Clinical Studies of Preoperative PCI

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A variety of retrospective analyses extending from the pre-stent era to current practice have addressed the utility of preoperative PCI for reducing the likelihood of adverse cardiac events. The conclusions that can be drawn from these studies are, however, quite limited. Almost all reports suffer from small size, retrospective design, frequent absence of standardized indications to determine which patients were referred for PCI, wide variety of surgical procedures, variable timing between preoperative PCI and subsequent noncardiac surgery (days to years), and, perhaps most importantly, lack of control groups in most studies. Also, in these retrospective trials, because patients who died after PCI would not have gone on to noncardiac surgery and therefore would not be included in follow-up, the true complication rates from a strategy of preoperative PCI are likely to have been underreported.35 Within studies of preop-erative angioplasty performed in pre-stent era, inhospital mortality after noncardiac surgery ranged from 0% to 2.7% for patients who had undergone either recent (within 2 weeks) or remote (up to 29 months) preoperative balloon angioplasty (Table 7-4). Higher perioperative mortality rates (ranging from 2.9% to 20%) were reported in several more recent studies that examined outcomes of coronary stent implantation shortly before noncardiac surgery, but again none of these observational reports employed a control group (Table 7-5).36-40

In one retrospective analysis of 501 patients who underwent a major vascular surgical procedure, pre-

Table 7-4. Complication Rates of Noncardiac Surgery after Balloon Angioplasty

Author (Year)*

Infarction

(%)

Interval Between Angioplasty and Surgery

Allen (1991)

148

0.7

2.7

11 mo

Huber (1992)

SO

S.6

1.9

9 days

Elmore (1 993)

14

0

0

10 days

Jones (1 993)

108

3.7

0.9

14 days

Gottleib (1998)

194

0.S

0.S

11 days

Posner (1999)

686

2.2

2.6

1 yr

Hassan (2001)

2S1

0.8

0.8

21 mo

'Complete references for these studies can be found in the source article.

Adapted from Eagle KA, Berger PB, Calkins H, et al: ACC/AHA guideline update for perioperative cardiovascular evaluation for noncardiac surgery: Executive summary. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation 2002;105:1257-1267.

'Complete references for these studies can be found in the source article.

Adapted from Eagle KA, Berger PB, Calkins H, et al: ACC/AHA guideline update for perioperative cardiovascular evaluation for noncardiac surgery: Executive summary. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation 2002;105:1257-1267.

Table 7-5. Complication Rates of Noncardiac Surgery after Recent Coronary Bare Metal Stent Placement

Author (Year)

Myocardial Infarction (%)

Major Bleeding (%)

Interval Between Stenting and Surgery

Kaluza (2000) Wilson (2003) Vicenzi (2006) Reddy (2005)

Total

40 207 103 56

21.2

<42 days <35 days <42 days <42 days operative PCI did appear to confer benefit. Within this cohort, the presence of moderate to severe inducible ischemia on preoperative thallium stress testing was associated with an overall 22.4% incidence of perioperative MI. Patients who underwent coronary revascularization before surgery, however, had only a 6.4% incidence of postoperative MI, which was similar to the rate observed among patients without ischemia on preoperative stress testing.41

The CARP Trial

To date, only one prospective randomized study, the Coronary Artery Revascularization Prophylaxis (CARP) trial, has examined the strategy of preopera-tive coronary revascularization for the reduction of early and late perioperative cardiac events after major vascular surgery.42 The CARP trial included 510 patients scheduled for vascular surgery at 1 of 18 Veterans Affairs medical centers. Patients were eligible for inclusion if angiographically proven coronary artery disease with at least 70% stenosis in at least one major epicardial coronary artery was present. Patients were randomized to undergo either coronary revascularization followed by vascular surgery (n = 258) or vascular surgery without preceding coronary revascularization (n = 252). Among the group randomized to coronary revascularization, 41% of patients underwent CABG and 59% were treated with PCI. The median age of enrolled patients was 66 years; angina was noted in 38%, 42% had a prior MI, and 74% were considered to possess at least an intermediate risk for a perioperative cardiac event based on either clinical risk factors or the results of nonin-vasive testing. Patients with a left main coronary artery stenosis of 50% or greater, a left ventricular ejection fraction of less than 20%, or severe aortic stenosis were excluded. P-Blocker therapy was em -ployed in approximately 85% of patients in both study arms.

The final results of the CARP trial indicated that preoperative revascularization was not associated with any apparent benefit over conservative therapy. Whereas patients assigned to coronary revasculariza-tion had a significantly longer delay between randomization and vascular surgery (54 versus 18 days), coronary revascularization was not associated with a reduction in the occurrence of adverse cardiac events after vascular surgery, either at 30-day or at 2.7-year follow-up (Fig. 7-6). Furthermore, subgroup analysis indicated that preoperative revascularization was not associated with a survival benefit in any low- or high-risk patient subgroup.

One criticism of the CARP trial was that process of preoperative risk stratification used in the study did not follow the ACC/AHA guidelines, by which coronary angiography is considered only after noninva-sive testing has demonstrated moderate or severe inducible ischemia. In the study, noninvasive testing was not mandated, and fewer than 50% of enrolled subjects underwent a stress imaging study in which moderate or severe ischemia was documented before coronary angiography was performed.43 Nevertheless, it is difficult not to concede that the population studied in the CARP trial represented a high-risk group of patients, as evidenced by the substantial overall 22% mortality rate at 2.7 years. Because the CARP trial included almost exclusively male patients and was limited to vascular surgery, generalization of results is somewhat restricted. Also, because only 9% of patients who were screened for study inclusion were ultimately enrolled, the possibility of selection bias exists; investigators may have excluded some

Years after randomization

No. at risk

Revascularization 226 175 113 65 18 7 No revascularization 229 172 108 55 17 12

Years after randomization

No. at risk

Revascularization 226 175 113 65 18 7 No revascularization 229 172 108 55 17 12

Figure 7-6. Kaplan-Meier survival curve for patients enrolled in the CARP trial. There was no difference in early or late mortality after noncardiac surgery among patients with coronary artery disease who were randomized to undergo preoperative coronary revascularization rather than conservative therapy. (From McFalls EO, Ward HB, Moritz TE, et al: Coronary-artery revascularization before elective major vascular surgery. N Engl J Med 2004;351:2795-2804.)

patients they believed to be at higher risk, simply referring them for revascularization outside the context of the study.

Despite its potential shortcomings, the CARP results lend strong support to the concept that performing prophylactic coronary revascularization for the purpose of "getting a patient through" noncar-diac surgery is generally not appropriate. It should be stressed that the majority of patients enrolled in the CARP trial were at intermediate risk for perioperative events, and the results of the study may not apply to higher-risk patients (including those with left main coronary artery disease, poor ejection fraction, severe valvular heart disease, unstable angina or angina not responsive to medical therapy, or recent MI). One retrospective analysis suggested that the subset of patients with three or more clinical risk factors and extensive ischemia on a stress imaging study has increased surgical risk despite P-blocker therapy and may represent an appropriate group in which to consider preoperative coronary revascularization.10

In summary, pending the results of further prospective trials, there is not sufficient evidence to suggest that routine preoperative PCI is effective in reducing the risk of noncardiac surgery among patients with documented coronary artery disease who are at moderate clinical risk. In these individuals, preoperative PCI should be performed only for patients who have an indication for coronary revas-cularization unrelated to the noncardiac surgery. For a limited group of patients at higher risk, data are lacking, and the perceived risks and benefits of pre-operative revascularization need to be carefully weighed on an individual basis. Multidisciplinary communication, including the patient's medical specialist, cardiologist, cardiac surgeon, anesthesiologist, and surgeon intending to perform the noncardiac procedure, can be quite helpful in determining a rational preoperative strategy. Such a discussion can allow consideration of issues such as life expectancy; anticipated risks and benefits of PCI, CABG, and the planned noncardiac surgery itself; the urgency of the noncardiac surgery; and the potential risks that medical treatments such as aspirin or thienopyridine therapy may pose during the noncardiac surgery.

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