Bipolar radiofrequency ablation of refractory ventricular arrhythmias: results from a multicentre network.

AIMS: Advanced ablation strategies are needed to treat ventricular tachycardia (VT) and premature ventricular complexes (PVC) refractory to standard unipolar radiofrequency ablation (Uni-RFA). Bipolar radiofrequency catheter ablation (Bi-RFA) has emerged as a treatment option for refractory VT and PVC. Multicentre registry data on the use of Bi-RFA in the setting of refractory VT and PVC are lacking. The aim of this Bi-RFA registry is to determine its real-world safety, feasibility, and efficacy in patients with refractory VT/PVC. METHODS AND RESULTS: Consecutive patients undergoing Bi-RFA at 16 European centres for recurring VT/PVC after at least one standard Uni-RFA were included. Second ablation catheter was used instead of a dispersive patch and was positioned at the opposite site of the ablation target. Between March 2021 and August 2024, 91 patients underwent 94 Bi-RFA procedures (74 males, age 62 ± 13, and prior Uni-RFA range 1-8). Indications were recurrence of PVC (n = 56), VT (n = 20), electrical storm (n = 13), or PVC-triggered ventricular fibrillation (n = 2). Procedural time was 160 ± 73 min, Bi-RFA time 426 ± 286 s, and mean Uni-RFA time 819 ± 697 s. Elimination of clinical VT/PVC was achieved in 67 (74%) patients and suppression of VT/PVC in a further 10 (11%) patients. In the remaining 14 patients (15%), no effect on VT/PVC was observed. Three major complications occurred: coronary artery occlusion, atrioventricular block, and arteriovenous fistula. Follow-up lasted 7 ± 8 months. Nineteen patients (61%) remained VT free. ≥80% PVC burden reduction was achieved in 45 (78%). CONCLUSION: These real-world registry data indicate that Bi-RFA appears safe, is feasible, and is effective in the majority of patients with VT/PVC.

Impact of preventive substrate catheter ablation on implantable cardioverter-defibrillator interventions in patients with ischaemic cardiomyopathy and infarct-related coronary chronic total occlusion.

AIMS: Primary prevention patients with ischaemic cardiomyopathy and chronic total occlusion of an infarct-related coronary artery (CTO) are at a particularly high risk of implantable cardioverter-defibrillator (ICD) therapy occurrence. The trial was designed to evaluate the efficacy of preventive CTO-related substrate ablation strategy in ischaemic cardiomyopathy patients undergoing primary prevention ICD implantation. METHODS AND RESULTS: The PREVENTIVE VT study was a prospective, multicentre, randomized trial including ischaemic patients with ejection fraction ≤40%, no documented ventricular arrhythmias (VAs), and evidence of scar related to the coronary CTO. Patients were randomly assigned 1:1 to a preventive substrate ablation before ICD implantation or standard therapy with ICD implantation only. The primary outcome was a composite of appropriate ICD therapy or unplanned hospitalization for VAs. Secondary outcomes included the primary outcome's components, the incidence of appropriate ICD therapies, cardiac hospitalization, electrical storm, and cardiovascular (CV) mortality. Sixty patients were included in the study. During the mean follow-up of 44.7 ± 20.7 months, the primary outcome occurred in 5 (16.7%) patients undergoing preventive substrate ablation and in 13 (43.3%) patients receiving only ICD [hazard ratio (HR): 0.33; 95% confidence interval (CI): 0.12-0.94; P = 0.037]. Patients in the preventive ablation group also had fewer appropriate ICD therapies (P = 0.039) and the electrical storms (Log-rank: P = 0.01). While preventive ablation also reduced cardiac hospitalizations (P = 0.006), it had no significant impact on CV mortality (P = 0.151). CONCLUSION: Preventive ablation of the coronary CTO-related substrate in patients undergoing primary ICD implantation is associated with the reduced risk of appropriate ICD therapy or unplanned hospitalization due to VAs.

Assessment of Esophageal Shifts during Catheter Ablation of Atrial Fibrillation Using Intracardiac Ultrasound Integrated with 3-Dimensional Electroanatomical Mapping System.

Purpose: Atrioesophageal fistula is one of the most feared complications of radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) as it is associated with high mortality. Determining the esophagus location during RFCA might reduce the risk of esophageal injury. The present study aims to evaluate the feasibility of using intracardiac echocardiography integrated into a 3-dimensional electroanatomical mapping system (ICE/3D EAM) for the assessment of esophageal position and shifts in response to ablation. Methods: We prospectively enrolled 20 patients that underwent RFCA of AF under conscious analgosedation. The virtual anatomy of the left atrium, the pulmonary vein (PV) ostia, and the esophagus was created with ICE/3D EAM. The esophageal positions were obtained at the beginning of the procedure and then after left and right PV isolation (PVI). Esophageal shifts were measured offline after the procedure using the tools available in the 3D EAM system. Results: Most esophagi moved away from the ablated PV ostia. After the left PVI, the median of the shifts was 2.8 mm (IQR 1.0-6.3). In 25% of patients, the esophagus shifted by >5.0 mm (max. 13.4 mm). After right PVI, the median of shifts was 2.0 mm (IQR 0.7-4.9). In 10% of patients, the esophageal shift was >5.0 mm (max. 7.8 mm). Conclusions: ICE/3D EAM enables the intraprocedural visualization of baseline esophageal position and its shifts after PVI. The shifts are variable, but they tend to be small and directed away from the ablation site. Repeated intraprocedural visualization of the esophagus may be needed to reduce the risk of esophageal injury.

How Imaging Techniques Improve Ventricular Arrhythmia Ablation: A Multimodality-Based Approach.

Although implantable cardioverter defibrillators offer the best protection against sudden cardiac death, catheter ablation for ventricular arrhythmias (VAs) can modify or prevent this event from occurring. In order to achieve a successful ablation, the correct identification of the underlying arrhythmogenic substrate is mandatory to tailor the pre-procedural planning of an ablative procedure as appropriately as possible. We propose that several of the imaging modalities currently used could be merged, including echocardiography (also intracardiac), cardiac magnetic resonance, cardiac computed tomography, nuclear techniques, and electroanatomic mapping. The aim of this state-of-the-art review is to present the value of each modality, that is, its benefits and limitations, in the assessment of arrhythmogenic substrate. Moreover, VAs can be also idiopathic, and in this paper we will underline the role of these techniques in facilitating the ablative procedure. Finally, a hands-on workflow for approaching such a VA and future perspectives will be presented.

Zero fluoroscopy catheter ablation for atrial fibrillation: a systematic review and meta-analysis.

Introduction: Catheter ablation for atrial fibrillation (AF) is the most frequently performed cardiac ablation procedure worldwide. The majority of ablations can now be performed safely with minimal radiation exposure or even without the use of fluoroscopy, thanks to advances in 3-dimensional electroanatomical mapping systems and/or intracardiac echocardiography. The aim of this study was to conduct a meta-analysis to compare the effectiveness of zero fluoroscopy (ZF) versus non-zero fluoroscopy (NZF) strategies for AF ablation procedures. Methods: Electronic databases were searched and systematically reviewed for studies comparing procedural parameters and outcomes of ZF vs. NZF approaches in patients undergoing catheter ablation for AF. We used a random-effects model to derive the mean difference (MD) and risk ratios (RR) with a 95% confidence interval (CI). Results: Our meta-analysis included seven studies comprising 1,593 patients. The ZF approach was found to be feasible in 95.1% of patients. Compared to the NZF approach, the ZF approach significantly reduced procedure time [mean difference (MD): -9.11 min (95% CI: -12.93 to -5.30 min; p < 0.01)], fluoroscopy time [MD: -5.21 min (95% CI: -5.51 to -4.91 min; p < 0.01)], and fluoroscopy dose [MD: -3.96 mGy (95% CI: -4.27 to -3.64; p < 0.01)]. However, there was no significant difference between the two groups in terms of total ablation time [MD: -104.26 s (95% CI: -183.37 to -25.14; p = 0.12)]. Furthermore, there was no significant difference in the acute [risk ratio (RR): 1.01, 95% CI: 1.00-1.02; p = 0.72] and long-term success rates (RR: 0.96, 95% CI: 0.90-1.03; p = 0.56) between the ZF and NZF methods. The complication rate was 2.76% in the entire study population and did not differ between the groups (RR: 0.94, 95% CI: 0.41-2.15; p = 0.89). Conclusion: The ZF approach is a feasible method for AF ablation procedures. It significantly reduces procedure time and radiation exposure without compromising the acute and long-term success rates or complication rates.

Performance of the ablation index during pulmonary vein isolation: periprocedural data from a multicenter registry.

PURPOSE: Our study aimed to assess the achievement of target ablation index (AI) values and their impact on first-pass pulmonary vein isolation (FPI) as well as to identify FPI predictors. METHODS: Atrial fibrillation (AF) ablation was performed according to the local practice, and target AIs were evaluated. The actual AI was calculated as the median value of all ablation points for the anterior and posterior left atrial (LA) walls. RESULTS: A total of 450 patients from nine centers were enrolled. Patients with first-time ablation (n = 408) were divided into the FPI and non-FPI groups. In the FPI group, a higher median target AI was reported for both the anterior and posterior LA walls than those in the non-FPI group. A higher actual AI was observed for the anterior LA wall in the FPI group. The actual AI was equal to or higher than the target AI for the posterior, anterior, and both LA walls in 54%, 47%, and 35% (n = 158) cases, respectively. Parameters such as hypertension, stroke, ablation power, actual AI value on the anterior wall, target AI values on both LA walls, AI achievement on the posterior wall, carina ablation, and operator experience were all associated with FPI in a univariate logistic regression model; only carina ablation was an independent predictor of FPI. CONCLUSIONS: According to our multicenter study, FPI and a target AI were not achieved in a significant proportion of AF ablation procedures. Higher actual and target AI values were associated with FPI, but only carina ablation can independently predict FPI.

Conventional fluoroscopy-guided versus zero-fluoroscopy catheter ablation of supraventricular tachycardias.

PURPOSE: The aim of this study was to evaluate the safety and efficacy of zero-fluoroscopy (ZF) catheter ablation (CA) for supraventricular tachycardias (SVT). METHODS: 584 consecutive patients referred to our institution for CA of SVT were analysed. Patients were categorised into two groups; zero-fluoroscopy (ZF) group and conventional fluoroscopy (CF) group. The ZF group was further divided into two subgroups (adults and paediatric). Patient characteristics, procedural information, and follow-up data were compared. RESULTS: The ZF group had a higher proportion of paediatric patients (42.2% vs 0.0%; p < 0.001), resulting in a younger age (30.9 ± 20.3 years vs 52.7 ± 16.5 years; p < 0.001) and lower BMI (22.8 ± 5.7 kg/m2 vs 27.0 ± 5.4 kg/m2; p < 0.001). Procedure time was shorter in the ZF group (94.2 ± 50.4 min vs 104.0 ± 54.0 min; p = 0.002). There were no major complications and the rate of minor complications did not differ between groups (0.0% vs 0.4%; p = 0.304). Acute procedural success as well as the long-term success rate when only the index procedure was considered did not differ between groups (92.5% vs 95.4%; p = 0.155; 87.1% vs 89.2%; p = 0.422). When repeated procedures were included, the long-term success rate was higher in the ZF group (98.3% vs 93.5%; p = 0.004). The difference can be partially explained by the operators' preferences. CONCLUSION: The safety and efficacy of ZF procedures in adult and paediatric populations are comparable to that of CF procedures.

Biventricular versus His bundle pacing after atrioventricular node ablation in heart failure patients with narrow QRS.

Background: His bundle pacing (HBP) is a physiological alternative to biventricular (BiV) pacing. We compared short-term results of both pacing approaches in symptomatic atrial fibrillation (AF) patients with moderately reduced left ventricular (LV) ejection fraction (EF ≥35% and <50%) and narrow QRS (≤120 ms) who underwent atrioventricular node ablation (AVNA).Methods: Thirty consecutive AF patients who received BiV pacing or HBP in conjunction with AVNA between May 2015 and January 2020 were retrospectively assessed. Electrocardiographic, echocardiographic, and clinical data at baseline and 6 months after the procedure were assessed.Results: Twenty-four patients (age 68.8 ± 6.5 years, 50% female, EF 39.6 ± 4%, QRS 95 ± 10 ms) met the inclusion criteria, 12 received BiV pacing and 12 HBP. Both groups had similar acute procedure-related success and complication rates. HBP was superior to BiV pacing in terms of post-implant QRS duration, implantation fluoroscopy times, reduction of indexed LV volumes (EDVi 63.8 (49.6-81) mL/m2 vs. 79.9 (66-100) mL/m2, p = 0.055; ESVi 32.7 (25.6-42.6) mL/m2 vs. 46.4 (42.9-68.1) mL/m2, p = 0.009) and increase in LVEF (46 (41-55) % vs. 38 (35-42) %, p = 0.005). However, the improvement of the NYHA class was similar in both groups.Conclusions: In symptomatic AF patients with moderately reduced EF and narrow QRS undergoing AVNA, HBP could be a conceivable alternative to BiV pacing. Further prospective studies are warranted to address the outcomes between both 'ablate and pace' strategies.

Independent factors of low radiation dose during atrial fibrillation ablation with cryoballoon or radiofrequency: Results from the "Go for zero fluoroscopy" registry.

AIMS: Atrial fibrillation (AF) catheter ablation is a common procedure requiring in most cases the use of fluoroscopy. We aimed to evaluate the factors associated with a lower dose of fluoroscopy used during AF ablation with cryoballoon or radiofrequency. METHODS: In this prospective European registry, centers were requested to provide procedural characteristics of consecutive AF ablation cases. Lower doses of fluoroscopy were defined as those with dose-area-product (DAP) under the median dose used in the radiofrequency and the cryoballoon ablation groups. RESULTS: A total of 638 AF ablation procedures were collected (n = 492 for radiofrequency and n = 146 for cryoballoon ablation groups) in 25 centers. The median [IQR] DAP were 926 [349;2092] and 1516 [418;3408] cGy*cm2 in the radiofrequency and cryoballoon groups, respectively. Main factors associated with lower DAP in cryoballoon ablation group were electrophysiology dedicated laboratory (OR 6.04, 95%CI 1.16-31.54; P = .03) and frequent dosimetry report (OR 21.39, 95%CI 5.43-98.54; P = .03). Main factors associated with lower DAP in the radiofrequency ablation group were the use of a chest dosimeter (OR 12.57, 95% CI 2.88-54.90; P = .01), biplane X-ray equipment (OR 3.12, 95%CI 1.89-5.16; P < .01), university hospital (OR 2.10, 95%CI 1.35-3.25; P = .01), electrophysiology dedicated laboratory (OR 2.45, 95%CI 1.48-4.05; P < .01) and use of contact force enabled catheter (OR 22.60, 95%CI 6.82-74.88; P < .01). CONCLUSION: This real-life study of fluoroscopy use during AF ablation provides new data about current practices across European countries. Technological advances and quality of the fluoroscopic environment were the main factors associated with lower radiation dose during AF ablation.

Integrated 3D intracardiac ultrasound imaging with detailed pulmonary vein delineation guided fluoroless ablation of atrial fibrillation.

BACKGROUND: Intracardiac echocardiography (ICE) has become an all-round tool for ablation of atrial fibrillation (AF) since it plays an important role in all procedural steps. The key upgrade to the usefulness of ICE is its integration into three-dimensional (3D) electroanatomic mapping (EAM) system (ICE/EAM automatic integration system). The aim of this single-center retrospective study was to evaluate feasibility, safety and acute efficacy of ICE/EAM automatic integration system guided fluoroless ablation of AF. METHODS: The study included patients with symptomatic paroxysmal or persistent AF undergoing first pulmonary vein isolation (PVI) radiofrequency (RF) catheter ablation (RFCA) from September 2017 to August 2020. All procedures were performed without the use of fluoroscopy. A detailed 3D virtual anatomy of the left atrium (LA) and structures relevant to AF ablation was constructed from ultrasound contours obtained with ICE probe inside the LA. Pulmonary veins (PVs) and antral regions were additionally mapped with fast anatomical mapping (FAM). PVI was performed with contact force (CF) sensing catheter. Procedural endpoint was successful PVI. RESULTS: A total of 98 consecutive patients underwent RFCA (34.7% females, median age 64.4 years, 64.3% paroxysmal AF). Acute PVI was achieved in all patients (100%). Forty-three patients (43.9%) underwent additional ablations for concomitant arrhythmias. Adverse events were detected in four patients (4.1%). The median procedure duration was 130 min (IQR 103.8-151.3). If only PVI was done the median procedure duration was 110.5 (IQR 100.0-133.8) CONCLUSIONS: ICE/EAM automatic integration system guided fluoroless ablation of AF is feasible, safe and acutely effective method for treatment of symptomatic AF.

Intracardiac echocardiography-guided transseptal puncture for fluoroless catheter ablation of left-sided tachycardias.

BACKGROUND: Integration of intracardiac echocardiography (ICE) and 3D electroanatomic mapping (EAM) system allows transseptal punctures (TSP) without the use of fluoroscopy. Compared with fluoroscopy, ICE provides better visualization of the anatomy relevant to TSP and early recognition of complications. The aim was to evaluate efficacy and safety of entirely ICE-guided TSPs in patients who underwent fluoroless catheter ablation of left-sided tachycardias. METHODS: Consecutive 524 adult and pediatric patients referred to our institution from July 2014 to December 2019 were analyzed. Patients with cardiac implantable electronic devices (CIEDs) were also included. All procedures were performed with ICE-guided TSP combined with 3D EAM. Adverse events following TSP and within 30 days of the procedure were analyzed. RESULTS: Altogether 949 TSPs (363 double punctures, 76.5%) were performed in 586 fluoroless ablation procedures: 451 (77%) were ablation of atrial fibrillation or atypical flutter, 75 (12.8%) of left-sided accessory pathway, 33 (5.6%) of ventricular tachycardia, and 27 (4.6%) of focal atrial tachycardia. Forty-six (7.8%) procedures were performed in pediatric population and 36 procedures (6.1%) in patients with CIED. Only 2 TSPs were unsuccessful (2/949, 0.2%). Overall procedural complication rate was 1.9% (11/586 procedures). There was only 1 TSP-related pericardial tamponade (2/949, 0.2%). In CIED patients, there was 1 lead dislocation following TSP. CONCLUSIONS: Entirely ICE-guided TSPs for different left-sided tachycardias can be safely and effectively performed in adult and pediatric population without the use of fluoroscopy. However, caution is advised in CIED patients due to possible lead dislocation risk.

Role of wearable rhythm recordings in clinical decision making-The wEHRAbles project.

BACKGROUND: Multiple wearable devices for rhythm analysis have been developed using either photoplethysmography (PPG) or handheld ECG. HYPOTHESIS: The aim of this survey was to assess impact of these technologies on physicians' clinical decision-making regarding initiation of diagnostic steps, drug therapy, and invasive strategies. METHODS: The online survey included 10 questions on types of devices, advantages, and disadvantages of wearable devices as well as case scenarios for patients with supraventricular arrhythmias and atrial fibrillation (AF). RESULTS: A total of 417 physicians (median age 37 [IQR 32-43] years) from 42 countries world-wide completed the survey. When presented a tracing of a regular tachycardia by a symptomatic patient, most participants would trigger further diagnostic steps (90% for single-lead ECG vs 83% for PPG, P < .001), while a single-lead ECG would be sufficient to perform an invasive EP study in approximately half of participants (51% vs 22% for PPG, P < .001). When presented with a single-lead ECG tracing suggesting AF, most participants (90%) would trigger further diagnostic steps. A symptomatic AF patient would trigger anticoagulation treatment to a higher extent as an asymptomatic patient (59% vs 21%, P < .001). PPG tracings would only rarely lead to therapeutic steps regardless of symptoms. Most participants would like scientific society recommendations on the use of wearable devices (62%). CONCLUSIONS: Tracings from wearable rhythm devices suggestive of arrhythmias are most likely to trigger further diagnostic steps, and in the case of PPG recordings rarely therapeutic interventions. A majority of participants expect these devices to facilitate diagnostics and arrhythmia screening but fear data overload and expect scientific society recommendations on the use of wearables.

Occupational inhalation poisoning with the veterinary antibiotic tiamulin.

Introduction: Tiamulin is a semisynthetic pleuromutilin diterpene veterinary antibiotic, widely used in farms. We present a case of prolonged QT-interval and ventricular tachyarrhythmia after tiamulin inhalation.Case presentation: A 43-year-old veterinarian without previous medical history was dividing granulated powder of antibiotic gravimetrically without wearing personal protective equipment. Half an hour after exposure, nausea occurred; four hours later he started to vomit and soon after that he experienced syncope. He was unconscious three minutes; afterwards he became somnolent, dizzy and nauseated with sweating and salivation. On admission to hospital five hours after exposure, he was conscious and had heart rate 70 beats/min and blood pressure 140/80 mmHg. Initial laboratory results were normal. Electrocardiography showed a prolonged QTc-interval of 730 ms with numerous polymorphic ventricular extrasystoles and episodes of non-sustained polymorphic ventricular tachycardia that resolved after treatment with lidocaine and magnesium. Subsequent electrocardiography revealed gradual shortening of QTc-interval with QTc-interval normalization (430 ms) between 24 and 32 hours after tiamulin exposure. Laboratory tests, morphologic heart diagnostics and genetic testing excluded other potential causes of QTc-interval prolongation. Subsequent toxicology analysis by LC-MS/MS confirmed tiamulin in his serum samples on admittance (500 ng/mL).Conclusion: Tiamulin inhalation can be associated with prolonged QT-interval and ventricular tachyarrhythmia. QT-interval prolongation could be expected in overdoses of emerging human pleuromutilins.

Combined use of electro-anatomic mapping system and intracardiac echocardiography to achieve zero-fluoroscopy catheter ablation for treatment of paroxysmal atrial fibrillation: a single centre experience.

Fluoroscopy is the principal imaging method for catheter ablation (CA) of atrial fibrillation (AF). However, radiation exposure carries potential health risk to patients and operators alike. Our aim was to study safety and efficacy of zero-fluoroscopy CA of paroxysmal AF with a combined use of electroanatomic mapping system (EAM) and intracardiac echocardiography (ICE). In addition, impact of ICE/EAM automatic integration system and contact force (CF) sensing technology on procedural times were assessed. We included 144 consecutive patients (69% males, age 60 ± 10 years, BMI 29 ± 4,6) referred for CA of symptomatic paroxysmal AF. All procedures were performed only with EAM system and ICE. No fluoroscopy was used. The acute procedural success of complete pulmonary vein isolation was achieved in all patients (100%) and adverse events were detected in eight patients (5.6%). In 53 (37%) patients the use of ICE/EAM automatic integration system shortened procedural times compared to those performed without it (148 ± 35 vs. 187 ± 44 min, p < 0.05). Similarly, 89 (60%) procedures where CF sensing catheter was used were shorter compared to those performed without it (163 ± 41 vs. 188 ± 46 min, p < 0.05). Zero-fluoroscopy approach for treatment of paroxysmal AF seems feasible, safe, and acutely effective. Additional reduction of procedural times could be achieved with the use of ICE/EAM automatic integration system and CF sensing technology.

Repolarization heterogeneity in patients with cardiac resynchronization therapy and its relation to ventricular tachyarrhythmias.

BACKGROUND: Cardiac resynchronization therapy (CRT) has been shown to induce left ventricular reverse remodeling, but little is known about its influence on ventricular repolarization. OBJECTIVE: The purpose of this study was to evaluate changes in ventricular repolarization of native conduction after CRT and its relation to ventricular tachycardia (VT) and ventricular fibrillation (VF) during long-term follow-up. METHODS: We prospectively included 64 patients with heart failure treated with CRT. QT interval, TpTe, and TpTe/QT ratio were analyzed from 20-minute high-resolution ECGs that were recorded at baseline and 1, 3, 6, 9, and 12 months after CRT implantation. CRT was temporary inhibited during follow-up to record intrinsic ECG. Patients with a decrease of left ventricular end-systolic volume ≥15% at 12-month follow-up (mid-term follow-up) were considered as responders. Occurrences of VT/VF during follow-up were noted. RESULTS: Significant increase of repolarization heterogeneity in the first months after implantation was observed (P <.05) but then declined during 12 months of follow-up. Patients with VT/VF during long-term follow-up had higher repolarization heterogeneity at mid-term follow-up than patients without VT/VF (TpTe/QT ratio: 0.263 [0.204-0.278] vs 0.225 [0.204-0.239]; P = .045). Echocardiographic response at mid-term follow-up did not significantly influence the rate of VT/VF (log-rank P = .252). In multivariate Cox regression analysis, only high repolarization heterogeneity at mid-term follow-up (TpTe/QT ratio >0.260) was independently associated with high risk of VT/VF (hazard ratio 4.29; 95% confidence interval 1.40-13.15; P = .011). CONCLUSION: CRT induces time-dependent changes in repolarization parameters in the first year after implantation. High repolarization heterogeneity at mid-term follow-up was associated with higher rate of VT/VF during long-term follow-up.

The tip of the muscle is a dominant location of ventricular ectopy originating from papillary muscles in the left ventricle.

INTRODUCTION: Frequent ventricular premature complexes (VPCs) may cause symptoms and/or lead to deterioration of LV systolic function. Although frequent VPCs may be abolished by catheter ablation, it may be challenging in case of their origin from the LV papillary muscles (PMs). Our collaborative study aimed to analyze in detail the site of origin and the outcome of ablation. METHODS: Consecutive 34 patients (males: 68%; aged 62 ± 12 years; LV ejection fraction: 50 ± 9%) undergoing catheter ablation of VPCs originating from PMs were included. All procedures were guided by intracardiac echocardiography. RESULTS: The size and shape of PMs were highly variable. The length of anterolateral and posteromedial PM was 23 ± 4 mm and 28 ± 7 mm, respectively. In about one-third of patients, the PM was formed by two distinctly separate heads. The ectopic foci were located on anterolateral, posteromedial or both PM in 35%, 56% and 9% of cases, respectively. Their location was found within the distal, mid, or proximal (basal) third of PM in the 67%, 19%, and 14%, respectively. A total of 86% of PM foci were acutely abolished and long-term success was achieved in 65% of patients. Absence of VPCs of other morphologies and a high burden of ectopic activity before ablation were associated with favorable clinical outcome. CONCLUSION: VPCs originate predominantly from the distal portion of the PM. This knowledge may facilitate the mapping in patients with infrequent ectopic beats. Intracardiac echocardiography is of crucial importance for navigation of the ablation catheter and for assessment of its stability at PM target sites.