BackgroundThe adherence to cardiac rehabilitation is low. Social media has been used to improve motivation and cardiac rehabilitation completion, but the authors did not find Facebook interventions for these purposes in the literature.ObjectiveThe purpose of this study was to determine the feasibility of the Cardiac Rehabilitation Facebook Intervention (Chat) for affecting changes in exercise motivation and need satisfaction and adherence to cardiac rehabilitation.MethodsThe Behavioral Regulation in Exercise Questionnaire-3 and Psychological Need Satisfaction for Exercise were used to measure motivation and need satisfaction (competence, autonomy, and relatedness) before and after the Chat intervention. To support need satisfaction, the intervention included educational posts, supportive posts, and interaction with peers. The feasibility measures included recruitment, engagement, and acceptability. Groups were compared using analysis of variance and Kruskal-Wallis tests. Pairedttests were used to assess motivation and need satisfaction change, and Pearson or Spearman correlations were used for continuous variables.ResultsA total of 32 participants were lost to follow-up and 22 were included in the analysis. Higher motivation at intake (relative autonomy index 0.53, 95% CI 0.14-0.78;P=.01) and change in need satisfaction-autonomy (relative autonomy index 0.61, 95% CI 0.09-0.87;P=.02) were associated with more completed sessions. No between-group differences were found. Engagement included “likes” (n=210) and “hits” (n=157). For acceptability, mean scores on a 1 (not at all) to 5 (quite a bit) Likert scale for feeling supported and in touch with providers were 4.6 and 4.4, respectively.ConclusionsAcceptability of the Chat group was high; however, intervention feasibility could not be determined due to the small sample size. Those with greater motivation at intake completed more sessions, indicating its importance in cardiac rehabilitation completion. Despite challenges with recruitment and engagement, important lessons were learned.Trial RegistrationClinicalTrials.gov NCT02971813; https://clinicaltrials.gov/ct2/show/NCT02971813International Registered Report Identifier (IRRID)RR2-10.2196/resprot.7554