Findings and Implications
In the current issue of JCE, Aboelhassan et al report their findings
using an ipsilateral venogram to evaluate for venous stenosis and
lead-venous adherence. They found that the results of this simple
venogram could help predict the complexity of TLE. One hundred and five
patients were enrolled in the study with a median of two leads requiring
extraction in each and a median dwell time of 8 years. About half of
the patients were undergoing TLE for infectious indications and a little
over half had implantable cardiac defibrillators (ICDs). A dedicated
preoperative ipsilateral venogram was performed in all patients assessed
for the degree of venous stenosis and lead-venous adherence. TLE was
performed in a stepwise fashion in all patients, progressing from simple
traction to non-powered sheaths to powered sheaths (laser and
mechanical) and finally, to snares via femoral
access.6
Lead-venous wall adherence was defined as extensive if measured contact
or surrounding haziness was ≥ 50mm or if there was more than 10mm
distance between any lead and the venous lumen. Venous stenosis was also
assessed and was classified as not significant (<50%),
moderate (51-70%), severe (71-99%) and occlusive (100%). While total
number of leads was the only characteristic associated with occlusion,
Total number of leads and age of the oldest lead were both associated
with lead-venous adhesion.6 The study may
underestimate the prevalence of lead-vein adherence and venous stenosis.
Venograms were performed in a single projection, which may fail to
detect some areas of stenosis or adherence which might have been
discovered in another projection or by a three-dimensional study.
Nevertheless, this simple test detected severe stenosis or occlusion in
20% of subjects and lead adherence in almost half.
Of course, detection of adherence by venogram or other imaging
techniques is only useful if it helps guide decision-making for the
planned procedure. Aboelhassan et al found that detection of lead-venous
adherence may, indeed, guide preparation for TLE. The authors report
that lead-vein adherence was associated with higher TLE procedural
complexity. Patients with extensive lead-venous adherence required
advanced tools in 72% of cases and fluoroscopy time was 14.0 min
compared to 34.5% need for advanced tools (P<0.001) and mean
fluoroscopy time of 5.1 min (P<0.001) in those without
extensive adherence.6 This association between
lead-venous adhesion and increased complexity of TLE mirrors what has
been described for other imaging modalities.
Patel et al reported that when leads are seen outside the vein contour
by preoperative CT scans, procedure times are about one-third higher and
fluoroscopy times about 80% higher.1 Lead adherence
to central venous structures by CT is also associated with the need for
larger sheaths and more than a doubling of laser
times.7 Similarly, the finding of binding of leads to
other leads or to the right atrium or right ventricle by TEE is
associated with about a doubling of the likelihood of technical
difficulties during TLE.3 Other studies utilizing IVUS
and ICE have also reported an association between lead adherence and
increased TLE complexity.4,5 Interestingly, Beaser et
al. reported that the finding of minimal adhesions by intravascular
ultrasound were associated with lower complexity during TLE even in the
setting of other clinical factors which typically predict higher
complexity such as lead dwell time, presence of multiple leads and the
presence of an SVC coil.4 In fact, even adhesions in
the pocket have been associated with increased TLE complexity and the
need for a higher number of extraction tools.8
While Aboelhassan et al. found an association between lead-venous
adherence and procedure complexity, there was no such association in
patients with venous occlusion. It would seem to follow that venous
occlusion would imply greater fibrous ingrowth and binding to the leads
which, in turn, would impact the difficulty of TLE. While it is tempting
to think of lead-vein adherence and venous occlusion in the same light,
the current study demonstrates they can impact TLE quite differently.
The authors a found similar need for advanced tools (53.3% vs 52.2%, P
> 0.9) and fluoroscopy times (10.7 min vs 8.0 min, P = 0.6)
in those with and without venous occlusion. Furthermore, they report
complete procedural success in 100% of subjects with total occlusion
and 97.8% in those without (P > 0.9).6There are conflicting data on this point. Li et al studied patients with
a venogram and reported that among those with occlusion, procedure times
were more than 25% higher and fluoroscopy times were more than 50%
higher compared to those without occlusion.9Czajkowski et al also reported an association between the finding of
occlusion on venogram and longer procedures and need for more advanced
tools.10 Conversely, other studies utilizing either CT
or venography found no difference in TLE complexity between patients
with and without occlusion.7,11
While the finding of lead-venous adherence predicted complexity of the
extraction procedure, no difference was found in complete success rates
of extraction between those with and without adherence. There are likely
several reasons for this finding. In general, the success rates for TLE
are very high. The complete success rates from most large studies fall
in the range of 95-97%.12,13 In this study,
reflecting the results of most major trials, the complete procedural
success rate was excellent with reported rates of 98.0% in patients
with extensive adherence and 98.2% in those without (P >
0.9).6 So, even in difficult cases, complete success
was common. Furthermore, the authors report the results from a single
center which serves as a national referral center for TLE. Multiple
studies, including a relatively recent report from the ELECTRa registry,
have reported worse outcomes in low volume centers including lower
success rates and higher risk of procedure-related
death.14,15 So, while lead adherence was not
associated with significantly higher failure rates in this study, we
should not assume that excellent outcomes are a given in all centers
regardless of complexity.
The authors of the current study are careful to report that while
lead-venous adherence increased TLE complexity, the finding was not
associated with a statistically significant increase in risk of the
procedure. Here, the size of the study likely limits the ability to
detect differences in risk. While complications of TLE may be
catastrophic, the event rate is quite low. Most larger studies of TLE
report major complication rates of around 1-2% and minor complications
of about 1-6%.12,13,16 Intuitively, one might expect
higher rates of vascular lacerations in patients with venous adherence,
but, like other major complications, those rates are very low and thus
differences will be difficult to detect in smaller studies.
While statistical significance was not achieved in this study by
Aboelhassan et al, complications were more than doubled in the group
with lead-venous adhesion compared to those without (18% vs 7.3%). It
is tempting to look at these findings and assume they would reach
statistical significance in a larger trial, but adherence of the leads
to the veins and other structures is just one piece of the puzzle. The
risk of major complications is influenced by a myriad of patient, device
and procedural factors. For instance, female gender has been identified
as a risk factor in several studies.17-19 Markers of
patient frailty such as a depressed LVEF, thrombocytopenia, elevated INR
and low BMI are also associated with increased risk of complications in
TLE.12,20 Other patient factors such as age at initial
implantation and number of prior device procedures can impact
risk.18 Device factors including number of leads, type
of leads and the presence of abandoned leads may play a
role.18,21-24 Finally, center and operator experience
may influence the risk of TLE.15,25
While the difference in complications in patient with lead-venous
adherence in this study did not reach statistical significance, other
studies support an association. In the study by Aboelhassan et all, lead
dwell time and number of leads were both positively associated with a
higher likelihood of lead-venous adherence, a finding supported by other
studies as well.6,13 These predictors of adherence are
positively associated an in the increase the risk of TLE. The Canadian
Lead Extraction Risk (CLEAR) study identified advanced lead age and
extraction of 2 or more leads, among other factors, as contributors to
increased risk of major complications during TLE.17Derived from the ELECTRa Registry, the EROS score helps identify
patients at risk for major complications during TLE. The highest score,
EROS 3, is assigned if subjects have a pacemaker lead >15
years from implant or an ICD lead >10 years from implant.
Patients with this score are more than three times more likely to suffer
major complications including death during TLE.25While we should not expect smaller studies to identify associations with
major complications in TLE, it is reasonable to believe that factors
that increase the complexity of TLE may impact risk.