Coronary risk of noncardiac surgery

Cardiac risk assessment for noncardiac surgery: current concepts

Strategies for perioperative risk assessment in patients undergoing noncardiac surgery vary among physicians and are aimed to estimate the risk and minimize complications. We propose simplistic guidelines for assessing and modifying risk for patients undergoing a wide variety of procedures.

Negative impact of cardiac evaluation before vascular surgery

The optimal preoperative evaluation of cardiac risk in patients with peripheral vascular disease is controversial. In developing a paradigm for preoperative cardiac workup, potential adverse effects of evaluation and cardiac intervention must be considered. This study analyzed the deleterious outcomes of extensive, comprehensive cardiac evaluation and intervention before planned vascular surgery in patients treated at the Denver Department of Veterans Affairs Medical Center. Over a 12-month period between 1994 and 1995, 161 patients were scheduled to undergo major vascular operations; 153 patients came to operation. The decision to pursue a cardiac evaluation was variously made by a combination of surgeons, cardiologists, and anesthesiologists. No defined protocol was followed. Cardiac history, chest X-rays and ECGs were obtained for all patients. Extended cardiac evaluation included these studies plus special tests, including echocardiography (echo), radionuclide ventriculography (RNVG), dipyridamole thallium scintigraphy (DTS), and cardiac catheterization (CC). Extended cardiac evaluations were undertaken in 42 patients. Complications related to percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting (CABG) were also recorded. Cardiac mortality and morbidity after vascular interventions were itemized in all 153 patients. Forty-two male patients, aged 68 +/- 9 years, underwent extended cardiac evaluations before planned vascular operations. The median elapsed time for cardiac workup was 14 days (mean 30 +/- 59 days). The median and mean times from cardiac workup to vascular surgery were 25 days and 76 +/- 142 days, respectively. Eighteen (43%) patients had echo or RNVG; 22 (52%) patients had DTS; 27 (64%) had CC; 9 (21%) had PTCA; 7 (17%) had CABG. Sixteen (38%) patients had untoward events related to cardiac evaluation. Eight patients (19%: one with cerebrovascular disease, and seven with aortic aneurysms) refused vascular surgery after extended cardiac workup. Complications attributable to CC, PTCA, and CABG included prosthetic graft infection, pseudoaneurysms (two), sternal wound infections (two), renal failure and brain anoxia. Two patients with severe limb ischemia who were candidates for revascularization ultimately required amputations because of delay due to cardiac evaluations. Extensive cardiac evaluation prior to vascular operations can result in morbidity, delays, and refusal to undergo vascular surgery. The underlying indication for vascular operations and the local iatrogenic cardiac complication rates must be considered before ordering special studies.

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.

Dipyridamole thallium-201 single-photon emission computed tomography for prediction of perioperative cardiac events in patients with arteriosclerosis obliterans undergoing vascular surgery

The aim of the study was to determine whether or not dipyridamole thallium-201 single-photon emission computed tomography (201Tl-SPECT) has significant additive value for predicting perioperative cardiac events in patients with arteriosclerosis obliterans (ASO) undergoing vascular surgery. Routine preoperative 201Tl-SPECT was performed in 106 consecutive patients with ASO (age 68+/-8.9 years; 91 men and 15 women). The frequency of reversible defects in a clinical high-risk group (n=44) was significantly higher than in a low-risk group (n=62; 55% vs 24%, p<0.01). Perioperative cardiac events occurred in 9 patients, including 4 cardiac deaths, 1 non-fatal myocardial infarction, and 4 cases of unstable angina. Although clinical risk stratification was useful in predicting cardiac events (19% in the high-risk group vs 2% in the low-risk group, p<0.01), the positive predictive value was low. When considering a combination of 2 or more than 2 risk factors and a large reversible defect as a predictor, the positive predictive value and specificity increased from 19% to 47% and from 64% to 91%, respectively, whereas the sensitivity remained unchanged (89%). These results suggest that the addition of 201Tl-SPECT data to clinical risk-stratified patients with ASO allows better prediction of perioperative cardiac events.

Risk factors in patients undergoing major nonvascular abdominal operations that predict perioperative myocardial infarction

BACKGROUND

Perioperative myocardial infarction (PMI) is an uncommon but serious complication of major abdominal surgery. Identifying the patients at risk may potentially reduce morbidity and mortality. In this study we determined risk factors associated with PMI in patients undergoing abdominal, nonvascular surgery (ANVS).

METHODS

The utility of risk factors for PMI using Goldman's criteria and nine other variables were compared in patients diagnosed with PMI after ANVS (group I) and a control group (group II) matched for age, gender, and type of operation.

RESULTS

Thirty-four patients, 21 men and 13 women, with a mean age of 70 years were diagnosed with PMI, which was associated with a 41% mortality rate (14 of 34). Risk factors for PMI included poor general condition, congestive heart failure, abnormal cardiac rhythm, smoking, previous myocardial infarction (MI), and emergent operation.

CONCLUSION

Although PMI following ANVS is uncommon, the mortality rate remains high. Patients classified as Goldman's class III and IV, or with a history of cigarette smoking, previous MI, or angina merit further evaluation in order to reduce the incidence of this complication.

Safe pancreas transplantation in patients with coronary artery disease

BACKGROUND

This study was conducted to determine the risk of clinically significant posttransplant cardiac events (PCEs) in a cohort of diabetic patients referred for pancreas transplantation.

METHODS

Between April 1991 and December 1995, 316 insulin-dependent diabetics were evaluated for pancreas transplantation. Patients were assessed for risk factors for coronary artery disease (CAD), and underwent screening for significant CAD by a standardized algorithm that included selective coronary angiography. For the 3-year period following transplantation, PCEs were identified, and related to pretransplant cardiac risk factors.

RESULTS

Only four patients (1.3%) were turned down for cardiac contraindications. Coronary angiography was done in 74 patients (27% of the active transplant candidates) during the evaluation period because of the patient's history or a positive stress test. Significant coronary artery stenoses were found in 54% of the patients catheterized. Twenty-five of these 40 patients (63%) underwent revascularization with percutaneous transluminal coronary angioplasty and/or coronary artery bypass grafting. A total of 359 organs were subsequently transplanted into 194 of these patients. No deaths occurred within 30 days of any of the transplants; four percent of transplant recipients died of cardiac causes within the follow-up period (median 23 months). Those with no pretransplant evidence of CAD had significantly lower rates of PCE (2% and 8% at 1 and 3 years, respectively) than those with pretransplant evidence of CAD (11% and 29% at 1 and 3 years, P<0.01; relative risk, 4.3).

CONCLUSIONS

Routine cardiac screening of pancreas recipients with selective angiography and revascularization allows patients with significant CAD to safely undergo pancreas transplantation. Patients should rarely be excluded from pancreas transplantation for cardiac causes.

[Preoperative evaluation of coronary circulation]

To define a strategy for coronary circulation assessment is a difficult task as most of the studies have been carried out in vascular surgery, as some of them are controversial, and as no test has a 100% sensitivity and specificity. However patients with high perioperative risk of cardiac events have to be identified, in order to intensify medical treatment or to consider myocardial revascularisation. A first evaluation is based on history, physical examination and simple tests, such as rest electrocardiogram and thorax X-Ray. Additional tests are not required when surgery does not elicit a major activity of the cardiocirculatory system. Postoperative cardiac risk is low when none of the nine risk factors defined by Goldman and/or coronary insufficiency (residual angina elicited by minor physical activity, unstable angina, myocardial infarction) are present. The problem remains in patients with Goldman risk factors and/or at risk of coronary artery disease because of diabetes mellitus, heavy smoking, hypercholesterolaemia, arterial hypertension, undergoing major abdominal, thoracic or vascular surgery. Preoperative electrocardiographic Holter monitoring is still of value, especially in patients with known or supposed ischaemic heart disease and unable to make a physical effort. A poor exercise capacity and changes in electrocardiographic stress testing are factors of poor prognosis. The dobutamine stress echocardiography has a good sensitivity and specificity when an effort test cannot be performed. The value of dipyridamole-thallium 201 scintigraphy could be improved by a quantitative analysis of the number of affected segments and territories. Patients with angina or ischaemic episodes on continuous electrocardiogram, or with dobutamine echocardiography kinetic disturbances and with stress myocardic scintigraphy or stress exercise testing abnormalities could undergo a coronarography, in order to consider myocardic revascularization prior to surgery.

Assessment of cardiac risk in noncardiac surgery

Surgical techniques have been refined so that complications directly resulting from surgical procedures are relatively small. However, with the high prevalence of coronary artery disease in the United States, many surgical patients have concomitant coronary artery disease. Anesthesia as well as the surgical procedure induce stresses on the heart and circulatory system which could result in perioperative cardiac morbidity and mortality. Assessing patients prior to surgical procedures by history, physical examination, laboratory data, and newer cardiovascular diagnostic procedures can stratify the cardiac risk and help to predict the incidence of perioperative cardiac morbidity and mortality. If great risk exists, an alternative therapy or cancellation of the surgical procedure may be considered. In certain subgroups of patients, coronary artery revascularization, valvular heart surgery, or beginning medical therapy of the underlying cardiac pathology could be performed prior to the surgical procedure. If this cannot be arranged for high-risk patients, more intensive and invasive hemodynamic monitoring and optimal medical management perioperatively might reduce cardiac complications.

A stepwise strategy for coronary risk assessment for noncardiac surgery

Physicians should adapt a systematic approach to cardiac risk stratification for patients being considered for noncardiac surgery, involving clinical evaluation, functional assessment, and surgical risk assessment for all patients and then deciding which patient needs to undergo noninvasive testing, coronary angiography and revascularization, perioperative monitoring, and aggressive postoperative care.

Comparative prognostic value of clinical risk indexes, resting two-dimensional echocardiography, and dipyridamole stress thallium-201 myocardial imaging for perioperative cardiac events in major nonvascular surgery patients

The relative prognostic value of widely accessible resting two-dimensional echocardiographic ventricular function data has not been compared with recognized clinical and scintigraphic risk markers in patients who are unable to exercise before major nonvascular surgery. To this end, 53 consecutive patients aged 67 +/- 13 years undergoing preoperative evaluation (intraabdominal, 23%; orthopedic, 30%; thoracic, 9%; other, 38%) for known or suspected coronary artery disease were followed up to evaluate the prognostic value of these studies for the perioperative cardiac events (cardiac death [n = 4], myocardial infarction [n = 2], unstable angina [n = 3], and pulmonary edema [n = 8]) that occurred in 13 of the 53 patients (25%). Dipyridamole thallium-201 myocardial redistribution defects occurred in 15 (28%) patients. Resting echocardiographic left ventricular dysfunction was present in 21 (40%) patients. Multivariate analysis of clinical, echocardiographic, and scintigraphic risk predictors revealed that cardiac events were not predicted by clinical variables, including Goldman class or score. Cardiac events were independently predicted only by the presence of significant left ventricular dysfunction on resting two-dimensional echocardiography (p < 0.042) and dipyridamole thallium-201 defect redistribution (p < 0.026). A dipyridamole-induced reversible thallium-201 perfusion defect was predictive of subsequent cardiac death or myocardial infarction (p < 0.02), whereas left ventricular dysfunction on resting echocardiography was predictive of perioperative pulmonary edema (p < 0.023). We conclude that stress thallium-201 perfusion imaging and resting two-dimensional echocardiography provide independent prognostic information in patients undergoing major nonvascular surgery who are at significant risk for ischemic cardiac events and who are unable to perform standard exercise stress tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Degrees of coronary arterial narrowing at necropsy in men with large fusiform abdominal aortic aneurysm

In 27 patients (mean age at death 72 +/- 9 years) with abdominal aortic aneurysm (AAA) > or = 5.0 cm in its widest transverse diameter, the amounts of narrowing at necropsy in the 4 major (left main, left anterior descending, left circumflex, and right) epicardial coronary arteries were determined. During life, 12 of the 27 patients (44%) had symptoms of myocardial ischemia: angina pectoris alone in 2, acute myocardial infarction alone in 3, angina pectoris and acute myocardial infarction in 5, and sudden coronary death in 2. Ten of the 27 patients (37%) died from consequences of myocardial ischemia. Six (22%) died from rupture of the AAA. Grossly visible left ventricular necrosis or fibrosis, or both, was present in 15 patients (56%). Of the 27 patients, 23 (85%) had narrowing 76 to 100% in cross-sectional area of 1 or more major coronary arteries by atherosclerotic plaque. The mean number of coronary arteries per patient severely (> 75%) narrowed was 2.0 +/- 1.3/4.0. Of the 108 major coronary arteries in the 27 patients, 55 (51%) were narrowed > 75% in cross-sectional area by plaque. The 4 major coronary arteries in the 27 patients were divided into 5-mm segments and a histologic section, stained by the Movat method, was prepared from each segment. The mean percentages of the resulting 1,475 five-mm segments narrowed in cross-sectional area 0 to 25%, 26 to 50%, 51 to 75%, 76 to 95% and 96 to 100% were 17, 37, 28, 15 and 3%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of dipyridamole-thallium scanning for preoperative evaluation of cardiac risk for nonvascular surgery

The ability to stratify cardiac risk before nonvascular surgery using clinical markers and dipyridamole-thallium scanning (DTS) was assessed for patients with known or suspected coronary artery disease unable to exercise. Of 100 consecutively studied patients who proceeded to nonvascular surgery, 9 (9%) experienced greater than or equal to 1 perioperative cardiac ischemic event, including death in 2 patients (2%) and nonfatal myocardial infarction in 2 (2%). Logistic regression identified 2 clinical predictors (age greater than 70 years and history of heart failure), and 1 DTS (thallium redistribution) predictor of events. Of 45 patients with neither clinical variable, none (0%; 95% confidence intervals [CI] 0 to 8%) had events. Of 55 patients with greater than or equal to 1 clinical marker, 9 (16.4%; 95% CI 7 to 26%) had events. Within this subgroup, 1 of 31 patients (3.2%; 95% CI 0 to 16%) without thallium redistribution had events compared with 8 of 24 (33.3%; 95% CI 14 to 52%) with redistribution. An algorithm combining 5 independent clinical and 2 DTS predictors, derived previously in vascular surgery patients, was validated in the 100 nonvascular surgery patients. It is concluded that preoperative planar DTS is most useful to stratify selected nonvascular surgery patients at intermediate or high risk by clinical assessment. However, for almost half of those patients with known or suspected coronary artery disease, DTS may be unnecessary because of sufficiently low predictive value based on simple clinical descriptors.