Piloting Text Messages to Promote Positive Affect and Physical Activity

This is a single-arm study of text messaging in post-ACS patients. The convenience sample for this pilot study will be enrolled from two sources: (a) participants prospectively enrolled from inpatient cardiac units at MGH admitted for an ACS, and (b) participants in prior post-ACS studies performed with the investigators' team. A total of 28 intervention text messages (1/day for 4 weeks) will be sent to participants following the baseline assessment. After each message is sent, participants will receive a second text message asking them to rate the utility of the message, and this rating will be used by a machine learning algorithm to select subsequent messages. This will ensure that, over time, participants will receive messages that they are more likely to find useful. In the first part of the study, participants will receive 28 fixed text messages that alternate between physical activity and positive psychology messages. In the second part of the study, participants will receive 14 fixed text messages that range in topics from positive psychology to physical activity, diet, and medication adherence. In the second part of the study, participants will first receive a set of 14 pre-selected daily messages that contain a broad range of attributes to allow sufficient participant feedback to clearly identify preferences. After the first 14 messages, new messages will be selected based on the prior preferences of participants. The messages will be sent using the Twilio texting program used by REDCap, which also uses Amazon Web Services. Twilio allows software developers to programmatically make and receive phone calls and send and receive text messages using its web service. The investigators have purchased a Twilio account to allow messages to come from an anonymous phone number rather than the phone of a study staff member.