Abstract
BACKGROUND:
The incidence of perioperative myocardial ischemia (PMI) is the highest in patients who have coronary artery disease, and it is the best predictor of intrahospital morbidity and mortality.
OBJECTIVE:
To identify predictors of PMI in patients who have coronary artery disease and are undergoing abdominal nonvascular surgery.
METHODS:
A prospective, observational, clinical study of 111 consecutive patients with angiographically verified coronary artery disease, scheduled for open abdominal nonvascular surgery, was conducted. Patients received general anesthesia and were monitored by continuous electrocardiogram during surgery and immediately postsurgery (72 h period) in the intensive care unit at the University Clinical Center (Belgrade, Serbia). All of the patients had 12-lead electrocardiography immediately after the surgery, on postoperative days 1, 2 and 7, and one day before discharge from hospital. The patients were monitored until the 30th postoperative day.
RESULTS:
A total of 24 predictors for PMI were analyzed. The Pearson’s χ2 test and a binomial logistic regression model were used for statistical analysis. A significant difference in the incidence of PMI was found in the coronary artery disease patients with an associated risk factor (14 of 24 risk factors) compared with those without the risk factor. In particular, a highly significant difference in the incidence of PMI was found in coronary artery disease patients with angina pectoris, compared with those without angina pectoris.
CONCLUSION:
Using the multivariate logistic regression analysis, angina pectoris was an independent predictor of PMI.
Keywords: Beta-blockers, Cardioprotection, Coronary ischemia, Metoprolol, Surgery
Perioperative myocardial ischemia (PMI) is a very important cause of morbidity and mortality in cardiac patients undergoing noncardiac surgery. The incidence of PMI is the highest in patients who have coronary artery disease (1–14). Patients with verified coronary artery disease account for approximately one-third of all patients undergoing noncardiac surgery each year (15). A meta-analysis study showed the incidence of PMI to be between 20% and 63% (1–5,16,17). In 70% of cases, PMI leads to an unfavourable prognosis (unstable angina pectoris, nonfatal myocardial infarction, myocardial revascularization and heart death) (1,5). The majority of postoperative ischemia develops at the end of the surgical intervention, on the day of operation or on the first postoperative day (1). A large majority (more than 90%) of postoperative ischemias are asymptomatic (1,4). Postoperative ST-T segment changes include almost only the episodes of ST depression (1,4,5,18). Perioperative acute mental stress, pain, hypoxemia, anemia, hypothermia, extreme blood pressure and heart rate variations may result in myocardial ischemia at the site of hemodynamically significant coronary artery stenosis (1).
The aim of the present prospective, observational, clinical study was to identify predictors of PMI in the group of patients with angiographically verified coronary artery disease, undergoing open abdominal nonvascular surgery under general anesthesia.
Methods
Study population
A prospective, observational, clinical study was conducted, consisting of 111 consecutive patients with angiographically verified coronary artery disease, operated on at the Department of Digestive Surgery, Institute of Digestive System Diseases, University Clinical Center of Serbia (tertiary level teaching hospital), Belgrade, Serbia.
The criterion for being enrolled in the present study was having angiographically verified coronary artery disease. Consecutive patients with angiographically verified coronary artery disease were recruited because it was the only definitive way to test whether an association exists with PMI.
In Serbia, performing coronary angiography before an elective noncardiac surgery is not a routine procedure. Indication for coronary angiography and for myocardial revascularization was decided independently of the patient’s planned noncardiac surgery, by a cardiosurgical consultation team at our institution.
Mild stenosis of coronary arteries (less than 75%) with recommendation for drug therapy (beta-blockers, acetylsalicylic acid, statins) was angiographically verified in 56 patients (50.5%). Severe stenosis of coronary arteries (75% or greater) indicated for myocardial revascularization was found in 55 patients (49.5%).
Coronary artery bypass grafting was performed in 34 patients before the present surgically treated noncardiac disease manifested.
Study protocol
All patients provided their coronary angiography findings, along with other medical history, on admission to our institution for surgical treatment. The group of patients without previous coronary angiography was excluded from the study, because their coronary disease was diagnosed only by medical history, without any former diagnostic tests; there were no diagnostic tests available at that time to confirm or rule out coronary diseases in these patients.
Before surgery, all patients were subjected to a complete physical and cardiological examination, and other necessary specialist and subspecialist examinations related to their presenting diseases were performed. Preoperative 12-lead electrocardiography (Schiller AT-1, Schiller Corporation, Austria), heart and chest x-ray (Shimadzu RS-50 A, Shimadzu Corporation, Japan), transthoracic echocardiography (Siemens Sequoia 256, Siemens Corporation, USA) and complete laboratory tests (Olympus 400, Olympus, Japan) were carried out in all patients.
Perioperative management – risk reduction strategy
Patients with coronary artery disease were monitored by continuous electrocardiogram during the surgery as well as in the immediate 72 h postoperative period in the intensive care unit, which recorded blood pressure and frequency values every hour, electrocardiographic changes and saturation. All of the patients had 12-lead electrocardiography immediately after the surgery, and on postoperative days 1, 2 and 7, as well as one day before discharge from hospital. The patients were monitored on a daily basis during their stay in hospital and on discharge until the 30th postoperative day. The patients were examined by a cardiologist each day during hospitalization.
Indicated coronary artery bypass grafting before open abdominal nonvascular surgery was not performed in 21 patients (18.9%) because of emergency surgery and/or poor general health status.
Indicated beta-blockers (metoprolol) were administered to 83 patients (74.8%), and 28 patients (25.2%) did not receive beta-blocker therapy because the drugs were contraindicated (chronic obstructive pulmonary disease, hypotension, bradycardia, transient episodes of complete heart block, drug allergy). Beta-blocker therapy was not discontinued during the perioperative period until postoperative day 30.
Nitrates were applied in 78 patients (70.3%) who had angina during the entire perioperative period until postoperative day 30.
Acetylsalicylic acid was given to 56 patients (50.4%), and 55 patients (49.5%) did not receive acetylsalicylic acid because the drug was contraindicated (gastrointestinal bleeding, thrombocytopenia). Acetylsalicylic acid was discontinued three days before planned surgery, and reinstated on the fourth postoperative day.
Perioperative cardiac complications
Transient symptomatic or asymptomatic myocardial ischemia were the only observed perioperative cardiac complications.
Criteria for perioperative transient myocardial ischemia with or without angina pains were transient and/or repeating ST elevations 2 mm or greater in leads V1, V2 and V3, and 1 mm or greater in other leads, ST depressions 1 mm or greater in at least two adjacent leads, or symmetric inversion T waves 1 mm or greater documented by continuous ST-T segment monitoring and/or 12-lead electrocardiography (19).
Statistical analysis
Coronary artery disease patients were divided into two groups based on the presence or absence of associated risk factors of PMI. Group 1 included coronary artery disease patients with associated risk factors, and group 2 consisted of coronary artery disease patients without any associated risk factors. Both groups of patients were compared in relation to PMI.
Pearson’s χ2 test and binomial logistic regression were used for statistical analysis. Pearson’s χ2 test was used in the form of contingency tables, given that variables were of attributive categorical type and P<0.05 was considered to be statistically significant.
Binomial (or binary) logistic regression is a form of regression that is used when the dependent variable is a dichotomy and the independent variables are of any type. Logistic regression can be used to predict a dependent variable on the basis of continuous and/or categorical independents; to determine the percentage of variance in the dependent variable explained by the independent variables; to rank the relative importance of independents; to assess interaction effects; and to understand the impact of covariate control variables.
RESULTS
Clinical, angiographic and echocardiographic characteristics of the study patients are shown in Table 1.
TABLE 1.
Clinical, angiographic and echocardiographic characteristics of study patients
| Patient characteristics | n (%) |
|---|---|
| History of coronary artery disease | 111 (100) |
| Previous myocardial infarction | 84 (75.7) |
| Postinfarction angina pectoris | 51 (45.9) |
| Angina pectoris without previous myocardial infarction | 27 (24.3) |
| Previous myocardial infarction without postinfarction angina pectoris | 33 (29.7) |
| Mild angina pectoris | 58 (52.2) |
| Severe angina pectoris | 20 (18.0) |
| Angiographic characteristics of selected patients | |
| Coronary angiography | 111 (100) |
| Mild stenosis (less than 75%) | 56 (50.5) |
| Severe stenosis (75% or greater) | 55 (49.5) |
| Nonrevascularized myocardium but indicated for revascularization | 21 (18.9) |
| Single-vessel coronary disease | 11 |
| Two-vessel coronary disease | 6 |
| Two-vessel coronary disease with left main stem stenosis | 1 |
| Three-vessel coronary disease | 3 |
| Revascularized myocardium – coronary artery bypass grafting | 34 (30.6) |
| Echocardiographic parameters | |
| End-diastolic diameter of the left ventricle greater than 5.7 cm | 45 (40.5) |
| Left ventricular ejection fraction less than 35% | 15 (13.5) |
| Segmental wall motion abnormalities | 60 (54.0) |
Comorbid diseases and drug therapy of the study patients with coronary artery disease are presented in Table 2.
TABLE 2.
Comorbid diseases and drug therapy of study patients with coronary artery disease
| Comorbid diseases | n (%) |
|---|---|
| History of chronic or acute heart failure | 17 (15.3) |
| Valvular heart disease | 29 (26.1) |
| History of arrhythmias and conduction disturbances | 48 (43.2) |
| History of chronic or acute renal failure | 5 (4.5) |
| History of cerebrovascular accident | 17 (15.3) |
| History of peripheral arterial disease | 8 (7.2) |
| Chronic obstructive pulmonary disease | 11 (9.9) |
| Risk factors for coronary artery disease | |
| Hypertension | 70 (63.1) |
| Diabetes mellitus | 28 (25.2) |
| Dyslipidemia | 29 (26.1) |
| Active smokers | 28 (25.2) |
| Family history of coronary disease | 21 (18.9) |
| Age older than 70 years | 45 (40.5) |
| Male sex | 92 (82.9) |
Classification of the coronary artery disease patients according to type of surgery and nature of digestive illness are illustrated in Table 3.
TABLE 3.
Classification of coronary artery disease patients (n=111) according to type of surgery and nature of digestive illness
| Patient classifications | n (%) |
|---|---|
| Type of surgery | |
| Emergent/urgent surgery | 31 (27.9) |
| Elective surgery | 80 (72.1) |
| Nature of digestive illness | |
| Malignant disease | 52 (46.8) |
| Benign disease | 59 (53.1) |
| Esophageal surgery | 12 (10.8) |
| Hepatobiliary surgery | 48 (43.2) |
| Colorectal surgery | 36 (32.4) |
| Ventral hernia repair | 15 (13.5) |
| Duration of surgery longer than 3 h | 36 (32.4) |
A comparison of coronary artery disease patients with and without associated risk factors for PMI is presented in Table 4.
TABLE 4.
Comparison between coronary artery disease patients with (group 1) and without (group 2) associated risk factors for perioperative myocardial ischemia
| Risk factors for perioperative myocardial ischemia | Group 1, n (%) | Group 2, n (%) | P* |
Logistic regression analysis |
|
|---|---|---|---|---|---|
| Univariate | Multivariate | ||||
| Angina pectoris | 25 (32.0) | 0 (0.0) | <0.01 | 0.000 | 0.037 |
| Nonrevascularized myocardium (but indicated for revascularization) | 2 (5.9) | 23 (29.9) | >0.01 | 0.013 | 0.351 |
| Valvular heart disease | 11 (37.9) | 14 (17.1) | <0.05 | 0.127 | – |
| History of chronic or acute heart failure | 8 (47.0) | 17 (18.0) | <0.01 | 0.012 | 0.959 |
| History of arrhythmias and conduction disturbances | 17 (35.4) | 8 (12.7) | <0.01 | 0.006 | 0.311 |
| History of chronic or acute renal failure | 4 (80.0) | 21 (19.8) | <0.01 | 0.015 | 0.330 |
| History of cerebrovascular accident | 5 (29.4) | 20 (21.3) | >0.05 | 0.462 | – |
| History of peripheral arterial disease | 3 (37.5) | 22 (21.3) | >0.05 | 0.555 | – |
| Chronic obstructive pulmonary disease | 5 (45.4) | 20 (20.0) | >0.05 | 0.066 | – |
| Hypertension | 19 (27.1) | 6 (14.6) | >0.01 | 0.134 | – |
| Diabetes mellitus | 9 (32.1) | 16 (19.3) | >0.01 | 0.206 | – |
| Dyslipidemia | 16 (55.2) | 9 (11.0) | <0.01 | 0.000 | 0.104 |
| Active smoking | 12 (42.8) | 13 (15.7) | <0.01 | 0.003 | 0.857 |
| Family history of coronary disease | 10 (47.6) | 15 (16.7) | <0.01 | 0.004 | 0.429 |
| Age older than 70 years | 11 (24.4) | 14 (21.2) | >0.05 | 0.689 | – |
| Male sex | 21 (22.8) | 4 (21.0) | >0.01 | 0.866 | – |
| End-diastolic diameter of the left ventricle greater than 5.7 cm | 16 (35.5) | 9 (13.6) | <0.01 | 0.008 | 0.598 |
| Left ventricular ejection fraction less than 35% | 7 (46.7) | 18 (18.7) | <0.05 | 0.036 | 0.900 |
| Segmental wall motion abnormalities | 16 (26.7) | 9 (17.6) | >0.05 | 0.574 | – |
| Emergent surgery | 10 (32.2) | 15 (18.7) | >0.05 | 0.131 | – |
| Malignant disease of the digestive system | 17 (32.7) | 8 (13.5) | <0.05 | 0.019 | 0.154 |
| Duration of surgery longer than 3 h | 13 (36.1) | 12 (16.0) | <0.01 | 0.020 | 0.729 |
| Poor laboratory findings | 18 (36.7) | 7 (11.3) | <0.01 | 0.002 | 0.241 |
| Beta-blocker (metoprolol) | 14 (16.9) | 11 (39.3) | <0.05 | 0.014 | 0.071 |
Pearson’s χ2 test
Using the Pearson’s χ2 test, a significant difference in the incidence of PMI was found in the coronary artery disease patients with an associated risk factor in relation to patients without the risk factor – in 14 of 24 cases (Table 4).
The main result of the study was a highly significant difference in the incidence of PMI between coronary artery disease patients with angina pectoris and those without angina pectoris.
Using the univariate logistic regression analysis, the predictors of PMI were angina pectoris, nonrevascularized myocardium, history of heart failure, history of arrhythmias and conduction disturbances, history of renal failure, dyslipidemia, active smoking, family history of coronary disease, end-diastolic diameter of the left ventricle greater than 5.7 cm, left ventricular ejection fraction less than 35%, malignant disease of the digestive system, duration of surgery longer than 3 h, poor laboratory findings, and abrupt discontinuation or not given beta-blocker therapy (Table 4).
Using the multivariate logistic regression analysis, angina pectoris was established as an independent predictor of PMI (Table 4).
DISCUSSION
From our observations, PMI is very common and is a significant cardiac complication in coronary patients having undergone an open abdominal nonvascular surgery under general anesthesia.
The objective of our prospective, observational, clinical study was to identify the predictors of PMI in a selected group of patients. The group consisted of 111 consecutive patients with angiographically verified coronary artery disease and associated abdominal disease indicated for surgical intervention.
All of the patients had coronary angiographies performed before abdominal disease was diagnosed. A subgroup of patients with severe coronary artery stenosis was indicated for myocardial revascularization regardless of noncardiac surgery. Another subgroup with moderate coronary artery stenosis was indicated for drug therapy. In the subgroup with severe stenosis, myocardial revascularization was performed in 34 patients (30.6%) before admission to our institution, and not carried out in 21 (18.9%). The patients of the latter group were either scheduled for urgent surgery or their general health condition was poor, so myocardial revascularization before open abdominal nonvascular surgery was not performed at our institution.
Perioperative cardiac beta-blocker protection was applied in 83 patients (74.8%) throughout the entire perioperative period until postoperative day 30. It was not used in 28 patients (25.2%) because of already detected or newly identified contraindication for these drugs.
Twenty-four risk factors, proved in earlier studies to be the predictors of higher perioperative morbidity and mortality in cardiac patients in noncardiac surgery, were analyzed (20,21).
The patients were monitored during the operation, as well as in the immediate 72 h postoperative period in the intensive care unit, and afterwards at the wards on a daily basis until the end of their stay. Subsequently, on discharge, they were followed on an outpatient basis until the 30th postoperative day.
PMI was recorded by continuous ST-T segment monitoring and/or 12-lead electrocardiogram according to approved criteria (19).
Coronary patients were divided into two groups based on presence or absence of risk factors, and compared by incidence of PMI.
Pearson’s χ2 test and bionominal logistic regression (univariate and multivariate analyses) were used for statistical data processing.
The comparison of the two groups of coronary artery disease patients revealed that a significantly higher incidence of PMI was found in patients with associated risk factors than in those without these risk factors. We concluded that PMI is multifactorial in origin.
The most significant result of our study was that angina pectoris as a risk factor was an independent predictor of PMI.
Many authors (2,7,8,16,18,19,21–28) as well as the Study of Perioperative Ischemia (SPI) Research Group (3–14) have analyzed PMI, and shown that it is a very frequent and severe complication in patients with verified coronary artery disease and in patients with risk factors of coronary disease undergoing noncardiac surgery. It is a significant predictor of major and fatal perioperative cardiac complications, as well as early and late prognosis (1,5).
The incidence of PMI in our study ranged from 0% to 80%, with a mean value of 22.5%. In comparison with meta-analysis studies, the incidence of PMI in our study was at the lower limit, accounting for 22.5% versus 20% to 63% (1).
CONCLUSIONS
Using the multivariate logistic regression analysis, it was confirmed that angina pectoris was an independent predictor of PMI.
Footnotes
COMPETING INTERESTS: The authors declare that they have no competing interests.
REFERENCES
- 1.Priebe HJ. Triggers of perioperative myocardial ischaemia and infarction. Br J Anaesth. 2004;93:9–20. doi: 10.1093/bja/aeh147. [DOI] [PubMed] [Google Scholar]
- 2.Landesberg G, Mosseri M, Wolf Y, Vesselov Y, Weissman C. Perioperative myocardial ischemia and infarction: identification by continuous 12-lead electrocardiogram with online ST-segment monitoring. Anesthesiology. 2002;96:264–70. doi: 10.1097/00000542-200202000-00007. [DOI] [PubMed] [Google Scholar]
- 3.Mangano DT, Browner WS, Hollenberg M, Li J, Tateo IM. Long-term cardiac prognosis following noncardiac surgery. The Study of Perioperative Ischemia Research Group. JAMA. 1992;268:233–9. doi: 10.1001/jama.268.2.233. [DOI] [PubMed] [Google Scholar]
- 4.Mangano DT, Hollenberg M, Fegert G, et al. Perioperative myocardial ischemia in patients undergoing noncardiac surgery – I: Incidence and severity during the 4 day perioperative period. The Study of Perioperative Ischemia (SPI) Research Group. J Am Coll Cardiol. 1991;17:843–50. doi: 10.1016/0735-1097(91)90863-5. [DOI] [PubMed] [Google Scholar]
- 5.Mangano DT, Browner WS, Hollenberg M, London MJ, Tubau JF, Tateo IM. Association of perioperative myocardial ischemia with cardiac morbidity and mortality in men undergoing noncardiac surgery. The Study of Perioperative Ischemia Research Group. N Engl J Med. 1990;323:1781–8. doi: 10.1056/NEJM199012273232601. [DOI] [PubMed] [Google Scholar]
- 6.Browner WS, Li J, Mangano DT. In-hospital and long-term mortality in male veterans following noncardiac surgery. The Study of Perioperative Ischemia Research Group. JAMA. 1992;268:228–32. [PubMed] [Google Scholar]
- 7.Mangano DT. Characteristics of electrocardiographic ischemia in high-risk patients undergoing surgery. The Study of Perioperative Ischemia Research Group. J Electrocardiol. 1990;23(Suppl):20–7. doi: 10.1016/0022-0736(90)90068-d. [DOI] [PubMed] [Google Scholar]
- 8.London MJ, Tubau JF, Wong MG, et al. The “natural history” of segmental wall motion abnormalities in patients undergoing noncardiac surgery. SPI Research Group. Anesthesiology. 1990;73:644–55. doi: 10.1097/00000542-199010000-00010. [DOI] [PubMed] [Google Scholar]
- 9.Wallace A, Layug B, Tateo I, et al. Prophylactic atenolol reduces postoperative myocardial ischemia. McSPI Research Group. Anesthesiology. 1998;88:7–17. doi: 10.1097/00000542-199801000-00005. [DOI] [PubMed] [Google Scholar]
- 10.Halm EA, Browner WS, Tubau JF, Tateo IM, Mangano DT. Echocardiography for assessing cardiac risk in patients having noncardiac surgery. The Study of Perioperative Ischemia Research Group. Ann Intern Med. 1996;125:433–41. doi: 10.7326/0003-4819-125-6-199609150-00001. [DOI] [PubMed] [Google Scholar]
- 11.Hollenberg M, Mangano DT. Therapeutic approaches to postoperative ischemia. The Study of Perioperative Ischemia Research Group. Am J Cardiol. 1994;73:30B–33B. doi: 10.1016/0002-9149(94)90263-1. [DOI] [PubMed] [Google Scholar]
- 12.Eisenberg MJ, London MJ, Leung JM, et al. Monitoring for myocardial ischemia during noncardiac surgery. A technology assessment of transesophageal echocardiography and 12-lead electrocardiography. The SPI Research Group. JAMA. 1992;268:210–6. doi: 10.1001/jama.268.2.210. [DOI] [PubMed] [Google Scholar]
- 13.Hollenberg M, Mangano DT, Browner WS, London MJ, Tubau JF, Tateo IM. Predictors of postoperative myocardial ischemia in patients undergoing noncardiac surgery. The SPI Research Group. JAMA. 1992;268:205–9. [PubMed] [Google Scholar]
- 14.Mangano DT, Wong MG, London MJ, Tubau JF, Rapp JA. Perioperative myocardial ischemia in patients undergoing noncardiac surgery-II: Incidence and severity during the 1st week after surgery. The SPI Research Group. J Am Coll Cardiol. 1991;17:851–7. doi: 10.1016/0735-1097(91)90864-6. [DOI] [PubMed] [Google Scholar]
- 15.Maggio PM, Taheri PA. Perioperative issues: Myocardial ischemia and protection – beta-blockade. Surg Clin North Am. 2005;85:1091–102. doi: 10.1016/j.suc.2005.09.016. [DOI] [PubMed] [Google Scholar]
- 16.Fleisher LA, Rosenbaum SH, Nelson AH, Barash PG. The predictive value for postoperative ischemic cardiac events in vascular and nonvascular surgery patients. Am Heart J. 1999;122:980–6. doi: 10.1016/0002-8703(91)90461-p. [DOI] [PubMed] [Google Scholar]
- 17.Mangano DT. Perioperative cardiac morbidity. Anesthesiology. 1990;72:153–84. doi: 10.1097/00000542-199001000-00025. [DOI] [PubMed] [Google Scholar]
- 18.Fleisher LA, Nelson AH, Rosenbaum SH. Postoperative myocardial ischemia: Etiology of cardiac morbidity or manifestation of underlying disease? J Clin Anesth. 1995;7:97–102. doi: 10.1016/0952-8180(94)00030-8. [DOI] [PubMed] [Google Scholar]
- 19.Devereaux PJ, Goldman L, Yusuf S, Gilbert K, Leslie K, Guyatt GH. Surveillance and prevention of major perioperative ischemic cardiac events in patients undergoing noncardiac surgery. CMAJ. 2005;173:779–88. doi: 10.1503/cmaj.050316. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Fleisher LA, Beckman JA, Brown KA, et al. ACC/AHA 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery) developed in collaboration with the American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Rhythm Society, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, and Society for Vascular Surgery. J Am Coll Cardiol. 2007;50:e159–241. doi: 10.1016/j.jacc.2007.09.003. [DOI] [PubMed] [Google Scholar]
- 21.Auerbach A, Goldman L. Assessing and reducing the cardiac risk of noncardiac surgery. Circulation. 2006;113:1361–76. doi: 10.1161/CIRCULATIONAHA.105.573113. [DOI] [PubMed] [Google Scholar]
- 22.Devereaux PJ, Goldman L, Cook DJ, Gilbert K, Leslie K, Guyatt GH. Perioperative cardiac events in patients undergoing noncardiac surgery: A review of the magnitude of the problem, the pathophysiology of the events and methods to estimate and communicate risk. CMAJ. 2005;173:627–34. doi: 10.1503/cmaj.050011. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Reinfert S, Goldman L, Polanczyk CA, Cook EF, Lee TH. Value of immediate postoperative electrocardiogram to update risk stratification after major noncardiac surgery. Am J Cardiol. 2004;94:1017–22. doi: 10.1016/j.amjcard.2004.06.057. [DOI] [PubMed] [Google Scholar]
- 24.Higham H, Sear JW, Neill F, Sear YM, Foex P. Peri-operative silent myocardil iscahemia and long term adverse outcomes in noncardiac surgical patients. Anaesthesia. 2001;56:630–7. doi: 10.1046/j.1365-2044.2001.01977.x. [DOI] [PubMed] [Google Scholar]
- 25.Hynynen M. Perioperative myocardial ischemia in patients undergoing noncardiac surgery: Does prolonged ischemia result in myocardial necrosis? Acta Anaesthesiol Scand. 1999;43:121–3. doi: 10.1034/j.1399-6576.1999.430201.x. [DOI] [PubMed] [Google Scholar]
- 26.Mangano DT, Siliciano D, Hollenberg M, et al. Postoperative myocardial ischemia therapeutic trials using intensive analgesia following surgery. Anesthesiology. 1992;76:343–53. [PubMed] [Google Scholar]
- 27.Hopf HB, Tarnow J. [Perioperative diagnosis of acute myocardial ischemia.] Anaesthesist. 1992;41:509–19. [PubMed] [Google Scholar]
- 28.London MJ, Hollenberg M, Wong MG, et al. Intraoperative myocardial ischemia: Localisation by continuous 12-lead electrocardiography. Anesthesiology. 1988;69:232–41. [PubMed] [Google Scholar]