Perioperative and late outcome in patients with left ventricular ejection fraction of 35% or less who require major vascular surgery

Perioperative and late outcome in patients with left ventricular ejection fraction of 35% or less who require major vascular surgery Andris Kazmers, M D , M a n u e l D. Cerqueira, M D , and R. E u g e n e Zierler, M D ,

Seattle, Wash. Survival in patients with diminished left ventricular ejection fraction (El?) is reduced after major vasoxlar surgery. The objective o f this study was to determine perioperative (30day) and subsequent outcome after major vascular surgery in those with severe cardiac dysfunction, defined by El3 being 35% or less (normal El? greater than 50%). From Aug. 1, 1984 to Jan. 1, 1988, 35 patients with EF equal to 27.7% ± 6.1% (mean -+ 1 standard deviation) have required 47 major vasotlar procedures: 53% (n = 25) were limb revasotlarizations; 21% (n = 10) were direct aortoiliac aneurysm repairs: 23% (n = 11) were carotid endarterectomies: one patient had transaortic renal endarterectomy. Two deaths occurred within the first 30 days, yielding a 4.3% perioperative mortality rate (2 o f 47 procedures). The cumulative mortality rate for the entire group during follow-up of 410 -+ 390 days was 40% (14 o f 35 patients). Most late deaths (71%) occurred within the first 6 months after surgery and each was due to cardiovascular complications. Survival for those with an El? o f 29% or less was significantly worse than for those with an EF greater than 29%, determined by life-table analysis (2 < 0.012, Mantel-Cox). The cumulative mortality rate was 59% with an EF of 29% or less and 18% in those with an El? greater than 29% (p < 0.029, two-tailed Fisher exact test). The perioperative mortality rate for those with an EF of 35% or less who require major vascular surgery is acceptable, but overall survival during follow-up is diminished. Because only 41% o f the patients survived the short follow-up, those with an EF of 29% or less form a subgroup at even greater survival disadvantage. Although there was no apparent increase in perioperative cardiac complications or perioperative mortality, patients with an El? o f 29% or less should undergo vascular surgery for only the most compelling indications because o f markedly diminished late survival. However, when necessary, major vascular surgery required for life- or limb-threatening indications can be done with an acceptable perioperative mortality rate despite severe cardiac dysfimction as defined by an El? o f 35% or less. (J VAse SURG 1988;8:307-15.)

Preoperative clinical assessment is unable to define precisely who is at increased risk from major vascular surgery even when accepted techniques are used, such as the Goldman Risk Index} Invasive assessment with routine coronary arteriography obtained before major vascular surgery has similarly not proved to be advantageous. 2~ Noninvasive assessment o f cardiac perfusion and function by means o f thallium scintigraphy or radionuclide ventriculograFrom the Departments of Surgery, Division of Vascular Surgery and Radiology,Divisionof NuclearMedicine, SeattleVeterans Administration Medical Center, and The Universityof Washington. Presented at the Third Annual Meeting of the Western Vascular Society, Monterey, Calif., Jan. 28-31, 1988. Reprint requests: Andris Kazmers, MD, Dept. of Surgery, C-218, Universityof KentuckyMedical Center, 800 Rose St., Lexington, KY 40536-0084.

phy are alternate techniques for preoperative cardiac assessment, s-12 Studies from the Seattle Veterans Administration Medical Center (VAMC) evaluated the use o f radionuclide ventriculography before carotid surgery and direct abdominal aortic aneurysm repair} 3'14 Overall survival was significantly decreased during follow-up in those patients with left ventricular ejection fraction (EF) o f 35% or less, although the postoperative mortality rate (30-day) was not significantly increased in patients with such severe ventricular dysfunction.iS'x4 Others 9,x° have reported a perioperative mortality rate from 12% to 20% for those with an EF o f 35% or less after limb revascularization or aneurysm repair. The purpose o f this study was to define the outcome for all patients at our center having major vascular surgery who were found preoperatively to 307

308

Journalof VASCULAR SURGERY

Kazmers, Cerqueira, and Zierler

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Fig. 1. Distribution of EF for those with severeventricular dysfimcdon having major vascular surgery.

Table I. Hemodynamic measurements for those with pulmonary artery catheters (n = 22) present during the initial or only major operation Highest cardiac output (L/rain) Lowest cardiac output (L/min) Highest PCWP (mm Hg) Lowest PCWP (mm Hg)

5.15 + 1.54 3.29 - 1.14 20+8 9+5

PCWP, Pulmonary capillary wedge pressure.

have severe left ventricular dysfunction as defined by an EF of 35% or less. This is a high-risk population. A recent study describing the use of thallium scintigraphy with intravenous dipyridamole for cardiac evaluation before aortic surgery reported no patients in that series with an EF less than 35%. 12 PATI~ENTS A N D METHODS

Preoperative evaluation with radionudide ventriculography for those in need of major vascular surgery revealed 35 patients with an EF of 35% or less from Aug. 1, 1984 to Jan. 1, 1988. Patients had surgery at the Seattle VAMC (n = 33) or at the Uniw:rsity of Washington Hospital (n = 2) by the authors. Major vascular surgery was defined to indude direct abdominal aortic aneurysm (AAA) repair, carotid endarterectomy (CEA), or lower extremit7 or renal revascularization. It has become the standard clinical policy to obtain preoperative radionuclide ventriculography on each patient scheduled for major vascular surgery at the Seattle VAMC. During the period of this study, 545 major vascular operations were performed at the Seattle VAMC. Of

all patients having major vascular surgery at the VAMC, 7.9% of the operations (n = 43) were done in patients known to have an EF of 35% or less. Each radionuclide study preceded and was performed in close proximity to vascular surgery (n = 34). One patient had the left ventricular EF and wall motion assessed preoperatively with contrast ventriculography. A radionuclide study confirming the low EF and the presence of wall motion abnormalities would have been redundant and therefore was not performed. Radionuclide ventriculography was obtained by previously reported methods. 13,14An experienced nuclear cardiologist reviewed the cine studies done in three views for the presence or akinesis, dyskinesis, or hypokinesis. Resting global EF was calculated in the left anterior oblique view with backgroundsubtracted time activity curves. Preoperative cardiology consultation has been routine for patients in need of major vascular surgery who have clinical evidence of cardiac disease (i.e.~ angina, previous myocardial infarction [MI], congestive heart failure, ventricular dysrhythmia,oor previous coronary bypass) or for those found to have cardiac dysfunction by radionuclide ventriculography. After such consultation, operations were performed with standard surgical and anesthetic techniques. Each surviving patient was observed in the outpatient clinics after discharge. Perioperative death or complications were defined as those which occurred in the first 30 days after surgery, whereas late death was defined as that which occurred after the 30-day postoperative period. The primary end points evaluated were death and cardiac complications, as

Volume 8 Number 3 September 1988

Outcome in peripheral vascular surgical patients with left ventricular EF <~35%

100

309

--,,

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60 r~

~lnlnunlllnllmUlU

o~ 40 20

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6

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FOLLOWUP (MONTHS) nnmmnnn n=35

n=21

n=14

n=8

n=3

Fig. 2. Overall survival for 35 patients having 47 major vascular procedures from time of initial or only major vascular operation. Numbers below indicate number of patients at risk during overlying interval.

defined previously.13'14 These included (1) congestive heart failure requiring Specific therapy in the intensive care unit, (2) new ventricular dysrhythmia, and (3) MI, diagnosed by standard electrocardiographic (ECG) features or elevation of creatine kinase with MB fraction of greater than 5% and an appropriate clinical picture. Data were analyzed with BMD statistical software. Patients' ages ranged from 49 to 76 years (mean + 6 years [ - 1 standard deviation]). Cardiovascular risk factors included hypertension in 71%, diabetes mellitus in 46%, hyperlipidemia in 9%, and 86% continued to smoke cigarettes. Before surgery, 54% had angina pectoris. A history of MI was present in 86%, whereas preoperative ECG revealed evidence of prior MI in 58%. This apparently low incidence of MI by ECG relative to the high frequency of MI by history may in part be explained by resolution of ECG evidence for infarction or by the high incidence of left bundle-branch heart block (23%), which renders the ECG diagnosis of previous MI difficult. Only 12% of the patients had prior coronary artery bypass grafting (CABG); in no case was CABG done specifically to lower the risk of vascular surgery. RESULTS Left ventricular EF ranged from 14% to 35% (mean 27.7% +- 6.1%). Ventricular wall motion abnormalities were present in 97% of the patients. Five patients (14%) had an EF of 20% or less, a total of 10 patients (29%) had an EF of 25% or less, and a total of 19 patients (54%) had an EF of 30% or less

(Fig. 1). During the period of study these 35 patients had 47 major vascular reconstructive procedures: 53% (n = 25) were limb revascularization procedures; 21% (n = 10) were direct aortoiliac aneurysm repairs; 23% (n = 11) were CEAs; one patient had transaortic endarterectomy of five renal arteries. Two deaths occurred within the first 30 postoperative days, yielding a case mortality rate of 4.3% (2 of 47). There were no deaths within the first 30 postoperative days in patients having limb revascularization. The perioperative mortality rate after direct AAA repair was 10% and after CEA was 9%. Intraoperative hemodynamic assessment (Table I) revealed that cardiac output was well maintained during surgery in this group of patients but was often achieved at the expense of elevated filling pressures. In this regard, elevated intraoperative pulmonary capillary wedge pressures greater than or equal to 18 m m Hg were present during surgery in 57% of the patients (12 of 21) for whom these values were measured. The incidence of postoperative complications during the initial or only operation was high during the first 30 days: 29% of the patients (10 of 35) had cardiac complications, whereas 23% (8 of 35) had significant noncardiac complications. The overall incidence ofperioperative MI was 17% (n = 6); 11% (n = 4) had new ventricular dysrhythmia: significant congestive heart failure developed in 23% (n = 8) during the first 30 days after surgery. There was only one perioperative death after the initial or only major vascular procedure (2.9% mortality rate) and one

Journal o f VASCULAR SURGERY

310 Kazmers, Cerqueira, and Zierler

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Fig. 3. Overall survival differences between those with EF greater than 29% and EF of 29% or less (p < 0.012, Mantel-Cox) were evident for those having major vascular surgery. Numbers below indicate number of patients at risk during overlying interval.

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48

Fig. 4. There were no significant overall survival differences by type of initial or only vascular operation. Numbers below indicatc number of patients at risk during overlying interval. AAA, Abdominal aortic aneurysm repair; CEA, carotid endarterectomy; PVOD, lower extremity reconstruction for peripheral vascular occlusive disease.

perioperative death during one of the 12 subsequent vascular procedures (8.3% mortality rate). During follow-up of 410 __+390 days there was substantial late mortality (Fig. 2). The cumulative mort~Nty rate for the entire group during this period was 4:0% (14 of 35). Most late deaths (71%) occurred within this first 6 months of surgery, and each death was due to cardiovascular complications. One late death was also the second perioperativc death, which occurred during AAA repair--the second operative procedure for one of the study patients.

This death was due to a leukoagglutinin reaction occurring after intraoperative blood transfusion, thereby resulting in refractory cardiopulmonary failure. From the time of the initial vascular procedure this patient Showed deterioration of preoperative EF from 31% to 26% before the subsequent vascular procedure. This patient was included in the life-table analysis as a patient with an EF of greater than 29% because this reflected his cardiac status at the time of entry intO the study. However, this patient was not included in the calculation of cumulative

Volume 8 Number 3 September 1988

Outcome in peripheral vascular surgical patients with left ventricular EF <~35%

mortality because it was unclear into which group he should have been classified; that is, he died after a subsequent EF was found to be 29% or less before repeat surgery. At least 86% of all the deaths in this series appeared to be cardiac in origin. Survival was not worse for those with diabetes, hyperlipidemia, hypertension, continued cigarette smoking, angina, or evidence of previous MI by history or ECG. Patients who had previous vascular surgery did have significantly reduced overall survival during follow-up according to life-table analysis (p < 0.041, Mantel-Cox). Survival from the time of the initial or the only major vascular operation for those with an EF of 29% or less was significantly lower (Fig. 3) than for those with an EF greater than 29% (p < 0.012, Mantel-Cox). An EF of 29% was found to be the cut-off point that yielded the greatest statistical differentiation of survival between patients grouped according to EF with life-table methods during preliminary data analysis. The perioperative mortality rate for operations in patients with an EF of 29% or less was similar (4.5% [1 of 22 operations]) to that for those with an EF greater than 29% (4% [1 of 25 operations]). There was no statistical difference in age, incidence of hypertension, diabetes, hyperlipidemia, smoking, angina, previous MI, or previous CABG between patients grouped by EF of 29% or less and those with EF greater than 29%, although the duration of follow~up was less in those with an EF of 29% or less. The nature of the initial or only operative procedure did not appear to influence survival in a statistically significant fashion (Fig. 4). The incidence of perioperative cardiac and noncardiac complications for the first or only major vascular procedure was not statistically different between the two groups of patients. The incidence of perioperative MI, n e w ventricular dysthythmia, and significant congestive heart failure were not individually statistically different between the two groups of patients (Table II). Despite this lack of statistical difference in perioperative outcome including perioperative mortality, the cumulative mortality rate was 59% in patients with EF of 29% or less and 18% in those with EF greater than 29% during follow-up (p < 0.029, two-tailed Fisher exact test). The odds ratio of 6.67 (99% confidence limits of 4.59 to 8.75) indicated that it was much more likely that a patient with an EF of 29% or less would die at some point during the relatively short follow-up after major vascular surgery than would a patient with an EF greater than 29%. Life-table analysis indicated that patients with

311

Table II. Outcome of major vascular surgery with ejection fraction of 35% or less after the initial or only operation

Perioperative complications MI Ventricular dysrhythmia CHF Cardiac Death

EF <-29%

EF > 29%

(n = l z )

(n = ~8)

12% 12% 24% 24% 0%

22% 11% 22% 28% 5.6%

NS NS NS NS NS

MI, Myocardial infarction; CHF, congestive heart failure.

postoperative complications had significantly reduced survival (p < 0.003, Mantel-Cox) during follow-up (Fig. 5). This was true for those who had perioperative cardiac complications (p < 0.031, Mantel-Cox) or noncardiac complications (p < 0.003, Mantel-Cox). Logistic regression analysis did not identify any individual factor that proved significant in defining who was at increased risk for death after major vascular surgery. Discriminant analysis revealed that angina and noncardiac complications were the best variables for distinguishing between patients who were discharged alive and those who died after vascular surgery (p < 0.001). Logistic regression and discriminant analysis unfommately did not identify any preoperative factors that would be helpful in predicting who would have cardiac or noncardiac complications after major vascular surgery. DISCUSSION The risk of vascular surgery for an individual patient cannot be determined by purely clinical methods) ,ls-2° Routine coronary angiography has also been suboptimal for preoperative evaluation of those in need of vascular surgery.24"21Alternatives include ECG stress testing, which often is not possible for patients having vascular surgery who frequently have disabling medical problems that interfere with the ability to achieve an adequate exercise level. Furthermore, ECG stress testing has not proved more useful than resting ECG in those patients having major noncardiac surgery.22 Radionuclide techniques have been used for cardiac assessment before major vascular surgery,s~4 Mosley et al.7 reported patients with an EF of 30% or less who had major vascular surgery had a 75% mortality rate from refractory myocardial failure. Pasternack et al.9,10reported a 75% to 80% incidence of perioperative MI and a 12% to 20% incidence of death from cardiac causes after major vascular surgery

~ournalof 312

VASCULAR SURGERY

Kazmers, Cerqueira, and Zierler

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n=18

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n=27 n=8

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Fig. 5. Overall survival differences in those with (A) no complications vs some perioperative cardiac or noncardiac complication (p < 0.003, Mantel-Cox); (B) perioperative cardiac complications vs no cardiac complications (p < 0.04, Mantel-Cox); (C) perioperative noncardiac complications vs no noncardiac complications (p < 0.003, Mantel-Cox). Numbers below (A, B, and C) indicate number of patients at risk during overlying interval.

Volume 8 Number 3 September 1988

Outcome in peripheral vascular surgical patients with left ventricular EF <~35%

Q

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....

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Fig. 6. Overall survival differencesbetween patients in this study with (A) EF of 35% or less vs those with EF greater than 35% and those without a preoperative EF determination who had major vascular surgery at the Seattle VAMC from July 1, 1984 to June 30, 1985 (p < 0.0001, Mantel-Cox) and with (B) EF of 30% to 35% vs the group with EF greater than 35% and those who had no preoperative EF determination who had major vascular surgery at the Seattle VAMC from July 1, 1984 to June 30, 1985. Numbers below (A and B) indicate number of patients at risk during overlying interval.

in patients with an EF from 27% to 35%. Vascular surgery in those with severe ventricular dysfunction has been reasonably well tolerated, at least for the first 30 postoperative days, and was associated with a 17% incidence of MI at our center./° Cardiac and noncardiac complications were frequently present in those patients with an EF of 35% or less after vascular surgery, but one could not predict preoperatively who would have these complications. The postoperative (30-day) case mortality rate was 4.3% in our patients with an EF of 35% or less. However, overall survival after vascular surgery for those patients with an EF of 35% or less was unequivocally different from survival for those who had not been identified to have such cardiac problems (Fig. 6). Patients with

an EF of greater than 29% had no survival differences from those who either had an EF greater than 35% or had no preoperative EF determination and underwent major vascular surgery during the 19841985 academic year (p < 0.36, Mantel-Cox). In other words, those patients with an EF from 30% to 35% appear to have survival statistically indistinguishable from a standard vascular surgery patient population. Other techniques for preoperative cardiac assessment include thallium scintigraphy after exercise or administration of dipyridamole}1'~2 The usefulness of thallium exercise studies, particularly lower extremity exercise studies, is limited in patients having vascular surgery. Arm ergometry is an alternative that

Jotwnalof VASCULAR SURGERY

314 Kazmers, Cerqueira, and Zierler

may be useful for those with disabling claudication or previous amputation. 2s Intravenous dipyridamolc remains an investigational drug, and oral dipyridamole is a less satisfactory alternative when used in conjunction with thallium scintigraphy.24 The distribution of thallium after dipyridamole administration differs from that after exercise, and the clinical implications of this finding are unknown. 2s Left ventricular dysfunction from coronary disease results in diminished sl/rvival. 26 The cumulative survival rate at 1 year was 62% and at 2 years was 57% in those with an EF of 35% or less who had major vascular surgery at our center. Although other studies have reported even poorer outcome, the outlook for patients with severe ventricular dysfunction is not hopelessY The CASS (Coronary Artery Surgery Study) results indicate that those patients with EF of 35% or less have a 5-year survival with medical treatment of 54% vs 5-year survival of 68% after CABG. 28 In the subgroup with EF of 25% or less, 5-year survival was 43% with medical treatment vs 63% ~ e r CABG. Other studies also indicate improved survival after CABG for those with severe left ventricular dysfttnction. 29sl An added benefit to such coronary reconstruction is improvement in myocardial function or clinical status after surgery,s2s4 It remains unclear whether any or all patients with low EF should be subjected to coronary arteriography before vascular surgery. Arteriography for those with angina and low EF would seem appropriate because there may be clinical benefit from CABG in such patients, ss The mortality rate of CABG may be increased for those with severe left ventricular dysfunction, but late survival would be potentially improved. 28,s°'ss The incidence of sudden death, which is increased in those with severe ventricular dysfunction, may also be reduced by coronary reconstruction for those with an EF of 35% or less. s° The mortality rate for major vascular surgery appears to be reduced by prior coronary artery reconstruction, s6,s7It is likely survival would be improved by CABG in selected patients with an EF of 35% or less who need major vascular surgery. Appropriate medical therapy has also been found beneficial. Digoxin can increase EF, and afterload reduction has improved survival for those with severe ventricular dysfunction,s8"4° Additional methods of risk reduction include the avoidance of surgery except for the most compelling indications in patients with an EF of 35% or less. Many vascular procedures can be performed with local anesthesia, which may be preferable to regional or general anesthesia. Liberal use of Swan-Ganz catheterization and arterial pressure monitoring permit

continuous intraoperative and postoperative assessment of cardiovascular status thereby allowing rapid correction of hemodynamic abnormalities. Ventricular dysrhythmias are common in those with low EF and in our opinion should be treated aggressively. 41 Of those with new perioperative ventricular dysrhythmia in this series, 75% died during the course of the study. It has been routine to admit patients with ventricular dysfunction to the intensive care unit for 2 or more days after surgery for hemodynamic and ECG monitoring even when the vascular procedure goes smoothly and is relatively minor. Low perioperative m o r t ~ t y can be achieved in those with severe ventricular dysfunction who require major vascular surgery. Patients with an EF of 35% or less, particularly those with EF of 29% or less, should be carefully selected and operated on only for the most life- or limb-threatening vascular problems because they have diminished overall survival despite acceptably low perioperative mortality. It appears the threshold of operability has been extended to such patients who have been considered to be too infirm to have major vascular procedures) 2 It is necessary to evaluate critically the wisdom of extending operability to patients with severe ventricular dysfunction, particularly with an EF of 29% or less, unless an attempt is made to improve late survival by more aggressive management of their cardiac disease, which was responsible for at least 86% of the deaths in this series. Correction of any identifiable high-risk cardiac problem such as significant coronary artery disease (three-vessel disease or left main equivalent) may improve the outcome for these criticaUy ill patients, but this remains conjectural. Appropriate medical therapy is also likely to improve their outlook. Although a reasonable perioperative mortality rate can be achieved, it remains unclear how to best maximize overall survival for patients with severe ventricular dysfunction who need vascular surgery. The best approach to these patients remains to be defined by future studies. REFERENCES

1. Goldman L, Caldcra DL, Nussbaum SR, ct al, Multifactorial index of cardiac risk in noncardiac surgical procedures. N Engl J Med 1977;297:845-50. 2. Hertzer NR, Beven EG, Young JR, et al. Coronary artery disease in peripheral vascular patients. Ann Surg 1984; 199:223-33. 3. Hertzer NR, Young JR, Kramer JR, et al. Routine coronary angiography prior to electiveaortic reconstruction. Arch Surg 1979;114:1336-44. 4. Beven EG. Routine coronary angiography in patients undergoing surgery for abdominal aortic aneurysm and lower extremity occlusive disease. J VAsc SURG1986;3:682-4. 5. Fiser WP, Thompson BW, Thompson AR, Eason C, Read

Volume 8 Number 3 September 1988

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12.

13.

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15.

16.

17.

18.

19. 20. 21. 22. 23. 24.

Outcome in peripheral vascular surgical patients with left ventricular EF ~ 35 %

RC. Nuclear cardiac ejection fraction and cardiac index in abdominal aortic surgery. Surgery 1983;94:736-9. Jones RH, Douglas JM, Rerych SK, Newman GE, Sabiston DC. Noninvasive radionucllde assessment of cardiac fimction in patients with peripheral vascular disease. Surgery 1979; 85:59-70. Mosley JG, Clarke JMF, Ell PJ, Martston A. Assessment of myocardial fimction before aorv_icsurgery by radionucllde angiocardiography. Br J Surg 1985;72:886-7. Gallacher WN, Goldberg J, Houston P, Drnck M, Dunington S. The value of nuclear angiography in the preoperative assessment of patients undergoing elective aortic surgery. Can Anaesth Soc J 1984;31:523-7. Pasternack PF, Imparato AM, Bear G, et al. The value of radionucllde angiography as a predictor ofperioperative myocardial infarction in patients undergoing abdominal aorfc aneurysm resection. J VASC SuRe 1984;1:320-5. Pasternack PF, Imparato AM, Riles TS, et al. The value of the radionuclide angiogram in the prediction of perioperative myocardial infarction in patients undergoing lower extremity revascularization procedures. Circulation 1985;72(suppl II): 11-3. Boucher CA, Brewster DC, Darling RC, Okada RD, Strauss WH, Pohost GM. Determination of cardiac risk by dipyridamole-thallinmimaging before peripheralvascular surgery. N Engl J Med 1985;312:389-94. Curler BS, Leppo JA. Dipyridamole thallium 201 scintigraphy to detect coronary artery disease before abdominal aortic surgery. J VASCSuRe 1987;5:91-100. Kazmers A, Cerqueira M, Zierler RE. The role of preoperative radionucllde left ventricular ejection fraction for risk assessment in carotid surgery. Arch Surg 1988;123:416-9. Kazmers A, Cerqueira M, Zierler RE. The role of preoperative radionucllde ejection fraction in direct abdominal aortic aneurysm repair. J VASCSURe 1988;8:128-36. Calvin JE, Kleser TM, WalleyVM, McPhail NV, Barber GG, ScoNe TK. Cardiac mortality and morbidity after vascular surgery. Can J Surg 1986;29:93-7. Jamieson WRE, Janusz MT, Miyagishima RT, Gerein AN. Influence ofischemic heart disease on early and late mortality after surgery for peripheral occlusive vascular disease. Circulation 1982;66(Suppl I):92-7. Cooperman M, Pflug B, Martin EW Jr, Evans WE. Cardiovascular risk factors in patients with peripheral vascular disease. Surgery 1978;84:505-9. McPhail N, Menkis A, Shariatmadar A, et al. Statistical prediction of cardiac risk in patients who undergo vascular surgery. Can J Surg 1985;28:404-6. Jeffrey CC, Kunsman J, Cullen DJ, Brewster DC. A prospective evaluation of cardiac risk index. Anesthesiology 1983;58:462-4. Clayton JW, Lennihan R Jr, Warsal NF. Assessment ofcardiac risk in patients undergoing abdominal aortic aneurysmectomy. Del Med J 1986;58:323-7. Brown OW, HoNer LH, Pairolero PC, Kazimer FJ, McCready RA. Abdominal aortic aneurysm and coronary artery disease. Arch Surg 1981;116:1484-8. Carliner NH, Fisher ML, Plomick, et al. Routine preoperative exercise testing in patients undergoing major noncardiac surgery. Am J Cardiol 1985;56:5I-8. Balady GJ, Weiner DA, Rothendier JA, et al. Arm exercisethallium imaging testing for the detection of coronary artery disease. J Am Coil Cardiol 1987;9:84-8. Gould KL, Sorenson SG, Albro P, Caldwell JH, Chaudhuri

25.

26.

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41.

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