This thesis examines the influence that social connection has on people with cardiovascular disease. Both components, social connection and cardiovascular disease, are already often featured in the media or everyday life. For example, first aid courses for cardiac arrest are already often taught in schools and loneliness is the theme of “De Warmste Week” this year. So what does this social connection mean? Social connection has three parts, including loneliness (feeling alone or feeling like you have no one to talk to), social isolation (literally having few people around you) and social support (being able to call on people to listen to you, take you somewhere, help you find information...). Previous studies have already seen that a weak social connection, this is for example often feeling lonely and having little social support, can cause you to die earlier. This thesis investigated whether this effect also applies to people with cardiovascular disease. It was seen that this was indeed the case and that a weak social connection in people with cardiovascular disease causes them to die earlier or have a faster reinfarction. This influence is caused, among other things, by people with a weaker social connection smoking more, exhibiting more sedentary behaviour (this is sitting more often) or taking their medication less precisely. This social connection also negatively affects other lifestyle factors such as self-care and diet. When it was investigated whether this effect could be reduced by making interventions on social connection, it was seen that social connection can indeed be strengthened. This can be done, for example, by an app in which several people with cardiovascular disease are in a group chat and have to do challenges together. Unfortunately, the effect of these interventions on hard outcomes such as death was not yet shown and only a decrease in blood pressure was seen. Based on these results, it is clear that weak social connection harms the health of people with cardiovascular disease, but more research needs to be done on how to implement interventions that reduce this negative effect. The social benefit is that it was confirmed that social connection has a significant impact on the health of people with CVD. National health guidelines are needed so that doctors and other healthcare workers can then use these guidelines for screening purposes. This ensures that people with weak social health can be identified and could participate in an intervention. These interventions can in turn strengthen their social connection and reduce the negative impact of weak social connection on their health.