Angiotensin receptor neprilysin inhibition versus individualized RAAS blockade: design and rationale of the PARALLAX trial

AIMS: Although the effect of the angiotensin receptor blocker neprilysin inhibitor (ARNI) sacubitril/valsartan on heart failure (HF) hospitalizations and cardiovascular death has been evaluated, its effects on functional capacity in patients with HF and ejection fraction (EF) >40% has yet to be determined. In addition, no prior studies have compared sacubitril/valsartan with angiotensin-converting enzyme inhibitor therapy. We sought to compare the effect of ARNI to background-medication-based individualized comparators (BMICs) on N-terminal pro-B-type natriuretic peptide (NT-proBNP), functional capacity [6 min walk distance (6MWD)], symptoms, and quality of life [Kansas City Cardiomyopathy Questionnaire (KCCQ)] in patients with HF and EF >40% in a randomized clinical trial. METHODS: PARALLAX is a prospective, randomized, controlled, double-blind multicentre clinical trial in patients with chronic symptomatic HF with EF >40%, New York Heart Association (NYHA) class II-IV symptoms, elevated natriuretic peptides, and evidence of structural heart disease. Eligible patients are randomized to sacubitril/valsartan vs. BMIC for cardiovascular and related co-morbidities. BMIC includes (i) enalapril, (ii) valsartan, and (iii) placebo depending on the type of medical therapy prior to enrolment. The primary endpoints are the change in plasma NT-proBNP concentration from baseline to 12 weeks and the change from baseline in 6MWD distance at 24 weeks. The secondary endpoints assess quality of life and symptom burden. CONCLUSIONS: PARALLAX will determine if sacubitril/valsartan compared with standard medical therapy for co-morbidities improves NT-proBNP levels, exercise capacity, quality of life, and symptom burden in HF patients with EF >40%