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Panel Summary and Recommendations on the Role of Thrombectomy With Primary PCI for STEMI
This symposium has evaluated the latest data from randomized trials and registries on the use of thrombectomy devices with primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI). Our goal has been to provide the interventionalist a rational approach for the use of thrombectomy devices in STEMI patients.
It has been clearly demonstrated that the presence of a large thrombus burden at the time of primary PCI is associated with worse procedural outcomes and worse long-term clinical outcomes.1 This has led to the belief that thrombectomy or removal of thrombus in the infarct artery BEFORE primary PCI may prevent distal embolization and improve myocardial reperfusion and long-term clinical outcomes. Until recently, large clinical trials with devices designed to prevent distal embolizaton, have not proven beneficial. However, the publication of the TAPAS Trial with aspiration thrombectomy and the JetSTENT Trial with rheolytic thrombectomy have provided new evidence for the benefit of thrombectomy.2,3
In this symposium, Dr. Brodie reviewed data regarding the use of aspiration thrombectomy with primary PCI. The TAPAS Trial showed improved myocardial blush and reduced mortality at 1 year with aspiration thrombectomy.2,4 Four meta-analyses showed improved procedural outcomes and better myocardial reperfusion with aspiration, and 3 of 4 meta-analyses showed improved mortality.5–8 The AHA/ACC and ESC Guidelines Committees have given a Class IIa recommendation to aspiration thrombectomy for use with primary PCI in STEMI patients.9,10
Dr. Sianos demonstrated the importance of large thrombus burden on procedural and late clinical outcomes with primary PCI and demonstrated the importance of methodology in the classification of large thrombus burden. He stressed the importance of establishing reperfusion in totally occluded infarct vessels using a wire or a small balloon to allow visualization of the thrombus burden and to reclassify patients with Grade 5 thrombus burden into Grades 0–4 thrombus burden. Under this classification, patients with Grade 4, or large, thrombus burden had worse procedural and late clinical outcomes. Dr. Sianos also presented observational data that the use of RT is associated with improved long term outcomes in patients with large thrombus burden.
Dr. Sharma described his observational experience at Mount Sinai Hospital in the management of STEMI patients with moderate-to-large thrombus burden (Grades 3–5). Patients treated with RT compared to patients treated with primary PCI alone without thrombectomy had better TIMI flow post-PCI with less no-reflow, better myocardial blush, and better event-free survival at 1 year.
Drs. Szerlip and Grines reviewed data from Dr Grines’s meta-analysis of randomized trials and registries comparing rheolytic thrombectomy (RT) with primary PCI alone.11 Despite the fact that patients treated with RT were a higher risk group, with more large thrombus burden and more rescue PCI, outcomes were similar to patients treated with primary PCI alone. These observations suggest that RT may reduce the additional risk associated with visible thrombus in STEMI patients treated with primary PCI.
Dr. Antoniucci reviewed the results of the recent JetSTENT Trial, in which randomized STEMI patients with thrombus burdens Grades 3–5 to RT and stenting versus direct stenting alone.3 Patients treated with RT had better ST-segment resolution and lower MACE at 6 months and 1 year. He discussed some of the potential reasons for differences in outcomes between the AiMI Trial, which showed no benefit and possible harm with RT, and the JetSTENT Trial. AiMI enrolled patients regardless of whether there was visible thrombus present, while JetSTENT enrolled only patients with visible thrombus.12 In AiMI, the AngioJet was usually passed beyond the coronary occlusion before activation, which may predispose to distal embolization, while in the JetSTENT Trial the AngioJet was activated before antegrade passage. In AiMI, balloon pre-dilatation was usually performed before RT, which may predispose to distal embolization, while in JetSTENT pre-dilatation was not performed. In addition, the mortality in the control arm of AiMI was extremely low and may have occurred by chance. These reasons may explain some of the differences in outcomes between AiMI and JetSTENT.
Finally, Dr. Mehta presented his selective strategy for the management of thrombus in STEMI patients treated with primary PCI based upon the thrombus grade — with direct stenting recommended for low-grade thrombus (Grades 0–1), aspiration thrombectomy for moderate thrombus (Grade 2–3) and RT for high-grade thrombus (Grade 4). Experience from the SINCERE database has shown excellent outcomes with this approach.
The panel reviewed these data and tried to reach a consensus regarding the use of thrombectomy devices in the management of STEMI patients treated with primary PCI. These recommendations represent a consensus of the experienced interventionalists participating in this special supplement to the Journal of Invasive Cardiology. We recognize that some of these recommendations may not have sufficient evidence to reach the status of guidelines.
There was general agreement that baseline estimates of thrombus burden are helpful in predicting outcomes and deciding the optimal approach to the management of thrombus in STEMI patients treated with primary PCI. Establishing flow in the infarct artery — either with passage of the wire, Dottering the lesion, or dilatation with a small balloon — in patients with Grade 5 thrombus (totally occluded vessel) is helpful in visualizing the vessel and allowing reclassification of Grade 5 thrombus into Grades 0–4 thrombus.
There are few data and considerable controversy regarding whether thrombectomy devices should be used selectively or should be used in all patients with STEMI treated with primary PCI. TAPAS and AiMI treated all comers while JetSTENT treated only patients with visible thrombus. The panel’s view is that thrombectomy should be performed in patients with visible thrombus (Grades 2–4). While the panel’s general recommendation in patients with Grade 5 thrombus is to establish reperfusion and reclassify the thrombus grade (from Grade 5 to Grades 0–4) before deciding whether to use a thrombectomy device, it is not an unreasonable alternative to use a thrombectomy device in patients with Grade 5 thrombus.
There are differences of opinion regarding when manual thrombectomy should be used and when rheolytic thrombectomy should be considered in STEMI patients with visible thrombus. The TAPAS Trial evaluated the benefit of aspiration thrombectomy in all patients, regardless of thrombus grade, while the JetSTENT Trial evaluated RT only in patients with visible thrombus. None of the trials evaluating thrombectomy have had sufficient numbers of patients to evaluate subgroups based on thrombus burden.
Data supporting the benefit of aspiration thrombectomy in improving measures of myocardial reperfusion and reducing no-reflow and distal embolization are consistent and strong, and aspiration may provide a mortality benefit. Data from TAPAS and from 3 of 4 meta-analyses suggest a mortality benefit, but TAPAS was not powered to detect differences in clinical outcomes and meta-analyses have limitations.2,4,5–8 For these reasons, aspiration thrombectomy has been given a Class IIa and not a Class I indication for use with primary PCI by the ACC/AHA and ESC Guidelines Committees.9,10 Aspiration thrombectomy is easy to perform and relatively inexpensive, and the panel members agree that aspiration thrombectomy provides significant benefit with little risk and should be performed in STEMI patients presenting with visible thrombus. The panel did not feel there was compelling evidence to perform manual thrombectomy in patients with no visible thrombus present (Grades 0–1).
The recent JetSTENT Trial provides new evidence supporting the use of rheolytic thrombectomy with primary PCI for STEMI. The AiMI Trial, and meta-analyses largely driven by the results of the AiMI Trial, had previously shown no benefit with rheolytic thrombectomy with primary PCI — however, as discussed above, the AiMI Trial has limitations related to trial design, operator technique, and an unusually low mortality in the control arm of AiMI. New data from the JetSTENT Trial suggest better myocardial reperfusion (better ST-segment resolution) and lower MACE at 6 months and 1 year with RT in patients with moderate and large thrombus burden (Grades 3–5).3
Observational data presented by Sianos and Sharma in this supplement found that the use of RT in patients with large thrombus burden and moderate-to-large thrombus burden was associated with improved long-term outcomes. RT is very effective in removing large thrombus burden, while manual thrombectomy is less effective with very large thrombus burden and may leave residual thrombus. Based on these considerations, we believe that RT may be the best option with primary PCI for the treatment of STEMI patients with large thrombus burden (Grade 4), while aspiration thrombectomy is the best option for patients with moderate thrombus burden (Grades 2–3).
The panel also had several recommendations regarding technique with both aspiration thrombectomy and RT. Balloon pre-dilatation generally should not be performed with aspiration thrombectomy unless the device will not pass, because doing so lead to distal embolization. Aspiration should be initiated with antegrade passage. Repeat passages should be performed until visible thrombus is no longer present.
With RT, balloon pre-dilatation should also not be performed unless the device will not pass. The device should be activated at least 1 cm proximal to the thrombus before crossing the lesion, then the device should be advanced at 1 mm to 3 mm per second. The device should remain activated with distal-to-proximal pullback. One or more passes should be performed until all visible thrombus has been removed. Usually one or two passes will accomplish this. Most operators recommend that a temporary pacemaker be used with RT, especially in the right coronary artery, but some operators feel a pacemaker is not necessary, and temporary pacemakers were not used in the JetSTENT Trial.
