Abstract Body (Do not enter title and authors here): Background: As the burden of cardiovascular diseases (CVD) in sub-Saharan Africa (SSA) rises, context-specific evidence on how to successfully scale proven CVD prevention and control interventions is urgently needed.

Objective: To assess the current state of implementation science on priority CVD prevention and control interventions provided within health systems in low- and middle-income countries (LMICs).

Methods: EMBASE and MEDLINE databases were searched from 1990 through 2021 to identify implementation science studies on the World Health Organization priority CVD control interventions provided within health systems in LMICs. Any empirical and peer-reviewed studies that focused on these interventions and reported implementation outcomes were eligible for inclusion. Extracted data were synthesized narratively using descriptive statistics. Subgroup analysis was performed to describe the available context-specific evidence in SSA.

Results: Of the unique records screened for inclusion, 103 eligible studies evaluated 145 priority CVD prevention and control interventions implemented in 38 countries. Of these studies, only 8% were conducted in SSA and focused on 15 interventions. Prevention interventions accounted for 18% overall and 8% in SSA, screening for 12% overall and 23% in SSA, and treatment for 70% overall and 69% in SSA. The implementation strategies were not specified well enough. Feasibility was the most studied implementation outcome whereas sustainability was the least studied. Most studies used quantitative methods and weak study designs. Most studies reported funding (77%), with international funding being the predominant source. Most studies were pilot (86% overall vs 92% in SSA) and targeted the micro level of health system (73% vs 92% in SSA).

Conclusions: Implementation research on CVD in LMICs has risen steadily over the last few decades; however, major gaps in the science persists especially in SSA. Future studies should prioritize implementation at scale, target higher levels health systems and test sustainability of CVD programs. They should employ designs with stronger internal validity, be more conceptually driven, and use mixed methods to understand mechanisms. To maximize impact of the research under limited resources, adding implementation science outcomes to effectiveness research and regional collaborations are promising.