Reduced Rivaroxaban Dose Versus Dual Antiplatelet Therapy After Left Atrial Appendage Closure: ADRIFT a Randomized Pilot Study.

BACKGROUND: Percutaneous left atrial appendage closure (LAAC) exposes to the risk of device thrombosis in patients with atrial fibrillation who frequently have a contraindication to full anticoagulation. Thereby, dual antiplatelet therapy (DAPT) is usually preferred. No randomized study has evaluated nonvitamin K antagonist oral anticoagulant after LAAC, and we decided to evaluate the efficacy and safety of reduced doses of rivaroxaban after LAAC. METHODS: ADRIFT (Assessment of Dual Antiplatelet Therapy Versus Rivaroxaban in Atrial Fibrillation Patients Treated With Left Atrial Appendage Closure) is a multicenter, phase IIb study, which randomized 105 patients after successful LAAC to either rivaroxaban 10 mg (R10, n=37), rivaroxaban 15 mg (R15, n=35), or DAPT with aspirin 75 mg and clopidogrel 75 mg (n=33). The primary end point was thrombin generation (prothrombin fragments 1+2) measured 2 to 4 hours after drug intake, 10 days after treatment initiation. Thrombin-antithrombin complex, D-dimers, rivaroxaban concentrations were also measured at 10 days and 3 months. Clinical end points were evaluated at 3-month follow-up. RESULTS: The primary end point was reduced with R10 (179 pmol/L [interquartile range (IQR), 129-273], P<0.0001) and R15 (163 pmol/L [IQR, 112-231], P<0.0001) as compared with DAPT (322 pmol/L [IQR, 218-528]). We observed no significant reduction of the primary end point between R10 and R15 while rivaroxaban concentrations increased significantly from 184 ng/mL (IQR, 127-290) with R10 to 274 ng/mL (IQR, 192-377) with R15, P<0.0001. Thrombin-antithrombin complex and D-dimers were numerically lower with both rivaroxaban doses than with DAPT. These findings were all confirmed at 3 months. The clinical end points were not different between groups. A device thrombosis was noted in 2 patients assigned to DAPT. CONCLUSIONS: Thrombin generation measured after LAAC was lower in patients treated by reduced rivaroxaban doses than DAPT, supporting an alternative to the antithrombotic regimens currently used after LAAC and deserves further evaluation in larger studies. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03273322.

Identification of novel inhibitors of DNA methylation by screening of a chemical library.

In order to discover new inhibitors of the DNA methyltransferase 3A/3L complex, we used a medium-throughput nonradioactive screen on a random collection of 1120 small organic compounds. After a primary hit detection against DNA methylation activity of the murine Dnmt3A/3L catalytic complex, we further evaluated the EC50 of the 12 most potent hits as well as their cytotoxicity on DU145 prostate cancer cultured cells. Interestingly, most of the inhibitors showed low micromolar activities and little cytotoxicity. Dichlone, a small halogenated naphthoquinone, classically used as pesticide and fungicide, showed the lowest EC50 at 460 nM. We briefly assessed the selectivity of a subset of our new inhibitors against hDNMT1 and bacterial Dnmts, including M. SssI and EcoDam, and the protein lysine methyltransferase PKMT G9a and the mode of inhibition. Globally, the tested molecules showed a clear preference for the DNA methyltransferases, but poor selectivity among them. Two molecules including Dichlone efficiently reactivated YFP gene expression in a stable HEK293 cell line by promoter demethylation. Their efficacy was comparable to the DNMT inhibitor of reference 5-azacytidine.