The role of deferred stenting in the treatment of ST-elevation myocardial infarction: a systematic review and meta-analysis

Background: There have been a big number of studies assessing the efficacy of delayed coronary artery stenting (DCAS) in the prevention of no-reflow microvasculature injury compared to the standard immediate coronary artery stenting (ICAS) in ST-segment elevation myocardial infarction (STEMI). However, the results of these studies are contradictory in a lot of ways. Aim: To summarize studies on the assessment of DCAS in the prevention of no-reflow compared to the standard ICAS. Materials and methods: We performed a systematic literature search in PubMed, Google Scholar, and eLIBRARY.RU databases. The analysis included 17 studies with a total sample of 3505 patients. The comparative analysis included angiography-based endpoints prevalence of no-reflow (thrombolysis in myocardial infarction, TIMI 3 and myocardial blush grade, MBG 2, corrected TIMI frame count, CTFC) and clinical endpoints of all-cause mortality, cardiovascular mortality, major adverse cardiac events (MACE), recurrent myocardial infarction and recurrent revascularization. In addition, the analysis included the assessment of ST-elevation resolution, left ventricular ejection fraction values in the delayed post-intervention period and between-group differences. Results: The no-reflow phenomenon was significantly less frequent in the DCAS groups for the following parameters: epicardial flow TIMI 3 (odds ratio (OR) 2.00; 95% confidence interval (CI) 1.492.69; p 0.00001; I = 16%), myocardial perfusion MBG 2 (OR 4.69; 95% CI 1.9811.14; p = 0.0005; I = 59%), CTFC (mean difference (MD) 10.29; 95% CI 0.9619.62; p = 0.03; I = 96%). The analysis of secondary endpoints showed that MACE were less frequent in the DCAS groups (OR 1.29; 95% CI 1.041.60; p = 0.02; I = 42%), the difference becoming more significant in the studies with high initial thrombotic burden (TTG 3) (OR 1.83; 95% CI 1.282.62; p = 0.0009; I = 41%). The most clinically significant decrease of the MACE rate was found in 5 studies (n = 656) with high initial thrombotic burden (TTG 3) and mean time to repeated intervention from 4 to 7 days (OR 3.15; 95% CI 1.865.32; p 0.0001; I = 0%). The reverse trend for a benefit in the ICAS group was observed in the studies with a high initial thrombotic burden (TTG 3) and mean time to recurrent intervention of 48 hours (OR 0.60; 95% CI 0.301.19; p = 0.14; I = 20%). The ICAS and DCAS groups did not differ in overall mortality (p = 0.31), cardiovascular mortality (p = 0.49), repeated revascularization (p = 0.66), and ST resolution of 70% (p = 0.65). In the DCAS groups, there was an obvious trend to lower incidence of recurrent myocardial infarction (OR 1.28; 95% CI 0.951.73; p = 0.10; I = 0%), as well as to higher myocardial mass during the deferred analysis of left ventricular ejection fraction (OR -0.79; 95% CI -1.61 -0.04; p = 0.06; I = 36%). Conclusion: Deferred coronary artery stenting is an effective method for prevention of no-reflow. In patients with extended coronary thrombosis (TTG 3) and STEMI, the DCAS technique with time to recurrent intervention of 4 to 7 days decreases the probability of MACE compared to that with immediate stenting of the index coronary artery.