Effect of Sacubitril/Valsartan vs Standard Medical Therapies on Plasma NT-proBNP Concentration and Submaximal Exercise Capacity in Patients With Heart Failure and Preserved Ejection Fraction: The PARALLAX Randomized Clinical Trial

IMPORTANCE: There is limited evidence on the benefits of sacubitril/valsartan vs broader renin angiotensin system inhibitor background therapy on surrogate outcome markers, 6-minute walk distance, and quality of life in patients with heart failure and mildly reduced or preserved left ventricular ejection fraction (LVEF >40%). OBJECTIVE: To evaluate the effect of sacubitril/valsartan on N-terminal pro–brain natriuretic peptide (NT-proBNP) levels, 6-minute walk distance, and quality of life vs background medication–based individualized comparators in patients with chronic heart failure and LVEF of more than 40%. DESIGN, SETTING, AND PARTICIPANTS: A 24-week, randomized, double-blind, parallel group clinical trial (August 2017-October 2019). Of 4632 patients screened at 396 centers in 32 countries, 2572 patients with heart failure, LVEF of more than 40%, elevated NT-proBNP levels, structural heart disease, and reduced quality of life were enrolled (last follow-up, October 28, 2019). INTERVENTIONS: Patients were randomized 1:1 either to sacubitril/valsartan (n = 1286) or to background medication–based individualized comparator (n = 1286), ie, enalapril, valsartan, or placebo stratified by prior use of a renin angiotensin system inhibitor. MAIN OUTCOMES AND MEASURES: Primary end points were change from baseline in plasma NT-proBNP level at week 12 and in the 6-minute walk distance at week 24. Secondary end points were change from baseline in quality of life measures and New York Heart Association (NYHA) class at 24 weeks. RESULTS: Among 2572 randomized patients (mean age, 72.6 years [SD, 8.5 years]; 1301 women [50.7%]), 2240 (87.1%) completed the trial. At baseline, the median NT-proBNP levels were 786 pg/mL in the sacubitril/valsartan group and 760 pg/mL in the comparator group. After 12 weeks, patients in the sacubitril/valsartan group (adjusted geometric mean ratio to baseline, 0.82 pg/mL) had a significantly greater reduction in NT-proBNP levels than did those in the comparator group (adjusted geometric mean ratio to baseline, 0.98 pg/mL) with an adjusted geometric mean ratio of 0.84 (95% CI, 0.80 to 0.88; P