For decades, aspirin has served as the quiet guardian of implanted heart valves — familiar, inexpensive, and largely unquestioned. A landmark Norwegian trial now challenges that assumption, finding that anticoagulant drugs not only prevent dangerous clot formation on artificial valves far more effectively, but do so with a safety profile that defies long-held clinical intuition. As heart valve procedures extend to younger patients who will live with these devices for decades, the question of how best to protect them has never carried greater consequence.