A meta-analytic overview of thrombectomy during primary angioplasty

Even though primary angioplasty restores TIMI 3 flow in more than 90% of STEMI patients, the results in terms of myocardial perfusion are still unsatisfactory in a relatively large proportion of patients. Great interest has been focused in the last years on distal embolization as major determinant of poor reperfusion and clinical outcome after primary angioplasty. The aim of this article is to perform an updated meta-analysis of thrombectomy devices in STEMI patients undergoing primary angioplasty.

The literature was scanned by formal searches of electronic databases (MEDLINE, Pubmed) from January 1990 to December 2010, the scientific session abstracts (from January 1990 to December 2010) and oral presentation and/or expert slide presentations (from January 2002 to December 2010) (on TCT, AHA, ESC, ACC and EuroPCR websites). No language restrictions were enforced.

A total of 21 randomized trials were finally included in the meta-analysis, involving 4514 patients (2270 or 50.3% randomized to thrombectomy and 2244 or 49.7% to standard angioplasty). Overall thrombectomy did not reduce 30-day mortality, with more benefits observed only with manual thrombectomy. No difference was observed in the 30-day reinfarction rate, whereas a trend in higher risk of stroke was observed with thrombectomy (p=0.06). Manual but not mechanical thrombectomy significantly improved postprocedural TIMI 3 flow, however, both devices significantly improved myocardial reperfusion as evaluated by ST-segment resolution. By meta-regression analysis a linear relationship was observed between benefits from thrombectomy in ST-segment resolution and in the presence of thrombus at baseline angiography (p=0.0016).

The present meta-analysis has demonstrated that, among patients with STEMI, manual thrombectomy significantly improved myocardial perfusion, with a trend in short-term mortality benefits, whereas mechanical thrombectomy, despite the benefits in myocardial perfusion, did not impact on short-term survival. However, the benefits in myocardial perfusion were significantly related to prevalence of coronary thrombus. In light of the observed higher risk of stroke, thrombectomy cannot be routinely recommended, but should be used in case of evident intracoronary thrombus. Mechanical thrombectomy devices may be considered as well to further improve reperfusion and facilitate optimal stent implantation, especially in the presence of large thrombus burden.