Novel dual-reference approach facilitates the activation mapping and catheter ablation of premature atrial complexes with non-pulmonary vein and non-superior vena cava origins.

AIMS: Activation mapping of premature atrial complexes (PACs) proves challenging due to interference by mechanical bumping and non-targeted ectopies. This study aims to compare the mapping efficacy, instant success, and long-term recurrence of catheter ablation for PACs with non-pulmonary vein (PV) and non-superior vena cava (SVC) origins between the novel dual-reference approach (DRA) and the routine single-reference approach (SRA) of mapping. METHODS AND RESULTS: Patients with symptomatic, drug-refractory PACs, or frequent residual PACs after atrial tachyarrhythmia ablation were enrolled. During activation mapping, the coronary sinus (CS) catheter was used as the only timing reference in the SRA group. In the DRA group, another catheter, which was spatially separated from the CS catheter, was used as the second reference. The timing difference between the two references was used to discriminate the targeted PACs from the uninterested rhythms. Procedural parameters and long-term recurrence were compared. A total of 188 patients (109 in SRA and 79 in DRA) were enrolled. The baseline characteristics were similar. Compared with the SRA group, the DRA group had less repeated mapping (1.2 ± 0.4 vs. 1.4 ± 0.5, P = 0.004), shorter mapping (15 ± 6 vs. 23 ± 7 min, P < 0.001) and procedural time (119 ± 28 vs. 132 ± 22 min, P = 0.001), similar procedural complication rates (3.6 vs. 3.8%, P > 0.999), higher instant success (96.2 vs. 87.2%, P = 0.039), and lower recurrence rate (15.2 vs. 29.3%, hazard ratio 1.943, P = 0.033) during a 24-month follow-up. CONCLUSION: As a novel strategy, the DRA shortens the procedural time and improves both instant and long-term success of PAC ablation, serving as a promising approach in mapping PACs with non-PV and non-SVC origins.

Exosomes of bone-marrow stromal cells inhibit cardiomyocyte apoptosis under ischemic and hypoxic conditions via miR-486-5p targeting the PTEN/PI3K/AKT signaling pathway.

BACKGROUND: Myocardial ischemia-reperfusion injury (MIRI) is a major obstacle in the treatment of ischemic heart disease. Recent studies have shown that exosomes-small membrane vesicles secreted by most cell types-could have a protective effect on the ischemic myocardium. In this study we explored the effect of exosomes derived from bone-marrow stromal cells (BMSC-exo) on cardiomyocyte apoptosis and MIRI. METHODS: Exosomes were purified from culture media using the ExoQuick kit and observed using transmission electron microscopy. Cell viability was assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay. Cell apoptosis was analyzed by flow cytometry using the Annexin-V/PI stain. The expression levels of microRNA (miRNA), messenger RNA (mRNA) and PTEN/PI3K/AKT-pathway-related proteins were detected by qRT-PCR and western blot, respectively. Myocardial ischemia was simulated by incubating H9C2 cells in a hypoxia/reoxygenation (H/R) conditioned rat MIRI model. RESULTS: BMSC-exo induced the proliferation of H9C2 cells and rescued H9C2 cells from apoptosis in the H/R model, indicating that BMSC-exo has a protective effect on cardiomyocyte injury caused by H/R. Using transgenic H9C2 cells, we found that miR-486-5p in BMSC-exo suppressed the H/R-triggered apoptosis of H9C2 cells. In addition, BMSC-exo repressed the expression of PTEN in H9C2 cells via miR-486-5p, and subsequently activated the PI3K/AKT pathway in vitro. Moreover, the myocardial injury caused by ischemia/reperfusion was repaired by BMSC-exo which activates the PI3K/AKT pathway via miR-486-5p in vivo. CONCLUSION: Our results suggested that exosomes from BMSCs have a protective effect on myocardium ischemic injury. MiR-486-5p carried by BMSC-exo plays a pivotal role in the regulatory process by suppressing PTEN expression, activating the PI3K/AKT signaling pathway, and subsequently inhibiting the apoptosis of injured cardiomyocytes.