Benefit of switching dual antiplatelet therapy after ACS according to platelet reactivity: A prespecified analysis of the TOPIC randomized study

Background TOPIC (Timing Of Platelet Inhibition after acute Coronary syndrome) trial showed that switched dual antiplatelet therapy (DAPT) improved net clinical benefit after ACS. Purpose The objective of this analysis was to evaluate the impact of initial platelet reactivity on the benefit of this strategy. Methods Patients admitted with ACS requiring coronary intervention were randomly assigned to switch to aspirin and clopidogrel (switched DAPT) or continuation of their drug regimen (unchanged DAPT). All patients underwent platelet function testing at this time and were classified according to PRI VASP as low on-treatment platelet reactivity (LTPR = PRI VASP ≤ 20%) or no LTPR (PRI VASP > 20%). The primary endpoint of this analysis aimed to evaluate the impact of on-treatment platelet reactivity on clinical outcomes (a composite of ischemic and bleeding events at one year) in both groups. Results Six hundred and forty-five patients were included in the analysis, of whom 305 (47%) were classified as LTPR. LTPR patients were less often diabetic ( P  = 0.01), had lower BMI ( P P P P Fig. 1 ), and numerically lower incidence in non-LTPR (HR 95% CI 0.71 (0.43–1.18), P  = 0.19). In switching arm, LTPR patients had no significant difference in primary outcome incidence in comparison with no LTPR (HR 95% CI 0.79 (0.44–1.44), P  = 0.44) ( Fig. 1 ). Conclusion Switching DAPT strategy was superior regardless of initial platelet reactivity. Interestingly, the switching strategy was highly efficient in hyper responders, who had impaired prognosis with unchanged DAPT but similar prognosis after switching.