Inclusion Criteria:
* Willing and able to give written informed consent for participation in the trial and able to comply with all trial procedures and requirements.
* Male or female participant aged 40 to 70 years, inclusive, at the screening visit.
* Women of childbearing potential must practice abstinence from heterosexual intercourse or must agree to use a highly effective method of contraception.
Cohort-specific inclusion criteria:
Cohort 1, STEMI high-risk patients:
* NT-proBNP \>500 pg/mL within 48 hrs after PCI
* Post-PCI Thrombolysis In Myocardial Infarction (TIMI) score \<3.
* No previous history of coronary artery disease or heart failure.
Cohort 2, STEMI low-risk patients
* NT-proBNP \<500 pg/mL within 48 hrs after PCI
* Post-PCI TIMI score 3.
* No previous history of coronary artery disease or heart failure.
Cohort 3 (HFpEF patients)
* Presence of signs and symptoms of HF
* Ejection Fraction ≥50%
* Elevated levels of natriuretic peptides (NT-proBNP≥125pg/mL)
* At least one of the following:
* Relevant structural heart disease (left ventricular hypertrophy or left atrial enlargement)
* Diastolic dysfunction
Cohort 4 (healthy participants)
* Individuals with no history of coronary disease or heart failure.
* Medically healthy participant without abnormal clinically significant medical history, physical findings, vital signs, ECG, and laboratory values at the time of the screening visit, as judged by the Investigator.
Exclusion Criteria:
* Any contraindication for MRI according to a standard checklist
* Having worked as a metal worker or welder.
* Contraindication for gadolinium-based contrast agents such as risk of nephrogenic systemic fibrosis (NSF) or allergy to gadolinium.
* Kidney dysfunction measured as estimated Glomerular filtration rate (eGFR)\<30 mL/min/1.73m2
* History of any clinically significant disease or disorder which, in the opinion of the Investigator, may either put the participant at risk because of participation in the trial or influence the results or the participant's ability to participate in the trial.
* Any clinically significant illness, medical/surgical procedure, or trauma within 4 weeks of the screening visit.
* Any malignancy within the past 12 months before the screening visit, with the exception of successfully treated basal cell carcinoma of the skin or in situ prostate cancer under active surveillance, with no interventions scheduled during the period of trial participation.
* Any active gastrointestinal hemorrhage in the past six months.
* Acute or chronic disabling stroke.
* Aortic aneurysm or aortic dissection.
* Hypertensive crisis.
* Circulatory unstable condition in need for mechanical support.
* Any planned major surgery within the duration of the trial participation.
* Participants who are pregnant, currently breastfeeding, or intend to become pregnant during the course of the trial.
* Poor peripheral venous access, as judged by the Investigator.
* The participant has any laboratory abnormality or condition that, in the Investigator's opinion, could adversely affect the safety of the participant or impair the assessment of trial results.
* The participant is using any prohibited concomitant medications as described in the protocol, at the discretion of the Investigator.
* The Investigator considers the participant unlikely to comply with trial procedures, restrictions, and requirements.
Additional exclusion criteria for all participants (cohorts 1,2 and 4):
* History of coronary artery disease or heart failure.
