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ACC/AHA
Guideline Update for Perioperative Cardiovascular Evaluation
for Noncardiac Surgery
A
Report of the American College of Cardiology/American
Heart Association Task Force on Practice Guidelines
(Committee to Update the 1996 Guidelines on Perioperative
Cardiovascular Evaluation for Noncardiac Surgery)
IX.
Perioperative Surveillance
Although
much attention has been focused on the preoperative
preparation of the high-risk patient, intraoperative
and postoperative surveillance for myocardial ischemia
and infarction, arrhythmias, and venous thrombosis should
also lead to reductions in morbidity. Postoperative
myocardial ischemia has been shown to be the strongest
predictor of perioperative cardiac morbidity and is
rarely accompanied by pain (1).
Therefore, it may go untreated until overt symptoms
of cardiac failure develop.
The
diagnosis of a perioperative MI has both short- and
long-term prognostic value. Traditionally, a perioperative
MI has been associated with a 30% to 50% perioperative
mortality and has been associated with reduced long-term
survival (19,29,214,215).
Therefore, it is important to identify patients who
sustain a perioperative MI and to treat them aggressively
since it may reduce both short- and long-term risk.
A. Intraoperative
and Postoperative Use of Pulmonary Artery Catheters
1. General Considerations
The pulmonary artery catheter can provide significant
information critical to the care of the cardiac patient.
Its use, however, must be balanced against the cost
and risk of complications from insertion and use of
the catheter, which are low when the operators are experienced.
Several studies have evaluated the benefit of pulmonary
artery catheters in both randomized trials and those
using historical controls. In patients with prior MI,
when perioperative care included pulmonary artery and
intensive care monitoring for 3 days postoperatively,
there was a lower incidence of reinfarction than in
historical controls (29).
Other changes in management occurred during the period
under study, however, including the increased use of
beta-adrenergic sympathetic blockade. In particular,
patients with signs and symptoms of HF preoperatively,
who have a very high (35%) postoperative incidence of
HF, might benefit from invasive hemodynamic monitoring
(67).
2.
Summary of Evidence
Although a great deal of literature has evaluated the
utility of a pulmonary artery catheter during the perioperative
period in noncardiac surgery, relatively few controlled
studies have evaluated pulmonary artery catheterization
in relation to clinical outcomes. Randomized trials
have evaluated the routine use of pulmonary artery catheters
vs. central venous pressure catheters or selective use
of monitoring in abdominal aortic surgery and in elective
vascular surgery. In studies using appropriate patient
selection, no differences in cardiac morbidity (MI,
cardiac death) were detected (216,217,319,335,336).
An additional study demonstrated no difference in cardiac
morbidity in infrainguinal surgery patients when monitored
by a pulmonary artery catheter either from the evening
before surgery, 3 hours before surgery, or only if clinically
indicated; however, the groups with the pulmonary artery
catheter had fewer intraoperative hemodynamic disorders
(193).
Polanczyk et al performed a prospective cohort study
of 4,059 patients aged 50 years or older who underwent
major elective noncardiac procedures with an expected
length of stay of two or more days (337).
Major cardiac events occurred in 171 patients, and those
who underwent perioperative pulmonary artery catheterization
had a three-fold increased incidence of major postoperative
cardiac events (34 [15.4%] vs. 137 [3.6%]; p less than
0.001). In a case-control analysis of a subset of 215
matched pairs of patients who did and did not undergo
pulmonary artery catheterization, adjusted for propensity
of pulmonary artery catheterization and type of procedure,
patients who underwent perioperative pulmonary artery
catheterization also had increased risk of postoperative
congestive HF (odds ratio, 2.9; 95% CI, 1.4 to 6.2)
and major noncardiac events (odds ratio, 2.2; 95% CI,
1.4 to 4.9) (337).
Iberti et al demonstrated in a multicenter survey that
physicians' understanding of pulmonary artery catheterization
data is extremely variable, which may account for the
higher rate of postoperative congestive HF and greater
perioperative net fluid intake (338).
3.
Recommendations
Current evidence does not support routine use of a pulmonary
artery catheter perioperatively. Although evidence from
controlled trials is scant and a large-scale cohort
study demonstrated potential harm, the use of pulmonary
artery catheters may benefit high-risk patients. This
is in keeping with practice parameters for the intraoperative
use of a pulmonary artery catheter published by the
American Society of Anesthesiologists (218).
These parameters approach the decision to place the
pulmonary artery catheter as the interrelationship among
three variables: patient disease, surgical procedure,
and practice setting. With regard to the surgical procedure,
the extent of intraoperative and postoperative fluid
shifts is a dominant factor. Physician education on
the interpretation of the pulmonary artery catheterization
data is critical to achieve optimal benefit without
harm.
Recommendations
for Intraoperative Use of Pulmonary Artery Catheters
(218)
Class IIa
1. Patients at risk for major hemodynamic disturbances
that are most easily detected by a pulmonary artery
catheter who are undergoing a procedure that is likely
to cause these hemodynamic changes in a setting with
experience in interpreting the results (e.g., suprarenal
aortic aneurysm repair in a patient with angina).
Class
IIb
1. Either the patient's condition or the surgical procedure
(but not both) places the patient at risk for hemodynamic
disturbances (e.g., supraceliac aortic aneurysm repair
in a patient with a negative stress test).
Class
III
No risk of hemodynamic disturbances.
B.
Intraoperative and Postoperative Use of ST-Segment Monitoring
1. General
Considerations
Many contemporary operating rooms and intensive care
unit monitors incorporate algorithms that perform real-time
analysis of the ST segment. In addition, real-time ST-segment
monitoring via telemetry or ambulatory ECG (Holter)
monitors with alarms is being developed. Numerous studies
have demonstrated the limited ability of physicians
to detect significant ST-segment changes compared with
computerized or off-line analysis. If available, computerized
ST-segment trending is superior to visual interpretation
in the identification of ST-segment changes. Because
the algorithms used to measure ST-segment shifts are
proprietary, variability in accuracy between the different
monitors has been evaluated in several studies compared
with off-line analysis of standard Holter recordings
(339-341).
ST-trending monitors were found to have an average sensitivity
and specificity of 74% (range 60% to 78%) and 73% (range
69% to 89%), respectively (340).
Several factors have been identified that decreased
the accuracy of the monitors, which have been discussed
in detail elsewhere. Additionally, the lead system used
affects the incidence of ischemia detected, with leads
II and V5 detecting only 80% of all episodes detected
by 12-lead ECG (342).
2.
Summary of Evidence
Virtually all studies examining the predictive value
of intraoperative and postoperative ST-segment changes
have been performed using ambulatory ECG recorders.
Using retrospective analysis, investigators have
found postoperative ST-segment changes indicative of
myocardial ischemia to be In
patients at moderate risk for CAD (age less than 45
years without known CAD and only one risk factor), the
presence of intraoperative and postoperative ST-segment
changes was not associated with either ischemia on an
exercise stress test or cardiac events within 1 year
(343).
The total cohort of patients was small, which may limit
generalizability of these findings.
Intraoperative
ST-segment changes may also occur in low-risk populations.
ST-segment depression has been shown to occur during
elective cesarean sections in healthy patients (221,344).
Because these changes were not associated with regional
wall-motion abnormalities on precordial echocardiography,
in this low-risk population such ST-segment changes
may not be indicative of myocardial ischemia and CAD.
Thus,
although there are data to support the contention that
ST-segment monitoring detects ischemia, no studies have
addressed the issue of the effect on outcome when therapy
is based on the results of ST-segment monitoring.
Recommendations
for Perioperative ST-Segment Monitoring
Class IIa
When available, proper use of computerized ST-segment
analysis in patients with known CAD or undergoing vascular
surgery may provide increased sensitivity to detect
myocardial ischemia during the perioperative period
and may identify patients who would benefit from further
postoperative and long-term interventions.
Class
IIb
Patients with single or multiple risk factors for CAD.
Class
III
Patients at low risk for CAD.
C.
Surveillance for Perioperative MI
Multiple
studies have evaluated predictive factors for a perioperative
MI. The presence of clinical evidence of coronary artery
or peripheral vascular disease has been associated with
an increased incidence of perioperative MI. Factors
that increase the risk of a perioperative MI have been
discussed previously. Because of the increased risk
of both short- and long-term mortality from a perioperative
MI, accurate diagnosis is important.
1.
General Considerations
Perioperative MI can be documented by assessing clinical
symptoms, serial electrocardiography, cardiac-specific
biomarkers, comparative ventriculographic studies before
and after surgery, radioisotopic studies specific for
myocardial necrosis, and autopsy studies. The criteria
used to diagnose infarction in various studies differ
not only in the level of cardiac biomarkers that determine
abnormality but also the frequency with which they are
sampled following noncardiac surgery. The cardiac biomarker
profile after infarction exhibits a typical rise and
fall that differs among different biomarkers. Daily
sampling may miss detection of a cardiac biomarker rise
(such as MB isoenzyme of creatine kinase [CK-MB], thus
underestimating the incidence of perioperative infarction.
The ECG criteria used to define infarction may also
differ not only in the definition of a Q wave but also
with respect to the magnitude of ST-T wave shifts that
determine an abnormal response. In
the analysis of cardiac biomarker criteria, numerous
assays are available to measure CK-MB, cardiac troponin
I, and to a lesser extent, cardiac troponin T. CK-MB
may be released from noncardiac sources in patients
with ischemic limbs or those undergoing aortic surgery,
the group at highest risk for a perioperative MI. The
use of cardiac troponin I or T offers the potential
of enhanced specificity (223,345-350).
2.
Summary of Evidence
Very few studies have examined long-term outcome using
protocol-specific criteria for perioperative MI after
noncardiac surgery. Charlson et al (224)
reported on 232 mostly hypertensive or diabetic patients
undergoing elective noncardiac surgery. Serial ECGs
and CK-MB were collected for 6 days postoperatively.
The incidence of perioperative MI varied greatly depending
on the diagnostic criteria used. A strategy using an
ECG immediately after the surgical procedure and on
the first and second days postoperatively had the highest
sensitivity. Strategies including the serial measurement
of CK-MB had higher false-positive rates without higher
sensitivities. In contrast, Rettke et al (225)
reported that overall survival was associated
with the degree of CK-MB elevation in 348 patients undergoing
abdominal aortic aneurysm repair, with higher levels
associated with worse survival. Yeager et al (215)
evaluated the prognostic implications of a perioperative
MI in a series of 1,561 major vascular procedures. These
authors found that the incidence of subsequent MI and
coronary artery revascularization was significantly
higher in patients who suffered a perioperative MI,
except in the subset who only demonstrated an elevated
CK-MB without ECG changes or cardiovascular symptoms.
The
use of cardiac troponin I to examine the diagnosis of
perioperative MI was assessed in a series of 96 subjects
undergoing vascular surgery and 12 undergoing spinal
surgery. Blood samples were obtained every 6 hours for
36 hours postoperatively, and ECGs were acquired daily.
The appearance of a new segmental wall-motion abnormality
on a postoperative day 3 echocardiogram was used to
diagnose perioperative infarction. All 8 patients who
underwent vascular surgery and had segmental wall-motion
abnormalities had elevated cardiac troponin I levels;
6 had elevated CK-MB. Of 100 patients without new segmental
wall-motion abnormalities, 19 had CK-MB elevations;
1 had cardiac troponin I elevation (222).
Several studies have examined cardiac troponin T as
a marker for perioperative necrosis after noncardiac
surgery. Of 772 patients who underwent major noncardiac
procedures without major cardiovascular complications
during the index hospital admission, 12% and 27%, respectively,
had elevated cardiac troponin T and CK-MB values. During
six-month follow-up, 19 subjects had major cardiac complications
(14 cardiac deaths, 3 nonfatal MIs, and 2 admissions
for unstable angina). The relative risk of cardiac events
was 5.4 when cardiac troponin T was elevated, whereas
CK-MB did not predict late postdischarge cardiac events
(349).
In another report (346),
the diagnosis of perioperative MI was defined prospectively
as total CK-MB greater than 174 units per liter and
2 of the following: 1) CK-2/CK (mass or activity) greater
than 5%, 2) Q waves greater than 40 ms and 1 mm deep
in 2 contiguous leads, 3) troponin T greater than 0.2
mcg per liter, or 4) a positive pyrophosphate scan.
Of 323 patients undergoing noncardiac surgery (13.6%
vascular), 18 (5.6%) had a perioperative MI. The incident
rate of perioperative MI was 5.3% when the diagnosis
included autopsy data, new Q waves, or CK-2 elevation
greater than 5% of total CK associated with new ECG
changes. The incidence increased to 11.2% when the definition
included autopsy data, new Q waves, cardiac troponin
T greater than 0.2 mcg per liter, and ECG changes. The
MI rate increased to 20.7% when the definition of perioperative
MI included autopsy data, new Q waves, or cardiac troponin
T greater than 0.2 mcg per liter.
3.
Recommendations
Further evaluation regarding the optimal strategy for
surveillance and diagnosis of perioperative MI is required.
On the basis of current evidence, in patients without
documented CAD, surveillance should be restricted to
patients who develop perioperative signs of cardiovascular
dysfunction. In patients with high or intermediate clinical
risk who have known or suspected CAD and who are undergoing
high- or intermediate-risk
surgical procedures, the procurement of ECGs at baseline,
immediately after the surgical procedure, and daily
on the first 2 days after surgery appears to be the
most cost-effective strategy. Cardiac troponin measurements
24 hours postoperatively and on day 4 or hospital discharge
(whichever comes first) should be part of the diagnostic
strategy for perioperative MI detection
(350).
The majority of perioperative MI events will be non-Q
wave. Additional research is needed to correlate long-term
outcome results to magnitude of isolated cardiac troponin
elevations. The diagnosis of MI should be entertained
when the typical cardiac biomarker profile is manifest
in the immediate postoperative phase. A risk gradient
can be based on the magnitude of biomarker elevation
and presence or absence of concomitant new ECG abnormalities,
hemodynamic instability, and quality and intensity of
chest pain syndrome, if present. The ACC and the European
Society of Cardiology have provided a redefinition of
acute MI based on studies examining cardiac troponins
and clinical presentation/outcomes (351).
Patients who sustain a perioperative MI should have
evaluation of left ventricular function performed before
hospital discharge, and standard postinfarction therapeutic
medical therapy should be prescribed as defined in the
ACC/AHA Acute Myocardial Infarction guidelines (370).
Perioperative surveillance for acute coronary syndromes
using routine ECG and cardiac serum biomarkers is unnecessary
in clinically low-risk patients undergoing low-risk
operative procedures.
D.
Arrhythmia/Conduction Disease Disorders
Postoperative
arrhythmias are often due to remedial noncardiac problems
such as infection, hypotension, metabolic derangements,
and hypoxia. The approach taken to the acute management
of postoperative tachycardias varies depending on the
likely mechanism. If the patient develops a sustained
regular narrow-complex tachycardia, which is likely
due to atrioventricular nodal re-entrant tachycardia
or atrioventricular reciprocating tachycardia, the tachycardia
can almost always be terminated with vagal maneuvers
(Valsalva maneuver or carotid sinus massage) or with
intravenous adenosine. Most antiarrhythmic agents (especially
beta blockers, calcium channel blockers, and type 1a
or 1c antiarrhythmic agents) can be used to prevent
further recurrences in the postoperative setting. A
somewhat different approach is generally recommended
for atrial fibrillation and atrial flutter. The initial
approach to management generally involves the use of
intravenous digoxin, diltiazem or a beta blocker in
an attempt to slow the ventricular response. Among these
three types of medications, digitalis is least effective
and beta blockers most effective for controlling the
ventricular response during atrial fibrillation (313).
An additional benefit of beta blockers is that they
have been shown to accelerate the conversion of postoperative
supraventricular arrhythmias to sinus compared with
diltiazem (314).
Cardioversion of atrial fibrillation/flutter is generally
not recommended for asymptomatic or minimally symptomatic
arrhythmias until correction of the underlying problems
has occurred, which frequently leads to a return to
normal sinus rhythm. Also, cardioversion is unlikely
to result in long-term normal sinus rhythm if the underlying
problem is not corrected.
The avoidance of an electrolyte abnormality, especially
hypokalemia and hypomagnesemia, may reduce the perioperative
incidence and risk of arrhythmias, although acute preoperative
repletion of potassium in an asymptomatic individual
may be associated with greater risk than benefits (226-228,352).
Unifocal or multifocal premature
ventricular contractions do not merit therapy. Very
frequent ventricular ectopy or prolonged runs of nonsustained
ventricular tachycardia may require antiarrhythmic therapy
if they are symptomatic or result in hemodynamic compromise.
Patients with an ischemic cardiomyopathy who have nonsustained
ventricular tachycardia in the perioperative period
may benefit from referral for electrophysiologic testing
to determine the need for an ICD (353,354).
Ventricular arrhythmias may respond to intravenous beta
blockers, lidocaine, procainamide, or amiodarone (186,355-357).
Electrical cardioversion should be used for sustained
supraventricular or ventricular arrhythmias that cause
hemodynamic compromise.
Bradyarrhythmias
that occur in the postoperative period are usually secondary
to some other cause, such as certain medications, an
electrolyte disturbance, hypoxemia, or ischemia. On
an acute basis, many will respond to intravenous medication
such as atropine, and some will respond to intravenous
aminophylline. Bradyarrhythmias due to sinus node dysfunction
and advanced conduction abnormalities such as complete
heart block will respond to temporary or permanent transvenous
pacing or permanent pacing. The indications are the
same as those for elective permanent pacemaker implantations.
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