The goal of this open label randomized controlled trial is to evaluate the efficacy of an intervention through health education based on the Chronic Care Model's implementation to increase therapeutic adherence in patients with secondary prevention for cardiovascular disease. The main questions it aims to answer are:

• Null hypothesis (H0): In patients in cardiovascular secondary prevention, an intervention based on the application of the Chronic Care Model does not improve therapeutic adherence to the 3 preventive drugs: Angiotensin converting enzyme inhibitors/Angiotensin II receptor blockers, acetylsalicylic acid, and statins.
• Alternative hypothesis (H1): In patients in cardiovascular secondary prevention, an intervention based on the application of the Chronic Care Model improves therapeutic adherence to the 3 preventive drugs: Angiotensin converting enzyme inhibitors/Angiotensin II receptor blockers, acetylsalicylic acid, and statins.

Researchers will compare intervention group (health education, use of mobile phones, personalized dosage system) to the control group (routine follow-up).

Cardiovascular diseases are the worldwide's leading cause of mortality. Within the spectrum of these diseases, cerebrovascular disease, coronary heart disease, and peripheral vascular disease are included. Secondary prevention is an effective strategy in patients with previous events, being the most used drugs antihypertensives, statins and salicylic acetyl acid.

Therapeutic adherence in these patients is crucial, as the lack of it, results in increased morbidity and mortality, as well as decreased quality of life and raised healthcare costs. However, less than half of the patients take all three medications during the first year. In addition, the lack of therapeutic adherence is easier to measure in the primary care setting.

Objective: To evaluate the efficacy of an intervention through health education based on the Chronic Care Model's implementation to increase therapeutic adherence in patients with secondary prevention for cardiovascular disease.

Methods: Open label randomized controlled trial, selecting patients presenting the inclusion criteria through consecutive probability sampling. Random assignment will be carried out using a random number table.

Intervention on patients in the experimental group will be conducted through health education following the recommendations of the Chronic Care Model (CCM). The aim is to empower patients to manage their disease through therapeutic education measures and shared decision-making with the patient.

Two individual sessions (one in the first month and another in the fourth month) and four group sessions (one per quarter with 5 to 10 patients) will be conducted. The individual sessions will last 30 minutes, and the group sessions will last 1 hour.

In the first quarter, an individual session will be held in the first month, followed by a group session in the second month. In the second quarter, another individual session will be held in the fourth month, and a group session in the sixth month. Subsequently, group sessions will continue with one scheduled in the ninth month and another in the twelfth month.

Considering a therapeutic adherence of 50% in the control group and an expected therapeutic adherence of 80% in the intervention group, with a type II error of 20% (80% power), a type I error of 5% (95% confidence interval), and a 15% loss rate, a sample size of 45 patients in each group is estimated.

The follow-up period will be conducted for one year. After data collection, a descriptive univariate analysis of the variables and a bivariate analysis will be performed. Finally, a multivariate analysis will be conducted to isolate potential confounding factors and to analyze the impact of the intervention on therapeutic adherence.

Inclusion Criteria:

• Patients of both sexes, aged over 18 years old, who, after reading the patient information sheet, provide written informed consent.
• Patients in secondary prevention receiving daily single-dose angiotensin converting enzyme inhibitors/Angiotensin II receptor blockers, acetylsalicylic acid, and statins for 6 months or more.
• Diagnosis of any of the following cardiovascular diseases: cerebrovascular disease, ischemic heart disease, or peripheral vascular disease.
• Patients under follow-up at our primary care center.
• Patients identified with therapeutic adherence deficiency, defined as Haynes-Sackett test supplemented with Medication Possession Ratio (MPR) < 80% for any of the 3 drugs in the previous 6 months.

Exclusion Criteria:

• Patients who refuse to participate.
• Incomplete completion of informed consent.
• Language barrier.
• Patients diagnosed with psychiatric, psychological, neurological, and/or social problems that hinder intervention or follow-up.
• Life expectancy less than one year.
• Patients whose treatment is managed by a caregiver (professional or family member).
• Patients with Barthel Index <60.
• Institutionalized patients.
• Patients currently participating in similar research studies.