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.

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.

Fast and safe mapping of ventricular tachycardia in patient with left ventricular assist device

The characterization of the pathological substrate and/or mapping of the clinical ventricular tachycardia in patients with left ventricular assist device may represent a challenge, due to the risk of entrapment of the intracardiac catheter into the inflow cannula. Hereby, we present the technique of a fast and safe mapping using a 20-poles catheter which allowed the identification of the critical isthmus during ventricular tachycardia.

Usefulness of Electroanatomical Mapping with Contact Force Monitoring for Accessory Pathways Ablation in Pediatric Population

The current approach for catheter ablation (CA) of accessory pathways (AP) includes the use of standard catheters under fluoroscopic visualization. We hypothesize that use of contact force (CF) irrigated tip catheters might increase procedural safety in pediatric patients compared to standard irrigated tip catheters, by decreasing the number of radiofrequency (RF) pulses required to obtain AP elimination. Seventy-one pediatric patients (13.7 ± 2.5 years, 45 male) with ventricular pre-excitation were enrolled in the study. CA was performed with a standard irrigated tip catheter up to June 2013 in 41 patients (Group S) and with a CF sensing irrigated tip catheter later on in 30 patients (Group CF). In the Group CF, RF was applied with a minimal CF of 5 g; CF > 35 g was avoided. Group CF procedures required less fluoroscopy (6.8 ± 4.8 min), compared to Group S (12.2 ± 10.8 min, p = 0.007). The number of RF pulses was smaller in Group CF compared to Group S (2.5 ± 2.0 vs 5.5 ± 1.9, p < 0.01). The mean CF during the effective RF pulse was 18 ± 7.7 g, force-time integral was 1040.7 ± 955.9 gs, Ablation Index was 513.0 ± 214.2. The procedure was acutely successful in 70 patients; at 12 months follow-up 2 patients had AP recurrence, one for each group. No major complications were reported. The use of CF irrigated tip catheters was associated with a smaller number of RF pulses and less fluoroscopy, as compared to mapping and ablation with standard irrigated tip catheters.

Phrenic Nerve Limitation During Epicardial Catheter Ablation of Ventricular Tachycardia

OBJECTIVES

This study sought to investigate the incidence of phrenic nerve (PN) limitation and the utility of displacing the PN with a balloon.

BACKGROUND

The PN can limit the epicardial ablation of ventricular tachycardia (VT).

METHODS

From 2010 to 2017, 363 patients undergoing VT epicardial ablation at a single center were studied. Before the ablation, we used high output (20-mA) pacing maneuvers to verify the course of the PN. When we observed its capture, we used 1 of 3 different approaches to protect it: 1) non-balloon strategy (nerve-sparing ablation); 2) PN displacement with a small balloon (6 mm × 20 mm); or 3) PN displacement with a large balloon (20 mm × 45 mm).

RESULTS

PN capture occurred in 25 patients (7%) at the target ablation site. The most common cause was myocarditis (12 patients [48%]), and the incidence of the PN limitation was significantly higher in myocarditis than in other causes (19% vs. 4%, respectively; p = 0.0002). PN displacement was attempted in 7 patients by using large balloons and in 6 patients with small balloons, resulting in successful PN displacements and complete late potential (LP) abolition in 6 patients (86%) and 3 patients (50%), respectively. Among the 12 patients in whom the non-balloon strategy was used, only 1 patient (8%) achieved LP abolition (compared with the large balloon group; p = 0.002), whereas 3 patients experienced PN paralysis.

CONCLUSIONS

The PN limited the epicardial ablation in 7% of patients. Because nerve-sparing ablations often resulted in PN injuries, a possible solution could be to displace the PN with a large balloon, leading to a safer procedure and completion of LP abolition.

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.

Extracorporeal Membrane Oxygenation for Hemodynamic Support of Ventricular Tachycardia Ablation

Background—

We report the experience in a cohort of consecutive patients receiving extracorporeal membrane oxygenation during catheter ablation of unstable ventricular tachycardia (VT) at our center.

Methods and Results—

From 2010 to 2015, extracorporeal membrane oxygenation was initiated in 64 patients (average age: 63±15 years; left ventricular ejection fraction in 27±9%; cardiogenic shock in 23%, and electrical storm in 62% of patients) undergoing 74 unstable VT catheter ablation procedures. At least one VT was terminated in 81% of procedures with baseline inducible VT, and VT noninducibility was achieved in 69%. Acute heart failure occurred in 5 patients: 3 underwent emergency heart transplantation, 1 had left ventricular assist device (LVAD) implantation, and 1 patient eventually died because of subsequent mesenteric ischemia. All other patients were discharged alive. After a median follow-up of 21 months (13–28 months), VT recurrence was 33%; overall survival was 56 out of 64 patients (88%). Extracorporeal membrane oxygenation–supported ablation was the bridge to LVAD in 6.9% and to heart transplantation in 3.5% of patients. VT recurrence was related to ablation success (after 180 days of follow up: 19% when VT was noninducible, 42% if nonclinical VT was inducible, 75% when clinical VT was inducible, and 75% in untested patients, P <0.001). Incidence of all-cause death, heart transplantation, and LVAD was independently related to ablation outcome (at 180 days of follow-up: 9% when noninducibility was achieved, 50% in case of inducible VT, and 75% in untested patients, P <0.001). At multivariable analyses, noninducibility (hazard ratio 0.198; P =0.001) and left ventricular ejection fraction (hazard ratio 0.916; P =0.008) correlated with all-cause death, LVAD, and heart transplantation.

Conclusions—

Ablation of unstable VTs can be safely supported by extracorporeal membrane oxygenation, which allows rhythm stabilization with low procedure mortality, bridging decompensated patients to permanent LVAD or heart transplantation. Successful ablation is associated with better outcomes than unsuccessful ablation.

Left atrial appendage closure: A single center experience and comparison of two contemporary devices

OBJECTIVES

To compare indications and clinical outcomes of two contemporary left atrial appendage (LAA) percutaneous closure systems in a "real-world" population.

BACKGROUND

Percutaneous LAA occlusion is an emerging therapeutic option for stroke prevention in atrial fibrillation. Some questions however remain unanswered, such as the applicability of results of randomized trials to current clinical practice. Moreover, currently available devices have never been directly compared.

METHODS

We retrospectively analyzed consecutive patients who underwent LAA closure at San Raffaele Hospital, Milan, Italy between 2009 and 2015. Clinical indications and device selection were left to operators' decision; routine clinical and transesophageal echocardiography (TEE) follow-up was performed.

RESULTS

One-hundred and sixty-five patients were included in the study, of which 99 were treated with the Amplatzer Cardiac Plug (ACP) and 66 with the Watchman system. During the follow-up period (median 15 months, interquartile range 6-26 months) five patients died. The incidence of ischemic events was low, with one patient suffering a transient ischemic attack and no episodes recorded of definitive strokes. Twenty-six leaks ≥1 mm were detected (23%); leaks were less common with the ACP and with periprocedural three-dimensional TEE evaluation, but were not found to correlate with clinical events. Clinical outcomes were comparable between the two devices.

CONCLUSIONS

Our data show excellent safety and efficacy of LAA closure, irrespectively of the device utilized, in a population at high ischemic and hemorrhagic risk. The use of ACP and 3D-TEE minimized the incidence of residual leaks; however, the clinical relevance of small peri-device flow warrants further investigation. © 2016 Wiley Periodicals, Inc.

The value of the 12-lead electrocardiogram in localizing the scar in non-ischaemic cardiomyopathy

AIMS

Patients with non-ischaemic cardiomyopathy (NICM) and ventricular tachycardia can be categorized as anteroseptal (AS) or inferolateral (IL) scar sub-types based on imaging and voltage mapping studies. The aim of this study was to correlate the baseline electrocardiogram (ECG) with endo-epicardial voltage maps created during ablation procedures and identify the ECG characteristics that may help to distinguish the scar as AS or IL.

METHODS AND RESULTS

We assessed 108 baseline ECGs; 72 patients fulfilled criteria for dilated cardiomyopathy whereas 36 showed minimal structural abnormalities. Based on the unipolar low-voltage distribution, the scar pattern was classified as predominantly AS (n = 59) or IL (n = 49). Three ECG criteria (PR interval < 170 ms or QRS voltage in inferior leads <0.6 mV or a lateral q wave) resulted in 92% sensitivity and 90% specificity for predicting an IL pattern in patients with preserved ejection fraction (EF). The four-step algorithm for dilated cardiomyopathy included a paced ventricular rhythm or PR > 230 ms or QRS > 170 ms or an r ≤ 0.3 mV in V3 having 92 and 81% of sensitivity and specificity, respectively, in predicting AS scar pattern. A significant negative correlation was found between the extension of the endocardial unipolar low voltage area and left ventricular EF (r_s = -0.719, P < 0.001). The extent of endocardial AS unipolar low voltage was correlated with PR interval and QRS duration (r_s = 0.583 and r_s = 0.680, P < 0.001, respectively) and the IL epicardial unipolar low voltage with the mean voltage of the limb leads (r_s = -0.639, P < 0.001).

CONCLUSION

Baseline ECG features are well correlated with the distribution of unipolar voltage abnormalities in NICM and may help to predict the location of scar in this population.

Electroanatomical voltage and morphology characteristics in postinfarction patients undergoing ventricular tachycardia ablation: pragmatic approach favoring late potentials abolition

BACKGROUND

Catheter ablation is an important therapeutic option in postmyocardial infarction patients with ventricular tachycardia (VT). We analyzed the endo-epicardial electroanatomical mapping (EAM) voltage and morphology characteristics, their association with clinical data and their prognostic value in a large cohort of postmyocardial infarction patients.

METHODS AND RESULTS

We performed total and segmental analysis of voltage (bipolar dense scar [DS] and low voltage areas, unipolar low voltage and penumbra areas) and morphology characteristics (presence of abnormal late potentials [LPs] and early potentials [EPs]) in 100 postmyocardial infarction patients undergoing electroanatomical mapping-based VT ablation (26 endo-epicardial procedures) from 2010-2012. All patients had unipolar low voltage areas, whereas 18% had no identifiable endocardial bipolar DS areas. Endocardial bipolar DS area >22.5 cm(2) best predicted scar transmurality. Endo-epicardial LPs were recorded in 2/3 patients, more frequently in nonseptal myocardial segments and were abolished in 51%. Endocardial bipolar DS area >7 cm(2) and endocardial bipolar scar density >0.35 predicted epicardial LPs. Isolated LPs are located mainly epicardially and EPs endocardially. As a primary strategy, LPs and VT-mapping ablation occurred in 48%, only VT-mapping ablation in 27%, only LPs ablation in 17%, and EPs ablation in 6%. Endocardial LP abolition was associated with reduced VT recurrence and increased unipolar penumbra area predicted cardiac death.

CONCLUSIONS

Endocardial scar extension and density predict scar transmurality and endo-epicardial presence of LPs, although DS is not always identified in postmyocardial infarction patients. LPs, most frequently located in nonseptal myocardial segments, were abolished in 51% resulting in improved outcome.

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.

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.

Noninducibility and Late Potential Abolition

Background—

Successful late potential (LP) abolition and postprocedural ventricular tachycardia (VT) noninducibility constitute significant end points after catheter ablation for VT. We investigated the prognostic impact of a combined procedural end point of VT noninducibility and LP abolition in a large series of post–myocardial infarction patients with VT.

Methods and Results—

A total of 160 (154 men, 94% with implantable cardioverter defibrillators) consecutive post–myocardial infarction patients undergoing first-time ablation procedures from 2010 to 2012 were included. Of the 159 patients surviving the procedure, 137 (86%) were either inducible or in VT at baseline and 103 (65%) had baseline LP presence, of which 79 (77%) underwent successful LP abolition. The combined end point was assessable in 155 (97%) patients. There were 50 (32%) patients with VT recurrences and 17 (11%) cardiac deaths during follow-up. Patients who fulfilled the combined end point of VT noninducibility and LP abolition compared with inducible patients exhibited a significantly lower incidence of VT recurrence (16.4% versus 47.4%; log-rank P <0.001) and cardiac death (4.1% versus 42.1%; log-rank P <0.001). Among noninducible patients, those with additional LP abolition also had a lower incidence of VT recurrence (16.4% versus 46.0%; log-rank P <0.001). After multivariate analysis, the combined end point of VT noninducibility and LP abolition (hazard ratio, 0.205, P <0.001) was independently associated with VT recurrence and cardiac death (hazard ratio, 0.106; P =0.001).

Conclusions—

Achieving a combined catheter ablation procedural end point of VT noninducibility and LP abolition reduces VT recurrence rates to low levels (16%). The overall strategy was associated with a significant impact on cardiac survival.

Management of ventricular tachycardia in the setting of a dedicated unit for the treatment of complex ventricular arrhythmias: long-term outcome after ablation

BACKGROUND

We investigated the impact of catheter ablation on ventricular tachycardia (VT) recurrence and survival in a large number of patients with structural heart disease treated in the setting of a dedicated multiskilled unit.

METHODS AND RESULTS

Since January 2007, we have implemented a multidisciplinary model, aiming for a comprehensive management of VT patients. Programmed ventricular stimulation was used to assess acute outcome. Primary end points were VT recurrence and the occurrence of cardiac and sudden cardiac death. Overall, 528 patients were treated by ablation (634 procedures; 1-4 procedures per patient). Among 482 tested with programmed ventricular stimulation after the last procedure, a class A result (noninducibility of any VT) was obtained in 371 patients (77%), class B (inducibility of nondocumented VT) in 12.4%, and class C (inducibility of index VT) in 10.6%. After a median follow-up time of 26 months, VT recurred in 164 (34.1%) of 472 patients. VT recurrence was documented in 28.6% of patients with a class A result versus 39.6% of patients with class B and 66.7% with class C result (log-rank P<0.001). The incidence of cardiac mortality was lower in class A patients than in those with class B and class C (8.4% versus 18.5% versus 22%, respectively; log-rank P=0.002). On the basis of multivariate analysis, postprocedural inducibility of index VT was independently associated both with VT recurrence (hazard ratio, 4.030; P<0.001) and with cardiac mortality (hazard ratio, 2.099; P=0.04).

CONCLUSIONS

Within a dedicated VT unit, catheter ablation prevents long-term VT recurrences, which may favorably affect survival in a large number of patients who have VT.

Percutaneous cardiopulmonary support for catheter ablation of unstable ventricular arrhythmias in high-risk patients

BACKGROUND AND PURPOSE

In patients with severe cardiomyopathy, recurrent episodes of nontolerated ventricular tachycardia (VT) or electrical storm (ES) frequently cause acute heart failure and cardiac death; the suppression of the arrhythmia is therefore lifesaving, but feasibility of catheter ablation (CA) is precluded by the adverse hemodynamic conditions together with the characteristics of the arrhythmia that interdicts efficacious mapping. The use of the percutaneous cardiopulmonary support (CPS) for circulatory assistance may allow patient's stabilization and enhance efficacy and safety of CA in this emergency setting.

PATIENTS AND METHODS

19 patients (19 males; mean age 61 +/- 6 years; chronic ischemic cardiomyopathy, eleven patients; primary dilated cardiomyopathy, six patients; arrhythmogenic right ventricular dysplasia/ cardiomyopathy, two patients) with recurrent nontolerated VT episodes undergoing CPS-assisted CA were retrospectively evaluated. Twelve patients had acute hemodynamic failure refractory to inotropic agents and ventilatory assistance, seven patients had undergone a failing nonconventional CA procedure. 14 patients presented with ES, and in twelve the procedure was undertaken under emergency conditions within 24 h from admission. Patients were ventilated under general anesthesia and assisted by a multidisciplinary team. The CPS system consisted in a Medtronic Bio-Medicus centrifugal pump and in a Maxima Plus oxygenator, a 15-F arterial cannula, and a 17-F venous cannula.

RESULTS

Flows between 2 and 3 l/min were activated after induction of 56/62 forms of nontolerated VT, achieving hemodynamic stabilization in all patients. CA was mainly guided by conventional activation mapping and was effective in abolishing 45/56 supported VTs; in 10/19 patients all clinical VTs were suppressed by CA. Mean procedural time was 4 h and 20 min. Complete stabilization was achieved in 13 patients (68%) without VT recurrence during a 7-day in-hospital monitoring. A significant clinical improvement was observed in two patients (11%); one patient (5%) with persistent VT episodes acutely died after heart transplant. At a mean follow-up of 42 months (range 15-60 months), 5/18 patients (28%) were free from VT recurrence, 7/18 (39%) had a clear clinical improvement with reduced implantable cardioverter defibrillator interventions. 5/14 patients (36%) had ES recurrence; among them, three died because of acute heart failure. No serious CPS-related complications were observed.

CONCLUSION

The CPS warrants acceptable hemodynamic stabilization and efficacious mapping in high-risk patients undergoing CA for unstable VT in the emergency setting. Safety and efficacy of this technique translate into significant clinical improvement in the majority of patients. Even if only relatively invasive, CPS should be reserved to patients with ES or intractable arrhythmia causing acute heart failure; moreover, the need for an experienced team of multidisciplinary operators implies that its use is restricted to selected high-competency institutions.

Catheter ablation of ventricular tachycardia guided by noncontact mapping

Catheter ablation of untolerated and unstable ventricular tachycardia may not be performed using a conventional activation mapping tecnique. The noncontact mapping system enables reconstruction of the spreading of activation wave through a virtually generated ventricular chamber, even from a single tachycardia beat, and was introduced as a tool to guide mapping and ablation of untolerated or unsustained ventricular arrhythmias. The reduced accuracy in the setting of enlarged ventricles is recognized as the main limitation of this tecnique. While noncontract mapping appears to be especially suitable in guiding the ablation of unsustained idiopathic ventricular arrhythmias, it can also be successfully used as a guide to perform ablation of untolerated re-entry-related ventricular tachycardias during sinus rhythm.

Catheter Ablation for the Treatment of Electrical Storm in Patients With Implantable Cardioverter-Defibrillators

Background— Electrical storm (ES) caused by recurrent episodes of ventricular tachycardia (VT) can cause sudden death in patients with implantable cardioverter-defibrillators and adversely affects prognosis in survivors. Catheter ablation has been proposed for treating ES, but its long-term effect in a large population has never been verified.

Methods and Results— Ninety-five consecutive patients with coronary artery disease (72 patients), idiopathic dilated cardiomyopathy (10 patients), and arrhythmogenic right ventricular dysplasia/cardiomyopathy (13 patients) undergoing catheter ablation for drug-refractory ES were prospectively evaluated. Short-term efficacy was defined by a complete protocol of programmed electric stimulation and by in-hospital outcome; long-term analysis addressed ES recurrence, cardiac mortality, and VT recurrence. Pleomorphic/nontolerated VTs required electroanatomic and noncontact mapping in 48 and 22 patients, respectively, and percutaneous cardiopulmonary support in 10 patients. An epicardial approach was used in 10 patients. After 1 to 3 procedures, induction of any clinical VT(s) by programmed electrical stimulation was prevented in 85 patients (89%). ES was acutely suppressed in all patients; a minimum period of 7 days with stable rhythm was required before hospital discharge. At a median follow-up of 22 months (range, 1 to 43 months), 87 patients (92%) were free of ES and 63 patients (66%) were free of VT recurrence. Eight of 10 patients with persistent inducibility of clinical VT(s) had ES recurrence; 4 of them died suddenly despite appropriate implantable cardioverter-defibrillator intervention. All together, 11 of 95 patients (12%) died of cardiac-related reasons. In the group of patients presenting with all clinical VTs acutely abolished, no ES recurrence was documented, and cardiac mortality was significantly lower compared with the group of patients showing ≥1 clinical VT still inducible after catheter ablation.

Conclusions— Advanced strategies of catheter ablation applied to a large population of patients are effective in the short-term treatment of ES. By preventing ES recurrence, catheter ablation may play a protective role over the long term and, together with long-term pharmacological therapy, may favorably affect cardiac mortality.

A novel algorithm for determining endocardial VT exit site from 12-lead surface ECG characteristics in human, infarct-related ventricular tachycardia

INTRODUCTION

Characteristics of the 12-lead ECG during VT are used to guide initial placement of mapping catheters in endocardial ventricular tachycardia (VT) ablation. Previously constructed algorithms for guidance in human infarct-related VT are limited to patients known to have anterior or inferior infarcts only. We hypothesized that 12-lead ECG characteristics could be used to determine VT exit site in patients with all types of infarction of unknown location.

METHODS AND RESULTS

From noncontact activation maps of 121 LV VT in 51 patients undergoing catheter ablation, VT exit sites were determined and correlated with ECG characteristics according to bundle branch block configuration, limb lead polarity and patterns of precordial R-wave transition. Eight ECG patterns were identified that accounted for 71% of all VT and gave a positive predictive value (PPV) > or =70% using the first two criteria. No correlation was found with patterns of R-wave transition. Using these criteria an algorithm was developed, which was then applied prospectively and blinded to a further 17 VT in 11 patients. Of the 15 VT (88%) to which the algorithm predicted an exit site location (with a PPV > or =70%), 14 VT (93%) were correctly predicted by the algorithm.

CONCLUSION

This algorithm can be used to predict endocardial LV VT exit site location in patients undergoing catheter ablation of VT without knowledge of or reference to infarct location, and can be applied to patients with posterior and/or multiple sites of infarction.

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.

Ventricular tachycardia ablation

The role of catheter ablation in the treatment of ventricular arrhythmias has been changing in the last decade, and this form of therapy now aims at curing multiple ventricular tachycardia morphologies and complex substrates in patients with structural heart disease (post-infarction and idiopathic dilated cardiomyopathy). Under these circumstances, conventional mapping is not feasible and accurate, and the development of new diagnostic methods has become necessary. The non-contact mapping system has been introduced to study the activation pattern of any ventricular arrhythmia by a "single-cycle" analysis, and has brought to the characterization of unstable and of non-sustained forms of arrhythmia. The evaluation of the arrhythmogenic substrate has similarly become more precise by the more common use of the electroanatomic mapping (CARTO), which is being applied to identify areas of scarred tissue responsible for ventricular arrhythmias, to map stable tachycardias and to validate the creation of a line of block. By means of this technological advancement, the identification of critical isthmi and deep intramural circuits has also led to new ablation strategies, frequently simplifying the procedure and minimizing 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.

Incidence and significance of pleomorphism in patients with postmyocardial infarction ventricular tachycardia. Acute and long-term outcome of radiofrequency catheter ablation

AIMS

The prognostic significance of multiple ventricular tachycardia (VT) morphologies, whether spontaneous or induced, was investigated in patients who underwent radiofrequency catheter ablation (RFCA) for postinfarction ventricular tachycardia.

METHODS AND RESULTS

We studied 137 patients with postinfarction ventricular tachycardia. Catheter ablation of all induced ventricular tachycardias was attempted. A single ventricular tachycardia morphology was documented in 102/137 patients (MONO group); 35 patients had spontaneous pleomorphism (PLEO group). Multiple VT morphologies were induced in 58/102 (57%) MONO patients and in all PLEO patients. A higher rate of arrhythmia suppression was obtained in MONO as compared to PLEO patients (162/212 [76%] vs. 43/110 [39%]). Clinical presentation (VT pleomorphism) (OR: 0.22, CI: 0.08-0.62) and the induced VT cycle (mean PLEO/MONO: 338/385 ms, OR: 1.06) were independent predictors of acute RFCA success. Among MONO patients, the procedure was successful in 75% of the patients with a single induced ventricular tachycardia compared to 64% of those with multiple tachycardias. The acute success rate was lower in PLEO patients (23%). PLEO patients had a significantly higher 3- and 5-year arrhythmia recurrence rate than MONO patients. RFCA acute success was the only independent predictor of long-term outcome in multivariate analysis.

CONCLUSIONS

Spontaneous, but not induced, VT pleomorphism in patients with prior myocardial infarction adversely affects the acute and long-term success rate of RFCA.