Optimizing a Positive Psychology Intervention to Promote Health Behaviors After an Acute Coronary Syndrome: The Positive Emotions After Acute Coronary Events III (PEACE-III) Randomized Factorial Trial

Objective Despite the clear benefits of physical activity and related behaviors on prognosis, most patients experiencing an acute coronary syndrome (ACS) remain nonadherent to these behaviors. Deficits in positive psychological constructs (e.g., optimism) are linked to reduced participation in health behaviors, supporting the potential utility of a positive psychology (PP)-based intervention in post-ACS patients. Accordingly, we aimed to identify optimal components of a PP-based intervention to promote post-ACS physical activity. Methods As part of a multiphase optimization strategy, we completed a randomized factorial trial with eight conditions in 128 post-ACS patients to efficiently identify best-performing intervention components. All participants received a PP-based intervention, with conditions varying in duration (presence/absence of booster sessions), intensity (weekly/daily PP exercises), and content (PP alone or combined with motivational interviewing), allowing three concurrent comparisons within the trial. The study aims included assessments of the overall feasibility, acceptability, and impact of the intervention, along with the primary aim of determining which components were associated with objectively measured physical activity and self-reported health behavior adherence at 16 weeks, assessed using longitudinal models. Results The intervention was well accepted and associated with substantial improvements in behavioral and psychological outcomes. Booster sessions were associated with greater activity to a nearly significant degree ( = 8.58, 95% confidence interval = -0.49-17.65, effect size difference = .43, p = .064), motivational interviewing was associated with overall adherence ( = 0.95, 95% confidence interval = 0.02-1.87, effect size difference = .39, p = .044), and weekly exercise completion was generally superior to daily. Conclusions These findings will enable optimization of the PP-based intervention in preparation for a well-powered controlled trial. Clinical Trial Registration Clinicaltrials.gov, NCT02754895.