Technical Considerations of PCI

When the decision has been made to proceed with preoperative PCI, several important technical considerations exist. Foremost is the length of delay that is permissible between the PCI and the subsequent noncardiac surgical procedure, which often dictates whether stand-alone balloon angioplasty, bare metal stenting, or drug-eluting stent implantation is performed.

Balloon Angioplasty

Because of less reliable short- and long-term results, balloon angioplasty without stent placement has become an infrequently used strategy among most patients undergoing PCI. Stand-alone balloon angio-plasty may have a role in the preoperative setting, however, because this approach does not mandate the subsequent use of thienopyridine therapy and therefore allows surgery to be performed with little delay after PCI. Among 350 patients who underwent balloon angioplasty within 2 months before noncar-diac surgery at the Mayo Clinic from 1988 to 2001, the incidence of perioperative death or MI was only 0.9%. No perioperative events occurred among the subset of 162 patients in this cohort who underwent their noncardiac surgical procedure more than 2 weeks after coronary angioplasty.44

Current ACC/AHA guidelines recommend delaying surgery for at least 1 week after balloon angio-plasty to allow for initial healing at the site of vessel injury and to overcome the time frame during which acute vessel closure and recoil typically occurs. Surgery should not be delayed for longer than 8 to 12 weeks after angioplasty, however, because restenosis becomes a potential concern after this interval. Therefore, for a patient in whom PCI is deemed necessary before surgery, delay of surgery for more than 1 to 2 weeks is undesirable, and balloon angioplasty without stenting may represent a reasonable option. It should be kept in mind, however, that abrupt vessel closure or an inadequate angiographic result occurs in approximately 10% of attempts at standalone balloon angioplasty, and unplanned stenting may become necessary.

Bare Metal Stents

Among patients undergoing PCI, routine stent implantation is associated with improved immediate and late results compared with balloon angioplasty alone. In the face of noncardiac surgery, however, the presence of a recently placed coronary stent introduces the possibility of stent thrombosis during the perioperative period, an event that is associated with substantial morbidity and mortality. Antiplate-let therapy with acetylsalicylic acid (ASA) and a thi-enopyridine is typically recommended for at least 2 to 4 weeks after placement of a bare metal stent, to reduce the likelihood of stent thrombosis while stent endothelialization is occurring, which mandates a longer delay between PCI and subsequent noncardiac surgery. If noncardiac surgery is undertaken soon after coronary stent implantation, several retrospective reports have demonstrated an alarmingly high rate of adverse cardiac events (see Table 7-5).

An observational report by Kaluza and colleagues was the first to highlight concerns regarding stent placement before noncardiac surgery.36 Among 40 patients who underwent bare metal stenting less than 6 weeks before noncardiac surgery, there were 8 deaths, 7 MIs, and 11 major bleeding episodes at the time of surgery. The majority of ischemic cardiac events were the result of stent thrombosis, and all episodes of MI and death occurred among patients who underwent surgery within 2 weeks after stent implantation. In a subsequent report from the Mayo Clinic, among 207 patients who underwent a surgical procedure within 2 months after coronary bare metal stent implantation, the incidence of perioperative death, MI, or stent thrombosis was lower but still of concern at 4.0%. All events occurred among patients who underwent surgery within 6 weeks after stent implantation, with no major cardiac complications reported when surgery was delayed for longer than 6 weeks.37 In a separate analysis of 56 patients who underwent noncardiac surgery after remote or recent coronary stenting, perioperative major adverse cardiac events or bleeding occurred in 8 (50%) of 16 patients who had surgery within 42 days after stent placement but in no patient whose surgery was performed more than 42 days after the stent procedure.39

Vicenzi and colleagues performed a prospective evaluation of 103 patients who required noncardiac surgery within 1 year after coronary stenting.40 In an attempt to limit thrombotic events, all patients were started on either unfractionated or low-molecular-weight heparin before surgery, and their baseline antiplatelet therapy was continued throughout the perioperative period if feasible or, if necessary, discontinued for as short a duration as possible. Despite these precautions, the incidence of major and minor cardiovascular events was 43%, and the overall surgical mortality rate was 4.9%. The risk of an adverse event was 2.1-fold higher among patients who underwent noncardiac surgery after recent (<35 days) rather than more remote (>90 days) coronary stenting.

In summary, based on the association between stent placement and perioperative stent thrombosis when the interval between PCI and surgery is short, it appears preferable to delay surgery for 6 weeks after bare metal stent implantation. This permits at least partial endothelialization of the stent as well as completion of a full course of thienopyridine therapy, and it also allows for drug discontinuation and return of platelet function before surgery. Of note, the performance of surgery soon after discontinuation of antiplatelet medications may itself predispose to thrombotic events, because withdrawal of oral anti-platelet medications outside the context of surgery has been associated with increased rates of death, MI or bleeding events in the ensuing 30 days.45

Drug-Eluting Stents

Drug-eluting stents have reduced the likelihood of restenosis after PCI compared to bare metal stents, yet they may not be well suited for use in the preop-erative period. By inhibiting cellular proliferation, not only do drug-eluting stents limit the development of fibrointimal hyperplasia, but they also inhibit the protective process of stent endothelialization. The possibility of stent thrombosis therefore remains a concern for months to years (instead of weeks) after drug-eluting stent implantation and mandates a prolonged course of thienopyridine therapy.46 According to package labeling, dual antiplatelet therapy is recommended for at least 3 months after siro-limus-eluting stent placement and 6 months after implantation of a paclitaxel-coated stent, although reports of later thrombosis with both stent types suggest that even longer courses of thienopyridine therapy may be beneficial.47

Interruption of antiplatelet therapy to permit the performance of many types of noncardiac surgery even months after drug-eluting stent implantation may be hazardous. Although definitive studies examining the potential consequences of drug eluting stent implantation before noncardiac surgery are lacking, perioperative stent thrombosis has been reported after cessation of antiplatelet therapy up to 21 months after placement of a sirolimus- or pacli-taxel-eluting stent.48-50

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