Residual thrombus burden increased with facilitated PCI
MedWire News: The burden of intraluminal thrombus is greater with facilitated percutaneous coronary intervention (fPCI) than with primary PCI (pPCI), a post-hoc analysis of the ASSENT-4 PCI trial indicates.
Furthermore, fPCI was associated with less efficient tissue reperfusion and worse clinical outcomes compared with pPCI, report Frans Van de Werf (Katholike Universiteit, Leuven, Belgium) and team in the Journal of the American College of Cardiology.
The ASSENT-4 PCI (Assessment of the Safety and Efficacy of a New Treatment Strategy With Percutaneous Coronary Intervention) trial compared fPCI with pPCI in 1667 patients with ST-elevation myocardial infarction.
The trial's main finding was that facilitation with full-dose lytics, glycoprotein IIb/IIIa inhibitors, or both drugs did not improve clinical outcomes, despite achieving higher patency rates.
In this angiographic substudy, Van de Werf and team explored potential reasons for the unexpected failure of fPCI. They performed a blinded, detailed analysis of coronary angiograms from 1342 of the study participants (686 pPCI patients and 656 fPCI patients), all of whom had 90-day follow-up.
Compared with the pPCI group, significantly more patients in the fPCI group had an open infarct-related artery at the first contrast injection (73.7% vs 33.4%).
After PCI, however, the thrombus burden was higher in the fPCI than the pPCI group (19.7% vs 13.4%), although TIMI flow grade rates were similar. Furthermore, rates of the primary composite endpoint (death, congestive heart failure, or shock) and reinfarction were higher in the fPCI group at both 30 and 90 days.
In the fPCI group, ST-segment resolution and TIMI frame count each predicted post-PCI thrombus grade. In multivariate analysis, facilitation with tenecteplase and thrombus burden each independently predicted 90-day mortality.
The study authors write: "These findings stress the importance of optimal timing of PCI and of optimal antithrombotic co-therapy after fibrinolysis for STEMI."
In an accompanying editorial, Robert Applegate (Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA) said that these observations "suggest that focus on importance of residual thrombus and/or distal embolization in influencing clinical outcomes during therapy for STEMI is appropriate and should continue to be pursued."
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By Joanna Lyford