Safety and Efficacy of Omecamtiv Mecarbil by QRS Duration and Cardiac Resynchronization Therapy in GALACTIC-HF

BACKGROUND: Prolonged QRS duration portends worse outcomes in heart failure with reduced ejection fraction (HFrEF). In GALACTIC-HF, omecamtiv mecarbil (OM) reduced the primary composite endpoint of first heart failure (HF) event or cardiovascular death. OBJECTIVES: The objectives of this study were to evaluate whether QRS duration and the presence of cardiac resynchronization therapy (CRT) modify the treatment effect of OM. METHODS: GALACTIC-HF enrolled patients with symptomatic HF, HFrEF (≤35%), and elevated natriuretic peptides. Baseline QRS duration was available in 8,089 of 8,232 participants (98.0%), who were classified into 3 groups: QRS duration <120 ms without CRT (n = 3,724), QRS duration ≥120 ms without CRT (n = 3,225), and CRT regardless of QRS duration (n = 1,140). The authors assessed whether the effect of OM on the primary composite endpoint, first HF hospitalization, cardiovascular death, and all-cause death differed across these groups. In contrast, among patients treated with CRT, OM was beneficial regardless of QRS duration. CONCLUSIONS: In GALACTIC-HF, OM appeared less effective in patients with prolonged QRS duration who did not have CRT, whereas it remained beneficial in CRT-treated patients. (Global Approach to Lowering Adverse Cardiac Outcomes Through Improving Contractility in Heart Failure [GALACTIC-HF]; NCT02929329).