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Six-Week Changes in Global Longitudinal Strain and Rehabilitation Outcomes After Enhanced External Counterpulsation
Juan Su1, Li Zhang2, Cuihuan Xie1
1Department of Ultrasound, Central Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China.
Background:
Left ventricular pressure-strain loop (LV-PSL) analysis provides non-invasive myocardial-work indices by integrating strain with contemporaneous brachial systolic blood pressure. Follow-up myocardial-work assessment requires blood pressure measured at the same assessment.
Objective:
To describe baseline myocardial mechanical abnormalities after percutaneous coronary intervention (PCI) for myocardial infarction and to explore associations between a 6-week enhanced external counterpulsation (EECP) program and changes in global longitudinal strain (GLS) and rehabilitation outcomes.
Methods:
This single-center matched observational study was conducted from October 2021 through January 2023. It included 66 patients after PCI for myocardial infarction who completed a 6-week EECP program, 66 patients in a pre-existing matched standard-therapy comparator cohort, and 50 healthy reference participants. Baseline LV-PSL-derived myocardial-work indices were descriptive. Six-week between-group changes in GLS, peak strain dispersion (PSD), N-terminal pro-B-type natriuretic peptide (NT-proBNP), 6-min walk distance (6MWT), Seattle Angina Questionnaire (SAQ) summary score, and weekly angina frequency were analyzed using pair-aware methods with Benjamini-Hochberg false-discovery-rate (FDR) correction. A sensitivity analysis adjusted for baseline outcome value, baseline systolic blood pressure, heart rate, ST-segment-elevation myocardial infarction, ACEI/ARB/ARNI use, and calcium-channel-blocker use with pair-clustered robust standard errors.
Results:
Post-PCI patients had less negative baseline GLS and descriptively lower constructive myocardial-work values than healthy reference participants. In the matched exploratory comparison, the between-group difference in GLS change was -1.3 percentage points (95% CI, -2.0 to -0.6; P < 0.001; FDR q < 0.001). EECP exposure was also associated with larger improvements in 6MWT and SAQ score, a greater reduction in NT-proBNP, and a greater reduction in weekly angina frequency; PSD change was not different after FDR correction. The adjusted sensitivity analysis gave a GLS difference of -1.3 percentage points (95% CI, -1.9 to -0.7; P < 0.001; FDR q < 0.001).
Conclusion:
In this non-randomized matched cohort, EECP exposure was associated with larger 6-week improvements in GLS and selected rehabilitation outcomes. Baseline LV-PSL-derived myocardial work is presented only as descriptive context; no valid longitudinal myocardial-work comparison was possible because follow-up hemodynamic measurements were unavailable. The contribution of changes in loading conditions to GLS could not be assessed.
