Intraluminal thrombus in facilitated versus primary percutaneous coronary intervention: an angiographic substudy of the ASSENT-4 PCI (Assessment of the Safety and Efficacy of a New Treatment Strategy with Percutaneous Coronary Intervention) trial.

OBJECTIVES: This study investigated the occurrence of intraluminal thrombus and its potential implications with facilitated percutaneous coronary interventions (fPCIs).

BACKGROUND: The effect of fPCI on the presence and consequences of intraluminal thrombus is unknown.

METHODS: Thrombolysis In Myocardial Infarction (TIMI) flow grade, frame count, and thrombus grade; distal embolization; and slow flow in the infarct-related artery were assessed in a blinded fashion on coronary angiograms in 1,342 patients from the ASSENT-4 PCI (Assessment of the Safety and Efficacy of a New Treatment Strategy With Percutaneous Coronary Intervention) trial. Residual TIMI thrombus grade ≥2 and/or distal embolization and/or slow flow, reflecting thrombus burden (TB), following PCI were correlated with ST-segment resolution, epicardial blood flow, and clinical outcome. The clinical composite endpoint was death, congestive heart failure, or shock.

RESULTS: In the fPCI group, more TIMI flow grade 2/3 in the infarct-related artery at the first angiogram (73.7% vs. 33.4%, p < 0.001) and a higher TB following PCI (19.7% vs. 13.4%, p = 0.002) were found in comparison with the primary PCI group. Post-PCI TIMI thrombus grade was significantly associated with ST-segment resolution (p < 0.001) and TIMI frame count (p < 0.0001) in both groups. In the fPCI group, the presence of post-PCI thrombus was associated with a significantly worse outcome at 90 days (clinical composite endpoint: 32.1% vs. 18.6%, p = 0.023). Multivariable logistic regression showed that facilitation with tenecteplase (p = 0.005) and TB (odds ratio: 2.43, 95% confidence interval: 1.30 to 4.51, p = 0.0052) were independent predictors of 90-day mortality.

CONCLUSIONS: In ASSENT-4 PCI, despite more patency, residual TB was significantly higher in fPCI patients and was associated with less efficient tissue reperfusion and worse clinical outcomes. (A Trial Evaluating the Efficacy and Safety of Tenecteplase Together With Unfractionated Heparin Prior to Early Percutaneous Coronary Intervention [PCI] as Compared to Standard Primary PCI in Patients With Acute Myocardial Infarction [ASSENT-4 PCI]; NCT00168792).