Introduction: Prior to ablation, predicting the site of origin (SOO) of outflow tract ventricular arrhythmia (OTVA), can inform patient consent and facilitate appropriate procedural planning. We set out to determine if OTVA variability can accurately predict SOO. Methods: Consecutive patients with a clear SOO identified at OTVA ablation had their prior 24-hour ambulatory ECGs retrospectively analysed (derivation cohort). Percentage ventricular ectopic (VE) burden, hourly VE values, episodes of trigeminy/bigeminy, and the variability in these parameters were evaluated for their ability to distinguish right from left sided SOO. Effective parameters were then prospectively tested on a validation cohort of consecutive patients undergoing their first OTVA ablation. Results: High VE variability (coefficient of variation ≥ 0.7) and the presence of any hour with < 50 VE, were found to accurately predict RVOT SOO in a derivation cohort of 40 patients. In a validation cohort of 29 patients, the correct SOO was prospectively identified in 23/29 patients (79.3%) using CoV, and 26/29 patients (89.7%) using VE < 50. Including current ECG algorithms, VE < 50 had the highest Youden Index (78), the highest positive predictive value (95.0%) and the highest negative predictive value (77.8%). Conclusion: VE variability and the presence of a single hour where VE < 50 can be used to accurately predict SOO in patients with OTVA. Accuracy of these parameters compares favourably to existing ECG algorithms.

Background: Cardiac resynchronisation therapy-defibrillator (CRT-D) implantation via the cephalic vein is feasible and safe. Recent evidence has suggested a higher implantable cardioverter defibrillator (ICD) lead failure in multi-lead defibrillator therapy via the cephalic route. We evaluated the relationship between CRT-D implantation via the cephalic and ICD lead failure. Methods: Data was collected from three CRT-D implanting centres between October 2008 – September 2017. In total 631 patients were included. Patient and lead characteristics with ICD lead failure were recorded. Comparison of ‘cephalic’ (ICD lead via cephalic) vs ‘non-cephalic’ (ICD lead via non-cephalic route) cohorts was performed. Kaplan-Meier survival and a Cox-regression analysis were applied to assess variables associated with lead failure. Results: The cephalic and non-cephalic cohorts were equally male (82.2% vs 78.3%, p=0.28), similar in age (69.7±11.5 vs 68.7 ± 11.9, p=0.33) and body mass index (BMI) (27.7±5.1 vs 27.1±5.7, p=0.33). Most ICD leads were implanted via the cephalic vein (73.7%) and patients had a median of 2.8 leads implanted via this route. The rate of ICD lead failure was low and similar between both groups (0.4%/year vs 0.14%/year, p=0.34). Female gender was more common in the lead failure cohort than non-failure (50% vs 18.2%, respectively, p=0.01) as was hypertension (90% vs 54%, respectively, p=0.03). On multivariate Cox regression, female sex (p=0.007), hypertension (p=0.041) and BMI (p=0.042) were significantly associated with ICD lead failure. Conclusion: CRT-D implantation via the cephalic route is not associated with premature ICD lead failure. Female gender, BMI and hypertension correlate with lead failure.