Catheter Ablation of Ventricular Tachycardia in Patients With MitraClip Device: Preliminary Findings.

INTRODUCTION: Patients with mitral regurgitation are increasingly treated by percutaneous implantation of a MitraClip device (Abbott Park, IL, USA). We investigate the feasibility and safety of the transmitral catheter route for catheter ablation of ventricular tachycardia (VT) in these patients. METHODS: The mitral valve with the MitraClip in situ was crossed under transesophageal 3-dimensional echocardiographic and fluoroscopic guidance using a steerable sheath for ablation of the left ventricle. RESULTS: Five patients (all males, median age 74.0 ± 16.0 years) who had previously a MitraClip implanted were referred for catheter ablation of VT. The left ventricular ejection fraction was 29.0% ± 24.0%. One patient had both an atrial septal defect and a left atrial appendage occluder device in addition to a MitraClip. The duration between MitraClip implantation and ablation was 1019.0 ± 783.0 days. After transseptal puncture, ablation catheter was successfully steered through the mitral valve with the use of fluoroscopy. A complete high-density map of the substrate in sinus rhythm could be obtained in all patients using multipolar mapping catheters. In 1 patient, mapping was carried out using a mini-basket catheter. Procedural endpoints, noninducibility of all VTs, and abolition of all late potentials were achieved in all patients. Procedure time was 255.0 ± 52.5 minute, fluoroscopy time was 23.0 ± 7.3, and the radiation dose was 61.0 ± 37.5 Gycm2 . No mitral insufficiency or worsening of regurgitation was documented after the procedure. CONCLUSIONS: This is the first report demonstrating the feasibility and safety of VT ablation in patients with a MitraClip device using the anterograde transmitral catheter route.

Impact of a chronic total occlusion in an infarct-related artery on the long-term outcome of ventricular tachycardia ablation.

INTRODUCTION: In patients with a prior myocardial infarction (MI), angiographic predictors of ventricular tachycardia (VT) recurrence after ablation are lacking. Recently, a proarrhythmic effect of a chronic total occlusion (CTO) in a coronary artery has been suggested. METHODS AND RESULTS: A total of 191 patients with prior MI were referred to our Hospital between 2010 and June 2013 for a first ablation of VT. Of these, 84 patients (44%) with stable coronary artery disease that underwent a coronary angiography during the index hospitalization were included in this study. A CTO in an infarct-related artery (IRA-CTO) was present in 47 patients (56%). Patients with and without IRA-CTO did not differ in terms of comorbidities, severity of heart failure, presentation of VT or acute outcome of ablation, that was completely successful in 93% of cases. At electroanatomic mapping, IRA-CTO was associated with greater scar and especially with greater area of border zone (34 cm(2) vs. 19 cm(2) , P = 0.001). Median follow-up was 19 months (IQR 18). At follow-up, patients with IRA-CTO had a significantly higher rate of VT recurrence (47% vs. 16%, P = 0.003). At multivariate analysis, IRA-CTO resulted to be an independent predictor of VT recurrence after ablation (HR 4.05, P = 0.004). CONCLUSIONS: IRA-CTO is an independent predictor of VT recurrence after ablation and identifies a subgroup of patients with high recurrence rate despite a successful procedure. IRA-CTO is associated with greater scars and border zone area; however, this association does not completely justify its proarrhythmic effect.

New diagnostic criteria for identifying left-sided ventricular ectopy using non-contact mapping and virtual unipolar electrogram analysis.

AIMS: To assess the efficacy of non-contact mapping for outflow tract premature ventricular contraction (PVC) and ventricular tachycardia (VT) ablation in patients without structural heart disease and a precordial transition at V3 or later and to determine the diagnostic accuracy of new virtual unipolar electrogram criteria for distinguishing left from right-sided foci using a multi-electrode array positioned within the right ventricular outflow tract. METHODS AND RESULTS: Virtual unipolar electrograms at early activation (EA) and break out (BO) sites in 100 patients (36 left-sided foci) who underwent acutely successful outflow tract ablation were analysed and voltage and timing-based criteria measured. The best performing parameters were then re-assessed in 41 patients (14 left-sided) prospectively. Of the candidate criteria for determining a left from right-sided focus, the voltage at 20 ms after EA (EA-V20) and the time from BO to QRS onset (BO-QRS) were the best discriminators with area under the curve (AUC) values based on receiver operator characteristics (ROCs) of 0.947 (0.905-0.989), P < 0.001, and 0.951 (0.907-0.995), P < 0.001, respectively. These two parameters were subsequently assessed prospectively in a further 41 patients (14 left-sided) using the pre-specified cut-off values of -2 mV for EA-V20 and 10 ms for BO-QRS which demonstrated excellent diagnostic accuracy and sufficient inter-beat and inter-observer reproducibility. CONCLUSIONS: This large single-centre experience demonstrates that a strategy for outflow tract PVC/VT ablation using non-contact mapping allows for excellent success rates. Furthermore, detailed analysis of virtual unipolar electrograms allows accurate and reproducible determination of left from right-sided foci that may be used to guide mapping and ablation.

Electrical storm induced by cardiac resynchronization therapy is determined by pacing on epicardial scar and can be successfully managed by catheter ablation.

BACKGROUND: The mechanism of cardiac resynchronization therapy (CRT)-induced proarrhythmia remains unknown. We postulated that pacing from a left ventricular (LV) lead positioned on epicardial scar can facilitate re-entrant ventricular tachycardia. The aim of this study was to investigate the relationship between CRT-induced proarrhythmia and LV lead location within scar. METHODS AND RESULTS: Twenty-eight epicardial and 63 endocardial maps, obtained from 64 CRT patients undergoing ventricular tachycardia ablation, were analyzed. A positive LV lead/scar relationship, defined as a lead tip positioned on scar/border zone, was determined by overlaying fluoroscopic projections with LV electroanatomical maps. CRT-induced proarrhythmia occurred in 8 patients (12.5%). They all presented early with electrical storm (100% versus 39% of patients with no proarrhythmia; P<0.01), requiring temporary biventricular pacing discontinuation in half of cases. They more frequently presented with heart failure/cardiogenic shock (50% versus 7%; P<0.01), requiring intensive care management. Ventricular tachycardia was re-entrant in all. The LV lead location within epicardial scar was significantly more frequent in the proarrhythmia group (60% versus 9% P=0.03 on epicardial bipolar scar, 80% versus 17% P=0.02 on epicardial unipolar scar, and 80% versus 17% P=0.02 on any-epicardial scar). Ablation was performed within epicardial scar, close to the LV lead, and allowed CRT reactivation in all patients. CONCLUSIONS: CRT-induced proarrhythmia presented early with electrical storm and was associated with an LV lead positioning within epicardial scar. Catheter ablation allowed for resumption of biventricular stimulation in all patients.

Contact force monitoring for cardiac mapping in patients with ventricular tachycardia.

BACKGROUND: Although the importance of contact force monitoring during mapping and ablation procedures is widely recognized, only indirect measurements have been validated. METHODS: Real-time force values were measured using the force-sensing catheter and electroanatomical mapping system from 27 chambers (13 LVs, 6 RVs, and 8 epicardial space) in 17 patients affected by ventricular tachycardia. Left ventricular mapping was performed by the transaortic approach in all patients and in 5 patients also by a transseptal approach with the aid of a deflectable sheath. All points were divided into 2 groups according to the presence of positive contact force during diastole: good and poor contact. The frequency of good contact and its impact on electrophysiological parameters such as signal amplitude, local impedance, and frequency of late potentials was evaluated. The best cut-off value to discriminate the 2 groups was calculated by a generalized linear mixed-effects model. RESULTS: Among all 5,926 points, 1,566 (26%) points were taken with poor contact. In healthy tissue, categorical increase of contact force caused the increase of unipolar and bipolar signal potential amplitude followed by plateau. The frequency of late potentials in the poor contact group was significantly lower when compared to the good contact group (11.9 vs 23.2%; P < 0.0001). The best cut-off force value to predict good contact during left ventricular endocardial and epicardial mappings was 9 g. CONCLUSIONS: A combined transaortic and transseptal approach allows better endocardial contact during left ventricular mapping. Ventricular mapping with sufficient contact force produces better substrate characterization within pathological areas.

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.

Radiofrequency catheter ablation guided by noncontact mapping of ventricular tachycardia originating from an idiopathic left ventricular aneurysm.

Idiopathic left ventricular aneurysm and diverticulum is known to be an arrhythmogenic substrate associated to ventricular tachyarrhythmias, generally based on a reentry mechanism. A case of a young woman affected by a monomorphic ventricular tachycardia, refractory to medical treatment, originating from an aneurysm of the membranous interventricular septum is reported. The left ventricular aneurysm was well characterized by multislice computed tomography and left ventricular angiography. Because of the nonsustained and poorly tolerated nature of the target arrhythmia, a noncontact mapping system was used to guide radiofrequency catheter ablation, allowing the elaboration of a three-dimensional activation map of the left ventricle on the basis of a ventricular tachycardia single beat. The procedure was acutely successful, and the patient remained free of ventricular tachycardia recurrences without antiarrhythmic drugs during a subsequent 6-month follow-up period. This is the first report of a successful radiofrequency catheter ablation guided by noncontact mapping system of a ventricular tachycardia originating from an idiopathic left ventricular aneurysm. This nonfluoroscopic mapping method allows a reliable reconstruction of the spatial relationships between the left ventricular main cavity and the aneurysm and can be safely and effectively used to map the ventricular tachycardia and guide the ablation procedure, particularly when conventional mapping is not indicated or not effective because of nonsustained or not-tolerated characters of ventricular tachycardia.

Left mitral isthmus ablation associated with PV Isolation: long-term results of a prospective randomized study.

BACKGROUND: The deployment of an ablation line connecting the left inferior PV to the mitral annulus (mitral isthmus line [MIL]) enhances the efficacy of pulmonary vein disconnection (PVD) in preventing atrial fibrillation (AF) recurrences. OBJECTIVES: To investigate the long-term effect of the additional linear lesion in a prospective randomized study. METHODS: One hundred and eighty-seven patients (37 females, mean age: 55 +/- 11 years) with paroxysmal (126) or persistent (61 patients) AF, were prospectively randomized into two groups: PVD (group A, 92 patients) or PVD combined with MIL (group B, 95 patients), performed by means of an irrigated-tip ablation catheter. RESULTS: Successful disconnection of all PVs was achieved in all patients. A bidirectional block (BB) along the left atrial isthmus was obtained in 72 of 95 (76%) patients in group B, most of whom required additional RF pulses from within the distal CS. A transient ischemic attack occurred in 1 patient of group A, and a cardiac tamponade occurred in 1 patient of group B. At 1 year, 53 +/- 5% (group A) and 71 +/- 5% (group B) remained arrhythmia free (P = 0.01); subgroup analysis highlights a higher improvement among patients with persistent AF (74 +/- 9% vs 36 +/- 9%; P < 0.01) than what was observed in paroxysmal AF (76 +/- 6% vs 62 +/- 6%; P < 0.05); antiarrhythmic drugs were continued in 56% and 50%, respectively, in groups A and B (P = ns). CONCLUSIONS: The addition of mitral isthmus line to the PV disconnection allows a significant improvement of sinus rhythm maintenance rate, particularly in patients with persistent AF, without the risk for major complications.

Long-term follow-up after radiofrequency catheter ablation of atrial fibrillation: role of the acute procedure outcome and of the clinical presentation.

AIMS: This study is a single centre long-term experience on a consecutive cohort of patients with paroxysmal or persistent atrial fibrillation (AF) undergoing electrical disconnection of pulmonary veins (PVs) by means of catheter ablation. Long-term outcome was analyzed in relation to acute procedure success and to the clinical presentation. METHODS AND RESULTS: Two hundred and thirty-four patients (182 males, mean age 55.9+/-10.6 years), affected by paroxysmal (78%) or persistent AF, underwent an electrophysiologically guided isolation of PVs. ECG, Holter and clinical follow-up were obtained at 1, 3, 6 and 12 months. At discharge an antiarrhythmic drug, Flecainide, was given only in cases with incomplete disconnection; Amiodarone was administered in all persistent AF pts. Successful disconnection of all PVs was achieved in 90% of cases. The rate of stable sinus rhythm maintenance was 85%, 74%, 72% and 65% at 1, 3, 6 and 12 months, respectively. The one-year arrhythmia free survival rates were higher among patients with paroxysmal AF (68% vs. 54%, P 0.008), those with complete disconnection of all PVs and in patients younger than 55 years. CONCLUSIONS: The electrical disconnection of all the pulmonary veins should be the minimal endpoint of radiofrequency catheter ablation in patients with either paroxysmal or persistent AF. Incomplete disconnection of the PVs is predictive of recurrence. Long-term results of the ablation procedure were significantly better in patients with paroxysmal AF.