Primary Percutaneous Coronary Intervention and Risk of Stent Thrombosis

Abstract

P rimary percutaneous coronary intervention (PCI) is the preferred treatment for patients with ST-segment elevation myocardial infarction (STEMI) owing to improved vessel patency, decreased infarct size, lower rates of reinfarction, and improved survival compared with pharmacological reperfusion. However, stent thrombosis (ST) remains a major concern among STEMI patients with an excess 3-to 4-fold increased risk compared with PCI in an elective setting. In the present issue of Circulation, the Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial investigators provide a detailed report of the incidence, timing, and predictors of ST, specifically addressing the impact of stent type and antithrombotic regimen through 2 years. 1 Definite or probable ST was common (4.4%), with little more than half of events falling into the early period (Ͻ30 days), and the remainder being observed in the late period (up to 2 years), without apparent differences in terms of stent type and antithrombotic regimen. Primary Percutaneous Coronary Intervention and Stent TypeA recent systematic review comparing outcomes between drug-eluting stents (DES) and bare-metal stents (BMS) reported a 56% lower risk of repeat revascularization in favor of DES without differences in terms of death, MI, and ST. 2 A number of registry data extend the benefit of DES to more unselected patients undergoing primary PCI in routine clinical practice. Notwithstanding, there remains a nagging concern about the safety of DES in STEMI patients, particularly during long-term follow-up. What are the principal reasons underlying this clinical equipoise? Article see p 1745First, very late ST has been recognized as a distinct entity complicating the use of DES, particularly in the off-label setting. Along this line, observational studies have reported an increased risk of very late ST with DES compared with BMS among STEMI patients. 3,4 Second, none of the individual STEMI trials have been powered adequately to address infrequent adverse events, such as very late ST. Third, histopathological analysis of autopsy specimens revealed more inflammation, fibrin deposition, and uncovered struts among lesions treated with DES in STEMI patients compared with those with stable lesions, suggesting a differential arterial response to DES depending on underlying plaque morphology. 5 Fourth, late acquired stent malapposition (LASM) was more common among DES (31%) than BMS (8%, Pϭ0.02) 13 months after PCI in the Intravascular Ultrasound (IVUS) substudy of HORIZONS-AMI. 6 Although it remains a matter of debate whether LASM is causally related to very late ST, LASM in the presence of vessel remodeling is presumably caused by extensive inflammation elicited by DES and highly prevalent among patients presenting with very late ST (75%). 7 Because LASM is a dynamic process and only appears over time, it may become clinically apparent only during very long-term follow-up. The notion of a differential healing response between DES and BMS...

Safety and feasibility of intra-arterial bivalirudin bolus administration during primary angioplasty

“…The causes of acute stent thrombosis during primary PCI have included technical factors, such as suboptimal stent implantation, edge dissection, or suboptimal final antegrade flow [6][7][8][9] and the thrombogenic milieu [10].…”

“…Dangas et al [11] found preintervention heparin therapy and high-dose clopidogrel loading as the protective factors against acute stent thrombosis in the HORIZONS-AMI trial. Therefore, patients treated with bivalirudin monotherapy during primary PCI may be at risk because of residual thrombin activity with discontinuation of bivalirudin or inadequate platelet inhibition, as bivalirudin is not an effective antiplatelet therapy [10]. Recent study also reports the inadequate antiplatelet effect even with more potent oral antiplatelet agents during primary PCI, with high platelet reactivity as measured using VerifyNow assay even 2 h after the bolus administration [12].…”

Second-Generation Everolimus-Eluting Stents Versus First-Generation Sirolimus-Eluting Stents in Acute Myocardial Infarction

“…Despite the promising low percentage of stent thrombosis, long-term follow-up will have to demonstrate safety, as continuing rates of late stent thrombosis have been reported in first-generation DES during the first few years (5,25). Data on improved vascular healing and endothelialization of second-generation DES (7,26) provide some incentive for the hypothesis that in these newer-generation DES, incremental rates of (very) late stent thrombosis may be ameliorated, even in this highly thrombotic subset of patients.…”

Comparison of Biodegradable Polymer Versus Durable Polymer Sirolimus‐Eluting Stenting in Patients with Acute ST‐Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: Results of the RESOLVE Study

“…The use of drug‐eluting stents (DES) in primary PCI has resulted in lower rates of repeat revascularization procedures, particularly when compared with bare metal stents (BMS) . However, stent thrombosis (ST) of first‐generation DES that uses durable polymer coatings remains a major concern in STEMI patients, particularly during long‐term follow‐up …”

“…4 However, stent thrombosis (ST) of first-generation DES that uses durable polymer coatings remains a major concern in STEMI patients, particularly during long-term follow-up. [5][6][7] Several observational studies have demonstrated promising results with the use of DES with a biodegradable polymer coating in elective PCI, [8][9][10][11] and the Comparison of Biolimus Eluted From An Erodible Stent Coating With Bare Metal Stents In Acute ST-Elevation Myocardial Infarction (COM-FORTABLE AMI) Study compared the efficacy and safety of a biolimus A9-eluting biodegradable polymer DES with BMS in the setting of primary PCI for acute STEMI. 12 In COMFORTABLE AMI, the use of a biodegradable polymer DES was associated with improved rates of major adverse cardiac events (MACE) at 1-year follow-up, compared with BMS.…”