Multicenter experience with andexanet alfa for refractory pericardial bleeding during catheter ablation of atrial fibrillation.

INTRODUCTION: Pericardial bleeding is a rare but life-threatening complication of atrial fibrillation (AF) ablation. Patients taking uninterrupted oral anticoagulation (AC) may be at increased risk for refractory bleeding despite pericardiocentesis and administration of protamine. In such cases, andexanet alfa can be given to reverse rivaroxaban or apixaban. In this study, we aim to describe the rate of acute hemostasis and thromboembolic complications with andexanet for refractory pericardial bleeding during AF ablation. METHODS AND RESULTS: In this multicenter, case series, participating centers identified patients who received a dose of apixaban or rivaroxaban within 24 h of AF ablation, developed refractory pericardial bleeding during the procedure despite pericardiocentesis and administration of protamine and received andexanet. Eleven patients met inclusion criteria, with mean age of 73.5 ± 5.3 years and median CHA2 DS2 -VASc score 4 [3-5]. All patients received protamine and pericardiocentesis, and 9 (82%) received blood products. All patients received a bolus of andexanet followed, in all but one, by a 2-h infusion. Acute hemostasis was achieved in eight patients (73%) while three required emergent surgery. One patient (9%) experienced acute ST-elevation myocardial infarction after receiving andexanet. Therapeutic AC was restarted after a mean of 2.2 ± 1.9 days and oral AC was restarted after a mean of 2.9 ± 1.6 days, with no recurrent bleeding. CONCLUSION: In patients on uninterrupted apixaban or rivaroxaban, who develop refractory pericardial bleeding during AF ablation, andexanet can achieve hemostasis thereby avoiding the need for emergent surgery. However, there is a risk of thromboembolism following administration.

Catheter ablation of intramural outflow tract premature ventricular complexes: a multicentre study.

AIMS: Ablation of outflow tract ventricular arrhythmias may be limited by a deep intramural location of the arrhythmogenic source. This study evaluates the acute and long-term outcomes of patients undergoing ablation of intramural outflow tract premature ventricular complexes (PVCs). METHODS AND RESULTS: This multicenter series included patients with structurally normal heart or nonischemic cardiomyopathy and intramural outflow tract PVCs defined by: (a) ≥ 2 of the following criteria: (1) earliest endocardial or epicardial activation < 20ms pre-QRS; (2) Similar activation in different chambers; (3) no/transient PVC suppression with ablation at earliest endocardial/epicardial site; or (b) earliest ventricular activation recorded in a septal coronary vein. Ninety-two patients were included, with a mean PVC burden of 21.5±10.9%. Twenty-six patients had had previous ablations. All PVCs had inferior axis, with LBBB pattern in 68%. In 29 patients (32%) direct mapping of the intramural septum was performed using an insulated wire or multielectrode catheter, and in 13 of these cases the earliest activation was recorded within a septal vein. Most patients required special ablation techniques (one or more), including sequential unipolar ablation in 73%, low-ionic irrigation in 26%, bipolar ablation in 15% and ethanol ablation in 1%. Acute PVC suppression was achieved in 75% of patients. Following the procedure, the PVC burden was reduced to 5.8±8.4%. The mean follow-up was 15±14 months and 16 patients underwent a repeat ablation. CONCLUSION: Ablation of intramural PVCs is challenging; acute arrhythmia elimination is achieved in 3/4 patients, and non-conventional approaches are often necessary for success.

Prognostic Value of Nonischemic Ringlike Left Ventricular Scar in Patients With Apparently Idiopathic Nonsustained Ventricular Arrhythmias.

BACKGROUND: Left ventricular (LV) scar on late gadolinium enhancement (LGE) cardiac magnetic resonance has been correlated with life-threatening arrhythmic events in patients with apparently idiopathic ventricular arrhythmias (VAs). We investigated the prognostic significance of a specific LV-LGE phenotype characterized by a ringlike pattern of fibrosis. METHODS: A total of 686 patients with apparently idiopathic nonsustained VA underwent contrast-enhanced cardiac magnetic resonance. A ringlike pattern of LV scar was defined as LV subepicardial/midmyocardial LGE involving at least 3 contiguous segments in the same short-axis slice. The end point of the study was time to the composite outcome of all-cause death, resuscitated cardiac arrest because of ventricular fibrillation or hemodynamically unstable ventricular tachycardia and appropriate implantable cardioverter defibrillator therapy. RESULTS: A total of 28 patients (4%) had a ringlike pattern of scar (group A), 78 (11%) had a non-ringlike pattern (group B), and 580 (85%) had normal cardiac magnetic resonance with no LGE (group C). Group A patients were younger compared with groups B and C (median age, 40 vs 52 vs 45 years; P<0.01), more frequently men (96% vs 82% vs 55%; P<0.01), with a higher prevalence of family history of sudden cardiac death or cardiomyopathy (39% vs 14% vs 6%; P<0.01) and more frequent history of unexplained syncope (18% vs 9% vs 3%; P<0.01). All patients in group A showed VA with a right bundle-branch block morphology versus 69% in group B and 21% in group C (P<0.01). Multifocal VAs were observed in 46% of group A patients compared with 26% of group B and 4% of group C (P<0.01). After a median follow-up of 61 months (range, 34-84 months), the composite outcome occurred in 14 patients (50.0%) in group A versus 15 (19.0%) in group B and 2 (0.3%) in group C (P<0.01). After multivariable adjustment, the presence of LGE with ringlike pattern remained independently associated with increased risk of the composite end point (hazard ratio, 68.98 [95% CI, 14.67-324.39], P<0.01). CONCLUSIONS: In patients with apparently idiopathic nonsustained VA, nonischemic LV scar with a ringlike pattern is associated with malignant arrhythmic events.

Continuous rhythm monitoring-guided anticoagulation after atrial fibrillation ablation.

INTRODUCTION: Oral anticoagulation (OAC) based on estimated stroke risk is recommended following catheter ablation (CA) of atrial fibrillation (AF), regardless of the extent of arrhythmia control. However, discontinuing OAC in selected patients may be safe. We sought to evaluate a strategy of OAC discontinuation following AF ablation guided by continuous rhythm monitoring. METHODS AND RESULTS: We prospectively studied AF ablations performed at our institution from June 2015 to December 2019. Patients that had pre-existing cardiac implantable electronic devices (CIEDs) or underwent insertable cardiac monitor (ICM) implantation immediately following AF ablation were included. OAC was continued for 6 weeks following CA in all patients, following which OAC management was guided by CHA2 DS2 -VASc score and continuous rhythm monitoring results, according to a prespecified protocol. AF recurrence was defined as ≥30 s (CIEDs) or ≥2 min (ICM). We studied 196 patients (mean age 64.7 ± 11.3 years, 66.8% male, 85.7% ICM, 14.3% CIEDs). Mean CHA2 DS2- VASc score was 2.2 ± 1.5. One-year AF-free survival following CA was 83% for paroxysmal AF and 63% for persistent AF patients. Over 3 year follow-up, OAC was discontinued in 57 (33.7%) patients, mean 7.4 ± 7.1 months following ablation. Following discontinuation, OAC was restarted for AF recurrence in 9 (15.8%) patients, mean 11.7 ± 6.8 months after stopping. This discontinuation protocol led to a 21.9% reduction in overall time exposed to OAC. There were no thromboembolic or major bleeding events. CONCLUSION: OAC can be discontinued in a significant percentage of patients following CA of AF. When guided by continuous rhythm monitoring, this practice does not unacceptably increase the risk of thromboembolic events.

Catheter ablation of atrial arrhythmias following lung transplant: Electrophysiological findings and outcomes.

INTRODUCTION: Data on the mechanisms of atrial arrhythmias (AAs) and outcomes of catheter ablation (CA) in lung transplantation (LT) patients are insufficient. We evaluated the electrophysiologic features and outcomes of CA of AAs in LT patients. METHODS AND RESULTS: We conducted a retrospective study of all the LT patients who underwent CA for AAs at our institution between 2004 and 2019. A total of 15 patients (43% males, age: 61 ± 10 years) with a history of LT (60% bilateral and 40% unilateral) were identified. All patients had documented organized AA on surface electrocardiogram and seven patients also had atrial fibrillation (AF; 47% with >1 clinical arrhythmia). At electrophysiological study, 19 organized AAs were documented (48% focal and 52% macro-re-entrant). Focal atrial tachycardias/flutters were targeted along the pulmonary vein (PV) anastomotic site at the left inferior PV (n = 2), ridge and carina of the left superior PV (n = 2), left atrium (LA) posterior wall (n = 3), LA roof (n = 1), and tricuspid annulus (n = 1). Macro-re-entrant AAs included cavotricuspid isthmus-dependent flutter (n = 2), incisional LA flutter (n = 4), LA roof-dependent flutter (n = 1), and mitral annular flutter (n = 3). In patients with LA mapping (n = 13), PV reconnection on the side of the LT was found in six patients (40%, all with clinically documented AF), with a mean of 2.1 ± 0.9 PVs reconnected per patient. Patients with AF underwent successful PV isolation. After a median follow-up of 19 months (range: 6-86 months), 75% of patients remained free from recurrent AAs. No procedural major complications occurred. CONCLUSION: In patients with prior LT, recurrent AAs are typically associated with substrate surrounding the surgical anastomotic lines and/or chronically reconnected PVs. CA of AAs in this population is safe and effective to achieve long-term arrhythmia control.

Novel germinal mutation in NF1: case report.

BACKGROUND: Neurofibromatosis 1 is a systemic pathology that predominantly affects the central and peripheral nervous system and the skin, although it can potentially affect any organ of the human body. The NF1 gene (Neurofibromatosis 1) is located on chromosome 17q11.2, a gene of great length that encodes neurofibromin, a protein with a tumor suppressor function with a functional mechanism that is not clearly known. METHODS: We reviewed the medical records, radiologic images, genetic studies, and clinical photographs of a patient with confirmed diagnosis of Neurofibromatosis 1 who was attended in our center between 2012 and 2021. The clinical course, the applied therapeutics and genetic findings were assessed. RESULTS: We present the case of a 10-year-old patient with a clinical diagnosis of neurofibromatosis type 1 (more than 6 coffee-with-milk spots, axillary ephelides, a cutaneous xanthogranuloma and hyperhidrosis) in whom a c.6255delG mutation (pMet2085IlefsTer2) in exon 42 of the NF1 gene was detected. There was no family history of diagnosed NF1. Neuroimaging studies showed myelin vacuolization in the posterior fossa, in dentate nucleus, midbrain and both globus pallidus. These findings showed stability over time. The patient is now asymptomatic and under evolutionary follow-up. CONCLUSIONS: The mutation shown here has not been previously described. Reports of previously unknown mutations are an important source of knowledge that can contribute to improved genetic diagnosis and a better understanding of the pathophysiological and genetic characteristics of diseases.

Collateral injury of the conduction system during catheter ablation of septal substrate in nonischemic cardiomyopathy.

INTRODUCTION: In patients with nonischemic cardiomyopathy (NICM) little is known about the clinical impact of catheter ablation (CA) of septal ventricular tachycardia (VT) resulting in the collateral injury of the conduction system (CICS). METHODS AND RESULTS: Ninety-five consecutive patients with NICM underwent CA of septal VT. Outcomes in patients with no baseline conduction abnormalities who developed CICS (group 1, n = 28 [29%]) were compared to patients with no CICS (group 2, n = 17 [18%]) and to patients with preexisting conduction abnormalities or biventricular pacing (group 3, n = 50 [53%]). Group-1 patients were younger, had a higher left ventricular ejection fraction and a lower prevalence of New York Heart Association III/IV class compared to group 3 while no significant differences were observed with group 2. After a median follow-up of 15 months, VT recurred in 14% of patients in group 1, 12% in group 2 (P = .94) and 32% in group 3 (P = .08) while death/transplant occurred in 14% of patients in group 1, 18% in group 2 (P = .69) and 28% in group 3 (P = .15). A worsening of left ventricular ejection fraction (LVEF) (median LVEF variation, -5%) was observed in group 1 compared to group 2 (median LVEF variation, 0%; P < .01) but not group-3 patients (median LVEF variation, -4%; P = .08) with a consequent higher need for new biventricular pacing in group 1 (43%) compared to group 2 (12%; P = .03) and group 3 (16%; P < .01). CONCLUSIONS: In patients with NICM and septal substrate, sparing the abnormal substrate harboring the conduction system provides acceptable VT control while preventing a worsening of the systolic function.

Impact of a nurse-led limited risk factor modification program on arrhythmia outcomes in patients with atrial fibrillation undergoing catheter ablation.

BACKGROUND: We have previously demonstrated the feasibility of a nurse-led risk factor modification (RFM) program for improving weight loss and obstructive sleep apnea (OSA) care among patients with atrial fibrillation (AF). OBJECTIVE: We now report its impact on arrhythmia outcomes in a subgroup of patients undergoing catheter ablation. METHODS: Participating patients with obesity and/or need for OSA management (high risk per Berlin Questionnaire or untreated OSA) underwent in-person consultation and monthly telephone calls with the nurse for up to 1 year. Arrhythmias were assessed by office ECGs and ≥2 wearable monitors. Outcomes, defined as Arrhythmia control (0-6 self-terminating recurrences, with ≤1 cardioversion for nonparoxysmal AF) and Freedom from arrhythmias (no recurrences on or off antiarrhythmic drugs), were compared at 1 year between patients undergoing catheter ablation who enrolled and declined RFM. RESULTS: Between 1 November 2016 and 1 April 2018, 195 patients enrolled and 196 declined RFM (body mass index, 35.1 ± 6.7 vs 34.3 ± 6.3 kg/m2 ; 50% vs 50% paroxysmal AF; P = NS). At 1 year, enrolled patients demonstrated significant weight loss (4.7% ± 5.3% vs 0.3% ± 4.4% in declined patients; P < .0001) and improved OSA care (78% [n = 43] of patients diagnosed with OSA began treatment). However, outcomes were similar between enrolled and declined patients undergoing ablation (arrhythmia control in 80% [n = 48] vs 79% [n = 38]; freedom from arrhythmia in 58% [n = 35] vs 71% [n = 34]; P = NS). CONCLUSION: Despite improving weight loss and OSA care, our nurse-led RFM program did not impact 1-year arrhythmia outcomes in patients with AF undergoing catheter ablation.

Use of Intracardiac Echocardiography in Interventional Cardiology: Working With the Anatomy Rather Than Fighting It.

The indications for catheter-based structural and electrophysiological procedures have recently expanded to more complex scenarios, in which an accurate definition of the variable individual cardiac anatomy is key to obtain optimal results. Intracardiac echocardiography (ICE) is a unique imaging modality able to provide high-resolution real-time visualization of cardiac structures, continuous monitoring of catheter location within the heart, and early recognition of procedural complications, such as pericardial effusion or thrombus formation. Additional benefits are excellent patient tolerance, reduction of fluoroscopy time, and lack of need for general anesthesia or a second operator. For these reasons, ICE has largely replaced transesophageal echocardiography as ideal imaging modality for guiding certain procedures, such as atrial septal defect closure and catheter ablation of cardiac arrhythmias, and has an emerging role in others, including mitral valvuloplasty, transcatheter aortic valve replacement, and left atrial appendage closure. In electrophysiology procedures, ICE allows integration of real-time images with electroanatomic maps; it has a role in assessment of arrhythmogenic substrate, and it is particularly useful for mapping structures that are not visualized by fluoroscopy, such as the interatrial or interventricular septum, papillary muscles, and intracavitary muscular ridges. Most recently, a three-dimensional (3D) volumetric ICE system has also been developed, with potential for greater anatomic information and a promising role in structural interventions. In this state-of-the-art review, we provide guidance on how to conduct a comprehensive ICE survey and summarize the main applications of ICE in a variety of structural and electrophysiology procedures.

Roof-dependent atrial flutter with an epicardial component: Role of the septopulmonary bundle.

Catheter ablation of atrial fibrillation may predispose patients to the development of atypical atrial flutters (AFL). We describe two cases of roof dependent AFLs that failed to terminate despite posterior wall isolation. An epicardial breakthrough involving the septopulmonary bundle is proposed. The correlation between the electrophysiological findings and the anatomical substrate is described.

Three-dimensional myocardial scar characterization from the endocardium: Usefulness of endocardial unipolar electroanatomic mapping.

Epicardial ablation may be required to eliminate ventricular tachycardia (VT) in patients with underlying structural heart disease. The decision to gain epicardial access is frequently based on the suspicion of an epicardial origin for the VT and/or presence of an arrhythmogenic substrate. Epicardial pathology and VT is frequently present in patients with nonischemic right and/or left cardiomyopathies even in the setting of modest or no endocardial bipolar voltage substrate. In this setting, unipolar voltage mapping from the endocardium serves to help identify midmyocardial and/or epicardial VT substrate. The additional value of endocardial unipolar mapping includes its usefulness to predict the clinical outcome after VT ablation, to determine the irreversibility of myocardial disease, and to guide endomyocardial biopsy procedures to specific areas of intramural scarring. In this review, we aim to provide a guide to the use of endocardial unipolar mapping and its appropriate interpretation in a variety of clinical situations.

Catheter ablation of premature ventricular complexes with low intraprocedural burden guided exclusively by pace-mapping.

BACKGROUND: Catheter ablation (CA) of idiopathic premature ventricular complexes (PVCs) is typically guided by both activation and pace-mapping, with ablation ideally delivered at the site of the earliest local activation. However, activation mapping requires sufficient intraprocedural quantity of PVCs. This study aimed to investigate the outcome of CA of infrequent PVCs guided exclusively by pace-mapping. METHODS: We retrospectively analyzed all patients undergoing CA of idiopathic PVCs between 2014 and 2017. RESULTS: Among 327 patients, 24 (7.3%) had low intraprocedural PVC burden despite isoproterenol, including two patients with zero PVCs, rendering activation mapping impractical/impossible. All 24 had a history of symptomatic PVCs. During ablation, a median of 27 (17-55) pace-maps were performed, with best median PASO score of 97 (96-98)%. A median of 12 (8.75-18.75) radiofrequency (RF) lesions were delivered with 11.4 (8.5-17.6) minutes of total RF time. Clinical success, defined as more than 80% reduction in the burden of previously frequent PVCs and/or absence of symptoms as well as any documented clinical PVCs among those with infrequent or exercise-induced PVCs, was achieved in 19 (79%) patients over 9.2 (2.0-15.0) months of follow-up. CONCLUSIONS: When activation mapping cannot be performed due to inadequate intraprocedural PVC burden, detailed pace-mapping can frequently identify the precise arrhythmia site of origin, thereby guiding successful CA.

Papillary muscle ventricular arrhythmias in patients with arrhythmic mitral valve prolapse: Electrophysiologic substrate and catheter ablation outcomes.

BACKGROUND: Mitral valve prolapse (MVP) is a common valve condition and has been associated with sudden cardiac death. Premature ventricular contractions (PVCs) from the papillary muscles (PMs) may play a role as triggers for ventricular fibrillation (VF) in these patients. OBJECTIVES: To characterize the electrophysiological substrate and outcomes of catheter ablation in patients with MVP and PM PVCs. METHODS: Of 597 patients undergoing ablation of ventricular arrhythmias during the period 2012-2015, we identified 25 patients with MVP and PVCs mapped to the PMs (64% female). PVC-triggered VF was the presentation in 4 patients and a fifth patient died suddenly during follow-up. The left ventricle ejection fraction (LVEF) was 50.5% ± 11.8% and PVC burden was 24.4% ± 13.1%. A cardiac magnetic resonance imaging was performed in nine cases and areas of late gadolinium enhancement were found in four of them. A detailed LV voltage map was performed in 11 patients, three of which exhibited bipolar voltage abnormalities. Complete PVC elimination was achieved in 19 (76%) patients and a significant reduction in PVC burden was observed in two (8%). In patients in which the ablation was successful, the PVC burden decreased from 20.4% ± 10.8% to 6.3% ± 9.5% (P = 0.001). In 5/6 patients with depressed LVEF and successful ablation, the LV function improved postablation. No significant differences were identified between patients with and without VF. CONCLUSIONS: PM PVCs are a source of VF in patients with MVP and can induce PVC-mediated cardiomyopathy that reverses after PVC suppression. Catheter ablation is highly successful with more than 80% PVC elimination or burden reduction.

Long term follow-up after ventricular tachycardia ablation in patients with congenital heart disease.

BACKGROUND: Ventricular tachycardia (VT) is frequently encountered in patients with repaired and unrepaired congenital heart disease (CHD), causing significant morbidity and sudden cardiac death. Data regarding underlying VT mechanisms and optimal ablation strategies in these patients remain limited. OBJECTIVE: To describe the electrophysiologic mechanisms, ablation strategies, and long-term outcomes in patients with CHD undergoing VT ablation. METHODS: Forty-eight patients (mean age 41.3 ± 13.3 years, 77.1% male) with CHD underwent a total of 57 VT ablation procedures at two centers from 2000 to 2017. Electrophysiologic and follow-up data were analyzed. RESULTS: Of the 77 different VTs induced at initial or repeat ablation, the underlying mechanism in 62 (81.0%) was due to scar-related re-entry; the remaining included four His-Purkinje system-related macrore-entry VTs and focal VTs mainly originating from the outflow tract region (8 of 11, 72.7%). VT-free survival after a single procedure was 72.9% (35 of 48) at a median follow-up of 53 months. VT-free survival after multiple procedures was 85.4% (41 of 48) at a median follow-up of 52 months. There were no major complications. Three patients died during the follow-up period from nonarrhythmic causes, including heart failure and cardiac surgery complication. CONCLUSION: While scar-related re-entry is the most common VT mechanism in patients with CHD, importantly, nonscar-related VT may also be present. In experienced tertiary care centers, ablation of both scar-related and nonscar-related VT in patients with CHD is safe, feasible, and effective over long-term follow-up.

Anatomical proximity dictates successful ablation from adjacent sites for outflow tract ventricular arrhythmias linked to the coronary venous system.

AIMS: Catheter ablation of outflow tract ventricular arrhythmias (OTVAs) with the earliest activation within the coronary venous system (CVS) can be challenging. When ablation from the CVS is not feasible or ineffective, an approach from anatomically adjacent site(s) can be considered. We report the outcomes of an anatomical approach for OTVAs linked to the CVS. METHODS AND RESULTS: We retrospectively analysed 665 OTVA patients. Of these, 65 (9.8%) had the earliest activation within the CVS. In 53 (82%) cases, an anatomical approach was attempted. The targeted adjacent anatomical structure was the endocardial left ventricular outflow tract (LVOT) in 24 (45%), the left coronary cusp or the left/right cusp junction in 17 (32%) patients, and the right ventricular outflow tract (RVOT) in 12 (23%). The anatomical approach was successful in 26 (49%) patients (27% from the coronary cusps, 65% from the LVOT, and 8% from the RVOT). The difference in activation times between the earliest activation site within the CVS and the targeted site was not significantly different between the successful and unsuccessful groups (14.2 ± 11.2 ms vs. 13.2 ± 9.3 ms; P = 0.89). The anatomical distance from the earliest activation site to the targeted site was shorter for the successful group (9.7 ± 2.4 mm vs. 13.1 ± 6.5 mm; P < 0.05). In particular, when the anatomical distance was >12.8 mm, anatomical approach was successful in only 1/13 (8%). CONCLUSION: In patients with OTVAs linked to the CVS, an anatomical approach targeting an adjacent site can be effective, particularly when the distance between the sites is <12.8 mm.

Catheter Ablation of Idiopathic Ventricular Arrhythmias.

Ventricular arrhythmias (VA) are observed in the setting of structural heart disease. However, in a proportion of patients presenting with VT, the routine diagnostic modalities fail to demonstrate overt myocardial abnormality. These arrhythmias have been called idiopathic VAs. They consist of various subtypes that have been defined by their anatomic location of origin within the heart and/or their underlying mechanism. While the majority of patients are asymptomatic, some experience debilitating symptoms and may develop reversible ventricular dysfunction. Catheter ablation has been traditionally reserved for patients with incapacitating symptoms or progressive ventricular dysfunction. However, as many patients are young, and catheter ablation can be curative in >90% of cases with a low risk (<1%) of serious complications, it is increasingly being offered as a first-line treatment in symptomatic patients. The approach to arrhythmia mapping is guided by the 12-lead electrocardiograph (ECG) morphology of the ventricular tachycardia (VT). Use of three dimensional (3D) electroanatomic mapping systems and intra-cardiac echocardiography are helpful in localising sites for successful ablation.

QRS morphology shift following catheter ablation of idiopathic outflow tract ventricular arrhythmias: Prevalence, mapping features, and ablation outcomes.

INTRODUCTION: In patients with monomorphic idiopathic outflow tract ventricular arrhythmias (OT-VAs), catheter ablation (CA) at the earliest activation site can result in a shift in QRS morphology indicating a change in the activation patterns. This study aimed to investigate the prevalence, mapping features, and ablation outcomes of OT-VAs displaying a QRS morphology shift following CA. METHODS AND RESULTS: We retrospectively analyzed 446 patients with monomorphic OT-VAs. A QRS morphology shift following CA was observed in 17 (4%) patients. Initially, the earliest activation site was within the right ventricular outflow tract (RVOT) in one (6%) patient, the left ventricular outflow tract (LVOT) in 10 (59%) patients (left coronary cusp/right coronary cusp junction in seven patients and LVOT endocardium in three patients), and within the distal coronary venous system in six (35%) patients. The VA was suppressed in all 17 patients, but VA recurrence with a different QRS morphology was observed after a waiting period. The recurrent VA was remapped in all patients and was eliminated targeting the new earliest site in 15 (88%) cases. In 11 of 15 successful cases, the ablation site for the recurrent VA shifted to an anatomical structure distinct from but adjacent to the initial site. In the remaining four patients, the recurrent VA was eliminated within the same anatomical structure. CONCLUSIONS: In patients with idiopathic OT-VAs, a QRS morphology shift following CA can be observed in 4% of the cases. In these cases, detailed remapping is necessary since the successful ablation site for the VAs with altered QRS morphology shifts to different anatomical structures in most patients.

Lead I R-wave amplitude to differentiate idiopathic ventricular arrhythmias with left bundle branch block right inferior axis originating from the left versus right ventricular outflow tract.

INTRODUCTION: Differentiation of right versus left ventricular outflow tract (RVOT vs. LVOT) arrhythmia origin with left bundle branch block right inferior axis (LBRI) morphology is relevant to ablation planning and risk discussion. Our aim was to determine if lead I R-wave amplitude is useful for differentiation of RVOT from LVOT arrhythmias with LBRI morphology. METHODS: The R-wave amplitude in lead I was measured in a retrospective cohort of 75 consecutive patients with LBRI pattern ventricular arrhythmias (VAs) successfully ablated from the RVOT (n = 54), LVOT (n = 16), or the anterior interventricular vein (AIV; n = 5). The optimal R-wave threshold was identified and diagnostic indices were compared with the previously reported transitional zone (TZ) index and V2S/V3R index. RESULTS: An R-wave amplitude greater than or equal to 0.1 mV predicted LVOT origin with 75% sensitivity and 98.2% specificity. In comparison, the TZ and V2S/V3R indices had 50% and 68.8% sensitivity, and 75.9% and 88.9% specificity, respectively, for predicting LVOT origin. The area under the curve (AUC) was 0.85 for lead I R-wave amplitude, 0.87 for V2S/V3R, and 0.72 for the TZ index. Of 36 cases with QS in lead I, 30 (83.3%) were from the anterior RVOT, three (8.3%) from the LVOT, and three (8.3%) from the AIV. CONCLUSION: The presence of R-wave amplitude in lead I (≥0.1 mV) is a simple and useful criterion to identify LVOT cusp or endocardium focus in LBRI arrhythmias. A QS pattern in lead I suggests an origin in the anterior RVOT, or less commonly the adjacent LV summit.

Epicardial ventricular tachycardia in ischemic cardiomyopathy: Prevalence, electrophysiological characteristics, and long-term ablation outcomes.

INTRODUCTION: The characteristics of the epicardial (EPI) substrate responsible for ventricular tachycardia (VT) in ischemic cardiomyopathy (ICM) are undefined, and data on the long-term outcomes of EPI catheter ablation limited. We evaluated the prevalence, electrophysiologic features, and outcomes of catheter ablation of EPI VT in ICM. METHODS AND RESULTS: From December 2010 to June 2013, a total of 13 of 93 (14%) patients with ICM underwent catheter ablation at our institution and had conclusive evidence of critical EPI substrate demonstrated to participate in VT with activation, entrainment and/or pace mapping during sinus rhythm (two other patients underwent EPI mapping but had no optimal ablation targets). The electrophysiologic substrate characteristics and activation/entrainment mapping data were compared with a reference group of ICM patients without evidence of critical EPI substrate (N = 44), defined as a complete procedural success (noninducibility of any VT at programmed stimulation) after endocardial (ENDO)-only ablation. Patients with failed EPI access (N = 2) or history of cardiac surgery (N = 92) were excluded from the study. All 13 patients had evidence of abnormal EPI substrate with fractionated/late/split electrograms and low-bipolar voltage areas. The critical VT ablation sites were all located within the EPI bipolar "dense" scar (<1.0 mV) opposite the ENDO bipolar scar in 77% of cases and extending beyond the ENDO bipolar scar (within the ENDO unipolar low-voltage area) in the remaining patients. Compared with the reference ENDO-only group, patients with EPI VT had a smaller ENDO bipolar scar area, 54.0 (37.1-84) vs 86.7 (55.6-112) cm2 ; P = 0.0159, with a similar extent of ENDO unipolar low voltage. No other substrate characteristics or location differed between the two groups. After 35.2 ± 24.2 months of follow-up, VT-free survival was 73% in patients with EPI VT compared with 66% in the ENDO-only group (log-rank P = 0.56). CONCLUSIONS: The presence of the critical EPI substrate responsible for VT can be demonstrated in at least 14% of patients with ICM. The majority of EPI critical ablation sites are distributed opposite the ENDO bipolar scar area and catheter ablation is effective in achieving long-term arrhythmia control.

Percutaneous cryoablation for papillary muscle ventricular arrhythmias after failed radiofrequency catheter ablation.

BACKGROUND: Catheter ablation of ventricular arrhythmias (VA) from the papillary muscles (PM) is challenging due to limited catheter stability and contact on the PMs with their anatomic complexity and mobility. OBJECTIVE: This study aimed to evaluate the effectiveness of cryoablation as an adjunctive therapy for PM VAs when radiofrequency (RF) ablation has failed. METHODS: We evaluated a retrospective series of patients who underwent cryoablation for PM VAs when RF ablation had failed. The decision to switch to cryoablation was at the operator's discretion when intracardiac echocardiography (ICE) suggested that cryoablation might be more effective in achieving catheter stability and energy delivery. RESULTS: Sixteen patients underwent cryoablation of PM VAs between 2014 and 2016 after RF ablation was unsuccessful. VAs originated from the anterolateral left ventricle (LV) PM (six patients), posterolateral LV PM (six patients), and right ventricle PM (four patients). VAs were predominantly frequent premature ventricular complexes (PVCs); however, patients with sustained ventricular tachycardia and PVC-triggered VF were also represented. Fifteen of the 16 patients were treated with cryoablation; in one patient, a procedural complication with retrograde aortic access precluded treatment. In all patients treated with cryoablation, contact and stability was confirmed with ICE to be superior to the RF catheter, and there was acute and long-term elimination of VAs. CONCLUSION: Cryoablation is a useful adjunctive therapy in ablation of PM VAs, providing excellent procedural outcomes even when RF ablation has failed. Cryoablation catheters are less maneuverable than RF ablation catheters and care is required to avoid complications.