Bi-atrial characterization of the electrical substrate in patients with atrial fibrillation.

BACKGROUND: Little is known regarding the characterization of electrical substrate in both atria in patients with atrial fibrillation (AF). METHODS: Eight consecutive patients undergoing AF ablation (five paroxysmal, three persistent) underwent electrical substrate characterization during sinus rhythm. Mapping of the left (LA) and right atrium (RA) was performed with the use of the HD Grid catheter (Abbott). Bipolar voltage maps were analyzed to search for low voltage areas (LVA), the following electrophysiological phenomena were assessed: (1) slow conduction corridors, and (2) lines of block. EGMs were characterized to search for fractionation. Electrical characteristics were compared between atria and between paroxysmal versus persistent AF patients. RESULTS: In the RA, LVAs were present in 60% of patients with paroxysmal AF and 100% of patients with persistent AF. In the LA, LVAs were present in 40% of patients with paroxysmal AF and 66% of patients with persistent AF. The areas of LVA in the RA and LA were 4.8±7.3 cm2 and 7.8±13.6 cm2 in patients with paroxysmal AF versus 11.7±3.0 cm2 and 2.1±1.8 cm2 in patients with persistent AF. In the RA, slow conduction corridors were present in 40.0% (paroxysmal AF) versus 66.7% (persistent AF) whereas in the LA, slow conduction corridors occurred in 20.0% versus 33.3% respectively (p = ns). EGM analysis showed more fractionation in persistent AF patients than paroxysmal (RA: persistent AF 10.8 vs. paroxysmal AF 4.7%, p = .036, LA: 10.3 vs. 4.1%, p = .108). CONCLUSION: Bi-atrial involvement is present in patients with paroxysmal and persistent AF. This is expressed by low voltage areas and slow conduction corridors whose extension progresses as the arrhythmia becomes persistent. This electrophysiological substrate demonstrates the important interplay with the pulmonary vein triggers to constitute the substrate for persistent arrhythmia.

Electrogram fractionation during sinus rhythm occurs in normal voltage atrial tissue in patients with atrial fibrillation.

INTRODUCTION: Electrogram (EGM) fractionation is often associated with diseased atrial tissue; however, mechanisms for fractionation occurring above an established threshold of 0.5 mV have never been characterized. We sought to investigate during sinus rhythm (SR) the mechanisms underlying bipolar EGM fractionation with high-density mapping in patients with atrial fibrillation (AF). METHODS: Forty-five patients undergoing AF ablation (73% paroxysmal, 27% persistent) were mapped at high density (18562 ± 2551 points) during SR (Rhythmia). Only bipolar EGMs with voltages above 0.5 mV were considered for analysis. When fractionation (> 40 ms and >4 deflections) was detected, we classified the mechanisms as slow conduction, wave-front collision, or a pivot point. The relationship between EGM duration and amplitude, and tissue anisotropy and slow conduction, was then studied using a computational model. RESULTS: Of the 45 left atria analyzed, 133 sites of EGM fragmentation were identified with voltages above 0.5 mV. The most frequent mechanism (64%) was slow conduction (velocity 0.45 m/s ± 0.2) with mean EGM voltage of 1.1 ± 0.5 mV and duration of 54.9 ± 9.4 ms. Wavefront collision was the second most frequent (19%), characterized by higher voltage (1.6 ± 0.9 mV) and shorter duration (51.3 ± 11.3 ms). Pivot points (9%) were associated with the highest degree of fractionation with 70.7 ± 6.6 ms and 1.8 ± 1 mV. In 10 sites (8%) fractionation was unexplained. The EGM duration was significantly different among the 3 mechanisms (p = .0351). CONCLUSION: In patients with a history of AF, EGM fractionation can occur at amplitudes > 0.5 mV when in SR in areas often considered not to be diseased tissue. The main mechanism of EGM fractionation is slow conduction, followed by wavefront collision and pivot sites.

Etiology is a predictor of recurrence after catheter ablation of ventricular arrhythmias in pediatric patients.

BACKGROUND: Ventricular arrhythmias (VAs) are rare in pediatric patients, especially in absence of structural heart disease (SHD). Few data are available regarding the invasive VAs treatment with catheter ablation (CA) in pediatric patients and predictors of outcomes have not been fully investigated. OBJECTIVE: To describe the clinical presentation, procedural characteristics, and outcomes in pediatric patients undergoing CA for VAs. METHODS: Eighty-one consecutive pediatric patients (58 male [72%], 15.5 ± 2.2 years) treated by CA for ventricular tachycardia (VT) or premature ventricular beats (PVBs) were retrospectively evaluated. Study endpoints were VAs recurrence and mortality for any cause. RESULTS: Ninety-five procedures were performed in 81 patients, 52 (55%) PVBs and 43 (45%) VT ablations. During a follow-up of 35.0 months (interquartile range = 13.0-71.0), 14 patients (14.7%) had a VA recurrence: 11 (33.3%) patients treated with CA for VT and 3 (6.2%) patients treated for PVBs (p < .001). One patient (1%) died 26 months after the procedure during an electrical storm. Patients with SHD had higher VAs recurrence rate, as compared with idiopathic VAs (pairwise log-rank p < .001). Patients treated with CA for VT had higher VA recurrence rate, as compared with PVB patients (pairwise log-rank p = .002). At Cox multivariate analysis only SHD was an independent predictor of VAs recurrence (hazard ratio = 5.56, 95% confidence interval = 2.68-11.54, p < .001). CONCLUSION: CA of VAs is effective and safe in a pediatric population. CA of idiopathic and fascicular VAs are associated with lower recurrence rate, than VAs in the setting of SHD.

Late potentials abolition reduces ventricular tachycardia recurrence after ablation especially in higher-risk patients with a chronic total occlusion in an infarct-related artery.

INTRODUCTION: Late potentials (LP) abolition is recognized as an effective strategy for substrate ablation of ventricular tachycardia (VT). The presence of a chronic total occlusion in a coronary artery responsible for a previous myocardial infarction (infarct related artery CTO, IRA-CTO) is emerging as a predictor of ventricular arrhythmias and VT recurrence after ablation. We sought to analyze the effects of LP abolition, focusing on the high-risk subgroup of patients with IRA-CTO. METHODS AND RESULTS: This was a single-center, observational study that screened all patients with prior myocardial infarction and clinical VT, referred for VT ablation at San Raffaele Hospital between 2010 and June 2013. Patients were then included in the study if they had a coronary diagnostic angiography (without revascularization) performed during the index hospitalization. The main endpoint was VT recurrence after ablation. Eighty-four patients formed the population of the study. An IRA-CTO was present in 47 patients (56%) and the presence of an IRA-CTO was a predictor of VT recurrence (HR 3.7, P = 0.005). LP were observed in 51 patients and successfully abolished in 38 cases. LP abolition was associated with lower VT recurrence especially among patients with IRA-CTO (24% vs. 65%, P = 0.005). The presence of an IRA-CTO, in combination with no LP abolition, was the strongest predictor of VT recurrence (HR 4.4, P < 0.001). CONCLUSIONS: Late potentials abolition is an effective strategy for substrate ablation of ventricular tachycardia. The additional reduction of VT recurrence achieved with LP abolition on top of noninducibility is especially significant among high-risk patients with IRA-CTO.

Road-Map to Epicardial Approach for Catheter Ablation of Ventricular Tachycardia in Structural Heart Disease: Results From a 10-Year Tertiary-Center Experience.

BACKGROUND: Epicardial approach in ventricular tachycardia (VT) ablation is still regarded as a second-step strategy, due to the risk of complications. We evaluated the frequency that epicardial ablation targets were identified and ablation performed following pericardial access compared with unnecessary pericardial access for different VT causes and potential markers of epicardial VT. METHODS: All VT ablation procedures including epicardial approach over a 10-year period were included. First-line epicardial approach was indicated in arrhythmogenic right ventricular cardiomyopathy (ARVC) and postmyocarditis VT; in patients with idiopathic dilated cardiomyopathy (IDCM) and postmyocardial infarction, indications resulted from available imaging techniques or 12-lead VT morphology. The epicardial approach was considered useful if epicardial ablation was performed after epicardial mapping. Feasibility, complications, and long-term outcome were reported. RESULTS: Four hundred and eighty-eight subjects with a median age of 60 years (interquartile range, 47-65) and of left ventricle ejection fraction 41% (interquartile range, 30-55) underwent 626 epicardial VT ablations. Percutaneous access had a success rate of 92.2% and a complication rate of 3.6%. Overall, epicardial approach was, respectively, indicated to 11.8% of postmyocardial infarction patients, 49.5% in IDCM, 94% in myocarditis, and 90.7% in ARVC. Epicardial ablation at the first ablation attempt was performed in 9.3% of postmyocardial infarction patients, 28.8% in IDCM, 86.5% in myocarditis, and 81.3% in patients with ARVC. In first-line epicardial group, ARVC and myocarditis showed the highest odds for epicardial ablation (OR, 4.057 [95% CI, 1.299-8.937]; P=0.007; OR, 3.971 [95% CI, 1.376-11.465]; P=0.005, respectively). IDCM independently predicted unnecessary epicardial approach (OR, 2.7 [95% CI, 1.7-4.3]; P<0.001). After a follow-up of 41 months (interquartile range, 19-64), patients with IDCM experienced higher rate of recurrences and mortality compared with other causes. CONCLUSIONS: Epicardial approach is integral part of ablation armamentarium regardless of the VT cause, with high feasibility and low complication rate in experienced centers. Our data support its use at first ablation attempt in VTs related to ARVC and myocarditis.

Transcatheter Ablation of Atrial Fibrillation in Patients With Hypertrophic Cardiomyopathy: A Multicenter Propensity Score-Based Analysis.

Background: The prognostic impact of catheter ablation (CA) of atrial fibrillation (AF) in hypertrophic cardiomyopathy (HCM) patients has not yet been satisfactorily elucidated. Objectives: The aim of the study was to assess the impact of CA of AF on clinical outcomes in a large cohort of HCM patients. Methods: In this retrospective multicenter study, 555 HCM patients with AF were enrolled, 140 undergoing CA and 415 receiving medical therapy. 1:1 propensity score matching led to the inclusion of 226 patients (113 medical group, 113 intervention group) in the final analysis. The primary outcome was a composite of all-cause mortality, heart transplant and acute heart failure exacerbations. Secondary outcomes included AF recurrence and transition to permanent AF. Additionally, an inverse probability weighted (IPW) model was examined. Results: At propensity score matching analysis, after a median follow-up of 58.1 months, the primary endpoint occurred in 29 (25.7%) patients in intervention group vs 42 (37.2%) in medical group (P = 0.9). Thromboembolic strokes and major arrhythmic events in intervention vs medical group were 9.7% vs 7.1% (P = 0.144) and 4.4 vs 8.0% (P = 0.779), respectively. Fewer patients in intervention vs medical group experienced AF recurrences (63.7% vs 84.1%, P = 0.001) and transition to permanent AF pattern (20.4% vs 33.6%, P = 0.026). IPW analysis showed consistent results. Severe complications related to CA were uncommon (0.7%). Conclusions: After 5 years of follow-up, CA did not improve major adverse cardiac outcomes in a large cohort of patients with HCM and AF. Nevertheless, CA seems to facilitate the maintenance of sinus rhythm and slow the progression to permanent AF, without significant safety concerns.

Late potentials abolition as an additional technique for reduction of arrhythmia recurrence in scar related ventricular tachycardia ablation.

RATIONALE: To evaluate the efficacy of radiofrequency ventricular tachycardia (VT) ablation targeting complete late potential (LP) activity. METHODS AND RESULTS: Sixty-four consecutive patients (pts) with recurrent VTs and coronary artery disease or idiopathic dilated cardiomyopathy were evaluated. Fifty patients (47 male; 66.2 ± 10.1 years) had LPs at electroanatomical mapping; 35 patients had at least 1 VT inducible at basal programmed stimulation. After substrate mapping, radiofrequency ablation was performed with the endpoint of all LPs abolition. LPs could not be abolished in 5 patients despite extensive ablation, in 1 patient because of localization near an apical thrombus, and in 2 patients because of possible phrenic nerve injury. At the end of procedure, prevention of VT inducibility was achieved in 25 of 35 patients (71.4%) with previously inducible VT; VT was still inducible in 5 of 8 patients with incomplete LP abolition; and in 5 of 42 patients (16.1%) with complete LP abolition (P < 0.01). After a follow-up of 13.4 ± 4.0 months, 10 patients (20.0%) had VT recurrences and one of them died after surgical VT ablation; VT recurrence was 9.5% in patients with LPs abolition (4/42 pts) and 75.0% (6/8 pts) in those with incomplete abolition [positive predictive value (PPV): 75%, negative predictive value (NPV): 90.4%, sensibility: 60.0%, and specificity: 95.0%, P < 0.0001); although it was 12.5% (5/40 pts) in patients without inducibility VT after the ablation, and 50% (5/10 pts) in those with inducible VT (PPV: 50%, NPV: 87.5%, sensitivity: 50.0%, and specificity: 87.5%, P = 0.008). CONCLUSIONS: LP abolition is an effective endpoint of VT ablation and its prognostic value compares favorably to that achieved by programmed electrical stimulation.

Physical activity volume in patients with arrhythmogenic cardiomyopathy is associated with recurrence after ventricular tachycardia ablation.

PURPOSE: To assess the role of intense physical activity (PA) on recurrence after ventricular tachycardia (VT) ablation in arrhythmogenic cardiomyopathy (ACM). METHODS: We retrospectively analyzed 63 patients with definite diagnosis of ACM who underwent to catheter ablation (CA) of VT. PA was quantified in METs per week by IPAQ questionnaire in 51 patients. VT-free survival time after ablation was analyzed by Kaplan-Meier's curves. RESULTS: The weekly amount of PA was higher in patients with VT recurrence (2303.1 METs vs 1043.5 METs, p = 0.042). The best cutoff to predict VT recurrence after CA was 584 METs/week (AUC = 0.66, sensibility = 85.0%, specificity = 45.2%). Based on this cutoff, 34 patients were defined as high level athletes (Hi-PA) and 17 patients as low-level athletes (Lo-PA). During a median follow-up of 32.0 months (11.5-65.5), 22 patients (34.9%) experienced VT recurrence. Lo-PA patients had a longer VT-free survival, compared with Hi-PA patients (82.4% vs 50.0%, log-rank p = 0.025). At Cox multivariate analysis, independent predictors of the VT recurrence were PA ≥ 584 METs/week (Hi-PA) (HR = 2.61, CI 95% 1.03-6.58, p = 0.04) and late potential (LP) abolition (HR = 0.38, CI 95% 0.16-0.89, p = 0.03). CONCLUSIONS: PA ≥ 584 METs/week and LP abolition were independent predictors of VT recurrence after ablation.

Long-Term Follow-Up of Catheter Ablation for Premature Ventricular Complexes in the Modern Era: The Importance of Localization and Substrate.

Background: Large-scale studies evaluating long-term recurrence rates in both idiopathic and non-idiopathic PVC catheter ablation (CA) patients have not been reported. Objective: To evaluate the efficacy and safety of idiopathic and non-idiopathic PVC CA, investigating the predictors of acute and long-term efficacy. Methods: This retrospective multicentric study included 439 patients who underwent PVC CA at three institutions from April-2015 to December-2021. Clinical success at 6 months' follow-up, defined as a reduction of at least 80% of the pre-procedural PVC burden, was deemed the primary outcome. The secondary aims of the study were: clinical success at the last available follow-up, predictors of arrhythmic recurrences at long-term follow-up, and safety outcomes. Results: The median age was 51 years, with 24.9% patients being affected suffering from structural heart disease. The median pre-procedural PVC burden was 20.1%. PVCs originating from the RVOT were the most common index PVC observed (29.1%), followed by coronary cusp (CC) and non-outflow tract (OT) LV PVCs (23.1% and 19.0%). The primary outcome at 6 months was reached in 85.1% cases, with a significant reduction in the 24 h% PVC burden (−91.4% [−83.4; −96.7], p < 0.001); long-term efficacy was observed in 82.1% of cases at almost 3-year follow-up. The presence of underlying structural heart disease and non-OT LV region origin (aHR 1.77 [1.07−2.93], p = 0.027 and aHR = 1.96 [1.22−3.14], p = 0.005) was independently associated with recurrences. Conclusion: CA of both idiopathic and non-idiopathic PVCs showed a very good acute and long-term procedural success rate, with an overall low complication. Predictors of arrhythmic recurrence at follow-up were underlying structural heart disease and non-OT LV origin.

Significance of abnormal and late ventricular signals in ventricular tachycardia ablation of ischemic and nonischemic cardiomyopathies.

BACKGROUND: Abnormal ventricular signals (AVS) are the cornerstone of substrate-based ventricular tachycardia (VT) ablation in sinus rhythm. Signal characterization of AVS in ischemic and nonischemic cardiomyopathies has never been performed. OBJECTIVE: The purpose of this study was to describe ventricular signal abnormalities in 3 different pathologies and examine their association with the diastolic component of VT circuits. METHODS: A total of 45 patients (15 ischemic cardiomyopathy [ICM], 15 arrhythmogenic cardiomyopathy [ACM], 15 dilated cardiomyopathy [DCM]) who had undergone VT ablation with >50% of the diastolic pathway of the VT circuit recorded were studied. AVS were classified into late potentials (LPs) and continuous fractionated ventricular signals (CFVS), and their characteristics and correlation with the diastolic pathway of VT circuits were analyzed. RESULTS: Seventy-five VT circuits were analyzed. Bipolar scars were greatest in ICM endocardially (53 cm2 ICM vs 36 cm2 ACM vs 25 cm2 DCM; P = .010) and in ACM epicardially (98 cm2 ACM vs 25 cm2 ICM vs 24 cm2 DCM; P = .005). Location of the VT diastolic interval coincided with AVS location in 54% of VTs in ICM, 89% in ACM, and 72% in DCM (P = .036). There was a trend toward a greater association of diastolic intervals coinciding with LPs than with CFVS (78% vs 57%; P = .052) (69% diastolic intervals in ICM coincided with LPs, 33% with CFVS; P = .063). All patients (100%) with CFVS in ACM had VT diastolic components arising from CFVS (33% ICM, 64% DCM; P = .049). Positive predictive value for LPs vs CFVS was 77.8% vs 56.7%, and sensitivity was 67.3% vs 32.7%, respectively. CONCLUSION: The nature of abnormal signals in different cardiomyopathies reflects underlying pathology. LPs rather than CFVS seem to be more linked to diastolic components of VT circuits, especially in ICM. LPs have greater sensitivity and specificity for VT; however, CFVS may be of more relevance in ACM.

Patients with Cardiac Implantable Electronic Device Undergoing Radiation Therapy: Insights from a Ten-Year Tertiary Center Experience.

BACKGROUND: The number of patients with cardiac implantable electronic devices (CIEDs) receiving radiotherapy (RT) is increasing. The management of CIED-carriers undergoing RT is challenging and requires a collaborative multidisciplinary approach. AIM: The aim of the study is to report the real-world, ten-year experience of a tertiary multidisciplinary teaching hospital. METHODS: We conducted an observational, real-world, retrospective, single-center study, enrolling all CIED-carriers who underwent RT at the San Raffaele University Hospital, between June 2010 and December 2021. All devices were MRI-conditional. The devices were programmed to an asynchronous pacing mode for patients who had an intrinsic heart rate of less than 40 beats per minute. An inhibited pacing mode was used for all other patients. All tachyarrhythmia device functions were temporarily disabled. After each RT session, the CIED were reprogrammed to the original settings. Outcomes included adverse events and changes in the variables that indicate lead and device functions. RESULTS: Between June 2010 and December 2021, 107 patients were enrolled, among which 63 (58.9%) were pacemaker carriers and 44 (41.1%) were ICD carriers. Patients were subjected to a mean of 16.4 (±10.7) RT sessions. The most represented tumors in our cohort were prostate cancer (12; 11%), breast cancer (10; 9%) and lung cancer (28; 26%). No statistically significant changes in device parameters were recorded before and after radiotherapy. Generator failures, power-on resets, changes in pacing threshold or sensing requiring system revision or programming changes, battery depletions, pacing inhibitions and inappropriate therapies did not occur in our cohort of patients during a ten-year time span period. Atrial arrhythmias were recorded during RT session in 14 patients (13.1%) and ventricular arrhythmias were observed at device interrogation in 10 patients (9.9%). CONCLUSIONS: Changes in device parameters and arrhythmia occurrence were infrequent, and none resulted in a clinically significant adverse event.

Long-term results of thoracoscopic ablation of paroxysmal atrial fibrillation: is the glass half full or half empty?

OBJECTIVES: Previous series showed the outcomes of thoracoscopic ablation of stand-alone symptomatic paroxysmal atrial fibrillation (AF) for up to 7 years of follow-up. The goal of this study was to assess the long-term durability of surgical pulmonary vein isolation (PVI) beyond 7 years. METHODS: Fifty consecutive patients {mean age 55 [standard deviation (SD): 11.2] years, previous catheter ablation in 56%, left ventricular ejection fraction 60% (SD: 4.6), left atrium volume 65 ml (SD: 17)} with stand-alone symptomatic paroxysmal AF underwent PVI through bilateral thoracoscopy ablation between 2005 and 2014. The CHA2DS2-VASc score was ≥2 in 12 patients (24%). RESULTS: No hospital deaths occurred. At hospital discharge all patients but 1 (2%) were in sinus rhythm (SR). Follow-up was 100% complete [mean 8.4 years (SD: 2.3), max 15]. The 8-year cumulative incidence function of AF recurrence, with death as a competing risk, on or off class I/III antiarrhythmic drugs (AADs)/electrocardioversion/re-transcatheter ablation (TCA) was 20% (SD: 5; 95% confidence interval: 10, 32); and off class I/III AADs/electrocardioversion/re-TCA was 52% (SD: 7; 95% confidence interval: 0.83, 8.02). At 8 years, the predicted prevalence of patients in SR was 87% and 53% were off class I/III AADs/electrocardioversion/re-TCA. The recurrent arrhythmia was AF in all patients except 2, who had atypical atrial flutter (4%). No predictors of AF recurrence were identified. At the last follow-up, 76% of the patients showed European Heart Rhythm Association class I. No strokes or thromboembolic events were documented and 76% of the subjects were off anticoagulation therapy. CONCLUSIONS: Despite a considerable AF recurrence rate, our single-centre, long-term outcome of surgical PVI showed encouraging data, with the majority of patients remaining in SR, although many of them were on antiarrhythmic therapy.

Heart-team hybrid approach to persistent atrial fibrillation with dilated atria: the added value of continuous rhythm monitoring.

OBJECTIVES: To assess by a continuous implantable rhythm monitoring (ILR) the mid-term outcomes of a staged-hybrid approach for patients with persistent/long-standing persistent atrial fibrillation (AF) and dilated atria. METHODS: Fifty patients [age 57 (standard deviation, SD: 8.3), previous catheter ablation 66%, AF history 6.5 (2-12) years, left ventricular ejection fraction 56 (SD: 7.9)%, left atrial volume index 44 (38-56) ml/m2] with persistent (44%) or long-standing persistent (56%) AF, underwent a 2-staged hybrid ablation (thoracoscopic epicardial procedure with Cobra-Fusion system and transcatheter Rhythmia mapping with endocardial touch-up of gaps). All patients received an ILR. RESULTS: No hospital deaths and no stroke occurred. Follow-up was 98% complete [median 22 (11-34) months]. The 2-year arrhythmia-free survival off class I-III antiarrhythmic drugs/electrical cardioversion/redo catheter ablation and the arrhythmia control (maintenance of sinus rhythm with or without antiarrhythmic drugs/electrical cardioversion) were 65 (SD: 7.1)% and 82 (SD: 5.8)%, respectively. The occurrence of AF in the blanking period was identified as an independent predictor of AF recurrence (odds ratio 26.6, 95% confidence interval 5.3, 132.3; P < 0.001). At longitudinal analysis, the predicted prevalence of sinus rhythm and sinus rhythm off class I-III antiarrhythmic drugs/electrical cardioversion/redo catheter ablation was 82% and 69% at 2 years, respectively. Among patients with recurrence, 50% had short-lasting asymptomatic episodes, identified only by ILR monitoring. The proportion of patients with AF burden ≤1% was 82% and 91% at 1 and 2 years, respectively, and in these cases, left atrial volume index decreased from 46 (SD: 12) ml/m2 to 41 (SD: 11) ml/m2 (P = 0.026). CONCLUSIONS: A staged hybrid approach yields promising results in selected patients with persistent/long-standing persistent AF and dilated left atrium who are at very high risk of AF recurrence. The use of ILR in this setting should become a standard to optimize patient management.

Check the Need-Prevalence and Outcome after Transvenous Cardiac Implantable Electric Device Extraction without Reimplantation.

BACKGROUND: after transvenous lead extraction (TLE) of cardiac implantable electric devices (CIEDs), some patients may not benefit from device reimplantation. This study sought to analyse predictors and long-term outcome of patients after TLE with vs. without reimplantation in a high-volume centre. METHODS: all patients undergoing TLE at our centre between January 2010 and November 2015 were included into this analysis. RESULTS: a total of 223 patients (median age 70 years, 22.0% female) were included into the study. Cardiac resynchronization therapy-defibrillator (CRT-D) was the most common device (40.4%) followed by pacemaker (PM) (31.4%), implantable cardioverter-defibrillator (ICD) (26.9%), and cardiac resynchronization therapy-PM (CRT-P) (1.4%). TLE was performed due to infection (55.6%), malfunction (35.9%), system upgrade (6.7%) or other causes (1.8%). In 14.8%, no reimplantation was performed after TLE. At a median follow-up of 41 months, no preventable arrhythmia-related events were documented in the no-reimplantation group, but 11.8% received a new CIED after 17-84 months. While there was no difference in short-term survival, five-year survival was significantly lower in the no-reimplantation group (78.3% vs. 94.7%, p = 0.014). CONCLUSIONS: in patients undergoing TLE, a re-evaluation of the indication for reimplantation is safe and effective. Reimplantation was not related to preventable arrhythmia events, but all-cause survival was lower.

Characterization of cardiac electrogram signals in atrial arrhythmias.

Despite significant advancements in 3D cardiac mapping systems utilized in daily electrophysiology practices, the characterization of atrial substrate remains crucial for the comprehension of supraventricular arrhythmias. During mapping, intracardiac electrograms (EGM) provide specific information that the cardiac electrophysiologist is required to rapidly interpret during the course of a procedure in order to perform an effective ablation. In this review, EGM characteristics collected during sinus rhythm (SR) in patients with paroxysmal atrial fibrillation (pAF) are analyzed, focusing on amplitude, duration and fractionation. Additionally, EGMs recorded during atrial fibrillation (AF), including complex fractionated atrial EGMs (CFAE), may also provide precious information. A complete understanding of their significance remains lacking, and as such, we aimed to further explore the role of CFAE in strategies for ablation of persistent AF. Considering focal atrial tachycardias (AT), current cardiac mapping systems provide excellent tools that can guide the operator to the site of earliest activation. However, only careful analysis of the EGM, distinguishing low amplitude high frequency signals, can reliably identify the absolute best site for RF. Evaluating macro-reentrant atrial tachycardia circuits, specific EGM signatures correspond to particular electrophysiological phenomena: the careful recognition of these EGM patterns may in fact reveal the best site of ablation. In the near future, mathematical models, integrating patient-specific data, such as cardiac geometry and electrical conduction properties, may further characterize the substrate and predict future (potential) reentrant circuits.

Long-Term Outcome After Ventricular Tachycardia Ablation in Nonischemic Cardiomyopathy: Late Potential Abolition and VT Noninducibility.

BACKGROUND: In patients with an ischemic cardiomyopathy (ICM), the combination of late potential (LP) abolition and postprocedural ventricular tachycardia (VT) noninducibility is known to be the desirable end point for a successful long-term outcome after VT ablation. We investigated whether LP abolition and VT noninducibilty have a similar impact on the outcomes of patients with non-ICMs (NICM) undergoing VT ablation. METHODS: A total of 403 patients with NICM (523 procedures) who underwent a VT ablation from 2010 to 2016 were included. The procedure end points were the LP abolition (if the LPs were absent, other ablation strategies were undertaken) and the VT noninducibilty. RESULTS: The underlying structural heart disease consisted of dilated cardiomyopathy (DCM, 49%), arrhythmogenic right ventricular dysplasia (ARVD, 17%), postmyocarditis (14%), valvular heart disease (8%), congenital heart disease (2%), hypertrophic cardiomyopathy (2%), and others (5%). The epicardial access was performed in 57% of the patients. At baseline, the LPs were present in 60% of the patients and a VT was either inducible or sustained/incessant in 85% of the cases. At the end of the procedure, the LP abolition was achieved in 79% of the cases and VT noninducibility in 80%. After a multivariable analysis, the combination of LP abolition and VT noninducibilty was independently associated with free survival from VT (hazard ratio, 0.45 [95% CI, 0.29-0.69], P=0.0002) and cardiac death (hazard ratio, 0.38 [95% CI, 0.18-0.74], P=0.005). The benefit of the LP abolition on preventing the VT recurrence in patients with ARVD and postmyocarditis appeared superior to that observed for those with DCM. CONCLUSIONS: In patients with NICM undergoing VT ablation, the strategy of LP abolition and VT noninducibilty were associated with better outcomes in terms of long-term VT recurrences and cardiac survival. Graphic Abstract: A graphic abstract is available for this article.

High-Density Characterization of the Ventricular Electrical Substrate During Sinus Rhythm in Post-Myocardial Infarction Patients.

OBJECTIVES: The aim of this study was to characterize, during sinus rhythm, the electric activation abnormalities in post-myocardial infarction patients undergoing ablation of ventricular tachycardia (VT) in order to identify specific signatures of those abnormal electrograms (EGMs). BACKGROUND: In the setting of VT ablation, substrate characterization hinges on the identification of local abnormal ventricular activity (LAVA) and late potentials (LPs) that are considered to be related to the VT circuit. METHODS: Patients scheduled for VT ablation underwent high-density ventricular substrate mapping. The substrate map during sinus rhythm was then compared with the activation maps of the clinical VT. Abnormal EGMs (LAVA and LPs) during sinus rhythm were characterized according to their configuration, duration, and amplitude and distinguished as belonging to bystander region or to the re-entrant circuit. Underlying electrophysiological mechanisms (wave-front collision, slow conduction) were identified on the activation maps and assigned to corresponding EGMs. RESULTS: Ten patients satisfied the criteria to be enrolled in the study. A mean of 5 ± 1 slow-conduction areas and 4 ± 2 wave-front collisions were identified. LAVA was due to slow conduction in 60.5%, followed by wave-front collision (17.5%). LPs were caused by slow conduction in 52% of cases and by wave-front collision in 43% of cases. During sinus rhythm, entrance and exit sites were characterized by LAVA, while at the VT isthmus, only LPs were identified. Cutoff values of duration <24.5 ms (95% sensitivity and 99% specificity) and amplitude <0.14 mV (90% sensitivity and 48.1% specificity) discriminated those LPs belonging to the circuit from those playing a bystander role. CONCLUSIONS: In the setting of post-myocardial infarction cardiomyopathy, specific EGM signatures are expressions of distinct electrophysiological phenomena. LAVA and LPs may play a bystander or an active role in the VT circuit, but only LPs with low amplitude and short duration predicted the VT isthmus.

Bipolar radiofrequency ablation for ventricular tachycardias originating from the interventricular septum: Safety and efficacy in a pilot cohort study.

BACKGROUND: Interest has grown in recent years in bipolar radiofrequency ablation (B-RFA). However, indications and outcome in patients with ventricular tachycardia (VT) are still to be defined. OBJECTIVE: The purpose of this study was to describe patient selection, safety and effectiveness of B-RFA, in a pilot cohort study of patients with nonischemic dilated cardiomyopathy (NIDCM) and drug-refractory VT. METHODS: We enrolled 21 patients with NIDCM (mean age 66±10 years; 18/21 (86%) men; left ventricular ejection fraction 35%±14%; 100% redo procedures) scheduled for a B-RFA procedure because of drug-refractory VT of suspected septal (interventricular septum [IVS]) origin. After electroanatomic mapping by using the CARTO®3 system, B-RFA was performed in all patients. Short- and long-term outcomes, including procedural success, major complications, and occurrence of major ventricular arrhythmias (MVAs), were evaluated at 25±8 months of follow-up (FU). RESULTS: Endocardial mapping showed IVS scar in all patients and extra-IVS in 7 patients (33%). B-RFA was performed at an average power of 33 W, for 60-90 seconds, over a 4.1 cm2 area, with 13±3 mm distance between catheters tips. The impedance drop was 27±4 Ω. The primary end point of noninducibility of the target clinical VT was obtained in 20 patients (95%). During FU, MVAs were documented in 7 patients (33%). FU MVAs occurred in all (100%) patients with extra-IVS localizations (7 of 7) or inflammatory nonischemic cardiomyopathy etiology (2 of 2). IVS thinning (tip-to-tip catheter distance < 5 mm) represented the only anatomical limitation to B-RFA. CONCLUSION: B-RFA is feasible in patients with NIDCM and drug-refractory VT of septal origin. Extra-IVS substrate and inflammatory NIDCM etiology were associated with an adverse outcome.

Long-term Outcomes of Stand-Alone Maze IV for Persistent or Long-standing Persistent Atrial Fibrillation.

BACKGROUND: The study sought to assess the long-term outcomes of the stand-alone Cox-Maze IV procedure in symptomatic patients with refractory, persistent, or long-standing persistent atrial fibrillation (AF). METHODS: Fifty-nine consecutive patients (mean age 52 ± 10.5 years, previous catheter ablation 80%, left ventricular ejection fraction 55% ± 3.4%, median left atrial volume index 41 [interquartile range, 34-47] mL/m2) with symptomatic, refractory, persistent (56%), or longstanding persistent (44%) AF, underwent stand-alone Cox-Maze IV procedure. Biatrial ablations were performed with bipolar radiofrequency and cryoenergy. Left atrial appendage was excluded in 56 of 59 (95%) patients. RESULTS: No hospital deaths occurred and 1 (1.7%) patient required postoperative pacemaker implantation. Follow-up was 97% complete (median 5.8 [interquartile range, 3.92-7.11] years). The overall survival at 7 years was 97% ± 2.3%. The 7-year cumulative incidence function of AF recurrence and of AF recurrence off class I or III antiarrhythmic drugs (AADs), with death as competing risk, was 14.2% ± 5.6% (95% confidence interval [CI], 5.5%-26.8%) and 26.5% ± 6.9% (95% CI, 14.2%-40.4%), respectively. Multivariate analysis identified the duration of AF as the only predictor of AF recurrence (hazard ratio, 1.01; 95% CI, 1.01-1.02; P < .001). At 7 years, the proportion of patients in sinus rhythm was 84%, of whom 74% were off class I or III AADs. At the last follow-up, 75% of patients were in European Heart Rhythm Association functional class I, no stroke and thromboembolic events were documented, and 70% of patients were off anticoagulation therapy. Left ventricular ejection fraction improved from 53% ± 3.4% at baseline to 59% ± 3.4% at follow-up (P = .003). CONCLUSIONS: This study confirmed the safety and efficacy in the long term (7 years) of the stand-alone Cox-Maze IV surgical procedure for persistent or long-standing persistent AF. Indeed, more than 70% of the patients were in sinus rhythm off class I or III AADs and off oral anticoagulation.

The COVID-19 challenge to cardiac electrophysiologists: optimizing resources at a referral center.

PURPOSE: To describe how a referral center for cardiac electrophysiology (EP) rapidly changed to comply with the ongoing COVID-19 healthcare emergency. METHODS: We present retrospective data about the modification of daily activities at our EP unit, following the pandemic outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in Italy. In particular, in the context of a pre-existing "hub-and-spoke" network, we describe how procedure types and volumes have changed in the last 3 months. RESULTS: Since our institution was selected as a COVID-19 referral center, the entire in-hospital activity was reorganized to assist more than 1000 COVID-positive cases. Only urgent EP procedures, including ventricular tachycardia ablation and extraction of infected devices, were both maintained and optimized to meet the needs of external hospitals. In addition, most of the non-urgent EP procedures were postponed. Finally, following prompt internal reorganization, both outpatient clinics and on-call services underwent significant modification, by integrating telemedicine support whenever applicable. CONCLUSION: We presented the fast reorganization of an EP referral center during the ongoing COVID-19 healthcare emergency. Our hub-and-spoke model may be useful for other centers, aiming at a cost-effective management of resources in the context of a global crisis.