Heart failure (HF) is a growing public health problem, expected to increase in prevalence and incidence due to population aging. This challenge is compounded by the healthcare overload following the COVID-19 pandemic, particularly in primary care (PC). Early diagnosis of HF is critical for improving outcomes, reducing complications, and optimizing resource use. However, there is no robust scientific evidence supporting the effectiveness of early screening for HF in PC settings.

This study aims to evaluate whether an early cardiology assessment model for patients with suspected HF and elevated NT-proBNP levels (>300 pg/mL) improves clinical outcomes compared to the standard referral pathway. The hypothesis is that early intervention will reduce emergency visits, hospitalizations, and mortality related to HF.

This is a prospective, single-center, open-label, phase II randomized controlled trial with parallel group allocation (1:1). Patients presenting to PC with HF symptoms and no prior HF diagnosis, who have NT-proBNP levels >300 pg/mL, will be invited to participate. After informed consent, participants will be randomized to one of two groups:

• Intervention group: Early cardiology assessment within 7 days.
• Control group: Standard referral by PC physician per usual care.

Randomization will be computer-generated and managed independently to ensure allocation concealment. Patients will be followed for 12 months from the date of NT-proBNP testing. Outcomes will be collected through both cardiology and PC visits.

Our primary outcome measure will be the clinical benefit, defined as a hierarchical composite endpoint of:

1. Cardiovascular mortality
2. All-cause mortality
3. Number of hospitalizations due to HF
4. Number of urgent care visits due to HF
5. Number of GDMT (Guideline-Directed Medical Therapy) drugs initiated
6. Number of GDMT drugs with dose escalation
7. Proportional change in log (NT-proBNP) at 12 months

The primary analysis will use a win ratio methodology to maximize statistical efficiency and clinical interpretability.

Secondary outcomes include:

• Each component of the primary endpoint
• Stratified analysis by confirmed or excluded HF diagnosis
• Stratified analysis by HF phenotype (HFrEF vs HFpEF)
• Stratified analysis by sex

A sample size of 304 patients (152 per group) has been calculated to detect a win ratio of 1.7 with 80% power, based on expected clinical benefit and statistical assumptions from prior literature. The study is expected to complete recruitment within 12 months, with a total study duration of 24 months including follow-up and data analysis.

leads to better clinical outcomes compared to the usual referral pathway. Patients are randomized 1:1 to early cardiology evaluation (within 7 days of NT-proBNP result) versus standard PC-driven referral. This approach seeks to bridge the gap between suspicion and diagnosis, allowing for timely initiation or optimization of therapy when appropriate.

The study will be conducted in collaboration with the Córdoba-Guadalquivir Primary Care District. A training session has been held with primary care providers, and informed consent materials have been distributed throughout the district.

The primary outcome is a composite hierarchical endpoint, assessed using a win ratio approach. The components of this outcome include cardiovascular mortality, all-cause mortality, number of HF hospitalizations, number of urgent visits due to HF, number of GDMT drugs initiated (when indicated), number of GDMT drugs up-titrated (when indicated), and proportional change in log-transformed NT-proBNP at 12 months. The win ratio methodology allows for an ordered comparison of outcomes, giving greater weight to more severe events (e.g., death) while preserving statistical efficiency in detecting clinical benefit across multiple domains.

This design aligns with real-world priorities: reducing hard endpoints (mortality, hospitalization), improving evidence-based pharmacologic management, and optimizing biomarker control. It also recognizes the heterogeneity in HF diagnosis and severity among patients presenting to PC with unexplained dyspnea or fatigue.

The trial includes stratified secondary analyses in patients with and without confirmed HF, in those with HFpEF vs HFrEF phenotypes, and by sex, to explore differential responses to early intervention and inform future implementation strategies. All patients are followed for 12 months, with data collected from both cardiology and primary care visits. The target sample size of 304 participants provides adequate power to detect a clinically meaningful win ratio based on prior observational and interventional data. This total includes 152 patients per arm (early cardiology intervention vs. standard care), with a 1:1 allocation ratio

The study has received approval from the local ethics committee (reference number 6145). All participants are required to provide written informed consent before enrolling in the study, and are informed of their right to withdraw from the study at any time without giving any impact on their standard medical care. Participant confidentially is strictly maintained and all data are securely stored in compliance with data protection regulations. The study results will be disseminated through scientific publications and conference presentations.

Inclusion Criteria:

• Age ≥ 18 years.
• Signs and symptoms related to heart failure (HF).
• Patients assessed in primary care.
• No prior diagnosis of HF.
• NT-proBNP levels > 300 pg/mL.

Exclusion Criteria:

• Patients diagnosed with a chronic disease with persistently elevated NT-proBNP levels, assessed by Cardiology, in whom heart failure (HF) has been ruled out in the previous year (mainly by echocardiography).
• Chronic kidney disease on hemodialysis.
• Patients with a life expectancy of less than 1 year due to severe comorbidities such as advanced-stage cancer.
• Patients enrolled in other clinical trials.
• Inability of the patient to understand the clinical trial and to provide informed consent.