Coronary heart disease is one of the main causes of morbimortality around the world. Patients that survive a coronary event suffer a high risk of readmission, relapse and mortality, attributed to the sub-optimal control of cardiovascular risk factors (CVRF), which highlights the need to improve secondary prevention strategies aimed at improving their lifestyle and adherence to treatment. Through a randomized controlled clinical trial, this study aims to evaluate the effect of an intervention involving an online health application supported by a mobile telephone or tablet (mHealth) on lifestyle (diet, physical activity, and tobacco consumption) and treatment adherence among people with coronary heart disease after percutaneous coronary intervention. The sample will comprise 240 subjects (120 in each arm: intervention and usual care). They are assessed immediately and nine months after their hospital discharge about sociodemographic, clinical, CVRF, lifestyle, and treatment adherence characteristics. The educative intervention, involving a follow-up and self-monitoring, will be performed using an online mHealth tool consisting of an application for mobile phones and tablets. The quantitative primary outcomes from the two groups will be compared using an analysis of covariance (ANCOVA) adjusted for age and gender. A multivariate analysis will be performed to examine the association of the intervention with lifestyle habits, the control of CVRFs, and outcomes after discharge in terms of the use of health services, emergency visits, cardiovascular events and readmissions.