Table 1 Definitions of important concepts as used in this study protocol

• The term pilot study is used in this protocol because the study objective is not only to investigate whether HEARTS can be implemented in Guatemala but also to evaluate a smaller-scale version of a future planned scale-up study [21]

• The term feasibility can mean different things in pilot studies [22] and in global cardiovascular disease research [23]. In this protocol, we use feasibility to refer to implementation outcomes

• The evidence-based intervention (“the thing” [24]) in this study is the HEARTS package of evidence-based interventions. In this protocol, we use the name “Integrated Hypertension and Diabetes Primary Care Model” to refer to this evidence-based intervention as implemented in Guatemala

• This study will not evaluate implementation strategies (“the stuff we do to try to help people and places to do ‘the thing’” [24]). However, a key secondary objective of this study is to develop implementation strategies for each intervention component, thus informing a subsequent scale-up study of HEARTS implementation in Guatemala