Clinical Significance of Coronary Flow Reserve Improvement After Elective Percutaneous Coronary Intervention

BACKGROUND: Limited research has explored the prognostic significance of changes in coronary flow velocity reserve (CFVR), as measured by stress-transthoracic Doppler echocardiography (S-TDE), following elective percutaneous coronary intervention (PCI). This study aimed to assess whether post-PCI changes in CFVR are associated with major adverse cardiac events (MACE) and to identify baseline clinical factors that predict improvement of CFVR. METHODS: A retrospective analysis was performed on 184 patients who underwent elective FFR-guided PCI for the left anterior descending (LAD) artery. Standard pre-PCI TDE examinations and pre- and post-PCI physiological assessments using S-TDE were performed. Patients were categorized based on CFVR improvement, defined as an increase greater than the median value of CFVR changes. MACE, including all-cause death, myocardial infarction, ischemic stroke, and heart failure requiring hospitalization, was evaluated. RESULTS: The median improvement in CFVR was 0.50 (28.8%). During a median follow-up period of 1.9 years, MACE occurred in 26 patients (14.1%). Patients without CFVR improvement had significantly worse outcomes (p = 0.029). In multivariate Cox regression analysis, both lower pre-PCI CFVR and lack of CFVR improvement were associated with poor prognosis. A multivariate logistic regression analysis identified absence of diabetes, lower pre-PCI FFR, lower pre-PCI CFVR, and longer pre-PCI deceleration time of diastolic coronary flow as predictors of CFVR increase, with an AUC of 0.814 (95% CI: 0.755-0.873). CONCLUSIONS: In patients undergoing elective FFR-guided LAD PCI, a lower pre-PCI CFVR and lack of CFVR improvement were associated with poor prognosis, whereas a comprehensive pre-PCI evaluation predicted CFVR improvement.