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J Thorac Cardiovasc Surg 2003;125:1544-1546
© 2003 The American Association for Thoracic Surgery
Brief Communications |
From the Departments of Cardiothoracic Surgery and Cardiology, Sir Charles Gairdner Hospital, Perth, West Australia.
Received for publication July 15, 2002. Accepted for publication Oct 10, 2002. Address for reprints: J. M. Alvarez, FRACS, Department of Cardiothoracic Surgery, Verdun St, Nedlands, Perth, West Australia 6009 (E-mail: John.Alvarez{at}health.wa.gov.au).
A majority of percutaneous revascularization procedures incorporate percutaneous transluminal coronary artery stenting with balloon percutaneous transluminal coronary angioplasty (PTCA). Acute coronary stent thrombosis, however, remains an uncommon yet serious complication.
1 Recently, off-pump coronary artery bypass (OPCAB) surgery has gained widespread popularity. 2 However, the effect of OPCAB surgery on coagulation-fibrinolytic homeostasis is unclear. We report 2 cases of acute coronary stent thrombosis in previously stented ungrafted coronary arteries (ie, angiographically normal) after OPCAB surgery. Both patients had normal coagulation profiles.
Clinical summaries
PATIENT 1. A 42-year-old male smoker was admitted with unstable angina. The patient's sole previous history was of successful primary right coronary artery (RCA) PTCA after an inferior acute myocardial infarction (AMI) in 1995. Despite treatment with aspirin and intravenous heparin and glyceryl trinitrate, angina persisted; cardiac catheterization revealed a 90% discrete (19 mm) RCA stenosis and a total left anterior descending coronary artery (LAD) occlusion, and left ventricular function was normal. A 35 x 8-mm Tetra stent was successfully deployed to the RCA, and daily clopidogrel was added (Figure 1, A and B).
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, C). This was successfully opened by means of PTCA, and ReoPro (Eli Lilly) was commenced (Figure 1, D). Despite a perioperative AMI (creatine kinase, 2900 U/L), uneventful discharge home occurred 19 days later. PATIENT 2. A 61-year-old man admitted with unstable angina was treated with aspirin and intravenous heparin and glyceryl trinitrate. Six months previously, 4 stents were successfully and electively deployed to the LAD, RCA, circumflex artery, and diagonal artery. Risk factors were hypertension and hyperlipidemia. Angiography revealed RCA and circumflex artery in-stent restenosis (≥95%), the LAD stent was pristine (Figure 2, A), and left ventricular function was normal. Ongoing angina resulted in OPCAB surgery 4 days later. Saphenous vein grafts were performed to the circumflex artery and RCA by using the Octopus III stabilizer. Aspirin was restarted within 24 hours, and postoperative recovery was uneventful.
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, B), which was successfully treated with PTCA and ReoPro (Figure 2, C). Recovery from the AMI (creatine kinase, 3800 U/L) was complicated by deep sternal infection successfully managed with a bilateral myocutaneous pectoralis flap with an omental graft. The patient was discharged home 31 days after OPCAB surgery. Discussion
We report 2 cases of acute coronary stent thromboses after OPCAB surgery. In both cases the thrombosed stents exhibited no evidence of in-stent pathology preoperatively, and thus the respective coronary arteries were ungrafted. Direct surgical trauma to coronary stents causing stent thrombosis has been reported with coronary artery bypass grating (CABG) with cardiopulmonary bypass (CPB). 3 Ostensibly, such trauma could occur with cardiac manipulation during OPCAB surgery. However, the coronary anatomy in both cases precluded the need for such manipulation to infringe on these stents.
Aspirin is traditionally recommenced within 24 hours after CABG. Approximately 10% of all patients with CABG in our unit (400 patients per year) over the last 5 years have had previous percutaneous transluminal coronary artery stenting, with many of these stented coronaries being pristine, thus not requiring coronary grafting. The vast majority (>95%) of these operations were performed with CPB, and acute stent thrombosis never occurred. Ostensibly, the anticoagulant effect of CPB and postoperative aspirin prevents acute stent thrombosis in these angiographically pristine vessels.
Despite initial enthusiasm, the purported benefits from OPCAB surgery remain unproven. 2 With OPCAB surgery, the optimal heparin dose (we used 1 mg/kg) and whether to reverse this effect with protamine and at what dose (we used 100 and 50 mg, respectively, for patients 1 and 2) is unclear. However, this is at least one third of the heparin-protamine requirements with CPB.
Furthermore, all major operations induce a prothrombotic diathesis. With OPCAB surgery, unlike CABG with CPB, platelet numbers and function remain preserved. 4 Also, a prothrombotic effect partly attributed to increased platelet reactivity has been demonstrated after OPCAB surgery. 4
We have performed OPCAB surgery in 150 patients without evidence of acute coronary thrombosis. These 2 patients were the first to have OPCAB surgery with patent stents. In these patients with stented yet pristine coronary arteries, sole reliance on aspirin seems imprudent. We thus add clopidogrel. With this strategy, a further 8 patients with patent stents had uncomplicated OPCAB surgery.
References
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