Article Text
PDF
Abstract
Objectives Radiofrequency catheter ablation is the first-line treatment for idiopathic premature ventricular complexes (PVCs) and ventricular tachycardias (VTs). However, the outcomes were less compared among the categories. The study aims to assess the effectiveness and safety of catheter ablation for idiopathic PVC/VTs in a single high-volume centre, using the right ventricular outflow tract (RVOT) as a reference.
Design Retrospective cohort study.
Setting Patient data were collected from a tertiary hospital in Guizhou, China.
Participants Between September 2013 and September 2022, 1028 patients (male: 41.3%; age: 46.5±15.6 years) who underwent the first catheter ablation for idiopathic monomorphic PVC/VTs were enrolled.
Outcome measures Acute success, procedure-related complications, and long-term recurrence were assessed. Antiarrhythmic drugs (AADs) were not administrated after procedures unless recurrence was identified.
Results The overall acute success rate was 90.3%, with 368 patients (35.8%) experiencing left ventricular PVC/VTs. No cases of third-degree atrioventricular block or death were reported. Complications were more common in patients with left ventricular PVC/VTs than those with right-sided ones (4.6% vs 0.1%, p<0.001). A total of 926 patients (90.1%) were followed up for an average of 9.7±3.7 months, and only the PVC/VTs category was found to be associated with long-term success rates. The RVOT, endocardial left ventricular outflow tract (endoLVOT), tricuspid annulus (TA) free wall, posterior septum and fascicular VT had long-term success rates exceeding 85%. Other types of PVC/VTs showed significantly higher risks of recurrence.
Conclusions Besides RVOT and fascicular VT, single-procedure catheter ablation without AADs is highly effective for endoLVOT, TA-free wall and posterior septum. Patients with left ventricular PVC/VTs have higher complication risks compared with right ones.
- Pacing & electrophysiology
- Cardiac Epidemiology
- Cardiology
Data availability statement
Data are available upon reasonable request. Data are available upon reasonable request. The datasets used and analysed during the current study are available from the corresponding author upon reasonable request.
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
Statistics from Altmetric.com
Strengths and limitations of this study
The strength lies in the inclusion of a large number of patients (n=1028) and a highly accurate three-dimensional mapping system.
The large sample size enabled a quantitative comparison of the clinical outcomes among the premature ventricular complex/ventricular tachycardia categories following catheter ablation.
The limitations included its retrospective nature, single-centre design, limited use of novel ablation techniques and lack of adjunctive devices.
Introduction
Radiofrequency catheter ablation is the first-line therapy for symptomatic idiopathic premature ventricular complexes (PVCs) and ventricular tachycardias (VTs), with remarkable efficiency and low complication rate, particularly for those originating from right ventricular outflow tract (RVOT) and left fascicles.1 2 As our understanding of cardiac anatomy and electrophysiology improves, more patients undergo catheter ablation for different types of PVC/VTs.3 However, outcomes for PVC/VTs other than RVOT and left ventricular VT have been separately reported and were less compared.4–6 Moreover, advanced technologies, such as micro-puncture needles, ultrasound guided vessel puncture, intracardiac echocardiography (ICE), contact-force sensing catheters, high-density mapping and vascular closure devices,7–11 are not widely employed in developing countries. Comparing the efficacy and safety of catheter ablation among PVC/VTs is essential to provide clinical recommendations, especially in districts with limited access to adjunctive devices.
The current study retrospectively included patients who underwent their first catheter ablation for idiopathic monomorphic PVC/VTs, intending to evaluate the efficacy and safety of catheter ablation by using those originating from RVOT as a reference.
Methods
Patient selection
From September 2013 to September 2022, patients who underwent the first catheter ablation for PVC/VTs at Guizhou Provincial People’s Hospital were screened. The exclusion criteria were: (1) age <18 years, (2) polymorphic PVC/VT, (3) non-utilisation of a three-dimensional mapping system, (4) presence of structural heart disease such as chronic myocardial infarction, myocardial scar detected on MRI, congenital heart disease, valvular heart disease, hypertrophic cardiomyopathy or left ventricular enlargement with ejection fraction <50%.12 Patient demographics, PVC burden, presence of sustained or non-sustained VT, echocardiographic parameters, procedural details, electrophysiological diagnosis, complications and follow-up information were acquired from the clinical research database (BigData Search Software, ClinBrain Information Technology, Shanghai, China).
Patient and public involvement
Patient and public involvement in the study design and methodology was not applicable.
Mapping and ablation procedure
Four experienced operators (ZJ, QL, YT and LY) performed the procedures. Antiarrhythmic drugs (AADs) were discontinued for at least five half-lives. The Seldinger method with an 18-gauge needle was used for femoral vein/artery puncture guided by arterial pulse. An 8F sheath was inserted for each vascular access. Heparin was administered to maintain an activated clotting time of over 300 s in patients with arterial or transseptal access. Others received 3000 U of heparin, followed by 1000 U per hour. An 8F saline irrigating catheter (Thermocool or SmartTouch, Biosense Webster) was used for mapping and ablation. The use of other multipolar mapping catheters was left to the operators’ discretion. ICE was not employed in any of the procedures. Bipolar and unipolar electrograms were filtered at 30–500 Hz and 0.05–400 Hz, respectively. Intravenous isoproterenol at a rate of 1–5 µg/min and programmed pacing with up to three extra stimuli were used to provoke the PVC/VTs if necessary. Activation mapping of the PVC/VTs was performed using the three-dimensional mapping system (CARTO 3, Biosense Webster).
For the PVC/VTs with focal sources from the myocardium, the earliest ventricular activation sites with negative concordance patterns were identified as ablation targets.13 Pace mapping was performed for infrequent PVCs or unstable VTs, and ablation targets were determined based on sites with pacing QRS configurations ≥11/12. For PVC/VTs originating from the His-Purkinje system, the sites with the earliest His-Purkinje potentials and equal H-V interval between sinus rhythm and PVC were targeted.14 15 For left fascicular VTs, the earliest P2 or P1 potential was targeted.
The radiofrequency ablation was routinely performed at 30 W with an irrigation rate of 17 mL/min. If a para-Hisian origin was suspected, the power started at 10 W and titrated up by 5 W every 10 s to a maximum of 30 W with careful surveillance of junctional beats, AV interval and QRS morphology. Once the PVC/VTs were suppressed within 20 s, ablation was continued for 60–90 s. If an intramural origin was considered, the power was titrated up to a maximum of 50 W at the operators’ discretion. Adjacent cardiac structures were mapped if ablation targets were suboptimal or multiple ablations had failed, including the pulmonary cusps, opposite ventricle and cardiac venous system. Coronary angiography was performed when necessary.
After the procedures, venous sheaths were removed, and manual compression was applied for at least 5 min until haemostasis. Arterial sheaths were removed 4 hours later. Manual compression was applied for 15–20 min, followed by a groin compression bandage for 6 hours. Patients with haematoma or pain at the puncture sites underwent ultrasound examinations to rule out vascular complications. No additional AADs were administrated unless recurrence was identified during follow-up.
PVC/VT categorisation
The PVC/VTs were categorised based on their origins and mechanisms: focal PVC/VT or re-entrant VT. Origins were the anatomical locations where successful ablations were achieved. For those without acute success, the earliest activation sites or best-pacing sites with the highest matching scores were determined as origins. Any disagreement was resolved through consensus. PVC/VTs originating from the right ventricle (RV) were categorised into RVOT, tricuspid annulus (TA) free wall, posterior septum, paraHis, His-Purkinje PVC or endocavity. Those originating from the left ventricle (LV) were classified as endocardial left ventricular outflow tract (endoLVOT), summit, posterior septum, paraHis, left fascicular VTs, His-Purkinje PVCs or endocavity.
For long-term outcome analysis, the right and left ventricular PVC/VTs, including posterior septum, paraHis, His-Purkinje PVC and endocavity, were combined to increase the sample size because they have similar anatomical complexity, mapping strategy, catheter manipulation skills, ablation concerns, acute success rate and possible overlaps in origin localisation.
Clinical outcome assessment
Acute success was defined as PVC/VTs cannot be induced for at least 30 min after the last ablation with isoprenaline infusion and programmed stimulation. Reasons for acute failure included intramural origin, high-risk target, difficult contact, severe complication, abnormal impedance and tortuous route. The failure to eliminate PVC/VTs by endocardial approach and cardiac venous access suggested intramural origin. The high-risk target referred to the potential risk of atrioventricular block (AVB) or coronary artery injury. The difficult contact was defined as unstable catheter-myocardium contact. Severe complication indicated the procedural termination due to cardiac perforation, which required immediate drainage or surgical repair. Abnormal impedance was an unexpected elevation exceeding 200 Ohms when engaging the target with the catheter.16 The tortuous route implied unsuccessful access of ablation catheters into cardiac chambers. Procedure-related complications included cardiac tamponade, third-degree AVB, pseudoaneurysm, arteriovenous fistula, embolism and death.
Patients were evaluated through clinical visits within 3 months postprocedures, with scheduled 24-hour Holter monitoring. Subsequently, patients were followed up by clinical visits or telephone interviews every 3 months until the end of the first year. Patients were advised to return for 24-hour Holter monitoring if clinical symptoms indicated recurrence. Long-term success was defined as a reduction in the PVC burden exceeding 80% and the absence of VTs.
Statistical analysis
Continuous variables are presented as mean±SD. The Student’s t-test was used to compare if normally distributed; otherwise, the Mann-Whitney U tests were used. Categorical and binary variables are presented as frequencies (percentages). The χ2 test was used for comparison if the expected frequency is more than five; otherwise, the Fisher’s exact test was used. The curves of long-term success were created using the Kaplan-Meier method, and the difference among PVC/VTs was compared using the log-rank test. The Cox regression models were conducted to assess the HR of recurrence among the PVC/VT categories. Model 1 included variables of patient age, gender, presence of SVT, contact-force sensing ablation catheter, ventricular dimension and PVC/VT origin (right or left ventricle). Model 2 included variables of patient age, gender, contact-force sensing ablation catheter and PVC/VT categories. A two-tailed p value of less than 0.05 was considered statistically significant. Statistical analyses were performed using the R software (V.4.1.2, The R Foundation, Vienna, Austria).
Results
Patient characteristics
A total of 1028 patients (male: 41.3%; age: 46.5±15.6 years) with idiopathic monomorphic PVC/VTs were included in the study (figure 1). The mean PVC burden was 20.1±7.6%, and the left ventricular ejection fraction was 62.8±4.9% (table 1). Among them, 368 (35.9%) patients had PVC/VTs originating from the LV. Patient characteristics such as age, gender, presence of sustained VTs, PVC burden, ventricular diameter and estimated glomerular filtration rate differed significantly between those with RV and LV origins (p<0.05) (table 1). However, these differences were not clinically significant.
Patient flowchart. EF, ejection fraction; endoLVOT, endocardial left ventricular outflow tract; LV, left ventricle; PVC premature ventricular complex; RV, right ventricle; RVOT, right ventricular outflow tract; VT, ventricular tachycardia.
Baseline patient and procedural characteristics
Procedural characteristics
Compared with the procedures for right ventricular PVC/VTs, those for left-sided ones were more time-consuming, used more contact-force sensing catheters, and required additional arterial and transeptal accesses (p<0.001) (table 1). The detailed procedural characteristics are presented in online supplemental tables 1 and 2.
Supplemental material
Supplemental material
Acute outcomes
Acute success was achieved in 90.3% of all patients (table 2). 18 (1.8%) patients suffered from complications, including 1 ischaemic stroke, 7 cardiac tamponades, 9 pseudoaneurysms and 1 arteriovenous fistula. One patient with cardiac perforation at the LV apex survived by emergent open-chest repair, while the other six recovered by pericardial drainages. No third-degree AVB or procedure-related death occurred. Compared with right ventricular PVC/VTs, the left ventricular ones had a significantly lower acute success rate (p<0.001), higher rates of complication such as cardiac tamponade (p=0.002) and pseudoaneurysm (p=0.003). Detailed outcomes are presented in online supplemental tables 1 and 2.
Clinical outcomes
Figure 2 shows PVC/VT categories and the acute success rates. The left fascicular VT, RVOT, endoLVOT and TA-free wall had the highest acute success rates over 95.0%. Online supplemental figure 1 summarises the causes of failure, with intramural origin accounting for half of them in RVOT, endoLVOT and LV summit. The high-risk target was attributed to 24/24 (100.0%) and 5/7 (71.4%) failures in the paraHisian and His-Purkinje PVC. Difficult contact was the most frequent cause of the endocavitary PVC/VTs. Three ideal targets were abandoned due to abnormally elevated impedance. Three procedures were terminated due to acute cardiac tamponade. One patient with endoLVOT PVCs failed due to severe tortuosity in bilateral femoral arteries.
Supplemental material
Categorisation and representative 12-leads electrocardiography of right (A) and left (B) ventricular PVC/VTs. The origins are annotated by the circled numbers on the figures. The acute success rates are annotated as numbers (%) beneath the categories. APM, anterior papillary muscle; ASS, anterior superior septum; endoLVOT, endocardial left ventricular outflow tract; LAF, left anterior fascicle; LPF, left posterior fascicle; MB, moderator band; PPM, posterior papillary muscle; PVC, premature ventricular complex; RB, right bundle branch; RVFW, right ventricular free wall; RVOT, right ventricular outflow tract; SPM, septal papillary muscle; TA, tricuspid annulus; VT, ventricular tachycardia.
Long-term outcomes
926 (90.1%) patients were followed up for an average of 9.7±3.7 months (table 2). To increase the sample size for further analysis, we combined the right and left ventricular PVC/VTs, including the posterior septum, paraHis, His-Purkinje PVC and endocavity. The success rates at 12 months were over 85.0% for RVOT, endoLVOT, TA-free wall and left fascicular VT, while other PVC/VTs had success rates of less than 80.0% (log-rank p<0.001) (figure 3). In the Cox regression analysis, the left ventricular PVC/VTs were associated with a higher risk of recurrence (HR: 1.86; 95% CI 1.29–2.68, p=0.001) (table 3). Compared with the RVOT, para His (HR: 5.87, 95% CI 3.26–10.55; p<0.001), LV summit (HR: 4.52; 95% CI 2.64–7.75; p<0.001), endocavity (HR:3.26, 95% CI 1.90–5.59; p<0.001) and His-Purkinje PVC (HR: 2.59; 95% CI 1.29–5.20; p=0.008) were significantly associated with higher risks of recurrence, which was unrelated to patient age, gender, employment of contact-force sensing catheter or presence of sustained VTs.
Kaplan-Meir analysis on long-term success among PVC/VT categories. The long-term success rates are annotated as percentages following the categories. endoLVOT, endocardial left ventricular outflow tract; LV, left ventricle; PVC premature ventricular complex; RV, right ventricle; RVOT, right ventricular outflow tract; TA, tricuspid annulus; VT, ventricular tachycardia.
Cox regression analysis of recurrence HR
Discussions
Major findings
The present study first quantitatively analysed the clinical outcomes of single-procedure catheter ablation for idiopathic PVC/VT categories. RVOT, endoLVOT, TA-free wall, posterior septum and left fascicular VT had success rates over 85.0% at 12 months. Other PVC/VTs were associated with higher risks of acute failure and recurrence. Intramural origins and high-risk targets most frequently caused acute failures. The overall complication rate was 1.8%, with 94.4% occurring in patients with left ventricular PVC/VTs. No patient had third-degree AVB or procedure-related death.
Ablation efficacy
Consistent with previous studies, the outcomes of catheter ablation are significantly associated with the origins of PVC/VTs.17 18 The LV summit PVC/VTs exhibit multiple breakthroughs from RVOT, LVOT and distal cardiac veins. The region could include overlapping multiplanar intercepting myocardium,19 making it challenging to localise deep intramural true origins that are refractory to conventional ablation.20 In a recent multicentre study, most cases required repeat ablation and novel approaches such as simultaneous unipolar ablation, bipolar ablation, low-ionic solution irrigation and ethanol ablation.21 Hayashi et al reported similar clinical success rates for single-procedure catheter ablation of PVC/VTs from RVOT and LVOT, including LV summit.3 However, our acute success rate was lower, possibly due to the infrequent use of novel approaches. ECG characteristics such as deep Q-waves in aVL and aVR, no S-waves in V5/V6, a peak deflection index >0.6, early transition in precordial leads and spiked helmet sign in lead III could aid shared decision-making regarding ablation referral.22 23
Previous studies have reported a success rate of 90.0%–96.6% for PVC/VTs originating from the TA-free walls.24 25 However, this success rate decreases to 57.0%–66.7% for those originating from the TA septum due to its proximity to the His bundle and the complex anatomy of the inferior crux.26 Our study excluded the PVC/VTs originating from the paraHisian region. The acute success rates were 31/32 (96.9%) for PVC/VTs in the TA-free wall and 8/10 (80.0%) for those in the posterior septum. ECG characteristics, including rS/QS pattern in lead V1, precordial R wave transition and QRS complex notching, can help differentiate between PVC/VTs originating from the TA-free wall and septum.24–26 For PVC/VTs originating from the paraHisian region, permanent AV block risk was considered a major reason to abandon ablation attempts. Cryoablation is an alternative energy source in such cases due to its feature of reversible lesion formation. However, it has shown suboptimal long-term success rates and can lead to severe complications.27
The success rate of catheter ablation for His-Purkinje PVCs was high when targeting the earliest Purkinje potential. However, in our study, procedural failure occurred in six cases due to the proximity of the targets to the bifurcation of His bundle. Additionally, mechanical injury frequently suppressed the His-Purkinje PVCs, which could have led to an inaccurate target for ablation.
The long-term success rate of endocavitary PVC/VTs was significantly lower because of the complex anatomy, catheter stability and myocardium thickness. Endocavitary structures make it difficult to interpret mapping approaches, as they could either be the origins of PVC/VT or obstacles that hinder accurate mapping.28 A recent study reported that over 1/3 of papillary-muscle PVC/VTs originated from false tendons.29 Although contact-force sensing catheters are preferred for endocavitary PVC/VTs, our study showed that SmartTouch did not have a higher long-term success rate than Thermocool (table 3). ICE provides more information on intracardiac structures and helps assess catheter-myocardium contact. The absence of ICE may have contributed to more procedural failures and recurrences in our study.30
Safety concerns
In our study, the complication rate of catheter ablation for idiopathic PVC/VTs was similar to previous studies. We found that patients with left ventricular PVC/VTs had a higher risk of groin-related complications and cardiac tamponades. Pseudoaneurysm and arteriovenous fistula were caused by accidental artery injury and improper compression after sheath removal. Using ultrasound-guided puncture and vessel closure devices could help reduce these risks.31 Cardiac tamponade and ischaemic stroke may occur due to high-power, long-duration ablation in challenging cases, resulting in char formation, steam pop, inadvertent catheter bump or inadequate anticoagulation. Contact-force sensing catheters and ICE could provide additional information to minimise the risk of cardiac tamponade.
Clinical implications
Our study only administered the AADs to patients who experienced recurrences during follow-up. The long-term success resulted from single-procedure catheter ablation without AADs. The PVC/VTs originating from RVOT, left fascicular VT, endoLVOT, TA-free wall and posterior septum had fair long-term success rates with rare complications using standard radiofrequency ablation catheters and few adjunctive devices. These data support catheter ablation as first-line therapy for patients with such PVC/VT categories.
Limitations
The study has several limitations. First, generalising the results from a single centre should be done cautiously due to potential biases. Second, although the study involved a large cohort of patients, the sample size in each PVC/VT category was relatively small. Third, the success rate depends on individual knowledge, experience and skills; however, a chronological analysis of the success rates is impossible due to the small sample size. Fourth, only the sequential unipolar radiofrequency ablation technique was used in this study; employing novel approaches and adjunctive devices at an advanced cardiac centre could significantly improve efficacy and safety.20 21 27 32 33 Additionally, due to the absence of ICE, it was impossible to localise the PVC/VT origins to endocavitary structures.27 30 34 35 Finally, the fluctuation in 24-hour PVC burden could impact both catheter ablation indication and recurrence assessment.36
Conclusions
In addition to PVC/VTs originating from the RVOT and left fascicular VT, single-procedure catheter ablation without AADs is highly effective for the endoLVOT, TA-free wall and posterior septum. The overall complication rate is low. Patients with left ventricular PVC/VTs have a higher risk of complications compared with right-sided ones.
Data availability statement
Data are available upon reasonable request. Data are available upon reasonable request. The datasets used and analysed during the current study are available from the corresponding author upon reasonable request.
Ethics statements
Patient consent for publication
Ethics approval
The study was approved by the ethics committee of Guizhou Provincial People’s Hospital, and patient informed consent was waived without involving patient privacy.
Acknowledgments
We thank Mengkun Du from ClinBrain Information Technology Co. for his dedicated assistance in data extraction. We thank Juan Chen, Zhichao Du, Zhaoyang Liu, Xueqi Yang, Ya Zhang and Song Zhao from the National Cardiac Electrophysiology Training Project for their dedicated help in data curation.
References
Supplementary materials
Supplementary Data
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Footnotes
ZJ and CG contributed equally.
Contributors ZJ and CG designed the present study and performed the statistical analysis. QL, LT, YY, JW and CC verified the analytical methods. ZJ and CG took the lead in writing the manuscript in consultation with YZ and LY. YL and QO aided in interpreting the results and worked on the manuscript. LY supervised the findings of this work and LY is the guarantor of the study. All authors discussed the results and contributed to the final manuscript.
Funding This work was supported by the Guizhou Provincial Science and Technology Agency Project (QianKeHeBasic-ZK[2022]General255); the Clinical Research Center Project of the Department of Science and Technology of Guizhou Province (No. (2017)5405); the Youth Fund of Guizhou Provincial People’s Hospital (GZSYQN(2019)19).
Disclaimer The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.
Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.