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.