Hypothesis, Trial Design, and Oversight
The Personalized Prospective Comparison of ARNI [angiotensin receptor/neprilysin inhibitor] with ARB [angiotensin-receptor blocker] in Patients With Natriuretic Peptide Elevation (PARABLE) randomized, double-blind, double-dummy, active comparator trial was conducted from April 2015 to June 2021 at a single outpatient cardiology center in Dublin, Ireland. The trial was designed to investigate the hypothesis that sacubitril/valsartan vs valsartan would reduce left atrial volume index over 18 months using volumetric cardiac magnetic resonance imaging in patients with pre-HFpEF. Ethical approval was obtained by the St Vincent’s University Hospital Ethics Committee and competent authority approval was obtained from the Health Protection Regulatory Authority in Ireland (EudraCT: 2015-002928-53; ClinicalTrials.gov identifier: NCT04687111). The protocol is available in 