Cardiac Risk (Anesthesia Text)

Baseline functional status must be assessed, as should cardiac risk factors such as age, male gender, smoking, DM, cholesterolemia, HTN, obesity, sedentary lifestyle, and CAD. Baseline EKG should be reviewed for evidence of previous MI, ischemic changes, conduction abnormalities, or left ventricular hypertrophy (LVH). Questions which must be asked: 1) functional status, 2) CVD history, 3) smoking, 4) diabetes, 5) cholesterol 6) medications

Major Risk Factors: recent myocardial infarction, congestive heart failure, and aortic stenosis are major predictors of perioperative mortality

Coronary Artery Disease: 40% of adults who have surgery will either have or be at risk for CAD [Mangano et. al.]. Clinical history is an important part of the evaluation – questions which must be asked include 1) functional status, 2) CVD history, 3) smoking, 4) diabetes, 5) cholesterol and 6) home medications. 2-3 flights of stairs suggest adequate cardiac reserve. There is no evidence that echocardiography in and of itself adds any appreciable information to clinical and EKG evaluations [Mangano et. al.; Hernandez et al].

Stable angina has not changed in 60 days or more, however, 70% of ischemic episodes are not associated with angina pectoris (although they do elicit chest pain at the time of injury) and as many as 15% of myocardial infarctions are silent, thus lack of angina is not a reliable positive predictor of good outcome. If angina does exist, the heart rate and blood pressure at which it occurs is informative. Note that an elevated heart rate is more likely than blood pressure to be associated with an ischemic event – Slogoff et. al. studied CCBs added on to beta-blockade in 444 patients, and found that, while ischemia appeared during anesthesia in 34.5% of all patients, its incidence was doubled (63%) when heart rate was greater than or equal to 110 [Slogoff et al].

Revised Cardiac Index

History of ischemia or heart disease, CHF, CVA, Cr > 2.0, IDDM, high risk surgery [Lee et al].

0: 0.4% risk of cardiac complications
1: 0.9% risk of cardiac complications
2: 7% risk of cardiac complications
3: 11% risk of cardiac complications

ACC/AHA and Cardiac Testing: Overview

Exercise Stress Test

Exercise Stress Test: perioperative cardiac risk is directly related to the extent of jeopardized viable myocardium identified by stress imaging [Beattie et al.].


Electrocardiogram: general consensus is to conduct this test within 30 days of surgery, although the optimal time is unknown. Retrospective study of 23,036 patients from Netherlands showed that patients with abnormal ECG had a greater incidence of cardiovascular death (1.8% vs 0.3%; adjusted OR 4.5) [Noordzij et al.].  Study of 405 major vascular surgery patients showed that voltage criteria for LVH (78 patients, 19%) and ST segment depression > 0.5 mm (98 patients, 24.2%) on preop ECGs were significantly associated with postop MI/cardiac death (OR 4.2 and 4.7; p <= 0.001) [Landesberg et al.].

Key evidence which can be obtained from the preoperative EKG include a) ischemia b) previous MI c) hypertrophy d) arrhythmia and e) electrolyte abnormalities

Resting LV Function

Resting Left Ventricular Function: has not been shown to be a consistent predictor of perioperative ischemic events [ACC/AHA Guidelines]

Utility of Preoperative EKG

There has been substantial debate over whether or not a preoperative EKG should be mandatory and if so, for whom. Tradition dictates that any male >= 40 years of female >=50 years of age requires an EKG. The following studies address are offered:

Noordzij (23,036 patients)

Noordzij et. al. retrospectively studied 23,036 patients who underwent 28,457 surgical procedures from 1991 to 2000. Patients were screened before surgery by type of surgery, cardiovascular risk factors, and preoperative electrocardiography. Multivariate logistic regression was applied to evaluate the relation between ECG abnormalities and cardiovascular death. Patients with abnormal ECG findings had a greater incidence of cardiovascular death than those with normal ECG results (1.8% vs 0.3%; adjusted OR 4.5, CI 3.3 to 6.0).

In patients who underwent low-risk or low- to intermediate-risk (orthopaedic, urologic) surgery, the difference in the incidence of cardiovascular death between those with and without ECG abnormalities was 0.2 to 0.7% with no cardiac risk factors, versus from 1.3 to 1.8% with one or more (absolute difference of 0.5%). In contrast, in intermediate-high or high risk procedures, the increase in cardiovascular death based on an abnormal preoperative EKG was 0.5 to 2.7% for patients with no cardiovascular risk factors, and 1.1 to 5.0% for patients with one or more

Relative Risk of Cardiovascular Death
(EKG Findings):
Atrial fibrillation 4.0
Left or right bundle branch block 2.0
Left ventricular hypertrophy 1.8
Premature ventricular complexes 2.3
Pacemaker rhythm 4.4
Q-wave 2.4
STD 2.1
Any abnormal EKG 4.5


Relative Risk of Cardiovascular Death
(Clinical History):
Heart failure 7.2
Renal insufficiency (Cr > 2.0) 7.0
Stroke 3.6
Coronary heart disease 3.6
Diabetes mellitus 2.0
[Noordzij et. al. Am J Cardiol 97:1103, 2006]

Landesberg (405 patients, major vascular surgery)

Landesberg et. al. combined two prospective studies on perioperative MI in patients undergoing major vascular surgery at two university hospitals to include 405 patients. A total of 19 postoperative cardiac complications occurred (two cardiac deaths and 17 myocardial infarctions). Voltage criteria for left ventricular hypertrophy (78 patients, 19%) and ST segment depression greater than 0.5 mm (98 patients, 24.2%) on preoperative ECGs were both significantly associated with postoperative myocardial infarction or cardiac death (odds ratio, 4.2 and 4.7; p = 0.001 and 0.0005, respectively). In each of the two study groups, a preoperative ECG abnormality that involved voltage criteria, ST segment depression, or both (134 patients, 33.1%) was more predictive of postoperative cardiac complications than any other preoperative clinical variable [Landesberg et. al. J Vasc Surg 26: 570, 1997]

Liu (513 NCS patients, prospective)

Liu et. al. conducted a prospective observational study of 513 patients > 70 years of age undergoing NCS (elective and emergent) at a UCSF facilities. The association between ECG abnormalities and postoperative cardiac complications was determined by multivariate logistic regression. 75.2% had at least one abnormality on their preoperative ECGs. On multivariate analysis, the predictors of postoperative cardiac complications included ASA >= 3 (OR 2.5 p = 0.007) and a history of CHF (OR 2.1, P = 0.034). The presence of abnormalities on preoperative ECGs was not associated with an increased risk of postoperative cardiac complications (OR 0.63, P = 0.26). Potential study limitation is that the patients who were scheduled for elective surgery may have had a preoperative evaluation by their primary care physicians in preparation for surgery. The authors indirectly evaluated this possibility by comparing the rates of preoperative ECG abnormalities of those who were scheduled for elective with those who presented for urgent/emergent surgery. Liu’s results suggested that the incidence of preoperative ECG abnormalities was not significantly different between the elective and the urgent/emergent groups in patients > 70 years of age undergoing NCS (73.9% vs 82%, P = 0.11). There were only 19 deaths and 52 perioperative complications (underpowered?). Authors did not stratify patients based on type of EKG changes [Liu et al.].

In patients with abnormal EKG (75.2%),
incidence of abnormalities:
Q waves 33.9%
Left axis deviation 19.3%
Right axis deviation 0.4%
ST junction/segment depression 17.9%
T wave changes 36.5%
Left ventricular hypertrophy 6.9%
Mobitz type II 0.2%
Left bundle branch block 4.3%
Right bundle branch block 5.3%
Frequent premature atrial complexes 7.0%
Frequent premature ventricular complexes 4.3%
Atrial fibrillation 3.5%
Sinus tachycardia 3.9%
Sinus bradycardia 0.4%
ST segment elevation 8.3%

van Klei (2967 NCS patients)

van Klei et. al. studied 2967 NCS patients > 50 years of age from 2 university hospitals, using multivariate logistic regression analysis to obtain the independent predictors of POMI and all-cause in-hospital mortality. The area under the ROC was estimated to evaluate different models. The ROC area of the model that included elements of the patient history but not the EKG was 0.80. ECG abnormalities that were associated with POMI were a right and a left bundle branch block. After adding these abnormalities in the regression model, the ROC area remained 0.80. Bundle branch blocks identified on the preoperative ECG were related to POMI and death but did not improve prediction beyond risk factors identified on patient history [van Klei et al.].


Podcast on Perioperative Beta Blockade: Discussion with Martin J. London, December 2009

Studies Showing Benefit

Mangano et. al.

Randomized, double-blind, placebo-controlled trial to compare the effect of atenolol with that of a placebo on overall survival and cardiovascular morbidity in patients with or at risk for coronary artery disease who were undergoing noncardiac surgery. The presence of coronary artery disease was indicated by a previous myocardial infarction, typical angina, or atypical angina with a positive stress test; a patient was considered at risk for coronary artery disease when he or she had at least two of the following cardiac risk factors: age >65 years, hypertension, current smoking, a serum cholesterol concentration >240 mg per deciliter (6.2 mmol per liter), and diabetes mellitus. Atenolol was given intravenously before and immediately after surgery and orally thereafter for the duration of hospitalization. A total of 200 patients were enrolled. Overall mortality after discharge from the hospital was significantly lower among the atenolol-treated patients than among those who were given placebo over the six months following hospital discharge (0 vs. 8 percent, P<0.001), over the first year (3 percent vs. 14 percent, P = 0.005), and over two years (10 percent vs. 21 percent, P = 0.019). The principal effect was a reduction in deaths from cardiac causes during the first six to eight months. Combined cardiovascular outcomes were similarly reduced among the atenolol-treated patients; event-free survival throughout the two-year study period was 68 percent in the placebo group and 83 percent in the atenolol group (p = 0.008) [Mangano et al.]. Unfortunately, Mangano’s study did not mention what percentage of the study population was on prior beta blocker therapy (as compared to the POISE trial, which excluded such patients), making it impossible to determine if the need for continued beta blockade, as opposed to initiation of beta blockade, might account for the difference in outcomes between the two large studies

Poldermans et. al.

Another study showed decreased rates of cardiac-related morbidity and mortality in high risk (at least one of the following: > 70 yo, angina, previous MI, CHF, current treatment for ventricular dysrhythmia, limited exercise capacity, dobutamine echo compatible with inducible ischemia) vascular surgery patients following bisoprolol administration (initial dose of bisoprolol was 5 mg orally once a day, one week after starting bisoprolol, the dose was increased to a maximum of 10 mg once daily if the heart rate remained above 60) [Poldermans] – reduction from 34 to 2% in 846 patients. Exclusion criteria in Poldermans included prior beta-blockade therapy, extensive wall-motion abnormalities, asthma, or strong evidence during stress testing of left main or severe three-vessel CAD.

POISE trial: B-blockers increase mortality

Despite the fact that two studies showed benefit of perioperative beta blockade, the POISE trial, which was larger, did not – patients with a history of CAD, PVD, CVA, hospitalization for CHF, undergoing major vascular surgery, or 3 of 7 (intrathoracic or intraperitoneal surgery, history of CHF, TIA, DM, Cr >175 μmol/L, >70, emergent/urgent surgery), given metoprolol ER 100 mg 2-4 hr preop. Total mortality increased from 2.3 to 3.1% at 30 days. An important exclusion criteria in POISE was “receiving a β-blocker or their physician planned to start one perioperatively” [POISE Study Group; Devereux et al].

Other Considerations

If used, it is believed that the dose of β-blocker should be titrated to 65 beats/min [Auerbach JAMA 287: 1435, 2002; Cohn Med Clin NA 87: 111, 2003] and avoided in those with asthma. Note that POISE excluded patients already on β-blockers. Alpha-2 agonists have also been shown to reduce perioperative cardiac events after both cardiac and non-cardiac surgery [Wijeysundera Am J Med 114: 742, 2003; Wallace Anesthesiology 101: 284, 2004], as well as provide pain relief. It is not known if these drugs are synergistic with B-blockers

Preoperative Intervention: the data?

Data do not show any benefit from preoperative CABG or percutaneous intervention for the sole purpose of reducing cardiac events – 5859 patients scheduled for vascular operations (33% AAA, 67% LE vascular occlusive disease) at 18 Veterans Affairs medical centers, 510 (9 percent) were considered at risk for perioperative cardiac morbidity by a cardiologist and were randomly assigned to either coronary-artery revascularization (59% percutaneous, 41% bypass) before surgery or no revascularization before surgery. The median time from randomization to vascular surgery was 54 days in the revascularization group and 18 days in the group not undergoing revascularization (p < 0.001). At 2.7 years after randomization, mortality in the revascularization group was 22 percent and in the no-revascularization group 23 percent (relative risk, 0.98; 95 percent confidence interval, 0.70 to 1.37; p=0.92). Within 30 days after the vascular operation, a postoperative myocardial infarction, defined by elevated troponin levels, occurred in 12 percent of the revascularization group and 14 percent of the no-revascularization group (p=0.37) [McFalls et al.]. Problems with this study – “at risk” at the discretion of a cardiologist (no guidelines).

Retrospective analysis did show a survival benefit in one subset of patients, those with L main stenosis > 50% (0.84% survival vs 0.52% survival, p < 0.01) [Garcia et al.]. A metaanalysis of one randomized, controlled trial (McFalls) and six retrospective studies included a total of 3949 patients, and found no long-term benefits associated with prophylactic coronary revascularization; the odds ratio was 0.81 (0.40-1.63) for long-term mortality and 1.65 (0.70-3.86) for late adverse cardiac events [Wong et al.].

Previous MI? How Long To Wait

Data which suggest waiting 6 months post-MI for elective surgery are based on several enormous (> 40,000 patients), one of which was at the Mayo Clinic, and most of which show a reduction in mortality when waiting 6 months after an MI. Note that these are in the pre-B-blocker era, however there are currently no better data refuting these findings

It is thought that recovery following myocardial infarction takes ~ 6 weeks. That said, studies from 1977-1990, when taken in aggregate, suggest that one should postpone elective surgery 6 months following a myocardial infarction.

Keep in mind, however, that while the incidence of perioperative MI stabilizes at 5-6% in patients with a previous MI, this is a 50-fold increase over the risk in patients who have never had an MI (0.13% overall risk). The majority of perioperative myocardial reinfarctions occur within 72 hours, however they can occur several months after surgery.

For patients who have gone elective percutaneous procedures, elective, non-cardiac surgery should be deferred for a period of time dependent on whether or not they received a drug eluting stent vs. a bare metal stent.

Data on non-cardiac surgery and stenting: adequate?

The risk of stent thrombosis seems to be low when surgery is delayed for at least 4 to 6 weeks after implantation of a BMS. The risk of stent thrombosis after DES implantation remains poorly studied, but may occur even in patients who have completed the recommended duration of antiplatelet therapy (3 months for SES and 6 months for PES) and subsequently undergo surgery, in most cases after stopping aspirin and clopidogrel. If major noncardiac surgery is planned within 1 month and certainly within 2 weeks, stent implantation generally should be avoided. If revascularization is required, then balloon angioplasty or coronary bypass surgery might well be preferred options. If surgery is planned between 1 and 12 months, particularly if complex anatomy is present, then BMS implantation may be preferable. If surgery is planned after 12 months, DES implantation may be an acceptable option [Brilakis et al.].

A 45% complication rate and a mortality of 20% were reported previously in patients undergoing non-cardiac surgery after coronary artery stenting. Discontinuation of antiplatelet drugs appeared to be of major influence on outcome. Thus Vicenzi et. al. undertook a prospective, observational multicentre study with predefined heparin therapy and antiplatelet medication in patients undergoing non-cardiac procedures after coronary artery stenting. 103 patients from three medical institutions were enrolled and received coronary artery stents within 1 yr before non-cardiac surgery (urgent, semi-urgent or elective). Antiplatelet drug therapy was not, or only briefly, interrupted. Heparin was administered to all patients. All patients were on an intensive/intermediate care unit after surgery. Main outcome was the combined (cardiac, bleeding, surgical, sepsis) complication rate. Of 103 patients, 44.7% (95% CI 34.9-54.8) suffered complications after surgery; 4.9% (95% CI 1.6-11.0) of the patients died. All but two (bleeding only) adverse events were of cardiac nature. The majority of complications occurred early after surgery. The risk of suffering an event was 2.11-fold greater in patients with recent stents (<35 days before surgery) as compared with percutaneous cardiac intervention more than 90 days before surgery [Vicenzi et al.].  In this study, it was generally recommended and agreed by the cardiology community to combine aspirin and clopidogrel or formerly ticlopidin for 1–3 months and then continue aspirin alone. During the course of the study, this recommendation was expanded to a 6–9 month combination therapy. The duration and combination of antiplatelet therapy appears to be of greater importance when drug-eluting stents are used, because they are apparently more prone to early thrombosis than bare metal stents. Furthermore, complete endothelialization of stents may occur within a few weeks, but this may also last longer than a year

In 2003, Wilson et al. published a retrospective study of 207 patients from the preceding decade, who underwent surgery within 60 days after PCI and stent placement. Eight patients (4%) suffered severe cardiac events inclusive of six patients who died (all of whom had PCI 6 weeks or less before surgery, no event occurred in patients with stents older than 6 weeks). Two additional patients experienced severe bleeding

Mayo Clinic Data: Bare Metal Stents

Retrospective study of 899 patients at Mayo Clinic showed that major adverse cardiac events (MACE) after non-cardiac surgery (NCS) decreased with increased time post-BMS placement – 10.5% (< 30d), 3.8% (31-90d), 2.8% (> 90d) and that bleeding complications were not associated with antiplatelet therapy within a week of surgery [