What Type of Stent Should Be Used to Treat Patients With STEMI? Part I: Bare Metal Stents (BMS) Remains the First Choice in ST-elevation Myocardial Infarction (STEMI)

Oct 26, 2015   |  Aloke V. Finn, MD; Anwer Khaled Habib, MD, FACC

Expert Analysis

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Editor's Note: This is Part I of a two-part Expert Analysis. Go to Part II.

The treatment of symptomatic coronary artery disease (CAD) has seen great advances especially in regards to the percutaneous treatment of acute coronary syndromes. While drug eluting stents (DES) reduce restenosis rates compared to bare metal stents (BMS), their use has been associated with an increased risk of late stent thrombosis due to delayed endothelial coverage and accelerated neointimal atherosclerosis (i.e. "neoatherosclerosis") secondary to disrupted endothelial junctions (Figure 1), both contributors to stent failure. These drawbacks mean their use needs to be carefully considered within the context of certain clinical situations for which they are employed. While primary percutaneous coronary intervention (PCI) for ST segment elevation myocardial infarction (STEMI) reduces risk of death compared with medical therapy alone, the advantage of DES over BMS for this indication remains uncertain1.

Figure 1
Figure 1. Endothelial healing of 1st generation DES compared with BMS. In pathologic studies, BMS shows greater endothelial healing at 1 month and up to 50 months. This is an example of BMS and sirolimus eluting stents (SES) in a single patient 15 months after implant showing complete endothelial healing of BMS but largely incomplete healing of SES (patient died of non-cardiac causes). Below panels show an example of scanning electron microscopy of BMS and SES showing incomplete endothelial barrier formation in the SES with disruption of barrier molecules (i.e. VE cadherin) from the cell borders into the cytosol (seen in green in the histologic insets). This is thought to be a mechanism in accelerated neoatherosclerosis in DES compared with BMS and a contributor to late stent failure.

The pivotal trials of drug eluting stents (DES) have been largely in the setting of symptomatic, "stable" coronary disease where acute coronary syndromes (ACS) patients are specifically excluded2. The U.S. Food and Drug Administration approval of DES was initially for the treatment of stable CAD. In fact, use of DES for the treatment of ACS is still considered an "off-label" use of these devices. Large registries, such as the Bern Rotterdam Experience, suggested 1st generation DES are associated with a steady rate of late stent thrombosis up to three years from the initial stent implantation with ACS being an independent predictor3. A meta-analysis of 16 randomized trials of early generation DES versus BMS for STEMI has shown reduced target-vessel revascularization. There was a trend towards fewer definite stent thrombosis within the first year but an increase in stent thromboses in later years, which seemingly offset any early benefit4. Some well-done trials such as the PASSION trial, in which BMS were compared to paclitaxel eluting stents for STEMI, did not show any benefit in terms of myocardial infarction, target lesion revascularization (TLR), or cardiac death at five year follow-up5. Real world registries of BMS versus DES for STEMI have shown similar findings, with an increased risk of late events with DES6. 2nd generation DES designed with thinner struts and side chain modifications of sirolimus meant to improve tissue retention of drug have generally shown improved outcomes compared with 1st generation DES. However, fewer trials have been conducted using 2nd generation DES in STEMI patients. In one of the few, the EXAMINATION trial randomized patients with STEMI to everolimus eluting stents versus BMS and showed no differences in the combined endpoint of death, MI, or TLR at 2 years7.

Additional safety concerns for the use of DES compared with BMS in the setting of primary PCI for STEMI also exist. In this scenario, unlike in clinical trials, the clinical picture is often incomplete. Does the patient have issues with compliance with dual anti-platelet therapy? Does the patient have bleeding risks or upcoming procedures? There are also larger economic concerns offering DES as they are not yet unequivocally proven better and are more costly than BMS. In conclusion, in the setting of primary PCI for STEMI the efficacy and safety of SES still remain uncertain, and thus their use may not be justified.

References

  1. Keeley EC, Boura JA and Grines CL. Primary angioplasty versus intravenous thrombolytic therapy for acute myocardial infarction: a quantitative review of 23 randomised trials. Lancet. 2003;361:13-20.
  2. Moses JW, Leon MB, Popma JJ, Fitzgerald PJ, Holmes DR, O'Shaughnessy C, Caputo RP, Kereiakes DJ, Williams DO, Teirstein PS, Jaeger JL, Kuntz RE and Investigators S. Sirolimus-eluting stents versus standard stents in patients with stenosis in a native coronary artery. N Engl J Med. 2003;349:1315-23.
  3. Daemen J, Wenaweser P, Tsuchida K, Abrecht L, Vaina S, Morger C, Kukreja N, Juni P, Sianos G, Hellige G, van Domburg RT, Hess OM, Boersma E, Meier B, Windecker S and Serruys PW. Early and late coronary stent thrombosis of sirolimus-eluting and paclitaxel-eluting stents in routine clinical practice: data from a large two-institutional cohort study. Lancet. 2007;369:667-78.
  4. Kalesan B, Pilgrim T, Heinimann K, Raber L, Stefanini GG, Valgimigli M, da Costa BR, Mach F, Luscher TF, Meier B, Windecker S and Juni P. Comparison of drug-eluting stents with bare metal stents in patients with ST-segment elevation myocardial infarction. Eur Heart J. 2012;33:977-87.
  5. Vink MA, Dirksen MT, Suttorp MJ, Tijssen JG, van Etten J, Patterson MS, Slagboom T, Kiemeneij F and Laarman GJ. 5-year follow-up after primary percutaneous coronary intervention with a paclitaxel-eluting stent versus a bare-metal stent in acute ST-segment elevation myocardial infarction: a follow-up study of the PASSION (Paclitaxel-Eluting Versus Conventional Stent in Myocardial Infarction with ST-Segment Elevation) trial. JACC Cardiovascular interventions. 2011;4:24-9.
  6. Brodie B, Pokharel Y, Fleishman N, Bensimhon A, Kissling G, Hansen C, Milks S, Cooper M, McAlhany C and Stuckey T. Very late stent thrombosis after primary percutaneous coronary intervention with bare-metal and drug-eluting stents for ST-segment elevation myocardial infarction: a 15-year single-center experience. JACC Cardiovascular interventions. 2011;4:30-8.
  7. Sabate M, Brugaletta S, Cequier A, Iniguez A, Serra A, Hernadez-Antolin R, Mainar V, Valgimigli M, Tespili M, den Heijer P, Bethencourt A, Vazquez N, Backx B and Serruys PW. The EXAMINATION trial (Everolimus-Eluting Stents Versus Bare-Metal Stents in ST-Segment Elevation Myocardial Infarction): 2-year results from a multicenter randomized controlled trial. JACC Cardiovascular interventions. 2014;7:64-71.

Keywords: Acute Coronary Syndrome, Atherosclerosis, Blood Platelets, Cadherins, Coronary Artery Disease, Cytosol, Drug-Eluting Stents, Follow-Up Studies, Metals, Microscopy, Electron, Scanning, Myocardial Infarction, Paclitaxel, Percutaneous Coronary Intervention, Randomized Controlled Trials as Topic, Registries, Sirolimus, Stents, Thrombosis


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