PRE-OPERATIVE CARDIAC EVALUATION FOR VASCULAR SURGERY

1
PRE-OPERATIVE CARDIAC EVALUATION FOR VASCULAR
SURGERY

• Jamil Mayet
• Consultant Cardiologist,
• St Marys Hospital

2
The scale of the problem

• Routine coronary angiography in 1000 vascular
  surgical candidates
• Normal coronary arteries in only 8.
• Where no clinical evidence of IHD 37 prevalence
  of significant coronary artery stenoses.
• Hertzer et al. Ann Surg 1984199223-33.

3
The scale of the problem

• Patients requiring elective vascular surgery are
  at high risk of both peri-operative and late
  cardiac events.
• Michigan experience
• 13.6 operative mortality in 1980.
• 5.6 operative mortality in 1990.
• Decrease in spite of aging population and
  increased co-morbidity.
• Late cardiac events in 9-12 of survivors within
  2 years of surgery.
• Katz et al. J Vasc Surg 199419804-17.

4
What are the specific problems

• Patients at high risk of coronary artery disease.
• Often patients unable to exercise to manifest
  symptoms of angina.
• Exercise treadmill testing is often limited due
  to claudication or resting ECG abnormalities (eg
  LBBB or LVH with ST/T segment abnormalities).
• Non-invasive pharmacological testing (eg stress
  echo and thallium scanning) is time consuming,
  requires specialist personnel and costly.
• Routine coronary angiography is costly and at
  higher risk than usual in these patients.

5
Risk Stratification

• Can a group of low risk patients be identified on
  the basis of history, examination and the ECG?
• Clinical risk factors
• High risk surgery (AAA repair, thoracic,
  abdominal)
• IHD (MI, Q waves, angina, nitrates, ve stress
  test)
• CCF (History, examination, CXR)
• Cerebrovascular disease (Stroke, TIA)
• IDDM
• Creatinine gt 177 micromol/l
• 2893 patients were the derivation cohort 110
  were AAA cases and 498 other vascular surgical
  cases.
• 1422 were the prospective validation cohort 64
  were AAA cases and 226 other vascular surgical
  cases.

6
Risk Stratification

• If number of risk factors 0 or 1 (36 and 39 of
  cases), major cardiac event rate was 0.4 and 1
  respectively
• If number of risk factors 2 or 3 (18 and 7 of
  cases), major cardiac event rate was 4.6 and
  9.7 respectively.
• Major cardiac events were defined as MI,
  pulmonary oedema, ventricular fibrillation or
  other primary cardiac arrest.
• Lee et al. Circulation 19991001043-9.

7
Can intermediate risk patients be further
stratified?

• Non-invasive cardiac testing
• 300 consecutive vascular surgical patients
  underwent DSE
• Negative test in 228 patients
• No peri-operative events.
• Ischaemia at high workload (gt70 maximum
  predicted HR)
• 16 peri-operative events 10 death or MI
• Ischaemia at low workload (lt70 maximum predicted
  HR)
• 66 peri-operative events 43 death or MI
• Poldermans et al. JACC 199526648-53.

8
Exercise treadmill testing
Author n Abnorm Criteria Events PPV NPV McCabe
1981 314 36 STD CP A 38 81 91 Cutler
1981 130 39 STD 7 16 99 Arous
1984 808 17 STD NR 21 NR Gardine
1985 86 48 STD 11 11 90 Carliner
1985 200 16 STD 32 16 93 von Knorring
1986 105 25 STD CP A 3 8 99 Kopecky
1986 114 57 lt400kpm 7 13 100 Leppo
1987 60 28 STD 12 25 92 McPhail
1988 100 70 lt85 Max 19 24 93 Urbinati
1994 121 23 STD 0 - 100 STD - ST depression,
CP - chest pain, A - cardiac arrhythmia, Max -
maximum predicted heart rate, NR - not reported
9
Stress echocardiography

• Dobutamine stress echo for pre-operative risk
  assessment
• Author n Ischaemia Events Criteria for ve
  test PPV NPV
• Lane 1991 38 50 8 New WMA 16 100
• Lalka 1992 60 50 15 New / worse WMA 23
  93
• Eichelberger 1993 75 36 3 New / worse WMA 7
  100
• Langan 1993 74 24 4 New WMA or ECG changes 17
  100
• Davila Roman 1993 88 23 2 New / worse WMA 10
  100
• Poldermans 1995 300 24 9 New / worse WMA 38
  100
• Events were death or MI WMA - wall motion
  abnormality
• Criteria for abnormal test new or worsening WMA
• 23-50 abnormal
• Positive predictive value 17-38
• Negative predictive value for normal test 99

10
Which non-invasive test?

• Exercise treadmill testing
• Very high risk patients generally excluded from
  studies
• Approx 33 abnormal
• Positive predictive value about 20
• Negative predictive value about 95
• Many patients cannot exercise
• Stress echo and nuclear imaging
• Similar positive and negative predictive value
• Can regionalise ischaemia
• Applicable to more patients

11
Should patients with positive non-invasive tests
proceed to angiography with a view to
intervention?

• No RCTs to assess overall benefit of prophylactic
  intervention to lower peri-operative risk.
• Retrospective studies suggest that patients with
  CABG have similar operative risk to those with no
  clinical indication of CAD.
• Diehl et al. Ann Surg 198319749-56.
• Crawford et al. Ann Thorac Surg 197826215-22.
• Reul et al. J Vasc Surg 19863788-98.
• Nielson et al. Am J Surg 1992164423-6.
• Eagle et al. Circulation 1997961882-7.

12
Should patients with positive non-invasive tests
proceed to angiography with a view to
intervention?

• Added risk of procedures
• 1000 elective vascular patients underwent
  angiography
• 251 had coronary disease to warrant CABG
• 216 underwent CABG
• Related mortality 5.3
• Later vascular surgical mortality 1.5
• Hertzer et al. Ann Surg 1984199223-33.
• Little data regarding angioplasty
• Advancing coronary techniques
• Routine CABG now lower risk
• Angioplasty /- stenting

13
Very high risk vascular surgery

• High cross-clamping of aorta in thoraco-abdominal
  surgery.
• Long operations with long recovery periods.
• High risk of concomitant cardiac disease.
• Little data in the literature to guide practice.

14
Protocol design
Patient referral for TAAA repair
Assessment cardiologist
Dobutamine stress echocardiography Coronary
angiography
TAAA Repair
No operation
Cardiac intervention followed by TAAA repair
15
Cardiac risk
Angina MI
Low
High
Angina alone
Previous MI
27

CABG
Asymptomatic
Intermediate
Clinical
Clinical ECG
16
Coronary angiography

• 34 patients
• 1 failed
• No complications
• All had some coronary atheroma
• Significant disease (gt70 stenosis of a main
  coronary artery) in 19/34 patients

17
Stress echocardiography

• 27 patients
• 7/27 had inducible wall motion abnormality
• All had significant coronary stenoses
• 20/27 no inducible wall motion abnormality
• 11/20 no significant coronary stenoses
• 5/20 significant coronary stenoses but extensive
  collateralisation
• 4/20 significant coronary stenoses without
  collateralisation
• Specificity 100, sensitivity 55-75

18
Stress echo positive for ischaemia in LAD
territory Tight proximal LAD stenosis
19
Angioplasty balloon inflated in LAD
20
Good end result
21
Stress echo negative for ischaemia Occluded LAD
but extensive collateralisation
22
LAD territory also supplied by RCA
23
Negative stress echo for ischaemia Tight proximal
RCA stenosis and moderate mid RCA stenosis
24
Angioplasty balloon inflated in proximal RCA
25
Good end result
26
Coronary intervention

• 12 patients
• 6 PTCA
• 2 unsuccessful (1 occluded vessel, 1 very
  tortuous artery)
• 1 stented
• No complications
• 6 CABG
• 1 post-op non-fatal CVA

27
Summary
40 Patients referred for TAAA repair
Assessment cardiologist
Dobutamine stress echocardiography Coronary
angiography
25 TAAA Repair
5 No operation
10 Cardiac intervention followed by TAAA repair
No major peri-operative cardiac complications
28
Drug treatment peri-operatively

• 1351 patients due to undergo major vascular
  surgery
• 846 with one or more risk factors underwent
  stress echocardiography
• 173 positive stress echos
• 59 randomised to bisoprolol, 53 to standard care
• Exclusions due to current beta-blocker treatment
  and extensive ischaemia on stress echo
• 3.4 (n2) versus 17 (n9) cardiac death
  (p0.02)
• 0 versus 17 (n9) non-fatal MI (plt0.001)
• Poldermans et al. N Engl J Med 19993411789-94.

29
Drug treatment peri-operatively

• Peri-op beta-blockade reduces amount of ischaemia
  detected by ECG.
• Stone et al. Anesthesiology 198868495-500.
• Atenolol reduced mortality and improved event
  free survival for up to 2 years after major
  non-cardiac surgery in one study (cardiac risk
  factors greater in placebo group).
• Mangano et al. N Engl J Med 19963351713-20.
• Beta blockers in general reduce size of and
  mortality from MI in patients with chronic stable
  angina.
• Pepine et al. Circulation 199490762-8.
• Aspirin prevents ischaemic events in patients
  with peripheral vascular disease. Their use in
  the operative setting is untested.

30
Summary

• Patients undergoing aneurysm surgery without any
  additional cardiac risk factors are probably at
  low cardiac risk.
• All patients should receive peri-operative
  beta-blockers unless clinically contra-indicated.
• Patients with additional cardiac risk factors
  should undergo non-invasive cardiac assessment.
  Those with extensive ischaemia should probably
  undergo coronary angiography with a view to
  coronary intervention.
• Whether patients with ischaemia in a small
  territory should proceed to coronary angiography
  or can be managed with peri-operative
  beta-blockade is unclear although in high stress
  procedures we advocate angiography.