Guidelines for perioperative cardiovascular evaluation for noncardiac surgery. Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Perioperative Cardiovascular Evaluation for Noncardiac Surgery)

Management of abdominal aortic aneurysms

Rupture of an abdominal aortic aneurysm (AAA) remains a common vascular catastrophe in all emergency departments. Currently, the natural history of AAAs indicates that risk of rupture increases considerably when the aneurysm is greater than 5 cm in diameter. Appropriate management of aneurysms is elective repair for patients with a good operative risk whose aneurysm is between 5 and 6 cm. For patients with a serious medical comorbidity, the threshold for AAA repair is usually 6 cm. Surgical management is generally safe with extraordinarily durable results. Another current option is an investigational endovascular stent graft, but the long-term outcome for these new devices remains unknown. In addition, optimal medical management should include careful control of hypertension and smoking cessation. The current prognosis for healthy patients who undergo elective aneurysm repair is excellent.

Usefulness of hypotension during dobutamine echocardiography in predicting perioperative cardiac events

This study was undertaken to determine the prognostic significance of hypotension induced during preoperative dobutamine stress echocardiography (DSE) before vascular and noncardiac thoracic surgery. Wall motion abnormality during DSE predicts perioperative risk. Although hypotension during DSE has not been shown to correlate with the presence or severity of coronary artery disease, its significance in perioperative risk assessment is unknown. We retrospectively studied 300 patients who had DSE within 6 months of noncardiac surgery. Perioperative events including death, myocardial infarction, ischemia, and arrhythmias were recorded. Odds ratios with 95% confidence intervals were used to examine the association between clinical and echocardiographic variables and perioperative events. A hypotensive response during DSE was seen in 85 patients (28%). Forty-eight patients (16%) had 54 perioperative complications including 4 cardiac-related deaths, 10 myocardial infarctions, 12 myocardial ischemic events, and 28 arrhythmias. Hypotension during DSE was predictive of the combined end point of perioperative cardiac mortality, myocardial infarction, and ischemia (odds ratio 4.04, 95% confidence interval 1.72 to 9.51). In a multivariate logistic regression model, hypotension during DSE remained a significant predictor (odds ratio 4.10, p<0.01). DSE-related hypotension was predictive of perioperative cardiac events and therefore may have a role in risk stratification before vascular or noncardiac thoracic surgery.

ACC/AHA guidelines as predictors of postoperative cardiac outcomes

PURPOSE

Recently, the American College of Cardiology - American Heart Association (ACC-AHA) published guidelines and an associated algorithm for preoperative cardiovascular evaluation of patients undergoing non-cardiac surgery. Our purpose was to (i) test guideline's ability to predict adverse cardiac events within seven days after surgery, (ii) determine whether medical clinical predictors or surgical risks was a better predictor of cardiac events.

METHODS

Retrospective review of 119 cardiology and anesthesia consultations over 15 mo, ending March 31, 1998. Patients were classified into their respective medical clinical predictor and surgical risk groups, as outlined in ACC-AHA guidelines. Associations between the medical predictor and surgical risk scores and adverse cardiac outcomes were quantified via multiple logistic regression analysis. Two outcomes were employed. Outcome I, included: myocardial infarction/ischemia; angina; congestive heart failure, arrhythmia or death. Outcome 2 expanded the definition to include "cancellation of surgery due to cardiac risk" as a negative cardiac outcome.

RESULTS

Diabetes, Canadian Cardiovascular Class (CCS) III or IV angina, and MI within six months before surgery were strongly associated with the two cardiac outcomes. For outcome 1 and 2, medical predictors and surgical risks, considered simultaneously, performed with a sensitivity of 93% and specificity of 46-51%. When considered separately, major clinical medical predictors had a sensitivity of 87-89%, while surgical risks showed a specificity of 89% in predicting the two outcomes.

CONCLUSION

Medical predictors in ACC-AHA classification scheme were highly sensitive whereas surgical risks were more specific in predicting adverse post-operative cardiac events. Prospective study is needed to confirm these observations.

Role of dobutamine stress echocardiography for preoperative cardiac risk assessment before major vascular surgery: a diagnostic tool comes of age

BACKGROUND

Cardiac complications are a major cause for perioperative mortality and morbidity. Also, the presence and severity of underlying coronary artery disease (CAD) determine long-term prognosis after successful surgery.

AIM

This overview evaluates the additional value of dobutamine stress echocardiography (DSE) to common clinical cardiac risk factors and other noninvasive cardiac imaging modalities for perioperative and late cardiac prognosis.

RESULTS

DSE provides theattending physician with preoperative prognostic information for perioperative and long-term prognosis for cardiac events. It also enables the selection of high risk patients for evaluation of cardiac risk reduction therapies.

CONCLUSIONS

DSE is a useful tool for preoperative cardiac risk evaluation in addition to common clinical cardiac risk factors.

The effect of bisoprolol on perioperative mortality and myocardial infarction in high-risk patients undergoing vascular surgery. Dutch Echocardiographic Cardiac Risk Evaluation Applying Stress Echocardiography Study Group

BACKGROUND

Cardiovascular complications are the most important causes of perioperative morbidity and mortality among patients undergoing major vascular surgery.

METHODS

We performed a randomized, multicenter trial to assess the effect of perioperative blockade of beta-adrenergic receptors on the incidence of death from cardiac causes and nonfatal myocardial infarction within 30 days after major vascular surgery in patients at high risk for these events. High-risk patients were identified by the presence of both clinical risk factors and positive results on dobutamine echocardiography. Eligible patients were randomly assigned to receive standard perioperative care or standard care plus perioperative beta-blockade with bisoprolol.

RESULTS

A total of 1351 patients were screened, and 846 were found to have one or more cardiac risk factors. Of these 846 patients, 173 had positive results on dobutamine echocardiography. Fifty-nine patients were randomly assigned to receive bisoprolol, and 53 to receive standard care. Fifty-three patients were excluded from randomization because they were already taking a beta-blocker, and eight were excluded because they had extensive wall-motion abnormalities either at rest or during stress testing. Two patients in the bisoprolol group died of cardiac causes (3.4 percent), as compared with nine patients in the standard-care group (17 percent, P=0.02). Nonfatal myocardial infarction occurred in nine patients given standard care only (17 percent) and in none of those given standard care plus bisoprolol (P<0.001). Thus, the primary study end point of death from cardiac causes or nonfatal myocardial infarction occurred in 2 patients in the bisoprolol group (3.4 percent) and 18 patients in the standard-care group (34 percent, P<0.001).

CONCLUSIONS

Bisoprolol reduces the perioperative incidence of death from cardiac causes and nonfatal myocardial infarction in high-risk patients who are undergoing major vascular surgery.

Screening for coronary artery disease

Unidentified coronary artery disease remains a significant cause of premature death and morbidity during the prime of life. The availability of effective interventions for the management of ischemia has provoked new interest in screening for this condition in asymptomatic patients, in the hope of reducing the burden of this condition. Although widespread use of stress testing is ineffective, the use of imaging techniques may offer better accuracy for detection of ischemia. Other tests that identify evidence of atheroma in the peripheral or coronary circulation may be useful to identify patients at risk.

Preoperative screening

In screening the preoperative patient, several sources of risk, each with potentially modifiable components, must be considered. These include risks related to the proposed procedure, anesthetic, and medical illnesses present in the patient. To screen effectively, one must look for potential factors in each area that may affect perioperative morbidity and mortality. Once risk areas are identified, it is helpful to quantify them further through a focused testing approach, especially when the anticipated surgical or anesthetic risks are high. Data obtained through this process should guide the optimization of the patient's medical status to modify risks when possible. Sharing information obtained during the preoperative assessment with both anesthesiologists and surgeons helps to refine plans for management and may better ensure patient safety in the perioperative period.

Pharmacological stress testing

Pharmacological stress in conjunction with radionuclide myocardial perfusion imaging has become a widely used noninvasive method of assessing patients with known or suspected coronary artery disease. In the United States, over one third of perfusion imaging studies are performed with pharmacological stress. Pharmacological stress agents fall into two categories: coronary vasodilating agents such as dipyridamole and adenosine, and cardiac positive inotropic agents such as dobutamine and arbutamine. For both, in the presence of coronary artery disease (CAD), perfusion image abnormalities result from heterogeneity of coronary blood flow reserve. Vasodilating agents work directly on the coronary vessels to increase blood flow, whereas inotropic agents work indirectly by increasing myocardial work load, which then leads to an increase in coronary blood flow. Both classes of agents have high accuracies for diagnosing coronary artery disease, and they have excellent safety records with acceptably low occurrences of side effects. For dipyridamole planar thallium imaging, pooled analysis yields a sensitivity of 85% and a specificity of 87% for diagnosis of coronary disease, but there is a large variation in reported values depending on various factors, such as the extent of postcatheterization referral bias, the type of imaging (planar versus single photon emission computed tomography [SPECT]), the types of patients being studied (single versus multivessel disease, men versus women), and the imaging agent used (thallium versus one of the technetium-based agents). Diagnostic accuracies for adenosine are similar to those of dipyridamole, with reported overall sensitivities ranging from 83% to 97%, and specificities ranging from 38% to 94%. For dobutamine, pooled analyses yield a sensitivity of 82% and a specificity of 75%. There is some concern that dobutamine may interfere with uptake of technetium-99m sestamibi, lowering the sensitivity for detection of disease, and thus the vasdodilating agents are generally preferred. Pharmacological stress testing has high clinical use for risk stratifying patients with known or suspected CAD, in patients after myocardial infarction, and in patients needing noncardiac surgery. Vasodilating agents are particularly advantageous in assessing post-myocardial infarction patients, allowing testing as soon as 2 days after the event. Like patients undergoing exercise stress testing, patients with normal perfusion images by pharmacological stress have a <1% annual incidence of cardiac events. The likelihood of an event increases with the extent and severity of perfusion abnormalities. However, it is important to consider clinical variables when using perfusion imaging for risk stratification, particularly in the presurgery patients. As with exercise testing, adjunct markers such as ST segment depression during testing, lung uptake of radiotracer (if thallium is used), and ventricular cavity dilatation add additional prognostic information to that available from the perfusion images alone. The aim of current research is to find better agents that are easier to use and that have fewer side effects. MRE-0470 is an experimental vasodilating agent that is more receptor selective than adenosine and promises a lower incidence of hypotension. Arbutamine more closely simulates exercise than dobutamine, and it can be administered by a closed-loop computerized delivery device. Work is also underway to look at novel uses of pharmacological stress agents, such as acquiring gated SPECT images during dobutamine infusion to enhance detection of myocardial viability. With increasing use of noninvasive testing in elderly patients and in patients with comorbidities that preclude adequate exercise, pharmacological stress testing has become an indispensable tool for radionuclide myocardial perfusion imaging studies. A good understanding of pharmacological stress testing is essential for performing high-quality nuclear cardiology

Stress myocardial perfusion imaging versus echocardiography for the diagnosis and risk stratification of patients with known or suspected coronary artery disease

Stress perfusion imaging and stress echocardiography (ECHO) are both very useful for assessment of diagnosis and risk stratification of patients with coronary artery disease (CAD). Both techniques have been well validated during exercise and inotropic stress, but coronary vasodilation stress is better used in combination with perfusion imaging. The overall sensitivity for detection of CAD is slightly higher by single photon emission computed tomography (SPECT) than by two-dimensional (2D) ECHO during all stress modalities, whereas the specificity is slightly higher by ECHO, although the differences in general are not statistically significant. SPECT, however, appears to be superior to ECHO in the diagnosis of isolated circumflex stenosis, as well as for the correct identification of multivessel CAD. A substantially greater amount of information is available regarding risk stratification with SPECT than with 2D ECHO. Although the data suggest that both techniques are very useful for risk stratification of patients with stable CAD, after myocardial infarction, and for preoperative risk stratification, the risk for cardiac events is lower in the presence of a normal stress SPECT study than of a normal stress ECHO.

The role of nuclear cardiology in clinical decision making

This review suggests that the field of nuclear cardiology is alive, well, and thriving, providing relevant information that aids in everyday clinical decision making for nuclear medicine and referring physicians alike. Despite the competition from other modalities, the clinically appropriate applications of nuclear cardiology techniques are likely to increase. The foundation of this optimism is based on the vast amount of data documenting cost-effective clinical applications for diagnosis, risk stratification, and assessing therapy in both chronic and acute coronary artery disease (CAD), the powerful objective quantitative analysis of perfusion and function provided by the technique, and the increasing general availability of the approach.

Dobutamine stress echocardiography for the preoperative evaluation of patients undergoing lung volume reduction surgery

BACKGROUND

Lung volume reduction surgery has been proposed as a bridge to lung transplantation and as definitive therapy for advanced chronic obstructive lung disease. However, patient selection criteria and optimal preoperative assessment have not been clearly defined.

OBJECTIVE

We investigated the feasibility, safety, and value of dobutamine stress echocardiography as a predictor of major early cardiac events in patients who underwent lung volume reduction surgery.

METHODS

The study population consisted of 46 patients (21 men and 25 women, mean age 59 +/- 9 years) who underwent dobutamine stress echocardiography (maximum dose 40 microg. kg(-1). min(-1) plus atropine if needed) 180 days or less before lung volume reduction surgery. Adverse cardiac events were prospectively defined and tabulated during hospitalization after the operation and at subsequent outpatient visits.

RESULTS

Dobutamine stress echocardiography was interpretable in 45 of 46 (98%) patients. There were no adverse events during testing. The studies revealed normal left ventricular systolic function at rest in all patients and normal right ventricular function in all patients but one. Thirteen patients had right ventricular enlargement. Estimated right ventricular systolic pressure was mildly elevated (>40 mm Hg) in 5 patients. Four patients (9%) had stress tests positive for ischemia. There were no perioperative deaths. Follow-up was available for 44 of 45 patients at a duration of 20.0 +/- 7.0 months. Two major adverse cardiac events occurred in the same patient in whom the results of dobutamine stress echocardiography were positive for ischemia (positive predictive value 25%, 95% confidence interval 0% to 83%; negative predictive value 100%, 95% confidence interval 90 to 100%).

CONCLUSION

Despite end-stage chronic obstructive lung disease and poor ultrasound windows, dobutamine stress echocardiography is feasible and safe in patients undergoing evaluation for lung volume reduction surgery. It yields important information on right and left ventricular function and has an excellent negative predictive value for early and late adverse cardiac events.

Cardiological applications of nuclear medicine

Cardiovascular mortality is falling in most industrialised nations. Primarily responsible for this encouraging trend are preventive measures such as risk-factor modification but improved medical and surgical management have helped too. Clinical decision making in the patient with coronary heart disease demands techniques that not only describe coronary anatomy but also provide functional indices for early detection and to monitor the severity and extent of disease. Nuclear medicine methods can characterise non-invasively myocardial function, perfusion, and metabolism. Novel radiopharmaceuticals, improvements in imaging equipment, and extensive validation have contributed to the growing clinical acceptance of these techniques and to their cost-effective integration in the workup of patients with cardiovascular disease.

Cost-effectiveness of stress-echocardiography

Because of constraints on the costs of providing medical care, cardiologists in the future will find themselves challenged to provide care for their patients in the most cost-effective manner possible. Although stress-echocardiography has been shown to compare favorably with other tests in diagnostic accuracy, data on cost-effectiveness are scarce. In this article, general concepts of cost-effectiveness as they relate to stress-echocardiography are reviewed and the available literature is summarized. Although definitive data are lacking, there is evidence to suggest that stress-echocardiography may prove to be cost-effective in several clinical situations.

Recognition and management of preoperative risk

Internists are frequently asked to do preoperative consultations and to manage perioperative complications. Realistic goals are to identify patient factors that increase the risk of surgery, to quantify this risk in order to make decisions about the appropriateness of and timing of the surgery, to provide recommendations on how to minimize the risk, to identify and manage coexisting medical conditions and their associated medication requirements, to monitor the patient for perioperative problems, and to make recommendations to deal with these problems when they occur. With few exceptions, nonselective imaging and laboratory screening tests have repeatedly been shown to be of little value when the history and physical do not suggest a problem. The risk associated with the planned surgery can be estimated, with the most common serious complications being cardiac events. Updated versions of Goldman's risk indices are particularly helpful for this. Clinical variables are optimally combined with selective stress testing to discern which patients will benefit from preoperative revascularization. This has been studied best in the setting of vascular surgery. A critical guiding principle is that the value of revascularization must be judged in terms of long term gains rather than just immediate perioperative benefit. Other interventions include the selective use of beta blockers, adequate analgesia for all, control of hypertension, and appropriate volume management, especially in the settings of preexisting CHF or valvular disease. It must also be recognized that perioperative ischemia and CHF often present atypically. An approach that combines aspects of both the ACC/AHA and the ACP guidelines seems optimal. A variety of noncardiac issues must also be addressed. Postoperative pulmonary complications are common, especially with preexisting pulmonary disease, thoracic and upper abdominal surgery, and obesity. PFTs and ABGs are indicated in selected patients. Stopping smoking, incentive spirometry, and selective use of bronchodilators and antibiotics are helpful. Patients with rheumatologic diseases have specific concerns based on systemic manifestations of disease including anemia, thrombocytopenia, pulmonary fibrosis, pericarditis, and hypercoagulability; medication effects particularly from steroids and nonsteroidal anti-inflammatory drugs; and specific joint problems including contractures and atlantoaxial joint instability. Diabetes increases the risk of infection and cardiac complications. Prevention of ketoacidosis and glucose control are necessary and can be achieved through a variety of approaches, depending on whether the patient suffers from Type 1 or Type 2 diabetes. The threshold for transfusion has increased in recent years, as has the use of erythropoietin and autologous blood donation. There is no longer an absolute hemoglobin that requires transfusion, although most require transfusion for hemoglobins less than 8 mg/dL, especially in the setting of cardiac disease and bloody surgery. The elderly require surgery at an increased rate and often do not do as well as younger patients. The primary issues are, however, not their age but their increased frequency of underlying disease and diminished reserve. The latter makes them prone to postoperative delirium, sensitivity to medications, and cardiac and pulmonary problems. Despite the many diseases that patients often have and the stresses of surgery itself, modern anesthetic and surgical techniques allow almost all patients to undergo necessary procedures at acceptable risk. The internist plays a critical role in minimizing this risk even further.

Pharmacologic stress echocardiography. Dobutamine and arbutamine stress testing

Pharmacologic stress testing is an important noninvasive method for evaluating patients with known or suspected coronary artery disease who are unable to adequately exercise. Pharmacologic stress echocardiography using dobutamine has been developed over the last 10 to 15 years as an alternative to vasodilator stress testing using nuclear perfusion imaging. As experience has grown, digital subtraction echocardiogram has been shown to be a safe, convenient, and reliable method for stress testing in a variety of patient populations. Digital subtraction echocardiogram has comparable sensitivity, specificity, and accuracy when compared to other stress testing methods which employ cardiac imaging and is superior to the exercise echocardiogram. It has certain advantages over nuclear perfusion imaging in terms of cost and convenience. The recent addition of arbutamine echocardiography (which has been shown to be comparable to digital subtraction echocardiogram) provides another alternative method for pharmacologic stress testing. Continued improvement in echocardiographic image quality and the development of new technologies such as tissue harmonic imaging and contrast echocardiography will hopefully improve the echocardiographic evaluation of wall motion therefore increasing the diagnostic accuracy of echocardiographic stress testing.

Exercise echocardiography. Principles, methods, and clinical use

Stress echocardiography is composed of a family of examinations in which various forms of cardiovascular stress are combined with echocardiographic imaging to assist in the diagnosis of coronary artery disease. Exercise cardiography has evolved over the past 20 years into a routinely available clinical tool employed in both university and community hospital settings. This article discusses advantages and disadvantages of using exercise echocardiography.

Anesthetic management of high-risk cardiac patients undergoing noncardiac surgery under the support of intraaortic balloon pump

Patients with severely impaired left ventricular function, an uncorrectable coronary artery disease, and a recent myocardial infarction are at high risk of cardiac complications after major noncardiac surgery. We present two patients with extensive three-vessel coronary artery disease who underwent intraperitoneal surgery under the support of intraaortic balloon pump (IABP). In one patient, the IABP was inserted urgently because of the development of chest pain with significant ST depression on arrival in the operating room, and the other patient was managed with prophylactic IABP. There were no intraoperative or postoperative cardiac events in either patient. Thus, IABP should be considered in the perioperative management of patients with severe cardiac diseases.

Prophylactic coronary artery revascularization for elective vascular surgery: study design. Veterans Affairs Cooperative Study Group on Coronary Artery Revascularization Prophylaxis for Elective Vascular Surgery

This article describes the design of an ongoing randomized trial intended to test whether patients who require elective vascular surgery would benefit from preoperative coronary artery revascularization prior to the vascular procedure. The primary objective is to determine whether coronary artery revascularization reduces long-term mortality (mean 3.5 years) in patients undergoing vascular surgery. The study design calls for 620 patients to be randomized and followed for a mean of 3.5 years following vascular surgery. Secondary endpoints include measures of quality of life and cost-effectiveness. Patients with coronary artery disease in need of an elective vascular operation are considered candidates for the study. Anatomic exclusion criteria include ejection fraction <20%, severe aortic stenosis (valve area <1.0 cm2), left main stenosis > or =50%, nonobstructive coronary artery disease (stenosis <70%), and coronary arteries that are not amenable to revascularization. Prior to the vascular surgery, the trial randomizes eligible patients to coronary artery revascularization (either bypass surgery or angioplasty) versus medical therapy. The trial stratifies the randomization by hospital and type of vascular surgery (intraabdominal versus infrainguinal) because of differences in long-term prognosis in those patients. A 1-year feasibility trial involving five Veterans Affairs (VA) medical centers of variable vascular surgical loads has been completed. The results showed that over 90% of expected patients could be randomized. As a result, a larger VA Cooperative Study involving 18 centers will begin recruitment of patients. The findings should help determine the best strategy for managing patients with coronary artery disease in need of elective vascular surgery.

Preoperative cardiac risk assessment

Preoperative cardiac evaluation is aimed at evaluating the patient's current medical status, making recommendations concerning the risk of cardiac problems in the perioperative period, and providing a clinical risk profile that the patient, primary physician, consultants, anesthesiologist, and surgeon can use in making treatment decisions. Patients can be stratified on clinical grounds into low-, medium-, and high-risk categories. Use of these categories, along with consideration of the type and urgency of noncardiac surgery, allows for a reasonable approach to preoperative testing. In general, indications for cardiac testing and treatment are similar to the nonoperative setting, but their choice and timing is dependent on factors specific to the patient, the type of surgery, and the clinical situation. Use of invasive and noninvasive testing should be limited to situations in which the results of the tests will clearly affect patient management. Further research is necessary to define the most appropriate role of such testing, both in terms of efficacy and of cost-effectiveness. Cardiac intervention is rarely necessary to lower the risk of surgery, but noncardiac surgery often represents the first opportunity for a patient to receive an appropriate assessment of short- and long-term cardiac risk, and this should be taken into consideration in planning perioperative evaluation.

Histological analysis of coronary artery lesions in fatal postoperative myocardial infarction

We sought to evaluate the underlying coronary pathology of fatal postoperative myocardial infarction (MI). It has been hypothesized that most MIs following noncardiac surgery occur in the setting of increased oxygen demand that exceeds coronary blood supply. However, most MIs not associated with surgery are caused by plaque rupture and intracoronary thrombosis. In a retrospective cohort study, we reviewed 1841 consecutive autopsy records from 1981 to 1995 at two institutions and identified 26 cases of postoperative MI with coronary arteries available. Plaque rupture was present in 12 cases (46%, 95% confidence interval [CI] 27%-67%). Of the 9 (35%) patients with intracoronary thrombus, 5 (56%; 19% of entire group) had total occlusion. Thrombus occurred on a >50% stenosis (by cross-sectional area) in a total of 33% (95% CI 16%-55%) of patients. The only statistically significant difference in clinical variables between patients with and without plaque rupture was longer interval from surgery to death in patients with plaque rupture (7.8+/-4.4 days versus 4.4+/-4.8 days; p = 0.047). In this autopsy series, coronary plaque rupture was associated with almost half of fatal postoperative MI cases. Strategies aimed at reducing triggers of plaque rupture with coronary occlusion might reduce postoperative MI fatality.

Renal failure predisposes patients to adverse outcome after coronary artery bypass surgery. VA Cooperative Study #5

BACKGROUND

More than 600,000 coronary artery bypass graft (CABG) procedures are done annually in the United States. Some data indicate that 10 to 20% of patients who are undergoing a CABG procedure have a serum creatinine of more than 1.5 mg/dl. There are few data on the impact of a mild increase in serum creatinine concentration on CABG outcome.

METHODS

We analyzed a Veterans Affairs database obtained prospectively from 1992 through 1996 at 14 of 43 centers performing heart surgery. We compared the outcome after CABG in patients with a baseline serum creatinine of less than 1.5 mg/dl (median 1.1 mg/dl, N = 3271) to patients with a baseline serum creatinine of 1.5 to 3.0 mg/dl (median 1.7, N = 631).

RESULTS

Univariate analysis revealed that patients with a serum creatinine of 1.5 to 3.0 mg/dl had a higher 30-day mortality (7% vs. 3%, P < 0.001) requirement for prolonged mechanical ventilation (15% vs. 8%, P = 0.001), stroke (7% vs. 2%, P < 0.001), renal failure requiring dialysis at discharge (3% vs. 1%, P < 0.001), and bleeding complications (8% vs. 3%, P < 0.001) than patients with a baseline serum creatinine of less than 1.5 mg/dl. Multiple logistic regression analyses found that patients with a baseline serum creatinine of less than 1.5 mg/dl had significantly lower (P < 0.02) 30-day mortality and postoperative bleeding and ventilatory complications than patients with a serum creatinine of 1.5 to 3.0 mg/dl when controlling for all other variables.

CONCLUSION

These results demonstrate that mild renal failure is an independent risk factor for adverse outcome after CABG.

Perioperative Risk Stratification in Patients Undergoing Noncardiac Surgery

Adverse cardiac events during noncardiac surgery are a major cause of morbidity and mortality. As the population ages, greater numbers of patients (including the elderly) are undergoing noncardiac surgical procedures; additional emphasis must therefore be placed on effective preoperative risk assessment. On a national level, the estimated annual expenditure for this process is already $3.7 billion. There is a need for both the specialist and primary care provider to execute a safe, methodical, and cost efficient screening plan. This process should identify both the patients at highest risk and also those at lowest risk. Subsequently, the emphasis should attempt to minimize the overall risk of perioperative complications. The cornerstone of risk assessment requires meticulous history taking, a thorough physical examination, and usually a chest radiograph and an ECG. Five subsequent (basic) steps for the evaluation of patients for noncardiac surgery are outlined here in assessment of clinical markers and the pa- tient's functional capacity, risk of the surgical procedure, the need for noninvasive testing, and when appropriate, the indications for invasive testing. The AHA/ACC Practice Guidelines Committee has outlined a clinical algorithm which provides a stepwise approach to guide the clinician during the decision making process. The purpose of preoperative evaluation is not to "give medical clearance" per se, but rather to evaluate the patient's current medical status, detect stress-induced ischemia in a cost effective manner, and to make recommendations about patient management throughout the entire perioperative period.

Assessment of cardiovascular risks and overall risks for noncardiac surgery

Appropriate care of the elderly patient requires a concerted multi-disciplinary approach before, during, and after surgery to optimize functional outcomes, with the principal focus placed on improving quality of life and strategies for risk reduction. Perioperative physicians must be able to assess the biologic, not the chronologic, age of geriatric patients and their capacity for independent function. Physicians need to understand alterations in the physiology of elderly patients attributable to the normal aging process as well as the prevalence of concurrent pathologic conditions that necessitate special precautions. Maintaining autonomy and function as a result of an acute surgical intervention may be the most important outcome to the elderly patient. Most of the data available and guidelines promulgated do not specifically address the elderly population. It is important to collect data prospectively and use sophisticated methods for analyses to develop better management algorithms for these (often complicated) clinical issues in the elderly.

Clinical review of attenuation-corrected cardiac SPECT

Rather than the introduction of a heralded technologic advancement in cardiac SPECT imaging challenging the accuracy of PET perfusion imaging, the commercial introduction of attenuation correction has been met with at least as many negative as positive reports. Some studies have reported significant improvements in specificity or specificity and sensitivity, especially for high-risk patterns of coronary artery disease; others have reported no improvement or a decrease in accuracy resulting from the introduction of troublesome artifacts. Although this review has attempted to emphasize the positive aspects of attenuation-corrected cardiac SPECT perfusion imaging and the potential for improved patient care it may provide, several negative reports continue to appear. Still there has been sufficient positive data reported to suggest that with fully developed, accurate, and robust correction methods, significant gains in SPECT assessments of the presence and extent of CHD, patient risk, and myocardial viability can be anticipated. Ultimately attenuation correction for cardiac SPECT should have a positive impact on the management of patients with coronary artery disease with important savings in lives and health care dollars.

How well does radionuclide dipyridamole stress testing detect three-vessel coronary artery disease and ischemia in the region supplied by the most stenotic vessel?

PURPOSE

This study was done to evaluate the accuracy of radionuclide dipyridamole stress imaging to detect multivessel disease and ischemia in segments of myocardium supplied by the most stenotic vessel.

METHODS

A retrospective analysis of consecutive patients with known triple-vessel disease of at least 50% stenosis in each of the three major epicardial coronary arteries who had exercise (n=44) or dipyridamole (n=86) stress testing, or both, within 6 months of coronary angiography.

RESULTS

The accuracy of dipyridamole stress testing to detect three-vessel disease was 52% and ischemia was detected in the region supplied by the most stenotic vessel in 67% of patients. The sensitivity and specificity rates of radionuclide imaging to detect ischemia in the region supplied by the vessel of tightest stenosis were 69% and 74% for the left anterior descending coronary artery (LAD), 61% and 78% for the right coronary artery (RCA), and 61% and 57% for the left circumflex coronary artery (LCX). Based on these values, in 39% of patients in whom the RCA or LCX was the most stenotic vessel and in 31% of patients in whom the LAD was the most stenotic vessel, perfusion defects were not present on their nuclear scans.

CONCLUSIONS

These results have important implications for interventional cardiologists who perform angioplasty on the most stenotic vessel, because the regions supplied by these vessels may not be the most ischemic. Furthermore, dipyridamole stress imaging may significantly underestimate the number of patients with substantial three-vessel coronary artery disease when qualitative imaging is done.

Comparison of dipyridamole stress echocardiography and perfusion scintigraphy for cardiac risk stratification in vascular surgery patients

Dipyridamole single-photon emission computed tomography (SPECT) has a high negative predictive value for perioperative cardiac events, but events are infrequent in patients with a positive test. In contrast, dipyridamole echocardiography is more selective for detection of multivessel disease and thus may have a greater specificity for cardiac events. We therefore compared the ability of dipyridamole SPECT and echocardiography to predict perioperative and long-term cardiac events in 133 patients referred for vascular surgery. The group was also evaluated based on clinical features and ejection fraction. Four patients had surgery cancelled because of high risk and were excluded from further analysis. Among the 129 remaining patients, 21 had coronary revascularization (n=12) or an early cardiac end point (n=9). The sensitivity of SPECT for the prediction of early events (90%) was not significantly different from that of echocardiography (66%, p=NS). The specificity of SPECT (68%) was less than that of echocardiography (88%, p <0.001%), as was the accuracy (72% vs 84%, p=0.02). These findings were replicated after exclusion of patients with treatment end points. During long-term follow-up, 12 patients experienced > or = 1 event: 6 died from cardiac causes, 4 underwent revascularization, and 3 had myocardial infarction. Thus, the specificity of SPECT and echocardiography for late events were 58% and 80%, respectively (p <0.001). The 3-year survival of patients without ischemia during echocardiography or at SPECT was not different (93% vs 94%, p=NS).

New guidelines for prevention, detection, evaluation and treatment of high blood pressure

New guidelines for the management of patients at risk of developing hypertension and associated conditions have recently been published. These guidelines include a new risk stratification and blood pressure classification, as well as an altered approach to drug therapy. This article describes the major changes from previous recommendations, highlights the role of oral health care providers and emphasizes the dental implications of caring for patients with blood pressure conditions.

A survey on the intended purposes and perceived utility of preoperative cardiology consultations

Cardiology consultations are often requested by surgeons and anesthesiologists for patients with cardiovascular disease. There can be confusion, however, regarding both the reasons for a consultation and their effect on patient management. This study was designed to determine the attitudes of physicians toward preoperative cardiology consultations and to assess the effect of such consultations on perioperative management. A multiple-choice survey regarding the purposes and utility of cardiology consultations was sent to randomly selected New York metropolitan area anesthesiologists, surgeons, and cardiologists. In addition, the charts of 55 consecutive patients aged >50 yr who received preoperative cardiology consultations were examined to determine the stated purpose of the consult, recommendations made, and concordance by surgeons and anesthesiologists with cardiologists' recommendations. Of the 400 surveys sent to each specialty, 192 were returned from anesthesiologists, 113 were returned from surgeons, and 129 were returned from cardiologists. There was substantial disagreement on the importance and purposes of a cardiology consult: intraoperative monitoring, "clearing the patient for surgery," and advising as to the safest type of anesthesia were regarded as important by most cardiologists and surgeons but as unimportant by anesthesiologists (all P < 0.05). Most surgeons (80.2%) felt obligated to follow a cardiologist's recommendations, whereas few anesthesiologists (16.6%) felt so obligated (P < 0.05). The most commonly stated purpose of the 55 cardiology consultations examined was "preoperative evaluation." Only 5 of these (9%) were obtained for patients in whom there was a new finding. Of the cardiology consultations, 40% contained no recommendations other than "proceed with case," "cleared for surgery," or "continue current medications." Recommendations regarding intraoperative monitoring or cardiac medications were largely ignored.

IMPLICATIONS

We conclude that there seems to be considerable disagreement among anesthesiologists, cardiologists, and surgeons as to the purposes and utility of cardiology consultations. A review of 55 consecutive cardiology consultations suggests that most of them give little advice that truly affects management.

Correlates of in-hospital cost among patients undergoing abdominal aortic aneurysm repair

BACKGROUND

Surgical repair of abdominal aortic aneurysms (AAA) is increasingly being performed, but little is known about the correlates of in-hospital cost associated with this procedure.

METHODS AND RESULTS

Baseline clinical characteristics, in-hospital outcomes, and total in-hospital costs were examined among a retrospective cohort of 71 patients who underwent AAA repair. Median age was 68 years, and 75% of the patients were men. High-risk characteristics for perioperative complications were common and included hypertension (73%), documented coronary artery disease (66%), smoking (60%), previous myocardial infarction (47%), history of congestive heart failure (12%), urgent or emergent AAA repair (16%), and diabetes mellitus (11%). Perioperative complications included congestive heart failure (13%), myocardial infarction (11 %), and death (1 %). Median length of stay in the surgical intensive care unit (SICU) was 2 days (range 0 to 28), and median in-hospital stay was 9 days (range 5 to 39). In-hospital cost for the 71 patients ranged from $13,766 to $82,435 (mean $25,931, median $21,633). Univariate and multiple linear regression analyses demonstrated that among the potential correlates investigated, number of SICU days (P= .007) and total length of stay (P< .0001) were the most closely associated with in-hospital cost.

CONCLUSIONS

Among patients undergoing AAA repair, the major correlates of in-hospital cost are the number of days spent in the SICU and the total number of days spent in the hospital. These results suggest that any intervention that reduces length of stay may significantly reduce the total in-hospital cost associated with AAA repair.

[Dobutamine echocardiography for the preoperative evaluation of patients for surgery of the abdominal aorta]

OBJECTIVE

The aim of the study was to assess the value of dobutamine echocardiography (DE) for detecting coronary artery disease (CAD) in patients scheduled for abdominal aortic surgery.

STUDY DESIGN

Preliminary prospective open study.

PATIENTS

Thirty-three consecutive patients due to undergo effective abdominal aortic surgery, assessed by preoperative DE.

METHODS

Previous myocardial infarction and atherosclerotic risk factors (RF) were noted. Incremental doses of dobutamine were administered in order to reach 85% of age-predicted maximal heart rate. The occurrence of regional wall motion abnormalities was considered as a positive test. In this case a coronary angiography was performed.

RESULTS

Four patients had a history of angina pectoris. DE was not interpretable in five patients. Among the patients without symptoms, 12 had three RF or more, 12 had less than three RF. In eight patients with a positive test, coronary angiography showed one or more significant main coronary artery stenoses. All patients with angina pectoris had a positive test. None of patients without symptoms and less than three RF had a positive test, one third of patients with no symptomatology but with three RF or more had a positive test (P < 0.05).

CONCLUSION

DE has the ability to identify patients with asymptomatic CAD. DE is recommended in patients with high probability of CAD, i.e. with three RF or more.

Correlation between exercise-induced ischemic ST-segment depression and myocardial blood flow quantified by positron emission tomography

BACKGROUND

Ischemic ST-segment depression (horizontal or downsloping) is the most common manifestation of exercise-induced myocardial ischemia. The mechanisms responsible for these types of ST-segment depression are largely unknown. We investigated the relation of these 2 types of exercise-induced ST-segment depression to changes in regional myocardial blood flow (RMBF) by using exercise positron emission tomography (PET).

METHODS AND RESULTS

The RMBF was measured with nitrogen-13 ammonia PET both at rest and during low-level supine bicycle exercise in 27 patients with angiographically proven coronary artery disease and in 6 healthy volunteers. ST-segment depression was measured from the isoelectric PR segment 80 ms after the J point. Exercise-induced horizontal ST-segment depression > or =0.1 mV was observed in 9 patients and downsloping depression > or =0.1 mV was observed in 18 patients. Multivessel disease was more frequent and areas of exercise-induced ischemia were larger in patients with downsloping depression than in patients with horizontal depression (P < .02, P < .05). In patients with horizontal ST-segment depression, RMBF in ischemic areas and in surrounding areas increased by a similar amount (31%+/-29% and 32%+/-16%) with exercise. In patients with downsloping ST-segment depression, RMBF was unchanged or decreased in ischemic areas (10%+/-24%) but increased in surrounding areas (46%+/-27%) with exercise. In healthy volunteers, RMBF increased in all areas (56%+/-30%) with exercise.

CONCLUSIONS

Compared with horizontal changes in ST-segment morphology, downsloping changes may better indicate severe ischemia and greater differences in the increase of blood flow with exercise in the ischemic myocardium and in the surrounding areas.