Stereotactic arrhythmia radioablation and its implications for modern cardiac electrophysiology: results of an EHRA survey.

Stereotactic arrhythmia radioablation (STAR) is a treatment option for recurrent ventricular tachycardia/fibrillation (VT/VF) in patients with structural heart disease (SHD). The current and future role of STAR as viewed by cardiologists is unknown. The study aimed to assess the current role, barriers to application, and expected future role of STAR. An online survey consisting of 20 questions on baseline demographics, awareness/access, current use, and the future role of STAR was conducted. A total of 129 international participants completed the survey [mean age 43 ± 11 years, 25 (16.4%) female]. Ninety-one (59.9%) participants were electrophysiologists. Nine participants (7%) were unaware of STAR as a therapeutic option. Sixty-four (49.6%) had access to STAR, while 62 (48.1%) had treated/referred a patient for treatment. Common primary indications for STAR were recurrent VT/VF in SHD (45%), recurrent VT/VF without SHD (7.8%), or premature ventricular contraction (3.9%). Reported main advantages of STAR were efficacy in the treatment of arrhythmias not amenable to conventional treatment (49%) and non-invasive treatment approach with overall low expected acute and short-term procedural risk (23%). Most respondents have foreseen a future clinical role of STAR in the treatment of VT/VF with or without underlying SHD (72% and 75%, respectively), although only a minority expected a first-line indication for it (7% and 5%, respectively). Stereotactic arrhythmia radioablation as a novel treatment option of recurrent VT appears to gain acceptance within the cardiology community. Further trials are critical to further define efficacy, patient populations, as well as the appropriate clinical use for the treatment of VT.

Circulating extracellular vesicles in human cardiorenal syndrome promote renal injury in a kidney-on-chip system.

BACKGROUNDCardiorenal syndrome (CRS) - renal injury during heart failure (HF) - is linked to high morbidity. Whether circulating extracellular vesicles (EVs) and their RNA cargo directly impact its pathogenesis remains unclear.METHODSWe investigated the role of circulating EVs from patients with CRS on renal epithelial/endothelial cells using a microfluidic kidney-on-chip (KOC) model. The small RNA cargo of circulating EVs was regressed against serum creatinine to prioritize subsets of functionally relevant EV-miRNAs and their mRNA targets investigated using in silico pathway analysis, human genetics, and interrogation of expression in the KOC model and in renal tissue. The functional effects of EV-RNAs on kidney epithelial cells were experimentally validated.RESULTSRenal epithelial and endothelial cells in the KOC model exhibited uptake of EVs from patients with HF. HF-CRS EVs led to higher expression of renal injury markers (IL18, LCN2, HAVCR1) relative to non-CRS EVs. A total of 15 EV-miRNAs were associated with creatinine, targeting 1,143 gene targets specifying pathways relevant to renal injury, including TGF-ß and AMPK signaling. We observed directionally consistent changes in the expression of TGF-ß pathway members (BMP6, FST, TIMP3) in the KOC model exposed to CRS EVs, which were validated in epithelial cells treated with corresponding inhibitors and mimics of miRNAs. A similar trend was observed in renal tissue with kidney injury. Mendelian randomization suggested a role for FST in renal function.CONCLUSIONPlasma EVs in patients with CRS elicit adverse transcriptional and phenotypic responses in a KOC model by regulating biologically relevant pathways, suggesting a role for EVs in CRS.TRIAL REGISTRATIONClinicalTrials.gov NCT03345446.FUNDINGAmerican Heart Association (AHA) (SFRN16SFRN31280008); National Heart, Lung, and Blood Institute (1R35HL150807-01); National Center for Advancing Translational Sciences (UH3 TR002878); and AHA (23CDA1045944).

RNA m6A-Regulated circ-ZNF609 Suppression Ameliorates Doxorubicin-Induced Cardiotoxicity by Upregulating FTO.

Cardiac death is a major burden for cancer survivors, yet there is currently no effective treatment for doxorubicin (DOX)-induced cardiotoxicity. Here, we report that circ-ZNF609 knockdown knockdown had cardioprotective effects against DOX-induced cardiomyocyte toxicity. Mechanistically, circ-ZNF609 knockdown alleviated DOX-induced cardiotoxicity through attenuating cardiomyocyte apoptosis, reducing reactive oxygen species production, ameliorating mitochondrial nonheme iron overload. circ-ZNF609 inhibition blocked the elevation of RNA N6-methyladenosine (RNA m6A) methylation level in DOX-treated mice hearts, whereas m6A demethylase fat mass and obesity associated (FTO) acted as the downstream factor of circ-ZNF609. Moreover, the stability of circ-ZNF609 was regulated by RNA m6A methylation alteration, and suppression of RNA m6A methylation by methyltransferase like 14 (METTL14) modulated the function of circ-ZNF609. These data suggest that circ-ZNF609 inhibition represents a potential therapy for DOX-induced cardiotoxicity.

Regulation and roles of RNA modifications in aging-related diseases.

With the aging of the global population, accumulating interest is focused on manipulating the fundamental aging-related signaling pathways to delay the physiological aging process and eventually slow or prevent the appearance or severity of multiple aging-related diseases. Recently, emerging evidence has shown that RNA modifications, which were historically considered infrastructural features of cellular RNAs, are dynamically regulated across most of the RNA species in cells and thereby critically involved in major biological processes, including cellular senescence and aging. In this review, we summarize the current knowledge about RNA modifications and provide a catalog of RNA modifications on different RNA species, including mRNAs, miRNAs, lncRNA, tRNAs, and rRNAs. Most importantly, we focus on the regulation and roles of these RNA modifications in aging-related diseases, including neurodegenerative diseases, cardiovascular diseases, cataracts, osteoporosis, and fertility decline. This would be an important step toward a better understanding of fundamental aging mechanisms and thereby facilitating the development of novel diagnostics and therapeutics for aging-related diseases.

Improvement in ejection fraction after cryoballoon pulmonary vein isolation for atrial fibrillation in individuals with systolic dysfunction.

BACKGROUND: Cryoballoon pulmonary vein isolation (PVI) is commonly used for rhythm control of atrial fibrillation (AF). Data are limited examining the outcomes of cryoballoon PVI in patients with systolic dysfunction. We evaluate the impact of cryoballoon PVI in patients with systolic dysfunction. METHODS: We evaluated a single-center prospective registry of patients undergoing cryoballoon PVI between 8/2011 and 6/2016. Patients with systolic dysfunction (EF < 55%) between the time of AF diagnosis and their cryoballoon PVI procedure were assessed for AF recurrence at 6 months and 1 year post-procedure, with a 3-month blanking period. RESULTS: Final analysis included 66 patients with systolic dysfunction undergoing cryoballoon PVI. An AF diagnosis for ≥ 1 year prior to PVI was present in 62.1% (n = 41), and 53.0% (n = 35) had systolic dysfunction for ≥ 1 year pre-procedure. The proportion of AF-free patients at 1 year was 51.5%. Of patients with echocardiograms performed at 1 year (n = 43), a greater proportion of individuals without AF recurrence had an improvement in EF of ≥ 10% than in those with AF recurrence (54.2% vs. 25.0%, p = 0.039). Of the patients who had systolic dysfunction at the time of the ablation (EF < 55%), there was a significant increase in EF post-procedure (36.5% pre-procedure vs. 48.3% post-procedure, mean change 11.8%, p < 0.001). CONCLUSION: In patients with systolic dysfunction, cryoballoon PVI provides an acceptable AF recurrence-free rate at 1 year. AF recurrence-free individuals were more likely to have improvement in EF. Further evaluation is needed to determine the potential role of early cryoballoon PVI in patients with a new diagnosis of systolic dysfunction and AF.

Elimination of Purkinje Fibers by Electroporation Reduces Ventricular Fibrillation Vulnerability.

Background The Purkinje network appears to play a pivotal role in the triggering as well as maintenance of ventricular fibrillation. Irreversible electroporation ( IRE ) using direct current has shown promise as a nonthermal ablation modality in the heart, but its ability to target and ablate the Purkinje tissue is undefined. Our aim was to investigate the potential for selective ablation of Purkinje/fascicular fibers using IRE . Methods and Results In an ex vivo Langendorff model of canine heart (n=8), direct current was delivered in a unipolar manner at various dosages from 750 to 2500 V, in 10 pulses with a 90-µs duration at a frequency of 1 Hz. The window of ventricular fibrillation vulnerability was assessed before and after delivery of electroporation energy using a shock on T-wave method. IRE consistently eradicated all Purkinje potentials at voltages between 750 and 2500 V (minimum field strength of 250-833 V/cm). The ventricular electrogram amplitude was only minimally reduced by ablation: 0.6±2.3 mV ( P=0.03). In 4 hearts after IRE delivery, ventricular fibrillation could not be reinduced. At baseline, the lower limit of vulnerability to ventricular fibrillation was 1.8±0.4 J, and the upper limit of vulnerability was 19.5±3.0 J. The window of vulnerability was 17.8±2.9 J. Delivery of electroporation energy significantly reduced the window of vulnerability to 5.7±2.9 J ( P=0.0003), with a postablation lower limit of vulnerability=7.3±2.63 J, and the upper limit of vulnerability=18.8±5.2 J. Conclusions Our study highlights that Purkinje tissue can be ablated with IRE without any evidence of underlying myocardial damage.