We conducted a single-blind randomized controlled trial at the Department of Cardiology, Rangpur Medical College Hospital, Rangpur, Bangladesh. In this trail, the patients were unaware of the treatment but researchers are aware of it, where 100 patients were randomly assigned comparative treatment arms ARNi and Valsartan to know the efficacy of the study drug. A total of 242 patients were screened between May 10, 2018 and December 3, 2018. Out of which 142 patients were excluded due to not meeting inclusion and exclusion criteria, withdrawal of consent or adverse events (Figure 1). Exclusion Criteria:

• Any prior measurement of LVEF < 40%.

• Acute coronary syndrome (including MI), cardiac surgery, other major CV surgery within 3 months, or urgent percutaneous coronary intervention within 3 months or and elective PCI within 30 days prior to entry.

• Any clinical event within the 6 months prior to entry could have reduced the LVEF (e.g., MI, CABG), unless an echo measurement performed after the event confirms a LVEF ≥ 45%.

• Current acute decompensated HF requiring therapy.

• Patients who require treatment with 2 or more of the following: an angiotensin converting enzyme inhibitor (ACEI), an angiotensin receptor blocker (ARB) or a renin inhibitor.

In this single-blind trial, the patients were enrolled with chronic HF aged on or above 40 years, considering based on NYHA class II - IV and LVEF 40% or less. Moreover, NT-proBNP was required to have 400 pg/ml or larger among the patients. In view of inclusion and exclusion criteria, 100 patients with heart failure were randomly assigned 1:1 to the treatment arms either angiotensin receptor neprilysin inhibitor (ARNi) or valsartan through purposive sampling technique and followed for a median of 88 days. The study was approved by ERC (Ethical Research Committee) and IRB (Institutional Review Board) of Rangpur Medical College authority, Rangpur, Bangladesh. The study was approved in April, 2018. All of the subjects were required to receive written informed consent prior to be included in the study. Each patient was prospectively included in the intention-to-treat analysis and study ended on March 3, 2019.

Subsequent to randomization, the patients were underwent angiotensin receptor neprilysin inhibitor (ARNi) 50 mg and titrated to their final dose of 100 mg twice a day or valsartan 40 mg and titrated to the final dose of 80 mg twice a day to identify the effect of angiotensin receptor neprilysin inhibitor (ARNi) on cardiac status compared to valsartan in patients with chronic heart failure with reduced ejection fraction. Prior to be enrolled in the study, each of total of 100 patients was discontinued on their background treatments (ACE-I or ARB) 24 hour earlier.

Transthoracic echocardiography (LA diameter, LVIDD, LVIDS and left ventricular ejection fraction) test was performed at baseline, 30 days and 90 days or end of the study. All the echocardiographys were performed in the Department of Cardiology, Rangpur Medical College Hospital, Rangpur, Bangladesh. Measurement is made in accordance with the recommendation of the American society of Echocardiography. Echo was performed by using Philip iE-33 echo machine. NT-proBNP was measured at screening/baseline and 90 days or at early termination of visits by Getein 1100 immunofluorescence Quantitative Analyzer. Level of blood sugar, serum creatinine, eGFR (estimated glomerular filtration rate) and level of serum electrolytes were also examined at baseline, 30 days and 90 days or at early termination of visit or end of the study [19]. To define the functional capacity, the New York Heart Association (NYHA) functional classification (I, II, III, IV) was used.

Based on New York Heart Association (NYHA) Classification:

1) Class I—No symptoms and no limitation in ordinary physical activity, e.g. shortness of breath when walking, climbing stairs etc.

2) Class II—Mild symptoms (mild shortness of breath and/or angina) and slight limitation during ordinary activity.

3) Class III—Marked limitation in activity due to symptoms, even during less-than-ordinary activity, e.g. walking short distances (20 - 100 m). Comfortable only at rest.

4) Class IV—Severe limitations. Experiences symptoms even while at rest. Mostly bedbound patients.

5) No NYHA class listed or unable to determine.

The clinical composite assessment was done in accordance with the NYHA functional classification, patient-reported outcomes (PROs) or major adverse clinical events (or both) [20]. The patients were considered as improved based on improvement in NYHA functional classification or patient-reported outcomes (PROs) and no major cardiovascular event was reported. In contrast, at the endpoint of follow up, the patients who did have a major cardiovascular event or deteriorating of their NYHA class or patient-reported outcomes (PROs) during this single-blind treatment were adjudicated to be inferior. The primary outcome was mode of cardiovascular death and rate of hospitalization for heart failure or overall mortality.

A total 100 patients were randomly assigned through system generated block randomization into two comparison treatment arms, considering 80% power and at 5% level of significance, to perceive 25% in the ratio of the NT-proBNP at a median of 88 days over baseline between ARNi and valsartan group, we used a two-sided t-test on the logarithm of this ratio (Table 1).

No significant difference was found to have between two groups. Plus-minus values indicate mean ± SD. IQR denotes interquartile range. The body-mass index is the weight in kilograms divided by the square of the height in meters.

We used statistical software STATA (version 13.0) for all of analysis according to intent-to-treat. For the primary endpoint of the single-blind trial, we performed Cox-proportional hazards models and Kaplan-Meier estimates for comparing time-to-event cardiovascular deaths and rehospitalization due to heart failure between the treatment arms. We then adjusted the effect of all prespecified subgroups with dichotomas variables through Cox-proportional hazards models as well. To compare the occurrence of adverse event for undergoing both treatments, we performed Fisher’s exact test.

Finally, a total of 100 patients with chronic heart failure were recruited to equally distributed between two groups. The patients were predominantly male (67%). The majority of patients reclined in the age group of (61 - 70) years (32%). The most collective symptom was found to have shortness of breath (83%) followed by chest pain (61%). The trial found tobacco smoking/chewing (30%) as the major risk factor followed by hypertension and diabetes (25% each). The both treatment arms were well-adjusted with reference to patient’s baseline characteristics.

The primary endpoints, occurrence of cardiovascular deaths occurred 4 (8%) in the ARNi treatment arm, while 11 (22%) in the valsartan treatment arm with significant hazard ratio in the ARNi group [Hazard Ratio = 0.37; 95% CI: 0.34, 0.64; p = 0.042] during a median of 88 days of follow up period (Table 2(a) and Figure 2). 2 (4%) of the patients from the ARNi treatment arm were hospitalized due to HF, while in the valsartan treatment arm, 10 (20%) patients were hospitalized due to HF followed by receiving treatment respectively with hazard ratio in the ARNi group [Hazard Ratio = 0.80; 95% CI: 0.57, 0.92; p < 0.037] (Table 2(a)). The secondary outcomes of the trial were to examine the differences of ejection fraction, NT-proBNP and e-GFR between two groups.

A significant effect was found to have in both ejection fraction and NT-proBNP at 95% confidence interval (p < 0.05). These effects resulted from somewhat increased in ejection fraction (30.4% ± 6.7% to 38.8% ± 8.1%) and intensely decreased in NT-proBNP (3066.5 ± 1882.1 pg/ml to 808.2 ± 592.5 pg/ml) in the ARNi group, as compared to valsartan group in LVEF (30.6% ± 6.0% to 35% ± 7.9%) and in NT-proBNP (3488.2 ± 2912.2 pg/ml to 1886.4 ± 1017.8 pg/ml) respectively (Table 2(b)).

But no evidence of differences was found to have between the ARNi and valsartan groups with respect to the other echocardiography measurements (LA Diameter, p-value 0.53; LVIDD. p-value 0.78; LVIDS and p-value 0.50) except ejection fraction at a median of 88 days of follow up (Table 3). Similarly, the ARNi and valsartan groups did not differ with regard to the blood sugar (p-value = 0.38), potassium (K) (p-value = 0.23) and chloride (Cl) (p-value = 0.68) but sodium (Na) (p-value = 0.028) of serum electrolytes demonstrated the significance difference between ARNi and valsartan groups.

EF denotes ejection fraction, e-GFR denotes estimated glomerular filtration rate and NT-proBNP denotes N-terminal prohormone of brain natriuretic peptide.

In the ARNi group, 2 patients (4%) were re-hospitalized followed by receiving treatment while ratio of re-hospitalized increased to a greater extent in the valsartan group, 10 patients (20%) (p-value = 0.014). No adverse effect was found in the ARNi group 0 (0%) with respect to renal impairment but in the valsartan group 4 patients (10.26%) did have the abnormal (≥2.5 mg/dl) level of serum creatinine (p-value = 0.026) (Table 5). The number of patients with elevated potassium or elevated blood sugar did not differ between the groups.