The Total Thrombus Formation (T-TAS) platelet (PL) assay, a novel test that evaluates whole blood platelet thrombus formation under physiological conditions

Dual antiplatelet therapy (DAPT, aspirin, and a P2Y₁₂ inhibitor) reduces thrombotic events in patients with coronary artery disease (CAD). The T-TAS PL assay uses arterial shear flow over collagen surface, better mimicking in vivo conditions compared to conventional agonist-based platelet function assays, to evaluate platelet function. Here, the platelet function in patients taking DAPT is evaluated with the T-TAS PL assay. In 57 patients with CAD, taking DAPT ≥7 days (n = 22 for clopidogrel, n = 15 for prasugrel, n = 20 for ticagrelor), T-TAS PL assessments were performed in duplicate, and expressed as area under the flow pressure curve within a 10-minute period (AUC10). The duplicate measurements were strongly correlated (r = 0.90, p < .001), with an intra-assay coefficient of variation (CV) of 11,5%. For clopidogrel, the median AUC10 was 11.5 (IQR5.9-41.8), for prasugrel 28.8 (IQR10.3-37.6), and for ticagrelor 8.9 (IQR 6.4-10.9). All measurements were below the AUC10 cutoff of 260 measured in healthy volunteers, suggesting excellent discrimination of DAPT-treated and untreated persons. The new T-TAS PL assay demonstrated complete discrimination of platelet function in patients on DAPT based on an established cutoff. Ticagrelor showed lower levels of platelet function and a more uniform response compared to prasugrel and clopidogrel.

3293Atherothrombotic risk and outcomes following guided de-escalation of antiplatelet treatment in patients with acute coronary syndrome:a post-hoc analysis of the TROPICAL-ACS trial

Background

A de-escalation of P2Y12-inhibitor treatment guided by platelet function testing (PFT) has been identified as a safe and alternative treatment strategy in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI). However, no specific data are available on the efficacy of such strategy in patients with high atherothrombotic risk (ATR).

Purpose

To investigate the safety and efficacy of guided de-escalation of P2Y12-inhibitor treatment in patients with low- vs. high-ATR.

Methods

The TROPICAL-ACS trial randomized 2,610 biomarker-positive ACS patients 1:1 to either conventional treatment with prasugrel for 12 months (control group) or to a PFT guided de-escalation treatment strategy (guided de-escalation group). The primary endpoint was defined as the composite of cardiovascular mortality (CVM), myocardial infarction (MI), stroke, and clinically overt bleeding (bleeding ≥ grade 2 according to the BARC criteria). The ischemic endpoint was defined as the composite of CVM, MI or stroke. We used semi-parametric Cox regression analysis and interaction testing to assess the effect of low- vs. high-ATR on the primary and ischemic endpoints. High-ATR was defined as one of the following: (i) age ≥65 years or (ii) age <65 and either history of peripheral artery disease or at least two of the following risk-factors: diabetes mellitus, current smoking or renal dysfunction.

Results

Patients with high- (n=990) versus low-ATR (n=1,620) exhibited a higher risk for the primary endpoint (11.0% vs. 6.7%; HR 1.67; 95% CI 1.28–2.18; p<0.001). Guided de-escalation was non-inferior to conventional treatment for the primary endpoint in both patients with high- (10.5% vs. 11.5%; pnon-inferiority = 0.029; Figure 1A) and low-ATR (5.6% vs. 7.7%; pnon-inferiority=0.001; Figure 1B). Moreover, there was no significant interaction in the prognostic value of guided de-escalation between high- and low-ATR groups for both the primary (HR 0.90 [0.61–1.32]; p=0.586 in patients with high-ART vs. 0.71 [0.48–1.04; p=0.082 in patients with low-ATR; pinteraction= 0.394) and combined ischemic endpoints (HR 0.83 [0.44–1.56]; p=0.567 in patients with high-ATR vs. 0.68 [0.35–1.34]; p=0.262 in patients with low-ATR; pinteraction =0.666).

Kaplan-Meier curves

Conclusion

A guided DAPT de-escalation strategy appears to be safe and effective in ACS patients regardless of the atherothrombotic risk. Further studies are needed for refining antiplatelet treatment strategies in ACS patients with varying levels of atherothrombotic risk.

Acknowledgement/Funding

Klinikum der Universität München, Roche Diagnostics, Eli Lilly, and Daiichi Sankyo.

252Guided de-escalation of antiplatelet treatment in patients with acute coronary syndrome and multivessel coronary artery disease: a post-hoc analysis of the TROPICAL-ACS trial

Background

The TROPICAL-ACS trial showed that platelet function testing (PFT) guided de-escalation of P2Y12-inhibitor is a safe alternative treatment strategy in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI). No specific data are available on the efficacy of this strategy in patients with multivessel coronary artery disease (CAD).

Purpose

To investigate the safety and efficacy of guided de-escalation of P2Y12-inhibitor treatment in patients with multivessel CAD.

Methods

Two-thousand six-hundred-two biomarker-positive ACS patients were 1:1 randomized to either conventional treatment with prasugrel for 12 months (control group) or to a PFT guided de-escalation treatment strategy (guided de-escalation group). The primary endpoint (net clinical benefit) was defined as the composite of cardiovascular mortality (CVM), myocardial infarction (MI), stroke, and clinically overt bleeding (bleeding ≥ grade 2 according to the BARC criteria). The ischemic endpoint was defined as the composite of CVM, MI or stroke. We used log-rank statistics and Cox regression analysis with interaction testing to assess the effect of multivessel CAD on the primary and ischemic endpoints.

Results

Patients with multivessel (n=709) versus single-vessel CAD (n=1,901) exhibited a higher risk for the primary endpoint (10.2% vs. 7.6%; HR 1.36; 95% CI 1.02–1.81; p=0.034). Guided de-escalation was non-inferior to conventional treatment for the primary endpoint in both patients with single-vessel CAD (6.7% vs. 8.5%; pnon-inferiority = 0.001; Figure 1A) and multivessel CAD (9,5% vs. 10.9%; pnon-inferiority=0.041; Figure 1B). Moreover, there was no significant interaction in the prognostic value of guided de-escalation between single-vessel and multivessel CAD for both the primary (HR 0.78 [0.56–1.08]; p=0.137 in patients with single-vessel CAD vs. 0.86 [0.54–1.37; p=0.524 in patients with multivessel CAD; pinteraction=0.732) and combined ischemic endpoints (HR 0.80 [0.44–1.45]; p=0.456 in patients with single-vessel CAD vs. 0.71 [0.35–1. 46]; p=0.356 in patients with multivessel CAD; pinteraction=0.823).

Kaplan-Meier curves

Conclusion

A guided de-escalation of P2Y12-inhibitor appears to be safe and effective in ACS patients with both single-vessel and multivessel CAD.

Acknowledgement/Funding

Klinikum der Universität München, Roche Diagnostics, Eli Lilly, and Daiichi Sankyo.

Transradial percutaneous coronary intervention in acute myocardial infarction

Although transradial coronary intervention is widely applied for percutaneous procedures, its safety in the setting of ST-segment elevation myocardial infarction (STEMI) is controversial. The benefit of transradial approach in terms of reducing access site complications is well documented. However, higher rate of procedural failure and longer procedural times reported by some authors raise concerns regarding its applicability in STEMI. Our aim was to review the safety and efficacy of transradial coronary intervention versus transfemoral intervention in acute ST-elevation myocardial infarction. This review focuses on key aspects of safety and efficacy: adverse ischemic and bleeding events, reperfusion times and radiation exposure.