Attenuated Structural Transformation of Aconitine during Sand Frying Process and Antiarrhythmic Effect of Its Converted Products

The transformation pathways of diterpenoid alkaloids have been clarified in the boiling and steaming process. Aconitine, a famous diterpenoid alkaloid, is successively transformed into benzoylaconine and aconine during the processes of boiling and steaming, but the transformation pathway remains to be determined in the sand frying process. The present study aims at investigating the transformation pathways of aconitine in the process of sand frying, as well as assessing the cardiotoxicity and antiarrhythmic activity of aconitine and its converted products. The parameters of temperature and time for the structural transformation of aconitine were confirmed by HPLC. The converted products were further separated and identified by column chromatography, NMR, and HR-ESI-MS. Furthermore, by observing the lead II electrocardiogram (ECG) changes in rats under an equivalent dose, the cardiotoxicity of aconitine and its converted products were compared. Ultimately, the antiarrhythmic effect of the converted products was investigated by employing the model of aconitine-induced arrhythmia. Consequently, the structure of aconitine was converted when processed at 120°C–200°C for 1–40 min. Two diterpenoid alkaloids, a pair of epimers, namely, pyroaconitine and 16-epi-pyroaconitine, were further isolated from processed aconitine. 0.03 mg/kg aconitine induced arrhythmias in normal rats, while the converted products did not exhibit arrhythmias under an equal dose. In the antiarrhythmic assay, 16-epi-pyroaconitine could dose-dependently delay the onset time of VPB, reduce the incidence of VT, and increase the arrhythmia inhibition rate, demonstrating comparatively strong antiarrhythmic activity. Conclusively, compared with the prototype compound aconitine, the converted products exhibited lower cardiotoxicity. Further investigations on the cardiotoxicity indicated that pyroaconitine with β configuration had a stronger cardiotoxicity than 16-epi-pyroaconitine with α configuration. Furthermore, 16-epi-pyroaconitine could antagonize the arrhythmogenic effect caused by the prototype compound aconitine; the antiarrhythmic effect of 16-epi-pyroaconitine was stronger than lidocaine and propafenone, which had the potential to be developed as antiarrhythmic drugs.

Dual Mechanisms of Cardiac Action Potential Prolongation by 4-Oxo-Nonenal Increasing the Risk of Arrhythmia; Late Na+ Current Induction and hERG K+ Channel Inhibition

4-Oxo-nonenal (4-ONE) is an endogenous lipid peroxidation product that is more reactive than 4-hydroxy-nonenal (4-HNE). We previously reported the arrhythmic potential of 4-HNE by suppression of cardiac human Ether-a-go-go Related Gene (hERG) K+ channels with prolonged action potential duration (APD) in cardiomyocytes. Here, we illustrate the higher arrhythmic risk of 4-ONE by modulating the cardiac hNaV1.5 channel currents (INaV). Although the peak amplitude of INaV was not significantly changed by 4-ONE up to 10 μM, the rate of INaV inactivation was slowed, and the late Na+ current (INaL) became larger by 10 μM 4-ONE. The chemical modification of specific residues in hNaV1.5 by 4-ONE was identified using MS-fingerprinting analysis. In addition to the changes in INaV, 4-ONE decreased the delayed rectifier K+ channel currents including the hERG current. The L-type Ca2+ channel current was decreased, whereas its inactivation was slowed by 4-ONE. The APD prolongation by 10 μM of 4-ONE was more prominent than that by 100 μM of 4-HNE. In the computational in silico cardiomyocyte simulation analysis, the changes of INaL by 4-ONE significantly exacerbated the risk of arrhythmia exhibited by the TdP marker, qNet. Our study suggests an arrhythmogenic effect of 4-ONE on cardiac ion channels, especially hNaV1.5.

POS1240 HYDROXYCHLOROQUINE CARDIOTOXICITY: A CASE-CONTROL STUDY COMPARING PATIENTS WITH COVID19 AND PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS

Background:Antimalarials have been associated with QT prolongation in COVID19 patients but are generally safe in patients with rheumatologic disease.Objectives:Aim of the study was to compare the prevalence of QTc prolongation between COVID19 and Systemic Lupus Erythematosus (SLE) patients treated with hydroxychloroquine (HCQ).Methods:We included consecutive patients with SARS-CoV-2 infection confirmed by nasopharyngeal swab and patients taking HCQ for SLE. A prolonged QTc was defined as an increase in QTc intervals >60 ms (compared with baseline) or as a QTc of ≥500 ms.Results:We enrolled 58 COVID19 patients (median age 70.5 years, IQR 25). HCQ, without or with azithromycin, was given to 26 (44.8%) and 15 patients (25.9%), respectively; 17 (29.3%) had not received either drug. The median baseline QTc was 432 (IQR 36) and prolonged QTc was observed in 15 (26%) patients (12 QTc≥500 ms and 3 patients ΔQTc>60 ms). We didn’t find significant differences in QTc prolongation among the three treatment groups. Baseline QTc (OR 111.5) and D-dimer (OR 78.3) were independently associated to QTc prolongation.Compared to the 50 SLE patients (median age of 38.5 years, IQR 22), chronically treated with HCQ, patients with COVID19 showed significantly longer QTc (p < 0.001) (Table 1).Conclusion:This is the first study demonstrating that, differently from COVID19 patients, patients with SLE are not susceptible to HCQ-induced long QT syndrome and arrhythmia. The combined arrhythmogenic effect of SARS-CoV-2 infection and HCQ could account for the excess of QTc prolongation and fatal arrhythmias described in patients with COVID19.Table 1.Difference in clinical and demographic features between Systemic Lupus Erythematosus and COVID19 patients.Demographic FeaturesSLE patientsCovid-19 patientsp-ValueN°5058Female4323< 0.001Age (years)45 (17)70.5 (25)< 0.001Comorbidities N %Hypertension15 (30)24 (48)0.2Cardiovascular diseses8 (16)13 (22.4)0.4COPD1 (2)9 (15.5)0.016Thyroid disease8 (16)8 (13.8)0.75Chronic kidney disease4 (8)5 (8.6)0.91Population characteristics Median (IQR)HCQ (mg/die)400 (125)400< 0.001HCQ Time (days)3255 (5790)7< 0.001QTc (ms)SLEDAI-2KSDI432 (36.25)0 (4)0395 (80)--< 0.001--Disclosure of Interests:None declared

Heart rate and conductivity disorders in juvenile myoclonic epilepsy: genetic predictors

General practitioners, therapists, and cardiologists do not have formal education (training) regarding cerebrocardial syndrome, primarily heart rhythm and conduction disorders in epilepsy and sudden unexpected death in epilepsy (SUDEP), as well as the potential arrhythmogenic effect of antiepileptic drugs. This lecture presents important elements of knowledge about the genetic predictors of cerebrocardial syndrome and SUDEP in juvenile myoclonic epilepsy, which is the most common form of genetic generalized epilepsy.

The Role of CaMKII Overexpression and Oxidation in Atrial Fibrillation—A Simulation Study

This simulation study aims to investigate how the Calcium/calmodulin-dependent protein kinase II (CaMKII) overexpression and oxidation would influence the cardiac electrophysiological behavior and its arrhythmogenic mechanism in atria. A new-built CaMKII oxidation module and a refitted CaMKII overexpression module were integrated into a mouse atrial cell model for analyzing cardiac electrophysiological variations in action potential (AP) characteristics and intracellular Ca2+ cycling under different conditions. Simulation results showed that CaMKII overexpression significantly increased the phosphorylation level of its downstream target proteins, resulting in prolonged AP and smaller calcium transient amplitude, and impaired the Ca2+ cycling stability. These effects were exacerbated by extra reactive oxygen species, which oxidized CaMKII and led to continuous high CaMKII activation in both systolic and diastolic phases. Intracellular Ca2+ depletion and sustained delayed afterdepolarizations (DADs) were observed under co-existing CaMKII overexpression and oxidation, which could be effectively reversed by clamping the phosphorylation level of ryanodine receptor (RyR). We also found that the stability of RyR release highly depended on a delicate balance between the level of RyR phosphorylation and sarcoplasmic reticulum Ca2+ concentration, which was closely related to the genesis of DADs. We concluded that the CaMKII overexpression and oxidation have a synergistic role in increasing the activity of CaMKII, and the unstable RyR may be the key downstream target in the CaMKII arrhythmogenic mechanism. Our simulation provides detailed mechanistic insights into the arrhythmogenic effect of CaMKII overexpression and oxidation, which suggests CaMKII as a promising target in the therapy of atrial fibrillation.

Simultaneous endo-epicardial mapping of programmed atrial extrasystoles in patients undergoing cardiac surgery

Introduction Atrial extrasystoles (AES) are usually innocent, however they can also trigger (post-operative) atrial fibrillation (AF). It is unknown what the arrhythmogenic effect of AES is on 3-dimensional atrial conduction. Purpose Therefore, the aim of this study was to examine the effect of programmed AES (PAES) provoked in the right atrium (RA) on both endo- and epicardial conduction. Methods Simultaneous endo-epicardial mapping of the RA was performed during PAES provoked from the RA free wall in patients undergoing cardiac surgery (256 electrodes). Areas of conduction block (CB) were defined as conduction delays of ≥12ms and endo-epicardial asynchrony (EEA) as activation time differences of exact opposite electrodes of ≥15ms. Results Simultaneous endo-epicardial mapping of the RA during 15 PAES were analyzed and compared with sinus rhythm (SR) (n=12, 58% male, age 68±7 years). Eleven PAES were premature (&gt;25% shortening cycle length (CL)), median preceding CL was 554.5ms [377.9–720.4] and median SR CL was 871ms [700.9–1021]. Amount of EEA (7.3% [2.6–17.8] vs 1% [1–2], p=0.002) and CB (9% [4.8–11.8] vs 1.4% [0.5–2.7, p=0.001) both increased during PAES compared to SR. Diabetes was the only cardiovascular risk factor associated with a higher incidence and degree of EEA and CB. Interestingly, CB during PAES was more severe in 4 patients (33.3%) who developed post-operative AF (11.9% [10.4–12.8] vs 5.4% [3.3–8.5], p&lt;0.001). Conclusion Asynchronous activation of the atrial wall and conduction disorders, which play an important role in arrhythmogenesis, are enhanced during PAES compared to SR. Enhanced electropathology together with triggers provoked by heart surgery may initiate post-operative AF. Funding Acknowledgement Type of funding source: None