Challenges in atrial fibrillation: detection, alert systems, fibrosis, and infection

Dapagliflozin reduces pulmonary vascular damage and susceptibility to atrial fibrillation in right heart disease

AIMS

Sodium-glucose cotransporter 2 inhibitors (SGLT2is) have made considerable progress in the field of heart failure, but their application in arrhythmia remains to be in-depth. Right heart disease (RHD) often leads to right heart dysfunction and is associated with atrial fibrillation (AF). Here, we explored the possible electrophysiologic effect of dapagliflozin (a type of SGLT2is) in the development of AF in rats with RHD.

METHODS AND RESULTS

Rats in the experimental group were intraperitoneally injected with a single dose of 60 mg/kg monocrotaline (MCT group, n = 32) on the first day of the experiment, whereas rats in the control group were injected with vehicle (CTL group, n = 32). Rats in the treatment subgroup were treated with dapagliflozin solution orally (MCT + DAPA and CTL + DAPA groups) for a total of 4 weeks, whereas rats in the rest of subgroups were given sterile drinking water. After 4 weeks, echocardiography demonstrated that MCT group rats developed obvious pulmonary arterial hypertension and right heart dysfunction. In addition, there were also obvious inflammatory infiltration, fibrosis, and muscularization in right atrial and pulmonary arteries. The P-wave duration (17.00 ± 0.53 ms, vs. 14.43 ± 0.57 ms in CTL; 14.00 ± 0.65 ms in CTL + DAPA; 14.57 ± 0.65 ms in MCT + DAPA; P < 0.05), RR interval (171.60 ± 1.48 ms, vs. 163.10 ± 1.10 ms in CTL; 163.30 ± 1.19 ms in CTL + DAPA; 163.10 ± 1.50 ms in MCT + DAPA; P < 0.05), Tpeak-Tend interval (65.93 ± 2.55 ms, vs. 49.55 ± 1.71 ms in CTL; 48.27 ± 3.08 ms in CTL + DAPA; P < 0.05), and corrected QT interval (200.90 ± 2.40 ms, vs. 160.00 ± 0.82 ms in CTL; 160.40 ± 1.36 ms in CTL + DAPA; 176.6 ± 1.57 ms in MCT + DAPA; P < 0.01) were significantly prolonged in the MCT group after 4 weeks, whereas P-wave amplitude (0.07 ± 0.0011 mV, vs. 0.14 ± 0.0009 mV in CTL; 0.14 ± 0.0011 mV in CTL + DAPA; 0.08 ± 0.0047 mV in MCT + DAPA; P < 0.05) and T-wave amplitude (0.04 ± 0.002 mV, vs. 0.13 ± 0.003 mV in CTL; 0.13 ± 0.003 mV in CTL + DAPA; P < 0.01) were decreased, and atrial 90% action potential duration (47.50 ± 0.93 ms, vs. 59.13 ± 2.1 ms in CTL; 59.75 ± 1.13 ms in CTL + DAPA; 60.63 ± 1.07 ms in MCT + DAPA; P < 0.01) and effective refractory periods (41.14 ± 0.88 ms, vs. 62.86 ± 0.99 ms in CTL; 63.14 ± 0.67 ms in CTL + DAPA; 54.86 ± 0.70 ms in MCT + DAPA; P < 0.01) were shortened. Importantly, the inducibility rate (80%, vs. 0% in CTL; 10% in CTL + DAPA; 40% in MCT + DAPA; P < 0.05) and duration of AF (30.85 ± 22.90 s, vs. 0 ± 0 s in CTL; 0.24 ± 0.76 s in CTL + DAPA; 5.08 ± 7.92 s in MCT + DAPA; P < 0.05) were significantly increased, whereas the expression levels of cardiac ion channels and calcium-handling proteins such as potassium/calcium channels and calmodulin were decreased. Mechanistically, 'NACHT, LRR, and PYD domain-containing protein 3' inflammasome-related pathway was significantly activated in the MCT group. Nevertheless, in the MCT + DAPA group, the above abnormalities were significantly improved.

CONCLUSIONS

Dapagliflozin reduces pulmonary vascular damage and right heart dysfunction, as well as the susceptibility to AF in RHD rats.

The Effects of Fibrotic Cell Type and Its Density on Atrial Fibrillation Dynamics: An In Silico Study

Remodeling in atrial fibrillation (AF) underlines the electrical and structural changes in the atria, where fibrosis is a hallmark of arrhythmogenic structural alterations. Fibrosis is an important feature of the AF substrate and can lead to abnormal conduction and, consequently, mechanical dysfunction. The fibrotic process comprises the presence of fibrotic cells, including fibroblasts, myofibroblasts and fibrocytes, which play an important role during fibrillatory dynamics. This work assesses the effect of the diffuse fibrosis density and the intermingled presence of the three types of fibrotic cells on the dynamics of persistent AF. For this purpose, the three fibrotic cells were electrically coupled to cardiomyocytes in a 3D realistic model of human atria. Low (6.25%) and high (25%) fibrosis densities were implemented in the left atrium according to a diffuse fibrosis representation. We analyze the action potential duration, conduction velocity and fibrillatory conduction patterns. Additionally, frequency analysis was performed in 50 virtual electrograms. The tested fibrosis configurations generated a significant conduction velocity reduction, where the larger effect was observed at high fibrosis density (up to 82% reduction in the fibrocytes configuration). Increasing the fibrosis density intensifies the vulnerability to multiple re-entries, zigzag propagation, and chaotic activity in the fibrillatory conduction. The most complex propagation patterns were observed at high fibrosis densities and the fibrocytes are the cells with the largest proarrhythmic effect. Left-to-right dominant frequency gradients can be observed for all fibrosis configurations, where the fibrocytes configuration at high density generates the most significant gradients (up to 4.5 Hz). These results suggest the important role of different fibrotic cell types and their density in diffuse fibrosis on the chaotic propagation patterns during persistent AF.