Drug-eluting stents (DES) are highly effective in reducing restenosis but have a small but significant risk for late stent thrombosis (LAST). Cessation of antiplatelet drugs for noncardiac surgery has been implicated in precipitating LAST, prompting surgery to be done on antiplatelet therapy, with all the attendant bleeding risks, or deferred until 12 months after DES implantation, despite limited data defining the risk for LAST. Using billing data from 2 large health funds, members who had DES insertion (n = 9,321) with subsequent noncardiac surgery (n = 4,126) were mailed a questionnaire regarding their noncardiac procedures, antiplatelet use, and subsequent coronary events. From 1,086 returned, 710 were suitable for inclusion, identifying 11 patients (1.5%) with perioperative myocardial infarctions confirmed by medical records. Angiography showed that only 2 had stent thromboses, while 7 had new culprit lesion (2 patients did not undergo angiography). Before their noncoronary procedures, 66% were receiving dual-antiplatelet therapy, and 30% were taking single agents. Surgery was performed on dual therapy in 18%, on single agents in 23%, and with no antiplatelet therapy in 59%. The mean time to surgery from stent implantation was 348 days, with 56% <12 months. In conclusion, noncardiac surgery after DES implantation is frequent and appears to have low cardiac morbidity despite variable antiplatelet cessation. Perioperative myocardial infarctions occur because of narrowings in nonstented coronary arteries rather than from LASTs.
Reduction in intimal proliferation with drug-eluting stents (DES) has curtailed restenosis but also significant increased late malapposition (in which stent struts are not covered by intima), providing a permanent stimulus to thrombus formation and a small but clinically significant risk for late stent thrombosis (LAST). Although the incidence of LAST is small, the morbidity and mortality are very high, creating a great deal of anxiety and impetus to try to avoid this devastating complication. LAST has been precipitated by the abrupt cessation of antiplatelet therapy, particularly within the first 12 months after implantation. The most common reason to stop antiplatelet therapy is to avoid excessive bleeding during noncardiac surgery (NCS). However, there are few hard data on the absolute risk for stent thrombosis with cessation of antiplatelet therapy. We used billing records from the 2 largest private health insurance providers in Australia to identify patients who underwent DES implantation with subsequent NCS. We mailed them a questionnaire regarding the cessation of antiplatelet therapy and perioperative events.
Methods
DES were first introduced into Australia in July 2002 (Cypher; Cordis Corporation, Miami Lakes, Florida) and were more commonly used after the introduction of the second stent (Taxus; Boston Scientific Corporation, Natick, Massachusetts) in August 2003. Approximately 50% of patients in Australia have private health insurance (i.e., 50% of about 20 million, or about 10 million). Of these patients, the largest number belong to Medibank Private (approximately 4 million), while a further 1.3 million patients belong to Health Contributions Fund. All patients who had undergone DES implantation followed by NCS were identified and mailed a questionnaire. Because of privacy laws, patients’ identities were revealed to the study investigators only after they had chosen to participate in the study. Thus, a questionnaire was mailed to each patient with a consent and patient information sheet. If the patient agreed to participate, he or she mailed back the completed questionnaire and consent form. Thus, the identities of those not agreeing to participate were unknown to the investigators, but it was possible to confirm that nonresponders did not die <30 days after their NCS.
The questionnaire was kept as simple and unambiguous as possible, asking for the date, cardiologist, and hospital of the original DES implantation procedure. It requested a list of NCS procedures performed since that time, which antiplatelet agents were being taken at the time preceding the NCS, and which if any of these were stopped for the procedure. Finally, we asked whether any cardiac problems occurred at the time of the procedure and obtained consent to access the medical records at the hospital at which the NCS and any subsequent cardiac procedures were performed as well as from their treating physicians. All events were verified with the medical records. There were no questions regarding bleeding with the surgery or any noncardiac complications of the surgery.
Results
From July 1, 2002, and May 1, 2007, 9,321 patients had DES implanted in ≥1 coronary artery. A total of 4,126 (44%) had subsequent surgery and were mailed questionnaires. Of these, 1,086 (26%) replied. Three hundred seventy-six of these underwent cardiac surgery only and were excluded, leaving 710 patients ( Figure 1 ). None of the nonresponders died <30 days after their noncardiac procedures.
The mean time from DES implantation to NCS was 348 ± 266 days. Twenty-three patients (3%) had surgery within 30 days, 191 (27%) within 6 months, and 397 (56%) within 12 months. Before NCS, 468 patients (66%) were taking aspirin and clopidogrel, 152 (21%) were taking aspirin alone, 63 (9%) were taking clopidogrel alone, and 27 (4%) were taking no antiplatelet agents. During surgery, 130 were receiving dual-antiplatelet therapy, 98 were taking aspirin alone, and 63 were taking clopidogrel alone, with 419 receiving no antiplatelet therapy. The mean duration of antiplatelet cessation in preparation for surgery was 7.1 days for aspirin and 8.5 days for clopidogrel.
Only 11 patients reported cardiac events that were confirmed to be due to acute coronary syndromes: 9 of 11 underwent coronary angiography, of whom 2 had angiographically confirmed stent thromboses (definite stent thrombosis by Academic Research Consortium definition). The remaining 7 had new culprit lesions remote from the previously implanted DES (but 2 within the previously stented vessels). The 2 patients in whom angiography was not repeated included 1 patient having palliative surgery for metastatic melanoma who had an acute ST elevation inferior myocardial infarction with previous right coronary DES implantation, in whom a conservative management strategy was adopted. Clinically, it seems probable that this might have been a third case of LAST (3 probable stent thromboses by Academic Research Consortium definition). The last patient had only a minor troponin increase without electrocardiographic changes, and angiography was deferred. Patients were grouped according to time from DES implantation to NCS and event rates compared along with antiplatelet therapy, baseline demographics, number of stents used, and type of NCS ( Table 1 ). Of the 11 events, 1 occurred < 30 days after DES implantation, none from 1 to 6 months, 6 from 6 to 12 months, and 4 >12 months. Only 1 patient was receiving antiplatelet therapy (aspirin alone). The 3 probable stent thromboses occurred at 186, 356, and 486 days, and no patient was taking any antiplatelet therapy.
| Variable | DES Implantation to NCS (months) | ||
|---|---|---|---|
| <1 (n = 23) | 1–12 (n = 374) | >12 (n = 336) | |
| Confirmed myocardial infarction | 1 | 6 | 4 |
| LAST | 0 | 2 | 1 |
| APT previous (dual/single) | 22/1 | 338/22 | 108/202 |
| APT during (dual/single) | 12/1 | 104/118 | 14/42 |
| Age (years), mean ± SD | 68 ± 8 | 71 ± 10 | 69 ± 11 |
| Men/women | 15/8 | 282/92 | 252/84 |
| Smoker (current/former) | 2/4 | 25/95 | 28/77 |
| Diabetes | 7 | 98 | 92 |
| NCS (vascular/neurologic/other) | 1/0/22 | 17/4/353 | 14/3/319 |
| Lesions stented (1/2/>2) | 18/2/3 | 322/34/18 | 302/24/8 |
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