Abstract 4141139: Decreased CD34 ⁺ Peripheral Cell Count is Associated with Worse Left Ventricular Function in Patients with Takotsubo Cardiomyopathy

Background: The underlying mechanisms of microvascular dysfunction in Takotsubo cardiomyopathy (TCM) remain incompletely understood. Aim: As CD34 + cells are central to coronary microvascular homeostasis we investigated the potential association between CD34 + cell count and changes in left ventricular function in patients with TCM. Methods: In a single-center prospective pilot cohort study we included 19 consecutive patients with TCM treated at our center between January 1 st , 2022, and December 31 st ,2023. Patients with a history of malignancy were not considered for this analysis. TCM diagnosis was established per InterTac Registry criteria. Patients were enrolled within 24h of admission and underwent comprehensive clinical examination, blood biochemical and hematological analysis, and echocardiography at baseline and 6-month follow-up. CD34 + cell count was measured using Beckman-Coulter Navios EX flow cytometry with standard antibodies according to ISAGE protocol. Results: Patient average age was 66±7 years, all patients were female, and hypertension and diabetes were present in 11 (57%) and 16 (84%) patients, respectively. The initial clinical presentation of TCM was acute chest pain in 15 (79%) patients and 16 (84%) patients displayed symptoms and signs of acute heart failure. Physical or psychological stress was identified in 17 (89%) of patients. Mean baseline left ventricular ejection fraction (LVEF) was 53±11% with apical dyskinesia being present in all patients. A peak mean troponin and NT-proBNP serum levels were 2353±2917 pg/mL and 3273±3196 pg/mL, respectively. The average baseline CD34+ cell count was 1.26±1.0x10 6 /L. We established a significant positive correlation between baseline LVEF (r=0.54; P=0.03) and LVOT VTI (r=0.61; P=0.01) and CD34+ cell count. When stratifying patients on LVEF, patients with LVEF≥50% displayed significantly higher CD34+ cell count than patients with LVEF<50% (1.7±0.9x10 6 /L vs. 0.7±0.0.8x10 6 /L; P=0.04). In the latter group, we also established a positive correlation between CD 34+ cell count and improvement in LVEF at 6-month follow-up (r=0.6; P=0.02). Conclusion: In patients with Takotsubo cardiomyopathy CD34+ peripheral cell count appears to correlate with the magnitude of left ventricular functional impairment and with the dynamics of left ventricular recovery. Further studies are needed to confirm our preliminary data and to explore CD34+ cells as a potential therapeutic target in this patient cohort.