Patients diagnosed with HFrEF being treated with sacubitril/valsartan according to the Canadian product label and treatment initiation with sacubitril/valsartan within the last 3 months. The usual recommended starting dose is one tablet of 49 mg sacubitril / 51 mg valsartan taken twice daily. The target dose is one tablet of 97 mg sacubitril / 103 mg valsartan taken twice daily. Investigator/designated will document sacubitril/valsartan treatment adherence throughout the 3 years study period

This study is designed as an observational, naturalistic, multicenter study in patients being treated with sacubitril/valsartan as per the Canadian product label. Treatment initiation with sacubitril/valsartan must be within the last 3 months. Sacubitril/valsartan will be used as commercially available supplies which are available as Film coated tablets in 3 dosage: 1) 24 mg sacubitril / 26 mg valsartan, 2) 49 mg sacubitril / 51 mg valsartan and 3) 97 mg sacubitril / 103 mg valsartan.

The primary objective is to describe baseline NT- proBNP, or BNP levels, in relation to total all- cause hospitalization or all-cause mortality in patients with HFrEF treated with sacubitril/valsartan

Symptomatic hypotension as reported by the treating physician and defined, but not limited to, severe dizziness or fainting (syncope), lack of concentration, blurred vision, nausea, cold, clammy pale skin, and rapid shallow breathing.