F2R and Hypertension: However, in a recent pilot-analysis by Helten et al. including patients with an indication for RAAS blockade (arterial hypertension or heart failure), ACE inhibitors were associated with increased platelet surface expression of protease-activated receptor-1 (PAR-1) and enhanced SFLLRN (=thrombin receptor activating peptide [TRAP])-inducible platelet reactivity compared to ARBs [15].