Time to Clinical Benefit of Dapagliflozin in Patients with Heart Failure with Mildly Reduced or Preserved Ejection Fraction: A Prespecified Secondary Analysis of the DELIVER Randomized Clinical Trial

Importance: Dapagliflozin was recently shown to reduce cardiovascular death or worsening heart failure (HF) events in patients with HF with mildly reduced or preserved ejection fraction in the Dapagliflozin Evaluation to Improve the Lives of Patients With Preserved Ejection Fraction Heart Failure (DELIVER) trial. Objective: To evaluate the time course of benefits of dapagliflozin on clinically relevant outcomes in this population. Design, Setting, and Participants: The DELIVER trial was a global phase 3 clinical trial that randomized patients with HF with mildly reduced or preserved ejection fraction to dapagliflozin or matching placebo. Inclusion criteria included symptomatic HF, left ventricular ejection fraction greater than 40%, elevated natriuretic peptide levels, and evidence of structural heart disease. In this prespecified secondary analysis of the DELIVER trial, to examine the timeline to onset of clinical benefit with dapagliflozin, hazard ratios (HR) and 95% CIs were iteratively estimated for the primary composite end point and worsening HF events alone with truncated data at every day postrandomization. Time to first and sustained statistical significance of dapagliflozin for these end points were then examined. Participants were enrolled from August 2018 to December 2020, and for this secondary analysis, data were analyzed from April to September 2022. Interventions: Dapagliflozin, 10 mg, once daily or matching placebo. Main Outcomes and Measures: The primary outcome was time to first occurrence of cardiovascular death or worsening HF (hospitalization for HF or urgent HF visit requiring intravenous HF therapies). Results: Overall, 6263 patients were randomized across 350 centers in 20 countries. Of 6263 included patients, 2747 (43.9%) were women, and the mean (SD) age was 71.7 (9.6) years. During a median (IQR) of 2.3 (1.7-2.8) years' follow-up, 1122 primary end point events occurred, with an incidence rate per 100 patient-years of 8.7 (95% CI, 8.2-9.2). Time to first nominal statistical significance for the primary end point was 13 days (HR, 0.45; 95% CI, 0.20-0.99; P =.046), and significance was sustained from day 15 onwards. First and sustained statistical significance was reached for worsening HF events (HR, 0.45; 95% CI, 0.21-0.96; P =.04) by day 16 after randomization. Significant benefits for the primary end point and worsening HF events were sustained at 30 days, 90 days, 6 months, 1 year, 2 years, and final follow-up (primary end point: HR, 0.82; 95% CI, 0.73-0.92; worsening HF events: HR, 0.79; 95% CI, 0.69-0.91). Conclusions and Relevance: In the DELIVER trial, dapagliflozin led to early and sustained reductions in clinical events in patients with HF with mildly reduced or preserved ejection fraction with statistically significant reductions observed within 2 weeks of treatment initiation. Trial Registration: ClinicalTrials.gov Identifier: NCT03619213.