PREDICTORS FOR FEMORAL BAILOUT
In line with previous reports, lead dwell time and number of leads extracted 8 9 were found as independent predictors for femoral bailout procedure in univariate analysis. Femoral approach may be needed for leads with longer dwelling time for the following reasons: Older leads tend to break during TLE making extraction from a different site mandatory 11, and in cases of leads with well-formed adhesions, mechanical support from inferior approach may be helpful 8. Increased lead number adds to lead-lead and lead-vascular adhesions and TLE complexity, promoting the need for femoral support.
The decision whether to extract or abandon non-infected CIED leads during system upgrade, lead failures or other reasons, remains an operational decision based on case by case risk-benefit ratio10. Eventually the presence of abandoned leads, adds to the number of leads in the vasculature and intuitively, abandoned leads also have longer dwell time and increase crowding within the vein that may result in occlusion. Increased use of femoral bailout for abandoned lead extraction has been observed previously12. Recently, Segreti et al reported a high success rate for abandoned lead extraction using mechanical tools with relatively limited need to switch to femoral approach. However, the median dwelling time of the oldest abandoned leads in their cohort was shorter than ours[108 months(60–168) vs 132 months(84-196)]13, and could account for the difference observed in our cohort.
Patients in the femoral bailout group were found to be younger. One might argue that any TLE cohort study may suffer from younger age selection bias, as a more aggressive approach with possibly complicated course(often requiring femoral bailout) for non-mandatory TLE indications is potentially carried out for younger patients10. However, this age-driven selection bias is less straightforward for TLE performed due to infectious etiologies for which the operator doesn’t have much leeway in the decision to abandon or extract a given lead. In accordance, our data shows that a large majority of our patients were elderly and extracted due to infectious etiologies and when compared with younger patients who were extracted due to similar indications the elderly group had less tendency for femoral bailout.
A partial explanation for femoral switchover tendency of younger patients, is that younger patients have longer lead dwell time in our cohort. This can be rationalized as younger patients have increased chance to have CIED implanted from a very young age due to diverse etiologies such as idiopathic dilated cardiomyopathy (DCM), channelopathies and hypertrophic cardiomyopathy (HCM)14. Our analysis reveals that younger age is an independent risk factors predisposing for a femoral bailout. It is possible that vascular calcifications and adhesions might be found in the overall younger patients population, resulting in reduced efficiency of mechanical and powered tools, eventually predisposing them for the need of a femoral bailout 15.
Venous occlusion after CIED implantation is quite common with a prevalence of up to 27% of all implantations 16, and site of occlusion is the subclavian vein in 60%, for 33% it is the brachiocephalic vein and for the remaining it is the SVC17 . Venous occlusion by itself is not an indication for lead extraction, but rather a class 2a indication for patients with ipsilateral venous occlusion preventing access to the venous circulation for required placement of an additional lead 10.
Presence of superior venous occlusion has been found to be a risk factor for major complications of TLE 6, although trials examining the outcomes of femoral support or bailout in the presence of superior occluded veins are lacking.
Sub analysis of the ELECTRa study found a correlation between the use of power sheaths for TLE of leads in occluded veins and vascular tears6. The authors recommended that venography should be considered preprocedurally for all patients undergoing extraction and that special precaution should be taken when using powered sheaths in the presence of occluded veins.
Recognition of the hazards of SVC tear during superior approach and the link between venous occlusion and the need for femoral support has been stressed by Isawa et al. 7, reporting a high prevalence of venous occlusion after routinely performing venography, and a low threshold for femoral support for patients with occluded veins, in order to avoid SVC tears. It has been previously suggested that when occluded veins are encountered during TLE, femoral support should be considered to stabilize the extracted lead4.
Suspected mechanism linking power sheath use in the presence of vascular occlusion and resulting vascular tears is not known. We can speculate that when faced with vascular obstruction in the brachiocephalic-SVC junction, difficulty might rise to keep the sheath co-axial with the lead, forcing unwanted contact between the sheath head and the SVC wall potentially causing vascular tears.
Despite of all mentioned above, Sohal et al. reported high success rates using laser sheaths for TLE due to occluded veins. However, their site of occlusion was mainly the subclavian vein, which is less likely to injure during TLE, in contrast to the brachiocephalic-SVC–high RA area. Furthermore, their use of intraprocedural venography as part of their extraction protocol to confirm intravascular position of tools could have potentially minimized vascular injuries 1819.
Our results add and show that venous occlusion is associated with a higher complication rate of TLE in the superior approach group, however, when a femoral bailout approach was used to extract leads from occluded veins, radiological success was achieved in all cases.