The goal of this observational study is to define the incidence of heart failure (HF) after acute coronary syndrome (ACS). The main question it aims to answer is:

• To define HF incidence in the medium and long-term in the context of public healthcare coverage ensuring universal access to early coronary revascularization after ACS and extended neurohormonal treatment.

Analyses will cover the entire population of Catalonia (North-Eastern region of Spain, N = 7.860.563 in 2020).

Researchers will compare HF incidence rate according to relevant subgroup characteristics including event type, age groups or sex, inter alia.

The aim of this project is to gain a better understanding, from a population perspective, of incident heart failure (HF) after acute coronary syndrome (ACS). The particular purpose is to define its incidence in the medium and long-term in the context of public healthcare coverage ensuring universal access to early coronary revascularization after ACS and extended neurohormonal treatment. To provide answer to this objective, a retrospective study were designed where a variety of study designs and analytic approaches will be used, aimed at maximizing the robustness of the results and at minimizing their sensitivity to specific study design assumptions. Analyses will cover the entire population of Catalonia (Spain, N = 7.860.563 as of December 31st, 2020), a region in which the Catalan Health Service granted universal health coverage. The study period will be defined between January 1st, 2012, and December 31st, 2021 covering 10 years. Inclusion criteria will be to have been admitted and diagnosed with a primary diagnosis of ACS (non-ST-segment elevation myocardial infarction -NSTEMI-, ST-segment elevation myocardial infarction -STEMI-, unstable angina -UA-) during the index event and to have been discharged alive during this period. The first co-primary outcome is to define the baseline characteristics of the ACS population, overall and according to clinical interest groups including event type (STEMI, NSTEMI, UA) and other relevant subgroups of patients. The second co-primary outcome of the study is the incidence rate of HF after ACS of all patients discharged alive after an ACS in Catalonia during this period. Incidence rate will also be described overall and according to relevant subgroup characteristics including event type, clinical phenotypes surrogate of impairment in regional or global systolic function, age groups, sex, diabetes mellitus, HF complicating index ACS, recurrent ACS after index ACS, socioeconomic status, treatments, comorbidity groups and procedures. Other clinical outcomes will be assessed as secondary outcomes (all-cause death, stroke, recurrent ACS, hospitalizations, major adverse cardiac event, etc.).

Inclusion Criteria:

• Admission with the primary diagnosis of acute coronary syndrome ( Non-ST-Elevation Myocardial Infarction -NSTEMI-, ST-Elevation Myocardial Infarction -STEMI-, Unestable Angina -UA-)

Exclusion Criteria:

• Diagnosis of heart failure (HF) in the year preceding the inclusion.
• Death before discharge from index event.

Analyses will cover the entire population of Catalonia (Spain, N = 7.860.563 as of December 31st, 2020), a region in which the Catalan Health Service granted universal health coverage.