Atrium Therapeutics launched as a spinout carrying Avidity Biosciences’ cardiac RNA delivery programs, debuting with about $270 million in cash to advance therapies for rare inherited cardiomyopathies. The company was formed after Novartis acquired Avidity; Atrium is led by former Avidity executives including CEO Kathleen Gallagher and chair Sarah Boyce. Its initial pipeline targets PRKAG2 syndrome and PLN cardiomyopathy and includes two programs with paths to the clinic. Atrium’s launch preserves RNA delivery assets Avidity did not include in the Novartis purchase and underscores continued investor belief in tissue‑targeted RNA modalities beyond the liver. The spinout was reported by MedCity News and company statements and positions Atrium to pursue rare cardiac indications with limited treatment options.