Circulating CD34+/CD45+ progenitor cells and functional parameters during cardiac rehabilitation after acute coronary syndrome

Aim. To assess the associations between baseline peripheral blood CD34+/CD45+ circulating progenitor cell (CPC) count and exercise capacity, hemodynamic response, laboratory parameters, and left ventricular structure during 12 months of cardiac rehabilitation after acute coronary syndrome (ACS).Materials and methods. This longitudinal observational study included 108 men with ACS who underwent urgent coronary stenting (mean age, 56.5 years); 88 patients with available baseline CPC measurements were included in the comparative analysis. Assessments performed on days 7-12, at 3-6 months, and at 12 months included bicycle ergometry, laboratory testing, echocardiography, and flow cytometric quantification of CD34+/CD45+ cells before exercise. Based on baseline CPC counts, patients were stratified into three groups: group 1, >4000 cells/mL (n=25); group 2, 2000-3999 cells/mL (n=46); and group 3, <2000 cells/mL (n=17). Data are presented as median (IQR). The Mann–Whitney U test, Wilcoxon signed-rank test, and Spearman correlation analysis were used; p<0.05 was considered statistically significant. Reported p values were nominal and were not adjusted for multiple comparisons.Results. In group 1, CPC count decreased from 4956.0 (4461.0-7399.5) to 3787.5 (2661.0-4472.3) cells/mL over 12 months (p<0.001) but remained higher than in groups 2 and 3 (p=0.024 and p=0.008, respectively). At 12 months, threshold workload was higher in group 1 than in groups 2 and 3: 100.0 (75.0-118.8) versus 75.0 (50.0-100.0) and 75.0 (50.0-93.8) W (p=0.014 and p=0.047, respectively). Work performed was also greater in group 1 (p=0.016 and p=0.001, respectively), and the exercise-induced change in rate–pressure product was greater than that in group 3 (p=0.031). Left ventricular end-diastolic volume did not change significantly in group 1 (p=0.984) but increased in groups 2 and 3 (p=0.046 and p=0.021, respectively). Baseline hemoglobin was lower in group 3 than in groups 1 and 2: 128.0 (122.5-144.0) versus 153.0 (140.5-160.5) and 145.5 (136.0-156.3) g/L (p<0.001 and p=0.002, respectively). Baseline CPC count correlated positively with hemoglobin levels at baseline (rₛ=0.389; p<0.001) and at 12 months (rₛ=0.293; p=0.018).Conclusions. In this exploratory analysis, a higher baseline CD34+/CD45+ cell count was associated with greater exercise capacity, a stronger hemodynamic response to exercise, and higher hemoglobin levels. These associations do not establish causality or independent prognostic value and require confirmation in larger prospective studies using multivariable analysis.