Predictors of lead break during transvenous lead extraction

Abstract Background The incidence, predictors, and clinical impact of lead break during transvenous lead extraction (TLE) were previously unknown. Methods We included consecutive patients who underwent TLE between September 2013 and July 2019 at our institute. Lead break during removal was defined as lead stretching and becoming misshapen, as assessed by fluoroscopy. Results A total of 246 patients underwent TLE for 501 leads. At a patient level, complete success was achieved in 226 patients (91.9%). At a lead level, 481 leads (96.0%) were completely removed and 101 leads (20.1%) were broken during the procedure. Of 392 identified pacemaker leads, 71 (18.3%) were broken during the TLE procedure. A multivariable analysis confirmed high lead age (odds ratio [OR] 1.12, 95% confidence interval (CI) 1.07‐1.17; P < .001), passive leads (OR 2.29 95% CI 1.09‐4.80; P = .028), coradial leads (OR 3.45 95% CI 1.72‐6.92; P < .001), and insulators made of nonpolyurethane (OR 2.38 95% CI 1.03‐5.26; P = .04) as predictors of lead break. Broken leads needed longer procedure times and were associated with a higher rate of cardiac tamponade. Conclusions Lead age, coradial bipolar leads, passive leads, and leads without polyurethane insulation were predictors of lead break and could increase the difficulty of lead extraction.

lead break, 6 the impact on break during TLE of detailed lead structure such as insulator, coil, and lead size remained unknown.
We therefore conducted a single-center observational registry study of lead removal including detailed information on lead structure and procedure outcomes.

| Patients population
We recruited consecutive patients who underwent either surgical or transvenous lead removal between September 2013 and July 2019 at our institute. Of these patients, we included those who underwent TLE, and excluded those who underwent lead explant (removal of leads within 1 year of implantation by manual traction) and those who underwent lead removal for a subcutaneous implantable cardioverter defibrillator (S-ICD). TLE was defined as any TLE in which at least one lead required the assistance of equipment not typically required during implantation or at least one lead had been in place for longer than 1 year. 3

| Extraction procedure and lead break
The procedures were performed under general or intravenous anesthesia according to the patient's condition. TLE was performed as previously described, using a variety of approaches and tools including simple manual traction, locking stylets, laser sheaths, femoral snares, mechanical sheaths, and rotational mechanical sheaths. 3,7,8 Minimum traction with a regular pacemaker stylet was applied to all leads at the beginning of each case. If manual traction did not result in successful lead extraction, an SLS II Excimer Laser Sheath (Spectranetics) with a locking stylet was normally used. Our method of using a laser sheath required two operators. One operator pushed the laser sheath while the other operator pulled the locking stylet. All extraction procedures were performed by one of the two experienced operators: operator A and B had an experience of performing TLE for 3 and 4 years, respectively. In some instances, different techniques and tools were used at the discretion of the operating physician, including an Evolution Mechanical Dilator Sheath (Cook Medical), adapted mechanical sheaths, and snares using a femoral approach. Lead break during removal was defined as the lead stretching and becoming misshapen, as assessed by fluoroscopy ( Figure 1).

| Clinical outcomes
Outcomes of TLE were defined in accordance with the 2017 HRS consensus statement and 2018 European Heart Rhythm Association (EHRA) expert consensus statement. 3,7 Complete success was defined as the complete extraction of all the targeted leads from the body of the patient with the absence of any complication or procedure-related death. Partial success was defined as removal of all targeted leads with the retention of no more than a small portion (<4 cm) of lead without any complication or procedure-related death. Failure was defined as the inability to achieve either complete or partial success. Complete lead removal was defined as the successful removal of all targeted lead material. Partial lead removal was defined as retention of a small part (<4 cm) of the lead and incomplete lead removal as a result of retention of the lead part ≥4 cm.

| Statistical analysis
Categorical variables are presented as number and percentage and were compared using the chi-square test. Continuous variables are expressed as mean ± SD or median with interquartile range and were compared using the Student t test or the Wilcoxon rank-sum test depending on their distributions. Multivariable logistic regression analysis was used to identify risk factors for lead break. Odds ratios (OR) and their 95% confidence interval (95% CI) were reported. All analyses were performed with JMP software version 13.2.1 (SAS Institute Inc). All reported P values were two-tailed, and P < .05 were considered statistically significant.

| Clinical outcomes
During the study period, a total of 265 patients with 532 leads underwent lead removal. Of those, we excluded 1 patient (2 leads)    (Table 3). Extraction tools were more often used for broken leads (100% vs 72.6%, P <.001). Broken leads were associated with a longer procedure time (from insertion of locking stylet to extraction:

| Risk factors of cardiac tamponade or fragment retention of broken leads
Of the 74 broken leads, cardiac tamponade or fragment retention occurred in 25 leads. The characteristics of the broken leads are summarized in (1/5), respectively.

| D ISCUSS I ON
This single-center observational study had the following salient findings. First, the incidence of pacemaker leads break during TLE was 18.9%. Second, older lead age, coradial leads, passive leads, and nonpolyurethane leads were independently associated with lead break.
Third, 24.3% of lead break resulted in incomplete lead removal, and lead break had long procedure times and occasionally resulted in cardiac tamponade.

| Structure and materials of lead break
Pacing leads have major components: electrodes, conductors, insulation, and fixation mechanism, which could cause break owing to strong stress. Lead break that occurred during TLE was defined as lead stretching and becoming misshapen, as assessed by fluoroscopy. The introduction of powered sheaths including laser sheaths has facilitated the removal of leads with a high age. 9

TA B L E 3
Univariate and multivariate analysis of predictors of lead breaks during transvenous lead extraction using a powered sheath was unknown. In our study, 77.8% of leads were removed using a powered sheath and the mean lead age was 9.4 ± 6.6 years. Lead break occurred in 29.2% of passive leads, and passive leads were an independent predictor of lead break. Over time, fibrous tissue develops in the electrode-myocardial interfaces of the heart, especially in the tip of the electrode. 12,13 In studies analyzing passive leads, old leads were more difficult to extract and passive leads were also easy to be broken. 6,[14][15][16] These studies and our data suggest that passive leads develop stronger adhesion to the fibrous tissue and could be more easily broken than active leads. Lead break occurred in only 10.7% of polyurethane insulator leads. Insulators of pacing leads are generally made of polyurethane or silicon. Polyurethane leads have higher tear strength and lower friction coefficient than silicon leads. 17 A relationship between lead insulator and TLE has rarely been reported, but one small previous study reported that polyurethane insulation was a predictor of procedure difficulty in lead removal. 18 However, in the present study,

| Complications of TLE
To our knowledge, the present study is the first to assess procedure outcomes in lead extraction where break occurs. Procedure time of the broken lead was significantly longer than that of the nonbroken lead. There are some possible reasons that procedure times are longer in cases of lead break. First, lead breaks require switching to a femoral approach, and therefore a longer procedure time.
Second, when a lead breaks, the procedure must be gentle to avoid cutting off the lead. In the present study, the rate of cardiac tamponade of the break lead was significantly higher than that of the nonbroken lead. The adhesion between the lead and the myocardium is generally strong when lead break occurs. Removing the tip of the lead, which has strong adhesion to the myocardium, could result in the surrounding tissue to tear off. This is the hypothesis that the risk of cardiac tamponade is high when lead break occurs.

| Limitations
The present study had some limitations, being a retrospective analysis in a single center. First, a larger study population and multiple centers are necessary to further validate the current findings.
Second, the method of TLE was determined at the discretion of the operating physician. Third, the usage rate of the rotational mechanical sheath was low at 4.1% because it was not approved for regular use in Japan until September 2018. Fourth, lead break was defined by fluoroscopy, and it is possible that a few cases of partial lead break were not detected by this method. The clinical result is applicable to fluoroscopy-apparent lead break. Last, unknown leads and leads which required conversion to sternotomy were excluded from this study. This is unlikely to have an impact on the results, as the number of excluded lead was small.

| CON CLUS IONS
In TLE, break occurred in 18.3% pacemaker leads. Lead age, coradial bipolar leads, passive leads, and leads without polyurethane insulation were predictive of pacemaker lead break and could increase difficulty of lead extraction.
When leads being extracted are old or passive, coradial, or without polyurethane, we should be careful of the risks of lead break and consider a femoral approach and gentle extraction.

CO N FLI C T S O F I NTE R E S T
Authors declare no Conflict of Interests for this article.

I N FO R M E D CO N S E NT
The institutional review board (IRB) at our center approved the trial, and all patients provided written informed consent before partici- Abbreviations: CI, confidence interval; OR, odds ratio.