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.

Aims: To investigate the utility of adenosine administration to test the durability of cavotricuspid isthmus (CTI) block after radiofrequency (RF) catheter ablation for typical atrial flutter. Methods: Adenosine 10mg was administered by bolus injection through a femoral sheath at 5 minutes after apparent completion of CTI ablation in consecutive patients, and its effect on CTI conduction was recorded. Conduction in both directions across the CTI was tested repeatedly until 20 minutes after the last energy delivery. Results: Among 132 patients treated with a Blazer 10mm (n=126) or 8mm (n=6) ablation catheter, bidirectional block of the CTI was achieved in all cases. Adenosine administration was followed by a transient recurrence of conduction in 3 cases (2.3%); in all of these, a persistent recurrence of CTI conduction was observed within the waiting period. Persistent recurrence of CTI conduction occurred within the waiting period in 3 patients (2.3%) whose adenosine test had been negative. In all cases, further RF delivery achieved CTI block that persisted to the end of a 20-minute waiting period. During 38 months of follow-up, 131 patients (99.2%) remained free of clinical recurrence of typical flutter. Conclusion: Administration of adenosine 10mg at 5 minutes after RF delivery reveals latent conduction in the CTI in some but not all cases that are revealed by a 20-minute wait. At this dosage and at this time-point, adenosine testing is not an adequate substitute for a waiting period.