 This randomized controlled trial RCT will examine a case management program for patients suffering from coronary heart disease with multimorbidity in Mannheim, Germany. The trail consists of 3 treatment arms: 1 intensified case management; 2 social interaction alone 3 standard care. The main objectives are to evaluate how case management and social interaction alone compared to standard medical care affect the primary and secondary outcomes: physical health, quality of life, loneliness, depression, self-efficacy, outcome expectancies, social support, health locus of control, lifestyle behavior, social network, vulnerability, intention, severity, health worries and cognitive functions. 