Effectiveness of mindfulness-based interventions on depressive symptoms in people with coronary artery disease: a systematic review of randomized-controlled trials

Abstract Funding Acknowledgements Type of funding sources: None.

Background: It has been well established that the prevalence of depression is higher in people with cardiovascular disease (CVD), leading to a significantly worse prognosis after coronary syndromes. A recent individual patient data meta-analysis has shown that Mindfulness-Based Interventions (MBIs) such as Mindfulness-Based Cognitive Therapy (MBCT) are not inferior to antidepressants in preventing depression relapse. A few reviews evaluated the effects of MBIs on mental health outcomes in CVD patients. However, none focused on coronary artery disease (CAD) and depression, nor did they include only randomised-controlled trials (RCTs).

Purpose: This review aims to evaluate the state of the present research on the effectiveness of MBIs on depression in patients with CAD.

Methods: This review was guided according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement. Studies were included in the review if they were RCTs; all participants had CAD; trials studied MBIs as stand-alone interventions; assessed depressive symptoms and reported subscale results if using a multidimensional tool. A search was conducted on MEDLINE, PsycINFO and ProQuest Central between inception and April 2020. Search strings focused on three concepts of the review question: ‘mindfulness’, ‘depression’ and ‘coronary artery disease’. Data were extracted and risk of bias was assessed by using Cochrane Collaboration tools.

Results: Three RCTs involving 124 patients with CAD were included. Figure 1 summarises the inclusion process in a PRISMA flowchart. All of the studies showed a significant reduction of depression in the intervention group when compared with usual care controls. A detailed summary of the included studies can be found in Table 1. Regarding the interventions, although different in types, MBCT, Mindfulness-Based Art Therapy (MBAT) and Mindfulness-Based Stress Reduction (MBSR) had similar content and lasted at least eight weeks. All three studies had low risk of selection bias from random sequence generation, low risk of attrition bias and high risk of performance bias. Notwithstanding, it is worth noting that blinding participants and personnel was not feasible because of the nature of the program.

Conclusions: In conclusion, the present review offers initial evidence supporting the effectiveness of MBIs for reducing depressive symptoms in CAD patients. However, due to short-term follow-up, small sample sizes and methodological flaws, these findings need to be interpreted with caution. Future research should design more rigorous RCTs with powered sample sizes and longer-term assessments. Despite that, this review highlights a promising clinically meaningful intervention for this population, raising the question of which timing and setting it would be most beneficial. Further studies should test it to prevent post-MI depression in a cardiac rehabilitation setting or treat depression in a cardiac outpatient clinic.