Six‐Week Changes in Global Longitudinal Strain and Rehabilitation Outcomes After Enhanced External Counterpulsation Following PCI for Myocardial Infarction: An Analysis of a Pre‐Existing Matched Cohort

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.