The analyses of Cmax was based on plasma concentrations of three sacubitril/valsartan analytes (AHU377 (sacubitril), LBQ657 (sacubitrilat), and valsartan). The plasma levels of sacubitril/valsartan analytes were determined using a validated LCMS/MS method with a lower limit of quantitation (LLOQ) of 1 ng/mL for sacubitril, 20 ng/mL for LBQ657, and 10 ng/mL for valsartan. The PK parameters were determined using the non-compartmental method(s).

Part 1 Pharmacokinetic (PK) Set: included all participants who completed Part 1 screening phase; who had received at least one dose of study drug during Part 1, and had at least one available, valid, PK concentration measurement (not flagged for exclusion or considered a protocol deviation from relevant PK data) during Part 1.

The analyses of Tmax was based on plasma concentrations of three sacubitril/valsartan analytes (AHU377 (sacubitril), LBQ657 (sacubitrilat), and valsartan). The plasma levels of sacubitril/valsartan analytes were determined using a validated LCMS/MS method with a lower limit of quantitation (LLOQ) of 1 ng/mL for sacubitril, 20 ng/mL for LBQ657, and 10 ng/mL for valsartan. The PK parameters were determined using the non-compartmental method(s).

Participants in the Part 1 PK Set were analyzed.

The analyses of AUCinf was based on plasma concentrations of three sacubitril/valsartan analytes (AHU377 (sacubitril), LBQ657 (sacubitrilat), and valsartan). The plasma levels of sacubitril/valsartan analytes were determined using a validated LCMS/MS method with a lower limit of quantitation (LLOQ) of 1 ng/mL for sacubitril, 20 ng/mL for LBQ657, and 10 ng/mL for valsartan. The PK parameters were determined using the non-compartmental method(s).

Participants in the Part 1 PK Set were analyzed.

As prespecified in protocol and SAP the analysis of this outcome measure was done based on dose of LCZ696 administered within the different age groups.

Participants in the Part 1 PK Set were analyzed.

The analyses was based on plasma concentrations of two sacubitril/valsartan analytes (AHU377 (sacubitril), and valsartan). The plasma levels of sacubitril/valsartan analytes were determined using a validated LCMS/MS method with a lower limit of quantitation (LLOQ) of 1 ng/mL for sacubitril, 20 ng/mL for LBQ657, and 10 ng/mL for valsartan. The PK parameters were determined using the non-compartmental method(s). CL/F was not estimated for LBQ657 as it is a metabolite.

Participants in the Part 1 PK Set were analyzed.

The analyses of T1/2 was based on plasma concentrations of sacubitril. The plasma levels of sacubitril/valsartan analytes were determined using a validated LCMS/MS method with a lower limit of quantitation (LLOQ) of 1 ng/mL for sacubitril, 20 ng/mL for LBQ657, and 10 ng/mL for valsartan. The PK parameters were determined using the non-compartmental method(s). T1/2 for other analytes of LCZ696 (LBQ657 and Valsartan) was not estimable due to the short sample collection timeframe.

Part 1 PK Set. The overall number of participants analyzed is the number of participants with data available for this endpoint. T1/2 could not be determined for participants under the arm LCZ696: 0.4 mg/kg (Age Group 3) as their PK data was inadequate for the T1/2 calculation. As participants were from the age of 1 month to less than 1 year, it was difficult to obtain multiple PK samples.

Biomarkers were used to assess the PD effects of LCZ696. Blood biomarkers of potential interest included plasma BNP. Biomarkers related to heart failure or the mechanism of action of the study drug were measured. Summary statistics for change from baseline at each time point is presented. The baseline assessment is defined as the last non-missing assessment (scheduled or unscheduled) prior to (the first dose time of the study drug within the dose associated period). For each post-dose time point, participants are included if and only if the participant has both pre-dose assessment and current time point assessment observed.

Part 1 PD set (PD1) included all participants who completed the Part 1 screening phase and had at least one dose of study drug during Part 1 of the study, at least one available PD measurement during Part 1 of the study and with no protocol deviations with relevant impact on PD data. Overall number of participants analyzed is the number of participants with data available for this endpoint.

Biomarkers were used to assess the PD effects of LCZ696. Blood biomarkers of potential interest included plasma NTproBNP. Biomarkers related to heart failure or the mechanism of action of the study drug were measured. Summary statistics for change from baseline at each time point is presented. The baseline assessment is defined as the last non-missing assessment (scheduled or unscheduled) prior to (the first dose time of the study drug within the dose associated period). For each post-dose time point, participants are included if and only if the participant has both pre-dose assessment and current time point assessment observed.

Part 1 PD set. The overall number of participants analyzed is the number of participants with data available for this endpoint. Data has not been reported for the arms of LCZ696: 0.8 mg/kg (Age Group 2) and LCZ696: 3.1 mg/kg (Age Group 2) as no participants participated in the optional 24 hrs post-dose assessment.

Biomarkers were used to assess the PD effects of LCZ696. Blood biomarkers of potential interest included plasma cGMP. Biomarkers related to heart failure or the mechanism of action of the study drug were measured. Summary statistics for change from baseline at each time point is presented. The baseline assessment is defined as the last non-missing assessment (scheduled or unscheduled) prior to (the first dose time of the study drug within the dose associated period). For each post-dose time point, participants are included if and only if the participant has both pre-dose assessment and current time point assessment observed.

Part 1 PD set. The overall number of participants analyzed is the number of participants with data available for this endpoint.

Biomarkers were used to assess the PD effects of LCZ696. Blood biomarkers of potential interest included urine cGMP. Biomarkers related to heart failure or the mechanism of action of the study drug were measured. Summary statistics for change from baseline at each time point is presented. The baseline assessment is defined as the last non-missing assessment (scheduled or unscheduled) prior to (the first dose time of the study drug within the dose associated period). For each post-dose time point, participants are included if and only if the participant has both pre-dose assessment and current time point assessment observed.

Part 1 PD set. The overall number of participants analyzed is the number of participants with data available for this endpoint.

Global ranking is based on 5 categories ranking worst to best outcome:Category 1:Death; United Network for Organ Sharing(UNOS)status 1A listing for heart transplant or equivalent; ventricular assist device(VAD)/extracorporeal membrane oxygenation(ECMO)/mechanical ventilation/intra-aortic balloon pump requirement for life support at end of study. Category 2:Worsening HF(WHF);defined by signs and symptoms of WHF that requires an intensification of HF therapy. Category 3:Worsened; worse New York Heart Association(NYHA)/Ross or worse Patient Global Impression of Severity(PGIS); and further ranking by Pediatric Quality of Life Inventory(PedsQL)physical functioning domain.Category 4:Unchanged; unchanged NYHA/Ross and unchanged PGIS; and further ranking by PedsQL physical functioning domain. Category 5:Improved; improved NYHA/Ross or improved PGIS(neither can be worse);and further ranking by PedsQL physical functioning domain. Participants with worst event in each category are reported here.

Full analysis set included all randomized participants with the exception of those participants who had not been qualified for randomization and had not received study drug but had been inadvertently randomized into the study. A total of 377 participants were randomized in Part 2 of which a total of 375 were analyzed. Two participants who were excluded did not receive study drug and did not qualify for randomization.

An adverse event (AE) is any untoward medical occurrence associated with use of a drug in humans, whether considered drug related or not, that occurs after a participant provides informed consent. TEAEs during part 1 are defined as any recorded AE with its start date (recorded or imputed) later than or equal to the date of the first dose of the study drug within part 1 and its start date prior to or equal to the end date of the part 1.

Part 1 Safety Analysis Set (SAF1) included all participants who completed the Part 1 screening phase and received at least one dose of study drug during Part 1 of the study.

An AE is any untoward medical occurrence associated with use of a drug in humans, whether or not considered drug related, that occurs after a participant provides informed consent. TEAEs during part 2 are defined as any recorded AE with its start date (recorded or imputed) later than or equal to the date of the first dose of the study drug within part 2 and its start date prior to or equal to the end date of part 2.

Part 2: Safety Set included randomized participants who received at least one dose of study drug. Participants were analyzed according to the treatment actually received. A total of 377 participants were randomized in Part 2 of which a total of 375 were analyzed. Two participants who were excluded did not receive study drug and did not qualify for randomization.

The exposure adjusted incidence rate is calculated as number of participants with at least one event divided by total participant years across all participants. Category 1: Death; UNOS status 1A listing for heart transplant or equivalent; VAD/ECMO/mechanical ventilation/intra-aortic balloon pump requirement for life support at end of study. Category 2: WHF; defined by signs and symptoms of WHF that requires an intensification of HF therapy.

Full analysis set included all randomized participants with the exception of those participants who had not been qualified for randomization and had not received study drug but had been inadvertently randomized into the study. A total of 377 participants were randomized in Part 2 of which a total of 375 were analyzed. Two participants who were excluded did not receive study drug and did not qualify for randomization.

NYHA classification is a subjective physician's assessment of participant's functional capacity and symptomatic status and can change frequently over time. NYHA is tool that classifies participants with heart failure into one of four classes according to their degree of symptoms at rest and with activity. Class I: No limitations of physical activity. Class 2: May experience fatigue, palpitations, dyspnea, or angina during moderate exercise but not during rest. Class 3: Symptoms with minimal exertion that interfere with normal daily activity. Class 4: Unable to carry out any physical activity because they typically have symptoms of HF at rest that worsen with any exertion. Participants with change from baseline were classified as improved (shifted from higher to lower class), unchanged (no change in class) or worsened (shifted from lower to higher class).

Participants in the full analysis set with available data were analyzed. The number analyzed is the number of participants with data available for analyses at specific timepoints. A total of 377 participants were randomized in Part 2 of which a total of 375 were analyzed. Two participants who were excluded did not receive study drug and did not qualify for randomization.

PGIS of Heart Failure Symptoms is a 1-item questionnaire to assess the participant's impression of symptoms severity, specifically: shortness of breath, fatigue and swelling. The PGI-S asks the participant to choose one response that best describes how his/her heart failure symptoms, specifically: shortness of breath, fatigue and swelling are now on a 5-point scale, ranging from 'Not at all' (1) to 'Very severe' (5). C1 = none (good), C2 = mild, C3 = moderate, C4 = severe, C5 = very severe (bad). Percentage of participants by change in score are reported. Participants with change from baseline were classified as improved (shifted from higher to score), unchanged (no change in score) or worsened (shifted from lower to higher score).

Participants in the full analysis set with available data were analyzed. Overall number analyzed is the number of participants with data available for analysis. Number analyzed is the number of participants with data available for analyses at specific timepoints. A total of 377 participants were randomized in Part 2 of which a total of 375 were analyzed. Two participants who were excluded did not receive study drug and did not qualify for randomization.

The analyses of CL was based on plasma concentrations of three sacubitril/valsartan analytes (AHU377 (sacubitril), LBQ657 (sacubitrilat), and valsartan). The PK parameters were determined using the non-compartmental method(s). In case of data limitations for estimating PK parameters using non-compartmental methods, a population PK approach was used to estimate exposure of sacubitril/valsartan analytes. The population PK model was developed to describe incoming data from pediatric patients based on an established model developed for the adult population.

The Full Analysis Set included all randomized participants who received study drug, with the exception of [2 patients in Part 2] who had not received any study drug but had been inadvertently randomized into the study (mis-randomized).

The analyses of volume of distribution was based on plasma concentrations of three sacubitril/valsartan analytes (AHU377 (sacubitril), LBQ657 (sacubitrilat), and valsartan). The PK parameters were determined using the non-compartmental method(s). In case of data limitations for estimating PK parameters using non-compartmental methods, a population PK approach was used to estimate exposure of sacubitril/valsartan analytes. The population PK model was developed to describe incoming data from pediatric patients based on an established model developed for the adult population.

The Full Analysis Set included all randomized participants who received study drug, with the exception of [2 patients in Part 2] who had not received any study drug but had been inadvertently randomized into the study (mis-randomized).

The analyses of Ka was based on plasma concentrations of three sacubitril/valsartan analytes (AHU377 (sacubitril), LBQ657 (sacubitrilat), and valsartan). The PK parameters were determined using the non-compartmental method(s). In case of data limitations for estimating PK parameters using non-compartmental methods, a population PK approach was used to estimate exposure of sacubitril/valsartan analytes. The population PK model was developed to describe incoming data from pediatric patients based on an established model developed for the adult population.

The Full Analysis Set included all randomized participants who received study drug, with the exception of [2 patients in Part 2] who had not received any study drug but had been inadvertently randomized into the study (mis-randomized).

The analyses of T1/2 was based on plasma concentrations of three sacubitril/valsartan analytes (AHU377 (sacubitril), LBQ657 (sacubitrilat), and valsartan). The PK parameters were determined using the non-compartmental method(s). In case of data limitations for estimating PK parameters using non-compartmental methods, a population PK approach was used to estimate exposure of sacubitril/valsartan analytes. The population PK model was developed to describe incoming data from pediatric patients based on an established model developed for the adult population.

The Full Analysis Set included all randomized participants who received study drug, with the exception of [2 patients in Part 2] who had not received any study drug but had been inadvertently randomized into the study (mis-randomized).

The analyses of Cmax was based on plasma concentrations of three sacubitril/valsartan analytes (AHU377 (sacubitril), LBQ657 (sacubitrilat), and valsartan). The PK parameters were determined using the non-compartmental method(s). In case of data limitations for estimating PK parameters using non-compartmental methods, a population PK approach was used to estimate exposure of sacubitril/valsartan analytes. The population PK model was developed to describe incoming data from pediatric patients based on an established model developed for the adult population.

The Full Analysis Set included all randomized participants who received study drug, with the exception of [2 patients in Part 2] who had not received any study drug but had been inadvertently randomized into the study (mis-randomized).

The analyses of Cmin was based on plasma concentrations of three sacubitril/valsartan analytes (AHU377 (sacubitril), LBQ657 (sacubitrilat), and valsartan). The PK parameters were determined using the non-compartmental method(s). In case of data limitations for estimating PK parameters using non-compartmental methods, a population PK approach was used to estimate exposure of sacubitril/valsartan analytes. The population PK model was developed to describe incoming data from pediatric patients based on an established model developed for the adult population.

The Full Analysis Set included all randomized participants who received study drug, with the exception of [2 patients in Part 2] who had not received any study drug but had been inadvertently randomized into the study (mis-randomized).

The analyses of AUCtau was based on plasma concentrations of three sacubitril/valsartan analytes (AHU377 (sacubitril), LBQ657 (sacubitrilat), and valsartan). The PK parameters were determined using the non-compartmental method(s). In case of data limitations for estimating PK parameters using non-compartmental methods, a population PK approach was used to estimate exposure of sacubitril/valsartan analytes. The population PK model was developed to describe incoming data from pediatric patients based on an established model developed for the adult population.

The Full Analysis Set included all randomized participants who received study drug, with the exception of [2 patients in Part 2] who had not received any study drug but had been inadvertently randomized into the study (mis-randomized).