A Study to Evaluate the Effect of the Transient Receptor Potential Vanilloid 4 (TRPV4) Channel Blocker, GSK2798745, on Pulmonary Gas Transfer and Respiration in Patients With Congestive Heart Failure

Inclusion Criteria:

- >=21 years of age at the time of signing the informed consent form.

- Diagnosis of heart failure (New York Heart Association Class II-IV) for a minimum of 3
months prior to screening.

- Clinically stable with no changes in optimized guidance-directed medications and no
hospitalizations for heart failure for at least 1 month prior to Screening.

- N-terminal pro-B-type Natriuretic Peptide (NT-proBNP) >1000 picogram per milliliter
(pg/mL) measured within 6 months prior to OR at Screening.

- Average DLco measurements outside the normal range (percent [%] predicted DLco < 80%)
during the Screening Period.

- Body mass index (BMI) >=18 and <=40 kilogram per meter square (kg/m^2).

- Male or female of non-childbearing potential-

- Capable of giving signed informed consent which includes compliance with the
requirements and restrictions listed in the consent form and in the protocol.

Exclusion Criteria:

- History of acute coronary syndromes including unstable angina or myocardial infarction
within 6 months of screening.

- Coronary revascularization including angioplasty and stenting within 6 months of
Screening.

- History of stroke or seizure disorder within 5 years of Screening.

- Diagnosis of asthma.

- Diagnosis of chronic obstructive pulmonary disease (COPD) with FEV1 <50% of predicted
measured within 4 weeks of Screening.

- History of a condition that required radiation therapy to the thorax.

- History of any type of malignancy within the past five years with the exception of
successfully treated basal cell cancer of the skin.

- Active ulcer disease or gastrointestinal bleeding.

- Current or chronic history of liver disease, known hepatic impairment, or biliary
abnormalities (with the exception of Gilbert's syndrome or asymptomatic gallstones).

- Alanine transaminase (ALT) >2x Upper Limit of Normal (ULN) and bilirubin >1.5xULN
(isolated bilirubin >1.5xULN is acceptable if bilirubin is fractionated and direct
bilirubin <35%).

- QT interval corrected (QTc) > 450 millisecond (msec) or QTc > 480 msec in subjects
with Bundle Branch Block.

- History or current evidence of any serious or clinically significant gastrointestinal,
renal, endocrine, neurologic, hematologic or other condition that is uncontrolled on
permitted therapies or that would, in the opinion of the investigator or the
GlaxoSmithKline (GSK) medical monitor, make the subject unsuitable for inclusion in
this study.

- Use of medications specified for the treatment of COPD including short- and long
acting bronchodilators (beta-agonists and anticholinergics) and inhaled
glucocorticoids as well as oxygen therapy.

- Use of a listed prohibited medication within the restricted timeframe relative to the
first dose of study medication.

- Use of a strong inhibitors or inducers of cytochrome P450 (CYP) 3A or p-glycoprotein.

- Current smoker.

- History of drug/substance abuse within the past 2 years.

- History of alcohol abuse within 6 months of the study. Defined as an average weekly
alcohol consumption of >14 drinks for men or >7 drinks for women. One drink is
equivalent to 12 grams (g) of alcohol: approximately 12 ounces (360 milliliters [mL])
of beer, 5 ounces (150 mL) of wine, or 1.5 ounces of (45 mL) 80 proof distilled
spirits.

- History of sensitivity to any of the study medications, or components thereof or a
history of drug or other allergy that, in the opinion of the investigator or Medical
Monitor, contraindicates their participation.

- Presence of hepatitis B surface antigen (HBsAg), positive hepatitis C antibody test
result at screening or within 3 months of screening. For potent immunosuppressive
agents, subjects with presence of hepatitis B core antibody (HBcAb) should also be
excluded.

- A positive pre-study drug/alcohol screen.

- Use of another investigational product in a clinical study within the following time
period prior to the first administration of study medication in the current study: 30
days, 5 half-lives or twice the duration of the biological effect of the
investigational product (whichever is longer).

- Exposure to more than 4 investigational medicinal products within 12 months prior to
the first administration of study medication.