A comprehensive analysis of the impact of high-intensity interval vs. moderate-intensity continuous training on global and regional myocardial function in patients early after acute myocardial infarction: the STRAICT randomized controlled trial

Clinical Snapshot

Key Findings

• P Value: Time effect P < 0.001 for both groups; time × group P = 0.71 (non-significant difference between groups)

• Effect Size: HIIT: -0.82% improvement, MICT: -1.11% improvement in global longitudinal strain

• Primary Outcome: Global longitudinal strain improvement in both groups

• Nnt Or Sensitivity: Both interventions showed equivalent efficacy with similar effect sizes and overlapping confidence intervals

• Confidence Interval: HIIT 95% CI: -0.19 to -0.61; MICT 95% CI: -1.17 to -0.51

Clinical Application

Both HIIT and MICT protocols are feasible in supervised cardiac rehabilitation settings with appropriate monitoring Aligns with CSANZ/ACRA cardiac rehabilitation guidelines. Both interventions could be implemented within existing Medicare-funded cardiac rehabilitation programs. TGA-approved echocardiographic equipment required for advanced strain imaging Post-acute myocardial infarction patients suitable for early cardiac rehabilitation within 6 weeks of event

Abstract

AIMS: This study aims to compare the effect of moderate-intensity continuous training (MICT) vs. isovolumic high-intensity interval training (HIIT) on left ventricular (LV) myocardial function early post-acute myocardial infarction (AMI). Training-induced changes were analysed at both global and segmental levels using advanced deformation echocardiographic imaging techniques. METHODS AND RESULTS: One hundred AMI patients were randomly assigned to participate in an 8-week training programme comprising either MICT (n = 50) or isovolumic HIIT (n = 50), starting within 6 weeks post-AMI. Before and after cardiac rehabilitation (CR), we carried out a comprehensive and detailed evaluation of myocardial function, including measurements of LV longitudinal strain (LS) and circumferential strain and torsional mechanics, LV myocardial work (MW) and mechanical dispersion [post-systolic shortenings (PSS)] indexes, and atrial strains. Mixed models were used to evaluate the effect of MICT and HIIT on speckle-tracking echocardiography parameter. Both MICT and HIIT resulted in a similar improvement in the amplitude and timing of LV LS (time effect P < 0.001 in each case), as depicted by the comparable increase in global LS [HIIT: -0.82%, 95% confidence interval (CI): -0.19/-61; MICT: -1.11%, 95% CI: -1.17/-0.51; time ∗ group P = 0.71], MW index and efficiency, constructive MW, and reduction in the number of PSS and wasted MW (time ∗ group P > 0.12 in each case) in the two groups. These improvements were observed in all myocardial territories, regardless of previous ischaemic risk status (culprit vessel-by-time-by-group interactions, P > 0.60 in each case). Circumferential strains remained unchanged in both groups while there was a trend (time ∗ group P = 0.04) for LV torsion to decrease for MICT (P = 0.06) and increase for HIIT (P = 0.36) after CR. Left atrial strains during the reservoir and conduit phases improved (time effect P < 0.05) similarly in MICT vs. HIIT (time ∗ group P > 0.54). V̇O2peak (P < 0.001) and quality of life (P < 0.001) improved equally in MICT and HIIT after CR. CONCLUSION: Early supervised exercise-based CR, whether using MICT or isovolumic HIIT, improves longitudinal myocardial function in both culprit and non-culprit territories after AMI. Exercise-based cardiac rehabilitation (CR) is an effective strategy for reducing cardiovascular morbidity and mortality in patients after a myocardial infarction (MI). While moderate-intensity continuous training (MICT) has been the traditional form of aerobic exercise in CR, high-intensity interval training (HIIT) is gaining popularity due to its demonstrated feasibility, safety, and potential superiority in improving physical fitness. The impact of CR on heart function after MI is not well understood. It is still unclear whether HIIT is more effective than MICT for improving heart function. This uncertainty is due to limitations in previous studies, such as differences in total workload realized, which is an important factor in CR. It is also unclear whether different types of exercise training have different effects on parts of the heart that were damaged due to reduced blood flow during the heart attack compared with the areas that were not affected. This study aims to fill these gaps by comparing HIIT and equal-volume MICT using advanced echocardiographic imaging techniques to evaluate overall and regional heart function, focusing on both affected and unaffected areas of the heart. We found thatExercise-based CR initiated early after the heart attack effectively improves cardiac function, with HIIT as effective as isovolumic MICT.These improvements were observed equally with both MICT and HIIT across all areas of the heart, confirming its ability to functionally recover even in regions previously impacted by reduced blood flow.

References

1. 1.Obert, P., Nottin, S., Belvisi, C., Robert, C., Miramont, V., de France, C., Carlioz, R., Landrier, J.-F., Poirier, P., & Dupeyron, A. (2026). A comprehensive analysis of the impact of high-intensity interval vs. moderate-intensity continuous training on global and regional myocardial function in patients early after acute myocardial infarction: the STRAICT randomized controlled trial. European Journal of Preventive Cardiology. https://doi.org/10.1093/eurjpc/zwaf127