This Study Will Evaluate the Efficacy and Safety of LCZ696 Compared to Enalapril on Morbidity and Mortality of Patients With Chronic Heart Failure

Inclusion Criteria: * Patients must give written informed consent before any assessment is performed. * Outpatients ≥ 18 years of age, male or female. * Patients with a diagnosis of CHF NYHA class II-IV and reduced ejection fraction (EF =\< 35%) and elevated BNP. * Patients must be on an ACEI or an ARB at a stable dose of at least enalapril 10 mg/d or equivalent for at least 4 weeks. * Patients must be treated with a β-blocker, unless contraindicated or not tolerated, at a stable dose for at least 4 weeks. Exclusion Criteria: * Use of other investigational drugs at the time of enrollment, or within 30 days or 5 half-lives of enrollment, whichever is longer. * History of hypersensitivity or allergy to any of the study drugs, drugs of similar chemical classes, ACEIs, ARBs, or NEP inhibitors as well as known or suspected contraindications to the study drugs. * Previous history of intolerance to recommended target doses of ACEIs or ARBs * Known history of angioedema. * Requirement of treatment with both ACEIs and ARBs. * Current acute decompensated HF (exacerbation of chronic HF manifested by signs and symptoms that may require intravenous therapy). * Symptomatic hypotension and/or a SBP \< 100 mmHg. * Estimated GFR \< 30 mL/min/1.73m2 as measured by the simplified MDRD formula * Serum potassium \> 5.2 mmol/L. Other protocol-defined inclusion/exclusion criteria may apply.