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Early studies suggested a mortality benefit with aspiration thrombectomy, and it thus found its way into early iterations of the ESC and ACC/AHA STEMI guidelines. The Thrombus Aspiration during Percutaneous Coronary Intervention in Acute Myocardial Infarction (TAPAS) trial randomized 1071 patients in a single center with acute STEMI, prior to diagnostic angiogram, to either thrombus aspiration or conventional PCI, looking at a primary endpoint of myocardial blush grade [9]. A 6Fr Export thrombus aspiration catheter was used for those patients randomized to the thrombus aspiration arm. A myocardial blush grade of 0 or 1 (i.e. absent or minimal myocardial perfusion) was found in 17.1% of the patients in the thrombus‐aspiration group but 26.3% of those in the conventional PCI group (risk ratio 0.65; 95% CI 0.51 to 0.83; p<0.001). Rates of death and major adverse cardiac events at 30 days were significantly related to myocardial blush grade, resolution of ST‐segment elevation, and ST‐segment deviation (p = 0.003 for death and myocardial blush grade, p<0.001 for all other associations). Note that unless contraindicated, abciximab was used in all patients in this study. Subsequent one year follow‐up revealed a hazard ratio of 1.93 (95% CI 1.11–3.37; p = 0.02) for cardiac death in the thrombus aspiration group compared to the conventional PCI group [10].

However, the Thrombus Aspiration in ST‐Elevation Myocardial Infarction in Scandinavia (TASTE) trial was a randomized, registry‐based clinical trial which enrolled 7244 patients with STEMI to either manual thrombus aspiration followed by PCI, or PCI only, looking at a primary endpoint of all‐cause mortality at 30 days, rather than a surrogate endpoint such as myocardial blush grade [11]. Results revealed no significant difference in mortality (hazard ratio for thrombectomy of 0.94; 95% CI 0.72–1.22; p = 0.63), as well as no significant differences with respect to the rate of stroke or neurological complications at the time of discharge (p = 0.87). Of note, due to the methodology of the trial being registry‐based, there was no additional monitoring and adjudication of the data for the TASTE trial beyond that of the regular Swedish Coronary Angiography and Angioplasty Registry (SCAAR) data validation. Also, for various reasons, only 59.7% of those patients considered for entry into the trial were actually randomized, and there was a large mortality difference between those who underwent randomization and those who did not (2.9% vs 10.6%). Subsequent one year follow‐up showed a hazard ratio for death from any cause of 0.94 (95% CI 0.78–1.15; p = 0.57) for patients in the thrombus aspiration group as compared to the PCI only group [12].

The Trial of Routine Aspiration Thrombectomy with PCI versus PCI alone in Patients with STEMI (TOTAL) trial attempted to clarify the conflicting results of the TASTE and TAPAS trials [13]. It recruited 10 732 patients at 87 hospitals in 20 countries undergoing primary PCI to a strategy of routine upfront manual thrombectomy with Export catheters versus PCI alone, looking at a primary outcome composed of a composite of death from CV causes, recurrent MI, cardiogenic shock or NYHA class IV heart failure within 180 days. It also included a safety outcome of stroke within 30 days. Overall, there was no significant difference in rates of the primary outcome (hazard ratio in the thrombectomy group 0.99; 95% CI 0.85–1.15; p = 0.86) however the hazard ratio for stroke within 30 days was 2.06 (95% CI 1.13–3.75; p = 0.02).

A subsequent meta‐analysis of all three trials combined revealed no improvement in clinical outcomes overall [14].

In terms of mechanical thrombectomy, the AngioJet Rheolytic Thrombectomy In Patients Undergoing Primary Angioplasty for Acute Myocardial Infarction (AIMI) study was a prospective, multicenter trial that randomly assigned 480 acute STEMI patients to treatment with rheolytic thrombectomy (RT) as an adjunct to conventional PCI or PCI alone [15]. All patients were treated with eptifibatide in addition, and it was recommended a temporary pacemaker was be inserted in the RT group. The routine use of RT did not reduce infarct size compared with primary PCI alone. In fact, final infarct size, as assessed by sestamibi imaging, was higher in the RT group compared with PCI alone (p = 0.03).

A further study evaluated the efficacy of the Rescue Catheter (Boston Scientific), randomizing 215 patients with STEMI to thrombectomy pretreatment or standard PCI. This again showed an increase in infarct size by sestamibi imaging (median 15% vs 8%; p = 0.004) [16].

The AngioJet Rheolytic Thrombectomy Before Direct Infarct Artery Stenting With Direct Stenting Alone in Patients With Acute Myocardial Infarct (JETSTENT) study [17], again assessed the Angiojet Rheolytic Thrombectomy device, in a multicenter, randomized study that looked at patients with high grade thrombus (TIMI grade 3 to 5) involving 501 patients, looking at both surrogate endpoints (degree of ST elevation resolution) and a composite of major adverse cardiovascular events at 1, 6, and 12 months. ST segment resolution was more frequent in the RT arm (85.8% vs 78.8%; p = 0.043), however no difference was found in other surrogate markers assessed, while at 6 months, there was a MACE event rate of 11.2% in the thrombectomy arm and 19.4% in the direct stenting arm (p = 0.011). This study suggested that in cases of patients with a high thrombus burden, there may be a role for mechanical thrombectomy.

On this basis of the overall evidence, both the most recent ESC STEMI guidelines, and the 2015 ACC/AHA/SCAI (Society for Cardiovascular Angiography and Intervention) STEMI guideline update, do not recommend routine use of thrombus aspiration [3,18].