Characterizing Antithrombotic Regimens After Isolated Mitral Valve Repair: A Retrospective Descriptive Study and Interview of Cardiac Surgeons.

The evidence for optimal antithrombotic therapy after isolated surgical mitral valve repair (MVr) is limited resulting in variable use of antithrombotic regimens in practice. This study aimed to characterize what antithrombotic regimens are being used and elucidate rationale. We conducted a retrospective descriptive study of adult patients after isolated surgical MVr at two cardiac surgery centers to characterize the type of antithrombotics used, timing of initiation, and duration. We then conducted semi-structured interviews of cardiac surgeons across Canada to elucidate post-MVr antithrombotic prescribing practices along with their rationale. Of 365 MVr patient screened, 89 had isolated MVr without a concomitant indication for anticoagulation and majority were prescribed dual antiplatelet therapy (DAPT) (40%) or warfarin (36%). Other regimens included antiplatelet (13%), warfarin plus acetylsalicylic acid (ASA) (6%), or apixaban (5%). The intended duration of therapy was 3 months in 85% of cases, and after completion of initial antithrombotic therapy most cases (80%) were followed by indefinite ASA thereafter. Of the 15 surgeons interviewed, preferred regimens included ASA (47%), warfarin plus ASA (20%), warfarin (13%), apixaban (13%), apixaban plus ASA (13%), or DAPT (13%). Surgeons identified convention or clinical experience as rationale for choice of therapy. Those preferring anticoagulation cited high rates of post-operative atrial fibrillation and concern for preventable strokes while those preferring antiplatelets cited minimal risk of stroke and high risks of bleeds. In conclusion, this retrospective descriptive study and semi-structured interview found substantial heterogeneity in the antithrombotic regimens used and prescribing patterns following isolated mitral valve repair.