Secondary preventive therapies play a key role in the prevention of adverse events after coronary artery bypass grafting (CABG). However, adherence to secondary preventive drugs after CABG is often poor. With the increasing penetration of smartphones, health-related smartphone applications might provide an opportunity to improve medication adherence. We aimed to evaluate the effectiveness and feasibility of using a smartphone-based application to improve medication adherence in patients after CABG.

The Measurement and Improvement Studies of Surgical coronary revascularizatION: medication adherence (MISSION-2) study is a multicenter randomized controlled trial that planned to enroll over 1000 patients who underwent isolated CABG at one of four large teaching hospitals in China; all enrolled participants had access to a smartphone and were able to operate at least three smartphone applications. The investigators randomly assigned the participants to one of two groups: (1) the intervention group with an advanced smartphone application for 6 months which was designed specifically for this trial and did not exist before. Participants could receive medication reminders and cardiac health education by the smartphone application or (2) the control group with usual care. The primary outcome was CABG secondary preventive medication adherence as measured by the translated Chinese version of the 8-item Morisky Medication Adherence Scale (MMAS-8) at 6 months after randomization. The secondary outcomes were mortality, major adverse cardiovascular and cerebrovascular events (MACCE), cardiovascular rehospitalization, self-reported secondary preventive medication use after 6 months of follow-up, blood pressure (BP), body mass index (BMI), and self-reported smoking status. All analyses were conducted using the intention-to-treat principle.

A total of 1000 patients (mean age, 57.28 [SD, 9.09] years; 85.5% male) with coronary heart disease after CABG were enrolled between September 2015 and September 2016 and were randomly assigned to the intervention (n = 501) or control group (n = 499). At 6 months, the proportion of low-adherence participants, categorized by MMAS-8 scores, was 11.8% in the intervention group and 11.7% in the control group (RR = 1.005, 95% CI 0.682 to 1.480, P = 1.000). Similar results were found in sensitivity analyses that considered participants who withdrew from the study, or were lost to follow-up as nonadherent. There were no significant differences in the secondary clinical outcome measures, and there were no significant differences in the primary outcome across the subgroups tested. In the intervention group, the proportion of participants who used and operated the application during the first month after CABG was 88.1%; however, the use rate decreased sharply from 42.5% in the second month to 9.2% by the end of the study (6 months).

A smartphone-based application supporting secondary prevention among patients after CABG did not lead to a greater adherence to secondary preventive medications. The limited room for improvement in medication adherence and the low participants' engagement with the smartphone applications might account for these non-significant outcomes.