A Systematic Review and Single-center Experience of Azygos Vein Defibrillator Lead Insertion

Defibrillation threshold (DFT) testing is performed in individuals with higher predicted risks of defibrillation failure. Many strategies have been explored to overcome the challenge of high DFT, including an insertion of a defibrillator lead into the azygos vein. We performed a systematic review of the literature to evaluate the safety and efficacy of azygos vein implantable cardioverter-defibrillator insertion for high DFT combined with the analysis of a single-center experience of the procedure at our institution. The literature search was performed in PubMed and Embase from database inception to December 2020 to identify all case reports and case series related to azygos vein defibrillator lead insertion. Our search identified 291 records. After excluding duplicate studies and those without DFT thresholds and non-azygos vascular destinations, 12 studies (23 cases) were reviewed from the current database. We also conducted a retrospective analysis of 5 cases performed at our institution, and a total of 28 patients were included in our final analysis. The mean age of the pooled cohort was 47 years (range, 17-88 years). Men composed 92% of the total cases, and the average body mass index was 34 kg/m². The mean ejection fraction (EF) was 25%, with 78% having non-ischemic cardiomyopathy. The left axillary (36%) or subclavian (48%) vein was the common percutaneous access point. The mean duration of azygos vein access and lead delivery was 22 min (range, 13-60 min). The average DFT prior to azygos coil insertion was 35 J (range, 20-45 J). Fifty-seven percent of cases achieved substantial DFT improvement, whereas 18% achieved relative improvement compared to the pre-procedural threshold. No immediate or remote procedure-related complications were reported in 24 cases where data were available. During an average follow-up period of 18 months, 5 patients had ventricular arrhythmic events requiring device therapy and 4 had successful cardioversion from the device. One patient died from cardiac arrest with variable device therapies of both unsuccessful and successful events. In conclusion, azygos vein defibrillator lead insertion has a considerable rate of success, ease of vascular access with minimal procedural time, and lower risks and complications. Larger studies and longer follow-up periods are warranted to establish its efficacy and safety.