The purpose of this study was to develop a heart health diary to promote self-care ability among patients with heart failure (HF), and to identify the diary's effect on self-care adherence, self-efficacy, and physical activity.

A randomized control-group pretest-posttest design was adopted using block randomization. A calender-typed health diary was developed and it included a self-care checklist and education information on HF management. The experimental group were given guided counseling and education for 8 weeks and wrote a daily health diary during that period. Data were collected from the outpatient department of a tertiary medical center from February to April 2016. To verify the hypotheses, data for the experimental group (n=28) and control group (n=33) were analysed using the independent t-test with SPSS/WIN 21.0.

At the end of 8 weeks the experimental group had significantly higher scores for self-care adherence (t=-2.48, p =.016) and exercise related self-efficacy (t=-3.44, p =.001) compared to the control group.

The findings show that the application of a patient-directed heart health diary is an effective nursing intervention for improving HF patients' self-care adherence and exercise self-efficacy. Strategies to promote dietary self-efficacy are necessary along with further studies including repeated research with an increasing intervention period. Healthcare providers need to encourage the utilization of a health diary for HF patients as a tool for evaluation and for implementation that leads to self-care.