PRE-OPERATIVE CARDIAC EVALUATION FOR VASCULAR SURGERY

1. PRE-OPERATIVE CARDIAC EVALUATION FOR VASCULAR SURGERY Jamil Mayet Consultant Cardiologist, St Mary’s 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 1984;199:223-33.

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 1994;19:804-17.

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 > 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 1999;100:1043-9.

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 (>70% maximum predicted HR) • 16% peri-operative events; 10% death or MI • Ischaemia at low workload (<70% maximum predicted HR) • 66% peri-operative events; 43% death or MI • Poldermans et al. JACC 1995;26:648-53.

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% <400kpm 7% 13% 100% Leppo 1987 60 28% STD 12% 25% 92% McPhail 1988 100 70% <85% 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 1983;197:49-56. • Crawford et al. Ann Thorac Surg 1978;26:215-22. • Reul et al. J Vasc Surg 1986;3:788-98. • Nielson et al. Am J Surg 1992;164:423-6. • Eagle et al. Circulation 1997;96:1882-7.

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 1984;199:223-33. • 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 Cardiac intervention followed by TAAA repair TAAA Repair No operation

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 (>70% 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 10Cardiac 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% (n=2) versus 17% (n=9) cardiac death (p=0.02) • 0% versus 17% (n=9) non-fatal MI (p<0.001) Poldermans et al. N Engl J Med 1999;341:1789-94.

29. Drug treatment peri-operatively • Peri-op beta-blockade reduces amount of ischaemia detected by ECG. Stone et al. Anesthesiology 1988;68:495-500. • 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 1996;335:1713-20. • Beta blockers in general reduce size of and mortality from MI in patients with chronic stable angina. Pepine et al. Circulation 1994;90:762-8. • 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.