Ruan, Yanfei

Background: Ibrutinib, a potent Bruton’s tyrosine kinase inhibitor with marked efficacy against hematological malignancies, is associated with the heightened risk of atrial fibrillation (AF). Although ibrutinib-induced AF is linked to enhanced oxidative stress, the underlying mechanisms remain unclear. Objective: This research aimed to explore the molecular mechanism and regulatory target in ibrutinib-induced AF. Methods: We performed in vivo electrophysiology studies using ibrutinib-treated mice, and then employed proteomic and single-cell transcriptomic analyses to identify the underlying targets and mechanisms. The effects of A-kinase anchoring protein 1 (AKAP1) depletion on mitochondrial quality surveillance (MQS) were evaluated using both in vivo and ex vivo AKAP1 overexpression models. Results: Atrial AKAP1 expression was significantly reduced in ibrutinib-treated mice, leading to inducible AF, atrial fibrosis, and mitochondrial fragmentation. These pathological changes were effectively mitigated in an overexpression model of ibrutinib-treated mice injected with an adeno-associated virus carrying Akap1. In ibrutinib-treated atrial myocytes, AKAP1 down-regulation promoted dynamin-related protein 1 (DRP1) translocation into mitochondria by facilitating DRP1 dephosphorylation at Ser637, thereby mediating excessive mitochondrial fission. Impaired MQS was also suggested by defective mitochondrial respiration, mitochondrial metabolic reprogramming, and suppressed mitochondrial biogenesis, accompanied by excessive oxidative stress and inflammatory activation. The ibrutinib-mediated MQS disturbance can be markedly improved with the inducible expression of the AKAP1 lentiviral system. Conclusions: Our findings emphasize the key role of AKAP1-mediated MQS disruption in ibrutinib-induced AF, which explains the previously observed reactive oxygen species overproduction. Hence, AKAP1 activation can be employed to prevent and treat ibrutinib-induced AF.

Abstract Aims Pericardiocentesis is usually completed under fluoroscopy. The electroanatomic mapping (EAM) system allows visualizing puncture needle tip (NT) while displaying the electrogram recorded from NT, making it possible to obtain epicardial access (EA) independent of fluoroscopy. This study was designed to establish and validate a technique by which EA is obtained under guidance of three-dimensional (3D) EAM combined with NT electrogram. Methods and results 3D shell of the heart was generated, and the NT was made trackable in the EAM system. Unipolar NT electrogram was continuously monitored. Penetration into pericardial sac was determined by an increase in NT potential amplitude and an injury current. A long guidewire of which the tip was also visible in the EAM system was advanced to confirm EA. Epicardial access was successfully obtained without complication in 13 pigs and 22 patients. In the animals, NT potential amplitude was 3.2 ± 1.0 mV when it was located in mediastinum, 5.2 ± 1.6 mV when in contact with fibrous pericardium, and 9.8 ± 2.8 mV after penetrating into pericardial sac (all P ≤ 0.001). In human subjects, it measured 1.54 ± 0.40 mV, 3.61 ± 1.08 mV, and 7.15 ± 2.88 mV, respectively (all P < 0.001). Fluoroscopy time decreased in every 4–5 cases (64 ± 15, 23 ± 17, and 0 s for animals 1–4, 5–8, 9–13, respectively, P = 0.01; 44 ± 23, 31 ± 18, 4±7 s for patients 1–7, 8–14, 15–22, respectively, P < 0.001). In five pigs and seven patients, EA was obtained without X-ray exposure. Conclusion By tracking NT in the 3D EAM system and continuously monitoring the NT electrogram, it is feasible and safe to obtain EA with minimum or no fluoroscopic guidance.