Primary percutaneous coronary intervention (PCI), if available in a timely fashion, is the optimal reperfusion method in the treatment of ST elevation myocardial infarction (STEMI). However, a limitation of modern primary PCI is distal embolization of thrombus during either balloon pre-dilatation or stent deployment, which can lead to impairment of microvascular perfusion. Measures of microvascular tissue perfusion that worsened after primary PCI and have been associated with mortality include angiographic blush grade and electrocardiographic ST segment resolution.^1,2

Removal of thrombus during primary PCI prior to stent deployment has been thought to be a logical way to reduce distal embolization and improve prognosis. In 2008, the single center TAPAS trial (N=1071) showed that routine manual thrombectomy during primary PCI improved the surrogate outcome of blush grade (primary outcome) but was also associated with marked reduction in mortality at 1 year.^3,4 The larger TASTE trial (N=7244) showed no reduction in mortality with routine thrombectomy during PCI for STEMI either at 30 days or 1 year.^5,6

The TOTAL trial is the largest trial of manual thrombecotmy (N=10,732) and randomized patients to a strategy of routine manual thrombectomy vs. PCI alone with only bailout thrombectomy.⁷ Bailout thrombectomy was allowed if there was a failure of the PCI alone strategy, which was defined as TIMI 0 or 1 flow with large thrombus after balloon pre-dilatation or large thrombus after stent deployment irrespective of TIMI flow.

TOTAL demonstrated that thrombectomy improved ST segment resolution and angiographic distal embolization. However, thrombectomy had similar rates of primary outcome of CV death, recurrent MI, cardiogenic shock or class IV heart failure at 180 days (6.9% vs. 7.0%; hazard ratio 0.99, 95% CI 0.85-1.15) but a significant increase in stroke at 30 days compared to PCI alone (0.7% vs. 0.3%; hazard ratio 2.06, 95%CI 1.13-3.75).⁸ These findings were similar at 1 year.⁹

The ACC/AHA/SCAI guidelines have been updated so that routine thrombectomy during primary PCI for STEMI has been given a class III indication and selective or bailout thrombectomy has been given a class IIb indication due to lack of data.¹⁰

Based on the evidence from large randomized trials, thrombectomy should not be used routinely during PPCI for STEMI. Instead, it should be used a bailout strategy in cases of heavy thrombus that do not respond to balloon pre-dilatation.

References

1. Henriques JP, Zijlstra F, van 't Hof AW et al. Angiographic assessment of reperfusion in acute myocardial infarction by myocardial blush grade. Circulation 2003;107:2115-9.
2. Buller CE, Fu Y, Mahaffey KW et al. ST-segment recovery and outcome after primary percutaneous coronary intervention for ST-elevation myocardial infarction: insights from the Assessment of Pexelizumab in Acute Myocardial Infarction (APEX-AMI) trial. Circulation 2008;118:1335-46.
3. Svilaas T, Vlaar PJ, van der Horst IC et al. Thrombus aspiration during primary percutaneous coronary intervention. N Engl J Med 2008;358:557-67.
4. Vlaar PJ, Svilaas T, van der Horst IC et al. Cardiac death and reinfarction after 1 year in the Thrombus Aspiration during Percutaneous coronary intervention in Acute myocardial infarction Study (TAPAS): a 1-year follow-up study. Lancet 2008;371:1915-20.
5. Frobert O, Lagerqvist B, Olivecrona GK et al. Thrombus aspiration during ST-segment elevation myocardial infarction. N Engl J Med 2013;369:1587-97.
6. Lagerqvist B, Frobert O, Olivecrona GK et al. Outcomes 1 year after thrombus aspiration for myocardial infarction. N Engl J Med 2014;371:1111-20.
7. Jolly SS, Cairns J, Yusuf S et al. Design and rationale of the TOTAL trial: a randomized trial of routine aspiration ThrOmbecTomy with percutaneous coronary intervention (PCI) versus PCI ALone in patients with ST-elevation myocardial infarction undergoing primary PCI. American heart journal 2014;167:315-321 e1.
8. Jolly SS, Cairns JA, Yusuf S et al. Randomized Trial of Primary PCI with or without Routine Manual Thrombectomy. N Engl J Med 2015;372:1389-98.
9. Jolly SS, Cairns JA, Yusuf S et al. Outcomes after thrombus aspiration for ST elevation myocardial infarction: 1-year follow-up of the prospective randomised TOTAL trial. Lancet 2015.
10. Levine GN, O'Gara PT, Bates ER et al. 2015 ACC/AHA/SCAI Focused Update on Primary Percutaneous Coronary Intervention for Patients With ST-Elevation Myocardial Infarction: An Update of the 2011 ACCF/AHA/SCAI Guideline for Percutaneous Coronary Intervention and the 2013 ACCF/AHA Guideline for the Management of ST-Elevation Myocardial Infarction: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Society for Cardiovascular Angiography and Interventions. J Am Coll Cardiol 2015; October, doi 10.1016/j.jacc.2015.10.005

Keywords: Acute Coronary Syndrome, Dilatation, Electrocardiography, Heart Failure, Percutaneous Coronary Intervention, Prognosis, Randomized Controlled Trials as Topic, Shock, Cardiogenic, Stents, Stroke, Thrombectomy, Thrombosis

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