Abstract Body: Background:
Cardiac rehabilitation (CR) is emerging as an essential aspect of secondary prevention in patients recovering from acute myocardial infarction (AMI) or coronary artery disease (CAD). Exercise-based rehabilitation involves high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), and maximum intensity interval training (MIIT). These are integral to improving cardiopulmonary fitness, cardiovascular outcomes, and affect health-related quality of life (HRQoL). HIIT is presumed to show better outcomes, though comparative evidence across exercise types remains inconsistent. Clarifying the differential impact of HIIT, MIIT, and MICT on physical and psychosocial outcomes is vital for optimizing CR.

Methods:
5 studies involving 650 post-AMI adults enrolled in CR were included. Most studies compared HIIT and MICT; one study also included maximal-intensity interval training (MIIT), and all others used usual care as a control. Outcomes included cardiorespiratory fitness (VO2 max), functional capacity (6-minute walk test [6MWT]), HRQoL (EQ-5D-5L, MacNew), mental health (PHQ, vitality), sleep quality (PSQI), fatigue (FSS), and physiological measures (blood pressure (BP), lipid profile, stroke volume, VE_peak). A qualitative synthesis of findings was performed due to heterogeneity across studies.

Results:
All 5 studies indicated that structured exercise improved outcomes. HIIT led to greater gains in VO2max compared to MICT. MIIT, assessed in one study, showed the largest VO2max improvements. HRQoL improved in all modalities across EQ-5D-5L, MacNew, PHQ, and visual analog scales. Functional metrics (6MWT, PPO) and cardiovascular parameters (HDL-C, HR recovery) improved more with HIIT. BP, BMI, and HbA1c improved similarly across groups. In several studies, HIIT had a stronger effect on physical functioning and emotional health. Only HIIT led to a significant drop in depression scores. HDL cholesterol improved more with HIIT.

Conclusion:
HIIT provides superior gains in cardiorespiratory fitness and physical function compared to MICT or MIIT in CR participants, without compromising safety/quality of life. Mental health, HRQoL, and physiological parameters improve comparably across exercise modalities. These findings support that HIIT is an effective, time-efficient option in contemporary CR planning. Future standardized, large-scale, and long-term studies are needed to assess sustained clinical impact and cardiovascular event reduction.