Discussion
ICE with three-dimensional electroanatomical mapping is increasingly
utilized in the management of ventricular
arrhythmias14. Although there is a paucity of evidence
regarding its safety and efficacy for PVCs, our study sought to examine
the associated complications and both the acute and long-term success of
PVC CA with and without ICE. Our findings reveal that (i) CA was
effective in eliminating PVCs or non-sustained VT, boasting an
approximate 90% long-term success rate; (ii) the usage of ICE did not
enhance acute or long-term outcomes; and (iii) ICE may be associated
with a lower incidence of perioperative complications, albeit not
reaching statistical significance.
Idiopathic ventricular arrhythmias, such as PVCs and VT, commonly
originate from OT, particularly RVOT. As substantiated by previous
reports and corroborated by our data, CA for PVCs stemming from the RVOT
had the highest success rate at around 90% and a low rate of
complications4,6. For non-OT PVC origins, success
rates were between 50-80%, with poorer outcomes observed from
epicardial sites, aligning with our findings4,6.
PVC-induced cardiac dysfunction is considered a significant prognostic
event for idiopathic ventricular arrhythmias15. In our
study, 17.6% of patients demonstrated abnormal LVEF or LVEDD.
Successful PVC elimination by CA was found to improve LVEF and decrease
LVEDD, consistent with results from other
studies3-5,16.
ICE provides high-resolution, real-time visualization of intracardiac
structures and catheters during interventional procedures, assisting
operators in monitoring lesion formation and
characteristics7. The benefits of ICE include enhanced
patient tolerance, as well as reduced radiation and contrast agent
exposure, echoing the ALARA (as low as reasonably achievable)
principle7. ICE-guided procedures for conditions such
as atrial fibrillation and left atrial appendage closure are
increasingly being used due to their safety and
efficacy17,18. Although comparative studies are
scarce, ICE is believed to heighten the safety and effectiveness of PVC
CA in comparison to traditional mapping technologies.
Michael and colleagues reported that in patients with a history of
implantable cardioverter defibrillator or cardiac resynchronization
therapy who underwent VT ablation, the usage of ICE was associated with
a decreased 12-month risk of VT-related readmission and a reduced need
for repeat VT ablation. Interestingly, this intervention did not
significantly alter complication rates8. A Japanese
nationwide observational study also found that ICE application notably
reduced the risk of cardiac tamponade, although it did not present
additional clinical benefits for other safety outcomes or
effectiveness9.
Clinically, long-term success rates are of immense concern. Factors
affecting outcomes primarily include PVC origin and
burden4,6, with RVOT-derived arrhythmias generally
showing better prognosis and epicardial origins being associated with
higher recurrence4. In our study, PVC origin was a
principal determinant of ablation outcomes as well.
ICE use has been increasingly utilized in PVCs ablation. CA of PVCs
originating from LV summit is challenging. However, utilizing ICE,
Santiago et al. achieved an 84% acute success rate with no
complications in a cohort of 26 patients receiving non-fluoroscopic
CA19. Traditional three-dimensional (3D)
electroanatomical mapping was less effective for papillary PVCs
ablation. Lin and colleagues showed that augmenting this technique with
ICE and ICE-generated 3D cardiac anatomy can raise the acute success
rate above 90%20. While in present study, ICE use
does not affect success rates, which may be related to the fact that all
the patients we selected have idiopathic PVCs. The ICE group may have
involved more complex origin sites, and non-RVOT origins were associated
with poorer outcomes4. Despite the challenges in
ablating originating from specific locations in the heart such as the
papillary muscles and the left ventricle summit21, we
have found in clinical practice that, for experienced operators, the
difficulty of catheter stability and positioning is related to the site
of origin. The success rate of ablation often depends on the depth of
the lesion, and the use of ICE cannot solve this problem. Consequently,
ICE utilization for idiopathic ventricular arrhythmias may offer limited
assistance in substrate identification.
Despite the absence of comparative studies, there is empirical evidence
suggesting that ICE usage may enhance the efficacy and safety of PVCs CA
and minimize radiation exposure compared to traditional 3D
electroanatomical mapping. In our study, we found that ICE application
not only reduced the X-ray dose20 but also, while the
acute success rate and long-term outcomes did not significantly improve,
the incidence of periprocedural complications did not significantly
differ from the control group. Furthermore, the ICE group had a longer
procedure duration. Although not statistically significant, the ICE
group showed a trend towards fewer ablation lesions and a shorter
average postoperative hospital stay, potentially enhancing efficiency
and compensating somewhat for the cost of ICE equipment.
PVCs are frequently encountered in clinical practice, and CA is an
effective method to alleviate symptoms and prevent cardiomyopathy
associated with PVCs. ICE is becoming increasingly prevalent due to its
proven benefits in managing atrial fibrillation and VT in patients with
structural heart disease. Our findings underscore that in the ablation
of idiopathic PVCs, while ICE did not significantly enhance success
rates or reduce complications, the efficacy of the ablation procedure
often depended on the precise location and depth of the PVCs. The study
also observed longer procedure times with less favorable outcomes,
emphasizing the importance of identifying the optimal ablation target
swiftly to minimize procedural delays.
Our study is subject to certain limitations. Firstly, as a retrospective
observational study, there is a potential for operator bias,
particularly as the use of intracardiac echocardiography (ICE) may be
preferentially chosen for complex lesions. This could skew the results.
Additionally, the follow-up process for Holter monitoring and
echocardiography was not standardized, raising the possibility of
follow-up attrition and the potential to misclassify endpoint events.
Despite this, the immediate success rate appears to have the most
significant influence on recurrence, suggesting that variations in
Holter follow-up may exert minimal impact on the long-term outcomes.
Secondly, the relatively small sample size limited our ability to
perform propensity score matching for variables between the study
groups, which might have influenced the observed incidence of endpoint
events. Thirdly, our analysis did not incorporate the morphology and
duration of QRS complexes as potential factors for assessing the risk
associated with procedural outcomes. These ECG characteristics are
indicative of the origins and depth of PVCs and have been linked to
ablation success in univariate analyses. Hence, the baseline QRS
characteristics could potentially serve as preliminary indicators of
ablation difficulty in clinical practice. In consideration of these
issues, future prospective randomized controlled trials are warranted to
clarify the definitive impact of ICE on the success and complications
related to PVC ablation.
Overall, while ICE assists in minimizing fluoroscopic doses during PVC
or non-sustained VT ablation, it does not appear to significantly
enhance acute and long-term success rates or substantially decrease
complication rates.
Data Availability Statements: The data underlying this article
will be shared on reasonable request to the corresponding author.
Funding: This work was supported by Natural Science Foundation
of China (81970282, 82270331), and by Qingdao Key Clinical Specialty
Elite Discipline (QDZDZK-2022008). The sources of funding were not
involved in any aspect of the study, including its design and execution;
the gathering, handling, analysis, and elucidation of data; or the
drafting, revision, and endorsement of the manuscript. Additionally,
they did not influence the choice to submit the manuscript for
publication.
Conflict of Interest: The authors disclose that there are no
conflicts of interest to report.
Ethics approval statement: The research received approval from
the local Institutional Review Board.
patient consent statement: All study participants provided
written informed consent.
Author contributions: ML and CM conceptualized and executed the
study, gathered and interpreted data, carried out subsequent monitoring,
and prepared the initial draft of the manuscript. BR, KZ, and JW
contributed to the study design and execution and authored portions of
the manuscript. TC and WH were responsible for data collection and
ongoing participant follow-up. JZ and LW played roles in the study’s
design and execution, data analysis, and provided critical revisions to
the manuscript. All authors have reviewed and consented to the published
version of the manuscript.