Remote magnetic navigation for ventricular ablation: did the machine win this round?
Remote magnetic navigation for ventricular ablation: did the machine win this round?
J. David Burkhardt 0
0 Texas Cardiac Arrhythmia Institute , 3000 N. IH 35, Suite 700, Austin, TX 78705 , USA
Remote magnetic navigation has been available as a tool
for mapping and ablation for well over a decade. In that
period of time, it has shown to be useful in nearly every
type of ablation procedure from the most simple to the
most complex [1–3]. Some operators prefer the system
for atrial fibrillation ablation, others for ventricular
tachycardia ablation, and some use it for any ablation. Despite
numerous publications showing reductions in fluoroscopic
exposure and the obvious benefits of not wearing lead and
standing tableside for hours, remote magnetic navigation
has not become the standard of care in the world . Most
publications appear to show similar success rates, and
many show favorable complication rates [5–7]. So what
is the limitation to universal acceptance? In addition,
many centers have purchased the system, yet it sits
unused. Why would a physician give up a more comfortable
procedure to perform an ablation wearing lead and being
exposed to more radiation?
One of the major factors preventing adoption is cost.
Not only is the system itself expensive but it also
requires shielding, specific X-ray systems, support
specifications, a significant space requirement, and cannot be
close to an MRI system. Outfitting an existing EP
laboratory with a system would likely require significant
construction costs. In general, it is much easier to plan for a
system in new construction.
Once the system is installed, the operator must commit
to overcoming the learning curve. Navigation with the
system is quite different than manual navigation.
Looping the catheter allows access to areas that cannot
be reached directly. There is no fixed curve, which allows
great versatility but is not always intuitive. Procedures
will take longer in the beginning, and learning the
advanced techniques takes significant time and patience. In
the current world, where we are pushed toward efficiency
and increasing volume and throughput, this time is
certainly a sacrifice. It is understandable why some would
choose not to continue using a system that slows them
down under such pressure.
Perhaps the most challenging limitation is
technological lag. Magnetic navigation systems require partnerships
with catheter manufacturing companies and mapping
companies to fully enjoy use of the system. These
companies have their own financial goals, and since magnetic
navigation is only a small portion of catheter sales, the
incentive to advance the technology is not present. Since
the release of the open-irrigated magnetic ablation
catheter almost 10 years ago, catheter technology has
significantly changed. New irrigation platforms, contact force
sensing, and balloon-based technologies have entered the
field, yet the magnetic catheter has remained unchanged
in that time. There is ample opportunity to improve the
magnetic catheter itself with increased magnetic force,
improved handling, and irrigation, but this cannot occur
without significant capital or a willing partner.
Despite these limitations, magnetic navigation seems to
have found a niche in ventricular tachycardia and
premature ventricular contraction (PVC) ablation. Magnetic
navigation seems well suited to the ventricle. One of the
limitations in the atrium is the relatively long stiff
segment of the catheter; however, this is not a problem in the
larger ventricle. One of the major advantages over manual
navigation is the ability to access the entire ventricle with
relative ease. Manual catheters are limited by fixed
curves, which makes navigating portions of the left
ventricle difficult, in some cases requiring deflectable sheaths
or multi-curve catheters. This limitation also makes
manual catheter contact force in certain areas inconsistent or
suboptimal, which may also result in insufficient ablation
lesions. Maps obtained via magnetic navigation tend to
have less distortion and more accurately represent the
chamber of interest [5, 8]. The more uniform and constant
contact may also improve the ablation lesions. Mapping
with a magnetic catheter also appears to produce less
ectopy, which is particularly important in PVC ablation
when a catheter-induced PVC could cause the operator
to ablate off target .
Epicardial mapping and ablation has been shown to be
useful in some ventricular tachycardia such as
arrhythmogenic right ventricular dysplasia (ARVD) . Magnetic
navigation has a particular advantage in this modality
because altering the vectors, allows a more direct approach
to mapping the epicardial surface. In addition, the vector
can be directed toward the heart surface, which may
reduce the collateral damage seen during epicardial ablation
to adjacent structures. Similarly, in congenital heart
disease, magnetic navigation may allow access to areas not
reachable via manual navigation [11–14].
In the paper, BComparison of Remote Magnetic
Navigation Ablation and Manual Ablation of Idiopathic
Ventricular Arrhythmia After Failed Manual Ablation,^
the authors studied a group of patients referred for
ablation after having failed a previous ablation for ventricular
arrhythmia. They found that the patients who underwent
mapping and ablation using the remote magnetic
navigation system had a significantly higher success rate (91 vs.
69 % p = 0.02). This is a difficult population
understanding that the patients were previously unsuccessfully
ablated. In addition, as expected, fluoroscopy time was
reduced. The authors also reported particular success in
the posterior right ventricular outflow tract and posterior
tricuspid valve area.
This is a retrospective analysis but does confirm that
magnetic navigation appears to have a particular benefit in the
ablation of ventricular arrhythmias. Despite the technological
improvements in manual ablation catheters, magnetic
navigation wins out in this study.
This win certainly enlightens us to the need for a prospective
trial, understanding that magnetic navigation still lacks the most
advanced catheter technology. If this is confirmed by such a
trial, then it would suggest that with some technological
advances, magnetic navigation could compete in other ablation
realms. Certainly new catheter designs that improve magnetic
force and handling would spur operators who use the system
only for ventricular arrhythmias to expand to the left atrium if
all the benefits were available in that chamber. If the system
could be designed to allow for placement in existing
laboratories at acceptable cost, then a vastly expanded group of
potential operators would be created, perhaps incentivizing further
investment into the technology and applications.
Remote magnetic navigation may be superior to manual
navigation in ventricular arrhythmia ablation . This needs
to be verified by a multi-center randomized study. Currently,
the MAGNETIC VT study (NCT02637947) is enrolling
across the world to answer this question in ischemic
cardiomyopathy patients with ventricular arrhythmias. More studies
are needed to validate this hypothesis in other types of
ventricular arrhythmias. Technological improvements are needed
to keep magnetic navigation, clearly a useful tool for some,
from unnecessarily dying out. The magnetic navigation
machine may have won this round, but it is a long fight.
1. Akca F , Schwagten B , Theuns DAJ , Takens M , Musters P , SziliTorok T. Safety and feasibility of single-catheter ablation using remote magnetic navigation for treatment of slow-fast atrioventricular nodal reentrant tachycardia compared to conventional ablation strategies . Acta Cardiol . 2013 ; 68 ( 6 ): 559 - 67 .
2. Kim S-H , Oh Y-S , Kim D-H , Choi IJ , Kim T-S , Shin W-S , et al. Long-term outcomes of remote magnetic navigation for ablation of supraventricular tachycardias . J Interv Card Electrophysiol . 2015 ; 43 ( 2 ): 187 - 92 .
3. Wu J , Deisenhofer I , Ammar S , Fichtner S , Reents T , Zhu P , et al. Acute and long-term outcome after catheter ablation of supraventricular tachycardia in patients after the Mustard or Senning operation for D-transposition of the great arteries . Europace . 2013 ; 15 ( 6 ): 886 - 91 .
4. Jin QI , Pehrson S , Jacobsen PK , Chen XU . Efficacy and safety of atrial fibrillation ablation using remote magnetic navigation: experience from 1,006 procedures . J Cardiovasc Electrophysiol . 2016 ;27 Suppl 1: S23 - 28 .
5. Weiss JP , May HT , Bair TL , Crandall BG , Cutler MJ , Day JD , et al. A comparison of remote magnetic irrigated tip ablation versus manual catheter irrigated tip catheter ablation with and without force sensing feedback . J Cardiovasc Electrophysiol . 2016 ;27 Suppl 1: S5 - S10 .
6. Jin Q , Pehrson S , Jacobsen PK , Chen X. Impact of catheter ablation with remote magnetic navigation on procedural outcomes in patients with persistent and long-standing persistent atrial fibrillation . J Interv Card Electrophysiol . 2015 ; 44 ( 2 ): 197 - 204 .
7. Zhang F , Yang B , Chen H , Ju W , Kojodjojo P , Cao K , et al. Magnetic versus manual catheter navigation for mapping and ablation of right ventricular outflow tract ventricular arrhythmias: a randomized controlled study . Heart Rhythm . 2013 ; 10 ( 8 ): 1178 - 83 .
8. Tahir SMA , Chaudhry GM , Syed MA , Marchese T , Kotler G , Haffajee CI , et al. Remote magnetic navigation system provides a superior catheter stability in acquisition of His bundle electrogram . J Interv Card Electrophysiol . 2008 ; 21 ( 3 ): 209 - 13 .
9. Aagaard P , Natale A , Briceno D , Nakagawa H , Mohanty S , Gianni C , et al. Remote magnetic navigation: a focus on catheter ablation of ventricular arrhythmias . J Cardiovasc Electrophysiol . 2016 ;27 Suppl 1: S38 - 44 .
10. Santangeli P , Dello Russo A , Pieroni M , Casella M , Di Biase L , Burkhardt JD , et al. Fragmented and delayed electrograms within fibrofatty scar predict arrhythmic events in arrhythmogenic right ventricular cardiomyopathy: results from a prospective risk stratification study . Heart Rhythm . 2012 ; 9 ( 8 ): 1200 - 6 .
Di Biase L , Santangeli P , Astudillo V , Conti S , Mohanty P , Mohanty S , et al. Endo-epicardial ablation of ventricular arrhythmias in the left ventricle with the remote magnetic navigation system and the 3.5- mm open irrigated magnetic catheter: results from a large singlecenter case-control series . Heart Rhythm . 2010 ; 7 ( 8 ): 1029 - 35 .
Di Biase L , Santangeli P , Burkhardt DJ , Bai R , Mohanty P , Carbucicchio C , et al. Endo-epicardial homogenization of the scar versus limited substrate ablation for the treatment of electrical 13.
storms in patients with ischemic cardiomyopathy . J Am Coll Cardiol . 2012 ; 60 ( 2 ): 132 - 41 .
J Cardiovasc Electrophysiol . 2016 ;27 Suppl 1: S45 - 56 .