Currently, the standard curative treatment for ventricular tachycardia (VT) and ventricular fibrillation (VF) is radiofrequency catheter ablation. However, when the VT circuit is deep in the myocardium, the catheter may not be delivered, and a new, minimally invasive treatment using different energies is desired.
This is a protocol paper for a feasibility study designed to provide stereotactic radiotherapy for refractory VT not cured by catheter ablation after at least one catheter ablation. The primary end point is to evaluate the short-term safety of this treatment and the secondary endpoint is to evaluate its efficacy as assessed by the reduction in VT episode. Cyberknife M6 radiosurgery system will be used for treatment, and the prescribed dose to the target will be 25Gy in one fraction. The study will be conducted on three patients.
Since catheter ablation is the only treatment option for VT that is covered by insurance in Japan, there is currently no other treatment for VT/VF that cannot be cured by catheter ablation. We hope that this feasibility study will provide hope for patients who are currently under the stress of ICD activation.
The study has been registered in the Japan Registry of Clinical Trials (jRCTs042230030).

UNASSIGNED: Cardiac sympathetic nerve system (SNS) might play an important role in arrhythmogenesis of arrhythmogenic cardiomyopathy (ACM). This study aims to assess the activity of cardiac SNS in ACM patients by heart rate variability (HRV), and to investigate its predictive value for sustained ventricular tachycardia (sVT).
UNASSIGNED: A total of 88 ACM patients and 65 sex- and age- matched healthy participants were enrolled. The time domain measures were used to evaluate the activity of cardiac SNS. An independent cohort with 48 ACM patients was as the validation cohort.
UNASSIGNED: ACM patients had lower levels of standard deviation of all NN intervals (SDNN) [118.0 (90.3, 136.8) vs. 152.0 (132.5, 174.5) ms, p < 0.001] compared with healthy participants. Further analysis showed ACM patients with sVT had lower levels of SDNN than those without sVT (105.0 ± 28.1 vs. 131.8 ± 33.1 ms, p < 0.001). Multivariate logistic regression analysis showed SDNN was independently associated with sVT in ACM patients [odds ratio (OR) 0.59, 95% confidence interval (CI) (0.45-0.78), p < 0.001]. Receiver operating characteristics curve demonstrated SDNN had clinical values in predicting sVT in ACM patients [area under the curve (AUC) = 0.73, 95% CI (0.63-0.84), p < 0.001], which was verified in the validation cohort.
UNASSIGNED: The present study suggests that HRV is impaired in patients with ACM, and the SDNN level has a moderate value in risk stratification for sVT in ACM patients. In addition, the finding might provide new target for the further management of ACM with integrated traditional Chinese and western medicine.

BACKGROUND: Obstructive sleep apnea (OSA) is a known independent risk factor for a multiple cardiovascular morbidities and mortality. The association of OSA and ventricular arrhythmias is less well understood. The aim of this analysis is to study the relationship between OSA and ventricular tachyarrhythmias.
OBJECTIVE: OSA is associated with increased ventricular arrhythmias.
METHODS: Data from the national inpatient sample (NIS) 2012 to 2014, were reviewed. Discharges associated with OSA were identified as the target population using the relevant ICD-9-CM codes. The primary outcome was a diagnosis of ventricular tachycardia (VT) in the OSA population. Secondary outcomes include the rate of ventricular fibrillation (VF) and cardiac arrest. Multivariable analyses were performed to examine the association of VT with multiple potential confounding clinical variables.
RESULTS: Of 18 013 878 health encounters, 943 978 subjects (5.24%) had a diagnosis of OSA. VT and VF were more prevalent among patients with OSA compared to those without a diagnosis of OSA (2.24% vs 1.16%; P < 0.001 and 0.3% vs 0.2%; P < 0.001, respectively). Odds ratio for cardiac arrest in OSA group was not statistically significant (1, 95% confidence interval 0.97-1.02, P < 0.76). In unadjusted analyses, all examined comorbidities were significantly more common in those with OSA, including diabetes mellitus, hypertension, chronic kidney disease, acute coronary syndrome, and heart failure.
CONCLUSIONS: OSA is associated with increased rates of ventricular tachyarrhythmia.