Background Restoration of myocardial perfusion is the goal of percutaneous coronary intervention (PCI) in patients with ST elevation myocardial infarction. A major predictor of no-reflow is the increasing time to treatment (TTT). Thrombus aspiration (TA) is reported to improve myocardial reperfusion as compared with standard PCI (SP).

Objective To investigate the influence of TTT on TA efficacy.

Design Pooled analysis of individual patients' data of three prospective randomised trials comparing TA and SP.

Patients A total of 299 patients (150 in TA group and 149 in SP group) entered the study. The study population was divided into three subgroups according to the TTT: ≤3 h (short TTT subgroup), >3 h to ≤6 h (intermediate TTT subgroup), >6 h to ≤12 h (long TTT subgroup).

Main outcome measures The goal of the study was the comparison of optimal myocardial reperfusion, defined as the combination of myocardial blush grade 2 or 3 at post-PCI angiography and ST resolution more than 70% at post-PCI ECG, between SP and TA according to TTT.

Results In the SP group, increasing TTT was associated with a decreased rate of optimal reperfusion (27.4% vs 17.9% vs 10%, p for trend=0.06), whereas in the TA group the same trend was not seen (40.9% vs 33.8% vs 50%, p for trend=0.93). In a multivariate logistic regression model, a significant interaction (p=0.04) between time to treatment and thrombus aspiration was observed.

Conclusions TA limits the adverse effects of TTT prolongation on myocardial reperfusion.