Positive Emotions Following Acute Cardiac Events

The investigators are proposing a study that will focus on testing the efficacy of a PP-MI intervention, with additional twice text messages for a total of 24 weeks (with interactive, algorithm-driven, goal-focused text messages in the final 12 weeks) in post-ACS patients. The investigators will enroll 280 post-ACS patients, who will take part in either a 12-week intervention (with 24 weeks of supplemental text messages), or receive post-ACS treatment as usual.

In this project, the investigators hope to do the following:

1. Examine the efficacy of a 12-week, phone-delivered PP-MI intervention for individuals with ACS on physical activity-related outcomes, as compared to the treatment as usual group. 2. Assess the intervention's impact on psychological (e.g. positive affect), functional (e.g. physical function), and behavioral (e.g. overall adherence) outcomes. 3. Explore the intervention's impact on markers of cardiovascular health (e.g., cardiac biomarkers), as well as major adverse cardiac events/readmissions.

Participants will be screened and enrolled during admission for an ACS. They will be provided with a accelerometer to monitor their physical activity for one week prior to their first in-person visit. At their first visit, they will answer questionnaires related to psychological and physical health and functioning, have their blood pressure and weight measured, and provide a fasting blood sample. Upon confirmation of adequate physical activity, participants will be randomized to receive the PP-MI intervention or treatment as usual.

Participants in the intervention will be provided a treatment manual, an activity tracker, and other treatment materials. The intervention will be introduced, and the first exercise will be assigned.

Following the first in-person visit, participants in the treatment condition will complete twelve weekly phone sessions with a study trainer. The phone sessions primarily will include a review of the prior week's session content and a discussion of the rationale and assignment of the next week's exercise/assignment.

Participants in the treatment condition will receive twice weekly text messages throughout the intervention (Weeks 1-12) and initial follow-up period (Weeks 13-24). These messages will focus on the PP activity and physical activity. During Weeks 13-24, participants in the PP-MI condition will engage with twice weekly, automated, interactive text messages related to PP and physical activity.

At Weeks 12, 24, and 48, participants will complete follow-up visits. One week prior to these visits, participants will be mailed an accelerometer and will wear it until their study visit. During these study visits, participants will be asked to answer questionnaires related to psychological and physical health and functioning, have their blood pressure and weight measured, and be asked about cardiovascular outcomes, including hospitalizations, cardiovascular procedures, and cardiac-specific hospitalizations. They will also provide a fasting blood sample.

Finally, participants will complete phone sessions every 6 months until study end to inquire about hospitalizations and adverse cardiac events.

• Change in Light Intensity Activity [Time frame: Measured for 7 days at baseline, 12 weeks, 24 weeks, and 48 weeks]
• Change in positive affect (Positive and Negative Affect Schedule [PANAS] positive affect items) [Time frame: Baseline, 12 weeks, 24 weeks, 48 weeks]