The goal of this observational study is to evaluate the clinical outcomes and management approaches of cardiogenic shock throughout the years in adult patients admitted to a Cardiology Department. The main questions it aims to answer are:

• How have management strategies and clinical outcomes for cardiogenic shock evolved over time?
• How do clinical, laboratory, and advanced hemodynamic monitoring parameters relate to patient survival and overall prognosis in this population?

Researchers will evaluate clinical data collected from 2017 onwards to see if therapeutic advancements and changes in clinical management over the years have led to improved patient survival and quality of care.

Participants will:

• Receive standard, routine medical care for cardiogenic shock as determined by their clinical team (no experimental interventions will be introduced).
• Have their clinical, laboratory, and imaging data collected from hospital electronic records during their stay.
• Be followed for up to 1 year after hospital admission to evaluate long-term survival and clinical outcomes.

The Cardiovascular Outcomes Registry in Cardiogenic SHOCK (COR-SHOCK) is hybrid (retrospective and prospective), observational registry designed to evaluate the clinical performance, therapeutic management, and outcomes of patients presenting with cardiogenic shock (CS).

Contemporary CS management has evolved beyond correcting macro-hemodynamic parameters. CS is now recognized as a highly dynamic, systemic syndrome characterized by microvascular hypoperfusion, systemic inflammatory response syndrome (SIRS), endothelial dysfunction, and profound neurohormonal and metabolic derangements. To capture this complexity, the COR-SHOCK registry systematically integrates granular, real-world data reflecting these pathophysiological axes. This includes laboratory evaluation, and advanced invasive hemodynamic profiling via pulmonary artery catheterization (Swan-Ganz).

Registry Procedures and Quality Assurance Plan

To ensure high-quality data collection and compliance with scientific standards, the registry implements the following procedures:

1. Quality Assurance (QA) Plan:

   The Steering Committee, led by the Principal Investigator, oversees the registry's operations. Internal data quality audits are conducted semi-annually to review enrollment rates, evaluate protocol adherence, and identify systematic data entry discrepancies.

2. Data Checks:

   Data is transcribed from electronic health records into a dedicated electronic database. The entry platform utilizes programmed range validation and consistency rules (e.g., preventing physiological out-of-range values for hemodynamics and laboratory results, and enforcing logical chronological order for clinical events, such as ensuring discharge dates succeed admission dates).

3. Source Data Verification (SDV):

   To guarantee data accuracy and completeness, a designated researcher who is not directly involved in the primary data entry performs random source data verification on 10% of all registry entries. This process involves cross-referencing database records with original paper and electronic health records.

4. Data Dictionary:

   A comprehensive data dictionary has been established, detailing every variable collected. It defines clinical terminology, laboratory reference ranges, and standardized categorization rules.

5. Standard Operating Procedures (SOPs):

   Formal SOPs govern all key registry processes, including:

   • Daily screening and identification of eligible patients in the cardiac intensive care unit (UNICOR).
   • Standardized timing for dynamic data collection.
   • Data security protocols, including patient pseudonymization and password-protected access control.
   • Event reporting protocols for predefined clinical complications.

6. Sample Size Assessment:

The registry aims to include approximately 750 to 800 patients. This target is calculated based on historical admission rates at the center, comprising a retrospective cohort of approximately 500 patients (2017-2025) and a prospective recruitment target of 80 to 100 patients annually over a 2-to-3-year period. This sample size provides sufficient statistical power to characterize temporal trends, evaluate subset populations (e.g., mechanical circulatory support, specific etiologies), and perform robust multivariable risk modeling.

Statistical Analysis Plan (SAP) Descriptive statistics will characterize the study population. Continuous variables will be presented as mean ± standard deviation (SD) or median with interquartile range (IQR), based on normality (assessed via Shapiro-Wilk test). Categorical variables will be expressed as frequencies and percentages.

To evaluate management and outcome trends over the years:

• Temporal trends in clinical management, therapeutic choices (such as the use of short-duration mechanical circulatory support [VA-ECMO, Impella, IABP] or advanced therapies [LVAD, cardiac transplantation]), and survival will be assessed using linear/logistic regression models across calendar years.
• Survival curves will be estimated using the Kaplan-Meier method and compared across different clinical phenotypes, therapeutic interventions, and time epochs using the log-rank test.
• Multivariable Cox proportional hazards regression and logistic regression models will be constructed to identify independent clinical, laboratory and hemodynamic predictors of short-term (ICU and in-hospital) and long-term (1 year) mortality. Model fit and calibration will be evaluated using standard diagnostic metrics (e.g., Harrell's C-index).

Inclusion Criteria:

-Cardiogenic shock according to the following criteria:

Cardiac disorder resulting in hypotension, defined as at least one of the following:

• Systolic blood pressure (SBP) <90 mmHg for ≥30 minutes, or
• Requirement for vasopressors, inotropes, or mechanical circulatory support to maintain SBP ≥90 mmHg

AND

Evidence of tissue hypoperfusion, defined by the presence of at least one of the following:

• Serum lactate >2 mmol/L
• Acute kidney injury and/or oliguria
• Acute hepatic injury
• Cool or mottled extremities
• Altered mental status

AND

Clinical presentation judged to be primarily attributable to a cardiac etiology.

Exclusion Criteria:

• Age < 18 years.
• Other primary etiologies of shock at presentation (e.g., hypovolemic, hemorrhagic, septic, obstructive shock due to acute pulmonary embolism, or anaphylactic shock).
• Refusal to participate in the study (applicable only to the prospective cohort).

The study population consists of adult patients admitted with cardiogenic shock. The population reflects a real-world, highly complex, and critically ill cohort comprising both a retrospective cohort (admitted from January 2017 onwards) and a prospective cohort consecutively enrolled at the center.

Individual Participant Data (IPD) will not be publicly shared to protect patient confidentiality and ensure strict compliance with legal and ethical standards. This study is conducted in accordance with the European Union General Data Protection Regulation (GDPR) and Portuguese Data Protection Law (Lei n.º 58/2019).

De-identified, aggregated data or specific proposals for collaborative academic research may be considered upon reasonable request, subject to approval by the study's Steering Committee and the institutional Ethics Committee (contact via jppereira@ulslo.min-saude.pt).