At 75% patient completion overall mortality was much lower than expected and without significant difference at day 90. No chance to reach the primary endpoint.

Patients presenting to the Emergency Department with shortness of breath and (suspected) heart failure will be screened and randomized to either a standard of care or a procalcitonin-guided arm.

Procalcitonin-guided arm: a procalcitonin level (cutoff 0.2 ng/ml) will be used to support decision on antibiotic therapy initiation.

Standard of care arm: the decision on antibiotic therapy will be based on the physicians intent to treat.

The patients will be followed up 30 and 90 days after randomization to evaluate the survival status, re-hospitalizations and further antibiotic therapies.

Inclusion Criteria:

1. Patients who present to the emergency department (ED) with leading symptom dyspnea
2. Suspected or known heart failure
3. midregional pro atrial natriuretic peptide (MR-proANP)>300 pmol/L, brain natriuretic peptid (BNP) >350 ng/ml or N-terminal of the prohormone brain natriuretic peptide (NT-proBNP)>1800 ng/l
4. Patient has given written Informed Consent within study timelines to allow antibiotic therapy within 8 hours
5. Adult patients (i.e. >18 years of age)
6. Hospitalization for at least 1 overnight stay planned

Exclusion Criteria:

1. Patient participates in any other interventional clinical trial
2. Trauma related shortness of breath
3. Patient diagnosed with lung or thyroid cancer
4. Known terminal disease with life expectancy of less than 6 months, e.g. advanced metastasized cancer disease
5. Organ transplant requiring immunosuppression
6. Abdominal, vascular or thorax surgery within the last 30 days
7. End stage/advanced heart failure - defined by planned heart transplantation, or cardiogenic shock
8. Female patients who have given birth within 3 months before study enrolment
9. Current use of antibiotics or requirement of immediate antibiotic therapy before randomization and measurement of Procalcitonin
10. End stage renal failure requiring dialysis
11. Patient is not willing, or it is not possible or advisable for the patient, to follow the study schedule, including antibiotic therapy and 90 days follow up
12. Patient has already participated in the clinical trial previously
13. Pregnant or lactating women
14. Patients who are institutionalized by official or judicial order
15. Dependants of the sponsor, the contract research organization (CRO), the study site or the investigator