Introduction: Cardiac diseases remain a global leading cause of morbidity, severely compromising patients’ quality of life (QoL). Although psychosocial factors influence health outcomes, the precise pathways connecting health literacy (HL) to QoL remain insufficiently clarified. This study aimed to examine the relationship between HL and QoL in cardiac patients, specifically testing social support (SS) as a mediator and spiritual well-being (SWB) as a moderator.
Methods: A cross-sectional analytical study was conducted among 322 patients with stable coronary heart disease in tertiary care cardiology departments. Health literacy, social support, spiritual well-being, and quality of life were measured using validated instruments. Direct and conditional indirect effects were examined using Hayes’ PROCESS Macro (Model 14) with 5,000 bias-corrected bootstrap resamples.
Results: Participants reported mean scores of 3.54 ± 1.11 for HL, 3.32 ± 1.08 for SS, 3.46 ± 1.07 for SWB, and 4.27 ± 1.18 for QoL. Bivariate analysis showed significant positive correlations among all constructs (r = 0.314–0.462, p < 0.001). HL was directly associated with QoL (β = 0.31, p < 0.001). SS significantly mediated the HL–QoL association (indirect effect = 0.12, 95% CI [0.06, 0.19]). SWB significantly moderated the path from SS to QoL (βinteraction = 0.15, p = 0.012), indicating that higher spiritual well-being strengthened the beneficial effect of social support on QoL.
Conclusion: Health literacy was positively associated with quality of life in patients with cardiac disease, both directly and indirectly via social support. Spiritual well-being moderated the social support–quality of life relationship. These findings highlight the value of cardiac rehabilitation programs that integrate health communication, social support, and spiritual care to improve patient outcomes.