At ACC26, Merck signaled it is leaning toward a lower Winrevair dose for a pivotal Phase 3 program after seeing what it called a “pretty profound” benefit at the lowest dose in a prior Phase 2 test. The update reflects a dosing optimization move ahead of later-stage readouts in an uncommon type of heart failure. Merck’s Chief Medical Officer Eliav Borowski described the rationale for focusing the next pivotal trial on the dose level where benefit emerged most clearly. That kind of dose selection is a key operational decision because it can directly affect safety margins, efficacy signals and eventual labeling. For the biotech and cardiology development community, Merck’s decision highlights how early clinical signals can reshape Phase 3 design even before full outcome comparisons are available.