Acute coronary syndrome (ACS; myocardial infarction or unstable angina) is a leading cause of morbidity and mortality in the U.S., with \>1 million cases per year. Survivors are at high risk for recurrent cardiovascular disease (CVD) events, particularly if they do not adhere to risk-reducing medications. Unfortunately, nonadherence among ACS patients is very common (\~50%), and no effective, scalable interventions exist. Addressing medication nonadherence in ACS patients requires an experimental medicine approach to identify specific mechanisms of behavior change in populations for whom those mechanisms are most relevant and modifiable.
Accumulating evidence suggests that the many patients who develop post-traumatic stress disorder (PTSD) symptoms following ACS view their medications as reminders of their cardiac event and their future CVD risk. Ironically, although it has rarely been studied outside of cancer survivors, this fear of recurrence (FoR) may undermine medication adherence in ACS patients. This project will use the Science of Behavior Change (SOBC) experimental medicine approach to investigate FoR as a putative mechanism of behavior change with respect to heart medication adherence among ACS patients with early PTSD symptoms at hospital discharge. The study will test a cognitive-affective intervention that has been shown to reduce FoR in cancer survivors, that is delivered electronically (electronic tablet) in the patient's home. The intervention has been adapted in this study for ACS to be tested using a double-blind randomized controlled design. One hundred suspected ACS patients will be enrolled who reported at least mild to moderate threat perceptions at the time of their initial visit to the emergency department. FoR and future time perspective will be assessed within six weeks of the initial visit to the emergency department, and then participants will be trained on the tablet intervention. Participants will complete the intervention over four weeks in eight half-hour sessions, twice each week. Medication adherence will be measured electronically using eCAP devices. FoR and future time perspective will be reassessed 1 month after the baseline session, and cognitive-affective change will be assessed electronically throughout the intervention period.
In addition to investigating FoR as the primary mechanism of behavior change, the study also investigates a secondary potential mechanism that is a distinct, but related, construct: future time perspective. Furthermore, in addition to examining medication adherence as the primary health behavior of interest, the study also examines a secondary health behavior that is reduced in fearful cardiac patients: physical activity. Collectively, the three aims below address these two putative mechanisms (FoR, future time perspective) and these two health behaviors (medication adherence, physical activity) in the randomly assigned groups (intervention, control).
Objectives
Aim 1 (main purpose of the trial):
The study will determine whether a tablet-based cognitive bias modification treatment (CBMT) intervention influences the two putative mechanisms of fear of recurrence (FoR) and future time perspective. Of primary importance within this first aim, it will test whether the intervention reduces cardiac-related FoR relative to control. The trial is statistically powered to test the first aim as it relates to FoR. Secondarily, it will also test whether the intervention increases an expansive future time perspective relative to control.
Aim 2 (exploratory):
The study will determine the extent to which the two potential mechanisms of behavior change-FoR and future time perspective-are each associated with health behaviors. Of primary importance within this second aim, it will test associations between these two potential mechanisms of behavior change and objectively measured and self-reported adherence to heart medications (antiplatelets to reduce risk of blood clotting, antihypertensive drugs to reduce blood pressure, or statins to lower cholesterol). Of secondary importance, it will test whether these two potential mechanisms of behavior change are associated with self-reported physical activity.
Aim 3 (exploratory):
The study will test whether the intervention improves the two health behaviors of interest. Of primary importance within this third aim, it will test whether the intervention relative to control is associated with higher heart medication adherence (objectively measured or self-reported) in the two months after the baseline visit and whether any such beneficial effects are mediated by reductions in the putative mechanisms of FoR or future time perspective. Secondarily, it will test whether the intervention relative to control is associated with greater increases in self-reported physical activity in the two months after the baseline visit and whether any such beneficial effects are mediated by reductions in the putative mechanisms of FoR or future time perspective.
