert their beneficial effects predominantly through heart rate control, leading to reduced oxygen demand during surgery. A heart rate between 65 and 70 bpm should be achieved. Irrespective of their lipid-lowering effects, statins seem to improve postoperative cardiac outcome by stabilizing coronary artery plaques, thereby preventing atherosclerotic plaque rupture. Aspirin reduces platelet activation and vasoconstriction, thereby limiting ischemic events and reducing nonfatal MI by 34%. Adding clopidogrel to low-dose aspirin might be beneficial toward postoperative cardiac outcomes; however, the effect on the incidence of postoperative bleeding complications may be a problem for future studies to resolve. Whereas beta-blockers inhibit the effect of catecholamines, alpha(2)-agonists inhibit catecholamine release and may be used in the perioperative setting when beta-blockers are contraindicated. Despite the blood pressure-lowering effect and anti-inflammatory properties of angiotensin-converting enzyme inhibitors, the literature does not support their use in patients undergoing MVS. The possible use of calcium antagonists before MVS should be further evaluated in high-risk patients with contraindications to beta-blockers, such as asthma, conduction abnormalities, or a history of stroke. Although nitrates are widely used for treating angina pectoris, the beneficial effect of their use in patients undergoing MVS remains controversial. Therefore, nitrates are not routinely used in the perioperative setting. The current American College of Cardiology/American Heart Association guidelines do not recommend prophylactic coronary revascularization before noncardiac surgery in patients with stable coronary artery disease.

Plasma N-terminal pro-B-type natriuretic peptide as a predictor of perioperative and long-term outcome after vascular surgery

N-terminal pro-B-type natriuretic peptide (NT-proBNP) is secreted by the heart in response to ventricular wall stress and has prognostic value in patients with heart failure, coronary artery disease, and heart valve abnormalities. Postoperative and long-term outcome is also related to these risk factors. This study assessed the additional prognostic value of NT-proBNP levels as a simple objective risk marker for postoperative cardiac events among vascular surgery patients. A detailed cardiac history (angina, myocardial infarction, age >70 years, diabetes mellitus, renal failure, stroke, heart failure), resting echocardiography, and NT-proBNP levels were obtained in 400 vascular surgery patients. Postoperative troponin-T levels and an electrocardiogram were obtained on days 1, 3, 7, and 30, and whenever clinically indicated. Patients were monitored every 6 months at the outpatient clinic. Study end points were perioperative cardiac events (ie, composite of cardiac death, myocardial infarction, and troponin release) and long-term all-cause mortality. The additional value of NT-proBNP was assessed with multivariable regression analysis. The optimal cutoff value was assessed by receiver operating characteristic curve analysis. Postoperative troponin T release occurred in 79 patients (20%). Cardiac risk factors were used to classify patients as low (0 risk factors), intermediate (1 to 2), and high (>3) cardiac risk (event rate of 7%, 15%, and 37%, respectively). The median NT-proBNP level was 206 pg/mL (interquartile range, 80-548 pg/mL). The risk of postoperative cardiac events was augmented with increasing NT-proBNP, irrespective of underlying cardiac risk factors and type of vascular surgery. In addition to cardiac risk factors only (C index, 0.66) or cardiac risk factors and site and type of surgery (C index, 0.81), NT-proBNP was an excellent tool for further risk stratification (C index, 0.86), with an optimal cutoff value of 350 pg/mL. In multivariate analysis, NT-proBNP >350 pg/mL remained significantly associated with perioperative cardiac events (odds ratio [OR], 4.7; 95% confidence interval [CI], 2.1-10.5, P < .001). NT-proBNP >350 pg/mL was also associated with an independent 1.9-fold (95% CI 1.1-3.2) increased risk for long-term mortality during a median follow-up of 2.4 years. NT-proBNP is an independent prognostic marker for postoperative cardiac events and long-term mortality in patients undergoing different types of vascular surgery and might be used for preoperative cardiac risk stratification.

The Ankle-to-Arm Blood Pressure Index Predicts Risk of Cardiac Complications After Noncardiac Surgery

Peripheral arterial disease, as detected by a reduced ankle-to-arm blood pressure index (AAI), has been shown to predict future cardiac events. However, the utility of measuring the AAI to predict postoperative cardiac complications in patients undergoing noncardiac surgery is unknown. We prospectively studied 242 consecutive patients aged 50 yr or older presenting to a university hospital preadmission clinic before elective noncardiac surgery. We performed a standardized clinical evaluation that included calculation of the revised cardiac risk index (rCRI) and measurement of the AAI using both palpation and Doppler techniques. Independent observers, blinded to preoperative assessment and AAI results, ascertained cardiac complications in the first 7 days after surgery. We assessed the ability of an abnormal AAI (<or=0.9 or absence of all four pedal pulses) to predict postoperative cardiac complications using likelihood ratios (LR), area under the ROC curves (AUC), and multivariable logistic regression in which we adjusted for the rCRI result. The cohort had a median age of 67 yr, 60% were male, 19% had diabetes, 14% had ischemic heart disease, and 35% underwent intraperitoneal or intrathoracic surgery. Postoperatively, 14 of 242 (6%) patients suffered cardiac complications, but no patients died. An abnormal AAI was present in 44 patients, 10 (23%) of whom had postoperative cardiac complications: positive LR 4.79 (95% CI: 3.04-7.54), negative LR 0.34 (95% CI: 0.15-0.77), AUC = 0.80. The AAI compared favorably with the rCRI, which had positive LR 4.22 (95% CI: 2.24-7.95), negative LR 0.57 (95% CI: 0.34-0.96), and AUC = 0.74. In multivariate analysis, the adjusted odds ratio for having a cardiac complication was 10.16 (95% CI: 2.90-36.02) for those patients with an abnormal AAI, even after adjusting for rCRI results. An abnormally low AAI, indicative of underlying peripheral arterial disease, is an independent risk factor for postoperative cardiac complications. The accuracy of the AAI is similar to the rCRI, and it provides additional independent predictive value for preoperative cardiac risk stratification.

Simultaneous sizing and preoperative risk stratification for thoracic endovascular aneurysm repair: Role of gated computed tomography

Risk factors are similar for the development of both thoracic aortic aneurysms (TAA) and other cardiovascular diseases. Coronary artery disease is highly prevalent in patients with TAA, with a reported prevalence of 30% to 70%. Knowledge of the underlying cardiac pathology can minimize perioperative risk and improve patient selection. This study investigated the feasibility of simultaneous assessment of thoracic aortic pathology and cardiac structures and function, including the coronary arteries, using electrocardiogram-gated 64-slice computed tomography (CT) angiography. ECG-gated 64-detector row CT examinations of 11 patients (8 men, 3 women; mean age, 67 +/- 16; range, 41-83 years) with thoracic aortic pathology, including aneurysms and dissections, were reviewed. Images were assessed for coronary artery disease, calcifications, cardiac function, and valve characteristics. Simultaneous assessment and measurements of thoracic aortic pathology were performed with the same scan. All images of the patients could be successfully assessed for calcium scores, coronary artery stenoses, coronary artery anomalies, interventricular septal wall thickness, myocardial scar, left ventricular ejection fraction, muscle mass, and aortic and mitral valve calcification, mobility, and valve anatomy. Diagnostic image quality was also achieved in all patients for the underlying thoracic aortic disease. This study introduces the feasibility of dynamic imaging of the thoracic aorta and cardiac structures and function, including the coronary arteries, with just one CT scan. The images could be successfully assessed for thoracic aorta pathology, cardiac disease, and extracardiac pathology. With further developments of CT scanners-and more detailed insight in the prognosis of patients based on ECG-gated CTA findings-this new technique may become the initial imaging modality for preoperative cardiac risk stratification in patients with TAAs or dissections.

Intense [18F]FDG tongue uptake in a case of acipimox-related angio-oedema during FDG-PET myocardial viability study

Tongue FDG uptake can occasionally be seen during FDGPET imaging, especially in patients talking after injection [1]. Orofacial angio-oedema can be triggered by various drugs [2]. Acipimox, a nicotinic acid analogue, used in FDG-PET myocardial viability studies can rarely cause angio-oedema [3]. A kidney mass suspicious for malignancy was found on MRI scan in a 74-year-old man with haematuria and coexistent advanced coronary artery disease. Myocardial perfusion assessment for pre-operative cardiac risk stratification further necessitated an FDG-PET viability study, which, because of the patient’s history, was combined with simultaneous whole-body scan. Acipimox was orally given before the administration of 460 MBq [F]FDG [3]. One hour after acipimox intake, the patient reported difficulty in swallowing. After scan completion, neck, tongue, tonsils and soft palate oedema was evident (a). Elevated total IgE (311 IU/ml; normal<100 IU/ml) was compatible with IgE-mediated angio-oedema. Whole-body scan was negative for malignancy. However, intense uptake (SUV maximum 8, average 6.2) in the tongue and mild activity along the pharynx and upper oesophagus were best shown in sagittal sections (b). Activity was located only at the posterior, swallowing-related and not at the anterior, freely moving part of the tongue. The area of activity was lacking the normal upward curved shape of the tongue, probably because of the swollen soft palate (c, arrow). In the presented case, intense FDG uptake of the tongue was shown in association with acipimox-related angiooedema. Increased muscular metabolism due to repeated swallowing efforts, triggered by the swollen soft palate, is proposed as the underlying mechanism. Eur J Nucl Med Mol Imaging (2007) 34:1320–1321 DOI 10.1007/s00259-007-0468-4

Preoperative cardiac risk stratification 2007: Evolving evidence, evolving strategies

Various guidelines and risk indices have optimized cardiac risk stratification, and the emphasis has shifted to reducing perioperative risk. This review is an update on invasive (CABG/PCI) and noninvasive (medical therapy with beta-blockers, alpha-agonists, and statins) strategies to reduce cardiac risk for noncardiac surgery and the controversies surrounding their use.

Vascular surgery critical care: Perioperative cardiac optimization to improve survival

To review the literature on perioperative cardiac management of patients who are scheduled to undergo vascular surgery. MEDLINE- and PubMed-based review of literature published from 1965 to 2005. Perioperative cardiac events (myocardial infarction, heart failure) remain the leading cause of morbidity and mortality in vascular surgery patients. Existing guidelines allow physicians to cost-effectively streamline preoperative cardiac risk assessment and stratification. Perioperative optimization of volume status and cardiac function and the routine use of perioperative beta-blockers can significantly improve outcomes after major vascular surgery. Perioperative addition of statins to beta-blockers in high-risk patients undergoing vascular surgery merits further evaluation. Preoperative coronary revascularization should be restricted to patients with unstable cardiac symptoms.

Clinician Agreement With Perioperative Cardiovascular Evaluation Guidelines and Clinical Outcomes

The American College of Cardiology/American Heart Association (ACC/AHA) published guidelines for preoperative cardiac risk stratification in 1996. Although clinician practice may differ from the guidelines, it remains unclear whether deviation from these guidelines affects clinical outcomes. This study sought to determine if discordance between clinician practice and the ACC/AHA guidelines affects perioperative cardiac outcomes. Eight hundred twenty-three patients who underwent 864 consecutive preoperative evaluations performed from 1995 to 1997 at a tertiary care academic medical center were prospectively followed. Clinician recommendations for preoperative cardiac testing were compared with ACC/AHA guideline recommendations. Frequencies of perioperative cardiac complications were compared between concordant and discordant testing recommendations. There were 33 perioperative cardiac complications (3.8%). Overall, there was no difference in the frequency of complications when there was discordance with the ACC/AHA guidelines compared with concordance (4.1% vs 3.7%, p = 0.81). The ACC/AHA guidelines recommended cardiac testing for 236 patients (27.3%). Clinicians ordered testing in half of those cases (n = 112). There was a lower frequency of cardiac complications when clinicians did not perform testing as recommended by the ACC/AHA guidelines (3.2% vs 10.7%, p = 0.02). Conversely, clinicians ordered cardiac testing in 45 patients (7%) when not recommended by the guidelines. Patients in this group had a trend toward more cardiac complications (6.7% vs 2.4%, p = 0.09). In conclusion, the failure of clinicians to follow the ACC/AHA guidelines when perioperative testing was recommended did not result in a higher frequency of cardiac complications.

Gated blood pool SPECT for measurement of left ventricular volumes and left ventricular ejection fraction: comparison of 8 and 16 frame gated blood pool SPECT

Gated blood pool SPECT (GBPS) is an alternative to planar radionuclide ventriculography (PRNV) and offers potential advantages. The aim of this study was to compare 8 and 16 frame GBPS for the determination of left ventricular ejection fraction(LVEF) and left ventricular volumes (LV) in subjects underwent two consecutive GBPS. About 66 consecutive patients (30 men, 36 women; mean age 62.3 +/- 10.4 years) referred for PRNV for evaluation of preoperative cardiac risk stratification (n = 40), prechemotherapy cardiac function evaluation (n = 18, breast cancer), and congestive heart failure patients (n = 8). All patients underwent PRNV of 16 frame and GBPS with both of 8 and 16 frame. The mean LVEF calculated with PRNV (58.3 +/- 16.8), showed statistically lower than 8-GBPS (70.6 +/- 17.7), and 16-GBPS (69.9 +/- 16.8) (PRNV vs. 8-GBPS, p < 0.01; PRNV vs 16-GBPS, p < 0.01; 8-GBPS vs 16-GBPS, p > 0.05). The correlation of LVEFS between 8-GBPS and 16-GBPS showed a correlation coefficient of 0.9194 (p < 0.01, 95% CI = 0.8712-0.9500). The mean left ventricular end-diastolic volumes (EDV) calculated with 8-GBPS (83.2 +/- 33.5 ml), and 16-GBPS (88.4 +/- 36.8 ml) showed no statistical differences (p > 0.05). The mean left ventricular end-systolic volumes (ESV) calculated with 8-GBPS (28.1 +/- 31.4 ml), and 16-GBPS (30.5 +/- 33 ml) showed also no statistical differences (p > 0.05). Comparison of EDV from 8 and 16-GBPS yielded a correlation coefficient of 0.7430 (p < 0.01, 95% CI = 0.6108-0.8349). The correlation between ESV of 8-GBPS and 16-GBPS showed a correlation coefficient of 0.9522 (p < 0.01, 95% CI = 0.9228-0.9705). This study demonstrated that the LVEFs of 8-GBPS correlated well with that of 16-GBPS. The LVEF of PRNV was significantly lower than those of 8 and 16-GBPS. Also, left ventricular EDV and ESV of 8-GBPS correlated well with those of 16-GBPS. Also, further studies, involving large lumber patients, should be performed to validate the usefulness of GBPS for the evaluation of left ventricular diastolic function.

Long-term survival after vascular surgery: Specific influence of cardiac factors and implications for preoperative evaluation

We sought to identify specific determinants of long-term cardiac events and survival in patients undergoing major arterial operations after preoperative cardiac risk stratification by American College of Cardiology/American Heart Association guidelines. A secondary goal was to define the potential long-term protective effect of previous coronary revascularization (coronary artery bypass grafting [CABG] or percutaneous coronary intervention [PCI]) in patients with vascular disease. Four hundred fifty-nine patients underwent risk stratification (high, intermediate, low) before 534 consecutive elective or urgent (<24 hours after presentation) open cerebrovascular, aortic, or lower limb reconstruction procedures between August 1996 and January 2000. Long-term follow-up (mean, 56 +/- 14 months) was possible in 97% of patients. The Kaplan-Meier method was used for survival data. Long-term prognostic variables were identified with the multivariate Cox proportional hazards model and contingency table analysis censoring early (<30 days) perioperative deaths. While 5-year survival was 72% for the overall cohort, cardiac causes accounted for only 24% of all deaths, and new cardiac events (myocardial infarction, congestive heart failure, arrhythmia, unstable angina, new coronary angiography, new CABG or PCI, cardiac death) affected only 4.6% of patients per year during follow-up. High cardiac risk stratification level (hazards ratio [HR], 2.2, 95% confidence interval [CI], 1.4-3.4), adverse perioperative cardiac events (myocardial infarction, congestive heart failure, ventricular arrhythmia; HR, 2.2; 95% CI, 1.2-4.1), and age (HR, 0.33; 95% CI, 0.2-0.6) were independently prognostic for latemortality. Preoperative cardiac risk levels also correlated with new cardiac event rates ( P < .01) and late cardiac mortality ( P = .02). Modestly improved survival in patients who had undergone CABG or PCI less than 5 years before vascular operations compared with those who had undergone revascularization 5 or more years previously and those at high risk without previous coronary intervention (73% vs 58% vs 62% 5-year survival; P = .02) could be demonstrated with univariate testing, but not with multivariate analysis. Type of operation, urgency, noncardiac complications, and presence of diabetes did not affect long-term survival. Despite cardiac events being a less common cause of late mortality after vascular surgery, perioperative cardiac factors (age, preoperative risk level, early cardiac complications) are the primary determinants of patient longevity. Patients undergoing more recent (<5 years) CABG or PCI before vascular surgery do not have an obvious survival advantage compared with patients at high cardiac risk without previous coronary interventions.

Limitations in the cardiac risk reduction provided by coronary revascularization prior to elective vascular surgery

Objective: The objective of this study was to evaluate the proposed cardiac protective effect of previous coronary revascularization (coronary artery bypass grafting [CABG] or percutaneous transluminal coronary angioplasty [PTCA]) before elective major arterial surgery. Method: Preoperative cardiac risk stratification using American College of Cardiology/American Heart Association (ACC/AHA) guidelines was done on 425 consecutive patients undergoing 481 elective major vascular operations at an academic VA Medical Center. The algorithm assumed asymptomatic patients with prior coronary revascularization (CABG, <5 year; PTCA, <2 year) were low cardiac risk. Coronary angiography was done for recurrent symptoms with secondary intervention when appropriate. Outcomes (myocardial infarction, unstable angina, congestive heart failure, ventricular arrhythmia, cardiac death, and mortality) within 30 days of vascular surgery were compared between patients with and without previous CABG or PTCA by contingency table and logistic regression analyses. Results: Coronary revascularization was classified as recent (CABG, <1 year; PTCA, <6 months) in 35 cases (7%), prior (1 year ≤ CABG < 5 year, 6 months ≤ PTCA < 2 year) in 45 cases (9%), and remote (CABG, ≥5 year; PTCA, ≥2 year) in 48 cases (10%). A larger fraction of patients with previous revascularization possessed pathologic cardiac risk variables and were stratified as high-risk preoperatively than their nonrevascularized counterparts. Outcomes in patients with previous PTCA were similar to those after CABG ( P = .7). Significant differences in adverse cardiac events ( P = .01) and mortality ( P = .05) were found between patients with CABG done within 5 years or PTCA within 2 years (6.3%, 1.3%, respectively), individuals with remote revascularization (10.4%, 6.3%), and nonrevascularized patients stratified at high risk (13.3%, 3.3%) or intermediate/low (2.8%, 0.9%) risk. De novo or recurrent 3-vessel coronary disease by angiography, but not the presence or timing of previous revascularization, was an independent predictor of cardiac events after vascular operations, whereas remote revascularization was associated with fatal outcomes by multivariate analysis. Conclusions: Previous coronary revascularization (CABG, <5 years; PTCA, <2 years) may provide only modest protection against adverse cardiac events and mortality following major arterial reconstruction. (J Vasc Surg 2002;36:526-33.)

Preoperative cardiac risk stratification: Ritual or requirement?

IS THERE ANY real benefit to doing preoperative cardiac evaluation and risk stratification tests in a stable patient? Most physicians would intuitively maintain that there is benefit in identifying the subset of patients at high risk of perioperative myocardial ischemia before surgery. 1 Eagle KA Brundage BH Chaitman BR et al. ACC/AHA Task Force Report: Guidelines for perioperative cardiovascular evaluation for noncardiac surgery. Circulation. 1996; 93: 1278-1317 PubMed Google Scholar Notably, patients with evidence of ongoing plaque rupture and thrombosis causing an acute unstable coronary syndrome should have cardiac intervention before noncardiac surgery. However, in all patients without evidence of an acute unstable coronary syndrome, several peer-reviewed publications advocate proceeding directly to surgery. 2 Bodenheimer MM Noncardiac surgery in the cardiac patient: What is the question?. Ann Intern Med. 1996; 124: 763-766 Crossref PubMed Scopus (43) Google Scholar , 3 D'Angelo AJ Puppala D Farber A et al. Is preoperative cardiac evaluation for abdominal aortic aneurysm repair necessary?. J Vasc Surg. 1997; 25: 152-156 Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar , 4 Lee TH Reducing cardiac risk in noncardiac surgery. N Engl J Med. 1999; 341: 1838-1840 Crossref PubMed Scopus (75) Google Scholar , 5 Rosenfeld BA Breslow MJ Dorman T Postoperative management strategies may obviate the need for most preoperative cardiac testing. Anesthesiology. 1996; 84 (letter): 1267-1268 Crossref Scopus (6) Google Scholar Other authors state the decision to pursue perioperative cardiac risk stratification tests and possible coronary revascularization should be the same as in the nonoperative setting. 6 Palda VA Detsky AS Guidelines for assessing and managing the perioperative risk from coronary artery disease associated with major noncardiac surgery. Ann Intern Med. 1997; 127: 309-312 Crossref PubMed Google Scholar , 7 Palda VA Detsky AS Perioperative assessment and management of risk from coronary artery disease. Ann Intern Med. 1997; 127: 313-328 Crossref PubMed Scopus (193) Google Scholar

Perioperative assessment and management of risk from coronary artery disease.

To summarize available evidence on preoperative cardiac risk stratification so that the internist may 1) use clinical and electrocardiographic findings to stratify a patient's perioperative risk for myocardial infarction and death; 2) decide which tests provide useful additional risk-related information; and 3) understand the benefits, risks, and evidence surrounding the decision to undertake coronary revascularization before elective noncardiac surgery. A MEDLINE search and review of the reference lists of identified articles. Sensitivities, specificities, and likelihood ratios for diagnostic tests were calculated, and a quality rating for study methods was applied. Myocardial infarction and mortality were the major outcomes considered, and a quality rating for study methods was applied. Clinical and electrocardiographic findings, organized by multivariate prediction indices, accurately identify patients as having low, intermediate, or high risk for myocardial infarction or death. Pharmacologic stress imaging with thallium or echocardiography probably improves risk stratification for intermediate-risk patients having vascular surgery. These tests have not been shown to be effective prognostic indicators for patients having nonvascular surgery. No studies of angiography for risk prediction have been reported. Decision analyses and retrospective series suggest that the risks incurred by doing coronary angiography and revascularization before elective surgery outweigh the benefits. Prospective, controlled studies of coronary revascularization are lacking. Evidence from a randomized, controlled trial has shown a survival benefit with the perioperative use of beta-blockers in patients at risk for coronary artery disease. Evaluation of all surgical patients by use of clinical indices is recommended. Low-risk patients need no further evaluation before surgery. High-risk patients need optimal management of their high-risk problems, including (if appropriate) beta-blocker use, and may need to have their elective procedures canceled. Intermediate-risk patients probably benefit from further noninvasive stress testing, especially if they are having vascular surgery. Further clinical trials are needed for most areas of concern.

Dipyridamole technetium 99m sestamibi myocardial tomography for preoperative cardiac risk stratification before major or minor nonvascular surgery

The value of dipyridamole technetium 99m sestamibi (MIBI) tomography for preoperative cardiac risk stratification was assessed in 285 consecutive patients being considered for nonvascular surgery. A “major” ( n = 140) or “minor” ( n = 89) nonvascular procedure was later done in 229 of these patients ≤4 months after dipyridamole testing. Perioperative cardiac events (unstable angina, acute ischemic pulmonary edema, nonfatal myocardial infarction, or cardiac death) occurred in 11 (8%) patients undergoing major nonvascular surgery and 1 (1%) undergoing a minor procedure. The only clinical or scintigraphic variables associated with significantly increased perioperative cardiac risk in patients having major surgery were Goldman class ≥II, an abnormal MIBI scan, and a fixed perfusion defect. In these patients, cardiac events occurred in 1% of those who had a normal MIBI study, 14% of those with an abnormal scan ( p < 0.01), 12% with a reversible MIBI defect ( p = 0.29), and 17% with a fixed MIBI defect ( p < 0.01). In the 60 patients whose Goldman class was ≥II, only an abnormal MIBI study and a fixed perfusion defect were associated with incremental risk of a perioperative cardiac event. The incidence of perioperative cardiac events in these patients was 4% with a normal MIBI scan, 27% with an abnormal study ( p < 0.05), 24% with a reversible MIBI defect ( p = 0.45), and 37% with a fixed defect ( p < 0.01). Event rates were low in patients having minor nonvascular surgery; none of the 25 with a normal MIBI study and only 1 of the 64 with an abnormal scan had a perioperative cardiac event ( p = not significant (NS). We conclude that dipyridamole MIBI tomography can provide important prognostic information in patients having major nonvascular surgery. A normal MIBI study indicates a low risk of perioperative cardiac events, whereas an abnormal study in patients with Goldman class ≥II undergoing major surgery is associated with significantly increased risk. The prognostic value of MIBI tomography in patients at low clinical risk undergoing minor surgery is limited.

Improved cardiac risk stratification in major vascular surgery with dobutamine-atropine stress echocardiography

This study sought to optimize preoperative cardiac risk stratification in a large group of consecutive candidates for vascular surgery by combining clinical risk assessment and semiquantitative dobutamine-atropine stress echocardiography. Dobutamine-atropine stress echocardiography has been used for the prediction of perioperative cardiac risk in a small group of patients scheduled for elective major vascular surgery on the basis of the presence or absence of stress-induced regional left ventricular wall motion abnormalities. Clinical risk assessment and dobutamine-atropine stress echocardiography were performed in 302 consecutive patients presenting for major vascular surgery. The extent and severity of stress wall motion abnormalities and the heart rate at which they occurred, in addition to the presence of wall motion abnormalities at rest, were assessed. The absence of clinical risk factors (angina, diabetes, Q waves on the electrocardiogram, symptomatic ventricular tachyarrhythmias, age > 70 years) identified a low risk group of 100 patients with a 1% cardiac event rate (unstable angina). Dobutamine-atropine stress echocardiographic findings were positive in 72 patients. Twenty-seven patients had a perioperative cardiac event (cardiac death in 5, nonfatal infarction in 12, unstable angina pectoris in 10); all 27 patients had positive stress test results (positive predictive value 38%, negative predictive value 100%). The semiquantitative assessment of the extent and severity of ischemia did not provide additional prognostic information in patients with positive test results. In contrast, the heart rate at which ischemia occurred defined a high risk group with a low ischemic threshold (38 patients with 20 events [53%]) and an intermediate risk group with a high ischemic threshold (34 patients with 7 events [21%]). All 5 patients with a fatal outcome and 8 of 12 with a nonfatal myocardial infarction were in the high risk group with a low ischemic threshold. Clinical variables identify 33% of patients at very low risk for perioperative complications of vascular surgery in whom further testing is redundant. In all other candidates, dobutamine-atropine stress echocardiography is a powerful tool that identifies those patients at intermediate risk and a small group at very high risk. Risk stratification with a combination of clinical assessment and pharmacologic stress echocardiography has the potential to facilitate clinical decision making and conserve resources.

Preoperative cardiac risk assessment for noncardiac surgery.

Patients presenting for noncardiac surgery should receive careful preoperative cardiac risk stratification. This has implications not only for the perioperative period, but also for long-term survival. After an initial clinical evaluation, certain patients will be referred for noninvasive testing. Those without significant inducible ischemia at a high workload have a low risk for perioperative cardiac complications. Patients who are unable to exercise adequately may require alternative forms of testing, of which dipyridamole thallium scintigraphy is the most thoroughly studied and validated option. Patients with either high-risk clinical profiles or significant thallium redistribution merit consideration for preoperative coronary angiography. Treatment options for high-risk patients include: (1) Proceeding with surgery as planned along with aggressive perioperative monitoring and anti-ischemic therapy, (2) coronary angiography with subsequent myocardial revascularization as appropriate before elective surgery, (3) selecting an alternative, lower risk surgical approach, and (4) cancellation of surgery in lieu of a trial of conservative therapy.

Preoperative cardiac risk assessment for patients having peripheral vascular surgery.

To review the methods used for preoperative cardiac risk stratification of patients having peripheral vascular surgery. Relevant studies published before August 1991 were identified using a MEDLINE search of the English-language literature, followed by a manual search of the references of all identified articles. All clinical studies evaluating methods used for preoperative cardiac risk stratification of patients having peripheral vascular surgery. The key data extracted from each article included the inclusion and exclusion criteria of the study patients, the techniques used for testing and the corresponding definitions of positive test results, and the clinical outcomes of the tested patients. Data were analyzed using a Bayesian conceptual framework, and pretest probabilities were converted to post-test probabilities using calculation of likelihood ratios. Patients with high scores on clinical cardiac risk indexes (Goldman index greater than 12 or Detsky index greater than 15), or more than three of the criteria identified by Eagle (age greater than 70 years, diabetes, angina, Q waves on electrocardiogram, or ventricular arrhythmias) are likely to be at higher risk for cardiac death and myocardial infarction after vascular surgery. Those with both low scores and none of Eagle's criteria may be at lower risk, but this result has not been reproduced by independent studies. Neither group of patients would benefit from further investigation for cardiac risk stratification. Patients with one or two of these criteria may be at intermediate risk and would benefit most from further testing for the purposes of risk stratification. Most of the published evidence shows that the absence of redistribution on dipyridamole-thallium scanning identifies a low risk for postoperative cardiac complications, whereas the presence of redistribution predicts a high risk. Preliminary reports suggest that preoperative monitoring for silent myocardial ischemia may also be useful in identifying a high-risk subset of patients. Patients identified clinically to be at either very low or high risk for cardiac complications after peripheral vascular surgery are unlikely to benefit from further risk stratification. Dipyridamole-thallium scanning is the test of choice for further evaluation of patients at intermediate clinical risk because studies have shown that it is sensitive enough to rule out a high-risk status for patients who do not have redistribution.

Noncardiac Surgery in the Patient with Heart Disease

Optimal care of the patient with heart disease undergoing noncardiac surgery requires that the members of the surgical team, including anesthesiologist, internist-cardiologist, and surgeon, be familiar with the cardiovascular response to surgery, preoperative cardiac risk stratification, and the unique pathogenesis of cardiac complications that may occur in the perioperative period. Preoperative evaluation and computation of cardiac risk, anesthetic considerations, along with perioperative care of the patient with ischemic heart disease, valvular heart disease, congestive heart failure, arrhythmias and conduction disorders, and hypertension is discussed.