Cardiac patients show alarming levels of nonadherence to medications. It is important to consider also patient activation levels. Furthermore, the partner could have a supporting role in these processes. The aim of this study was to investigate the mediating role of patient health self-efficacy (HSE) in the link between dyadic coping (DC) and two self-management outcomes (i.e. medication adherence and patient activation) across the first 6 months of cardiac disease. One hundred couples completed two self-report questionnaires during the hospitalisation for cardiac disease and 6 months after discharge. A longitudinal and dyadic research design was adopted. Cross-sectional analyses at T0 revealed that patient-provided and perceived positive DC and common DC are positively associated with HSE, which in turn is positively associated with medication adherence. HSE mediated the association between patient positive and common DC styles, with the only exception of Patient-provided positive DC, and patient activation. Conversely, patient-provided and perceived negative DC are negatively associated with HSE, which in turns is positively associated with medication adherence and patient activation. Prospective analyses showed that only patient-perceived negative DC at discharge is negatively associated with HSE at T1, which in turns is positively associated with patient activation over time. These results suggest to consider patient perceived and provided DC as antecedents of self-management outcomes via patient HSE. Furthermore, our results recommend to pay particular attention to negative DC, whose negative consequences are manifested also over time, planning interventions targeting partners' awareness of their own DC style.