Safety and efficacy of thrombectomy in patients undergoing primary percutaneous coronary intervention for Acute ST elevation MI: A Meta-Analysis of Randomized Controlled Trials

BMC Cardiovascular Disorders Safety and efficacy of thrombectomy in patients undergoing primary percutaneous coronary intervention for Acute ST elevation MI: A Meta-Analysis of Randomized Controlled Trials Umesh U Tamhane 0 Stanley Chetcuti 0 Irfan Hameed 0 P Michael Grossman 0 Mauro Moscucci 0 Hitinder S Gurm 0 0 Division of Cardiovascular Medicine, University of Michigan , Ann Arbor, MI , USA Background: Clinical trials comparing thrombectomy devices with conventional percutaneous coronary interventions (PCI) in patients with acute ST elevation myocardial infarction (STEMI) have produced conflicting results. The objective of our study was to systematically evaluate currently available data comparing thrombectomy followed by PCI with conventional PCI alone in patients with acute STEMI. Methods: Seventeen randomized trials (n = 3,909 patients) of thrombectomy versus PCI were included in this meta-analysis. We calculated the summary odds ratios for mortality, stroke, post procedural myocardial blush grade (MBG), thrombolysis in myocardial infarction (TIMI) grade flow, and post procedural ST segment resolution (STR) using random-effects and fixed-effects models. Results: There was no difference in risk of 30-day mortality (44/1914 vs. 50/1907, OR 0.84, 95% CI 0.54-1.29, P = 0.42) among patients randomized to thrombectomy, compared with conventional PCI. Thrombectomy was associated with a significantly greater likelihood of TIMI 3 flow (1616/1826 vs. 1533/1806, OR 1.41, P = 0.007), MBG 3 (730/1526 vs. 486/1513, OR 2.42, P < 0.001), STR (923/1500 vs. 715/1494, OR 2.30, P < 0.001), and with a higher risk of stroke (14/1403 vs. 3/1413, OR 2.88, 95% CI 1.06-7.85, P = 0.04). Outcomes differed significantly between different device classes with a trend towards lower mortality with manual aspiration thrombectomy (MAT) (21/949 vs.36/953, OR 0.59, 95% CI 0.35-1.01, P = 0.05), whereas mechanical devices showed a trend towards higher mortality (20/416 vs.10/418, OR 2.07, 95% CI 0.95-4.48, P = 0.07). Conclusions: Thrombectomy devices appear to improve markers of myocardial perfusion in patients undergoing primary PCI, with no difference in overall 30-day mortality but an increased likelihood of stroke. The clinical benefits of thrombectomy appear to be influenced by the device type with a trend towards survival benefit with MAT and worsening outcome with mechanical devices. - Background Primary percutaneous intervention (PCI) is the preferred reperfusion modality in patients with ST-elevation myocardial infarction (STEMI) [1]. While primary PCI is highly effective in achieving epicardial coronary reperfusion, a significant proportion of patients fail to achieve adequate myocardial reperfusion [2]. Measures of failed epicardial reperfusion such as persistent ST elevation or diminished myocardial blush grade (MBG) have demonstrated consistent association with poor left ventricular salvage and increased mortality and morbidity [3,4]. Angiographically evident thrombus is a major predictor of poorer myocardial reperfusion and this is believed to be secondary to embolization of thrombus and plaque detritus. Based on this line of reasoning multiple thrombectomy devices have been evaluated for treating patients with STEMI. Studies evaluating these devices have been small and underpowered for clinical endpoints and have demonstrated disparate results. Further, there are major differences in thrombectomy devices and the results obtained with one class of devices may not apply to all devices. Prior meta-analyses evaluating the impact of thrombectomy devices have combined studies of thrombectomy devices with those evaluating emboli protection devices (EPDs) and have failed to establish the utility or lack thereof of thrombectomy in patients with STEMI [5-7]. The purpose of this meta-analysis was to systematically evaluate currently available data comparing thrombectomy followed by PCI with conventional PCI alone in patients with acute STEMI and to assess for differences if any between the various types of thrombectomy devices. Methods We performed a computerized search to identify relevant articles from 1996 through December 2009 using MEDLINE (National Library of Medicine, Bethesda, Maryland), Google Scholar (Google Inc., Mountain View, California), Embase, ISI Web of Knowledge, Current Contents, International Pharmaceutical Abstracts databases, and the Cochrane Central Register of Controlled Trials. For MEDLINE we used the modified Robinson and Dickersin strategy as described by Biondi Zoccai et al [8] using the keywords thrombectomy, STEMI, thrombus aspiration, randomized and PCI. Abstract lists from the 2005 through 2009 scientific meetings of the American Heart Association, the American College of Cardiology, the European Society of Cardiology, published review articles, editorials, and internet-based sources of information (http://www.cardiosource.com, http://www.tctmd.com, http://www.crtonline.org, http://www.theheart.org, http://www.medscape. com) were reviewed. A study was included if it randomized patients with STEMI to aspiration thrombectomy prior to PCI or conventional PCI and provided information on 30-day outcomes. Data was independently abstracted by two reviewers (UT, IH) and disagreements were resolved by consensus. Reviewers were not blinded to study authors or outcomes. Attempt was made to retrieve the data from the original source in unpublished studies. Since no original data could be obtained in these studies, data was retrieved from earlier published meta-analysis [6]. Baseline demographic, clinical and angiographic characteristics including mean age of patients enrolled, percent of male participants, patients with diabetes mellitus, patients undergoing rescue PCI, proportion of patients with anterior wall STEMI, use of platelet glycoprotein IIb/IIIa receptor inhibitors, and mean symptom to balloon time were recorded for each study. The specific type of the thrombectomy device use in each study was recorded and devices were subcategorized based on the underlying mechanism into one of the three types (mechanical, manual, or vacuum) as previously reported [9]. We also assessed trial quality by evaluating specific elements of study design (i.e. concealment of allocation during randomization, intention to treat analysis and blinded assessment of outcome measures), but did not use a quality score given the limitations inherent to such an approach [10]. Endpoints Primary clinical endpoints included death, stroke, target vessel revascularization (TVR) and reinfarction. The composite endpoint point of major adverse cardiac events (MACE) at 30 days was not evaluated due to differences in definitions used in the selected studies. Myocardial perfusion was assessed by using angiographic and electrocardiographic measures. ST resolution was defined as per the study definition. Most studies defined ST resolution as more than 70% resolution in ST score [11] (defined as (...truncated)