Acute Heart Failure Patients With High Copeptin Treated With Tolvaptan Targets Increased AVP Activation for Treatment (ACTIVATE)

Inclusion Criteria: 1. Older than or equal to 18 years of age, with diagnosis and planned treatment for Acute Heart Failure 2. Dyspnea at rest or minimal exertion per the patient 3. Evidence of extracellular volume expansion by at least one of the following: JVD, Rales, Ascites, Edema or positive Chest X-ray defined as cardiomegaly, pulmonary vascular congestion, Kerley B-lines, pulmonary edema and/or pleural effusion. 4. Elevated BNP level \>200 pg/ml, or NTproBNP \> 1000pg/mL 5. Able to administer study drug within 8 hours from triage time Inpatient Hospitalized Inclusion Only: Co-peptin level \> 27 pmol/L Exclusion Criteria: 1. Unable to provide informed consent 2. Unable to have 30 day telephone follow up 3. Not expected to survive past 6 months 4. On Renal replacement therapy or creatinine \>3.5 5. History of allergy or intolerance to Tolvaptan 6. Suspected Pregnancy 7. Cardiogenic Shock 8. Participation in any interventional trial in prior 30 days. 9. Receiving or planned to receive IV Inotropic therapy 10. ACS now or in the past 30 days 11. Treatment with IV infusion vasoactive drugs in the hour prior to enrollment 12. Temperature \> 100.5 13. Heart Failure due to atrial fibrillation with Rapid Ventricular Response 14. SBP \< 90 mmHg