Kyoko Soejima

Catheter Ablation in Patients With Multiple and Unstable Ventricular Tachycardias After Myocardial Infarction Short Ablation Lines Guided by Reentry Circuit Isthmuses and Sinus Rhythm Mapping

Background—Extensive lines of radiofrequency (RF) lesions through infarct (MI) can ablate multiple and unstable ventricular tachycardias (VTs). Methods for guiding ablation that minimize unnecessary RF applications are needed. This study assesses the feasibility of guiding RF line placement by mapping to identify a reentry circuit isthmus. Methods and Results—Catheter mapping and ablation were performed in 40 patients (MI location: inferior, 28; anterior, 7; and both, 5) with an electroanatomic mapping system to measure the infarct region and ablation lines. The initial line was placed in the MI region either through a circuit isthmus identified from entrainment mapping or a target identified from pace mapping. A total of 143 VTs (42 stable, 101 unstable) were induced. An isthmus was identified in 25 patients (63%; 5 with only stable VTs, 5 with only unstable VTs, and 15 with both VTs). Inducible VTs were abolished or modified in 100% of patients when the RF line included an isthmus compared with 53% when RF had to be guided by pace mapping (P =0.0002); those with an isthmus identified received shorter ablation lines (4.9±2.4 versus 7.4±4.3 cm total length, P =0.02). During follow-up, spontaneous VT decreased markedly regardless of whether an isthmus was identified. VT stability and number of morphologies did not influence outcome. Conclusions—A 4- to 5-cm line of RF lesions abolishes all inducible VTs in more than 50% of patients. Less ablation is required if a reentry circuit isthmus is identified even when multiple and unstable VTs are present.

HRS expert consensus statement on the diagnosis and management of arrhythmias associated with cardiac sarcoidosis.

David H. Birnie, MD (Chair), William H. Sauer, MD, FHRS, CCDS (Chair), Frank Bogun, MD, Joshua M. Cooper, MD, FHRS, Daniel A. Culver, DO,* Claire S. Duvernoy, MD, Marc A. Judson, MD, Jordana Kron, MD, Davendra Mehta, MD, PhD, FHRS, Jens Cosedis Nielsen, MD, Amit R. Patel, MD, Tohru Ohe, MD, FHRS, Pekka Raatikainen, MD, Kyoko Soejima, MD From the University of Ottawa Heart Institute, Ottawa, Ontario, Canada, University of Colorado, Aurora, Colorado, University of Michigan, Ann Arbor, Michigan, Temple University Health System, Philadelphia, Pennsylvania, Cleveland Clinic, Cleveland, Ohio, VA Ann Arbor Healthcare System and University of Michigan, Ann Arbor, Michigan, Albany Medical College, Albany, New York, Virginia Commonwealth University, Richmond, Virginia, Mount Sinai School of Medicine, New York, New York, Aarhus University Hospital, Aarhus, Denmark, University of Chicago, Chicago, Illinois, Sakakibara Heart Institute of Okayama, Okayama, Japan, Heart Center, Tampere University Hospital, Tampere, Finland, and Kyorin University School of Medicine, Mitaka City, Japan.

Electrically Unexcitable Scar Mapping Based on Pacing Threshold for Identification of the Reentry Circuit Isthmus Feasibility for Guiding Ventricular Tachycardia Ablation

Background—We hypothesized that delineating electrically unexcitable scar (EUS) within low-voltage infarct regions will locate reentry circuit isthmuses by defining their borders. The pacing threshold and electrogram amplitude that best determines EUS is unknown. Methods and Results—The change in dimension of the virtual electrode was estimated in 11 patients and observed to increase by 4.4±2.5 mm as stimulus strength increases from threshold (2.9±1.8 mA) to 10 mA. EUS was defined as a threshold >10 mA. In 14 consecutive patients, mapping and ablation of ventricular tachycardia (VT) were performed using an electroanatomic mapping system. During sinus rhythm, unipolar pacing was performed at sites with bipolar electrogram amplitude <1.5 mV. EUS regions were marked on the maps. Reentry circuit isthmuses were identified by entrainment mapping or pace mapping, and ablation was performed. EUS was identified in the infarct in all 14 patients (11.8±13.9 cm2). All 20 VT circuit isthmuses identified were adjacent to EUS. Although electrogram amplitude correlated with pacing threshold (r =0.64, P <0.0001), many isthmuses had very low-amplitude electrograms, and EUS could not be identified from electrogram amplitude alone. RF ablation lines connecting selected EUS regions abolished all inducible VTs in 10 patients (71%); spontaneous VT was markedly reduced during follow-up (from 142±360 to 0.9±2.0 episodes per month, P =0.002). Conclusions—This new method of identifying EUS provides complimentary information to the electrogram amplitude in delineating potential reentry circuit paths, potentially facilitating ablation during sinus rhythm.

Catheter ablation of ventricular tachycardia after repair of congenital heart disease : Electroanatomic identification of the critical right ventricular isthmus

Background— Catheter ablation of ventricular tachycardia (VT) after repair of congenital heart disease can be difficult because of nonmappable VTs and complex anatomy. Insights into the relation between anatomic isthmuses identified by delineating unexcitable tissue using substrate mapping techniques and critical reentry circuit isthmuses might facilitate ablation. Methods and Results— Sinus rhythm voltage mapping of the right ventricle was performed in 11 patients with sustained VT after repair of congenital heart disease. Unexcitable tissue from patch material, valve annulus, or dense fibrosis, identified from bipolar voltage (<0.5 mV) and pacing threshold (>10 mA), was defined as an anatomic isthmus boundary bordering 4 isthmuses between (1) the tricuspid annulus and scar/patch in the anterior right ventricular outflow, (2) the pulmonary annulus and right ventricular free wall scar/patch, (3) the pulmonary annulus and septal scar/patch, and (4) the septal scar/patch and tricuspid annulus. The reentry circuit isthmuses of all induced 15 VTs (mean cycle length, 276±78 ms; 73% poorly tolerated), identified by activation, entrainment, and/or pace mapping, were located in an anatomic isthmus (11 of 15 VTs in anatomic isthmus 1). Transecting the anatomic isthmuses by ablation lesions abolished all VTs. During 30.4±29.3 months of follow-up, 91% of patients remained free of VT. Conclusions— Reentry circuit isthmuses in VT late after repair of congenital heart disease are located within anatomically defined isthmuses bordered by unexcitable tissue. The boundaries can be identified with 3-dimensional substrate mapping and connected by ablation lines during sinus rhythm. These findings should facilitate catheter and surgical ablation of stable and unstable VTs.

Catheter Ablation for Ventricular Tachycardia

Sustained ventricular tachycardia (VT) is an important cause of morbidity and sudden death in patients with heart disease.1 Implantable cardioverter-defibrillators (ICDs) terminate VT episodes, reducing the risk of sudden death. Recurrent VT develops in 40% to 60% of patients who receive an ICD after an episode of spontaneous sustained VT. A first episode of VT occurs in ≈20% of patients within 3 to 5 years after ICD implantation for primary prevention of sudden death in high-risk groups.2–4 ICD shocks reduce quality of life and are associated with an increased risk of death.2–4 Antiarrhythmic drug therapy with amiodarone or sotalol reduces VT episodes but with disappointing incidence of side effects and efficacy.2 Catheter ablation is useful for reducing VT episodes and can be life-saving when VT is incessant.1,5,6 Idiopathic VTs occur in patients without structural heart disease and rarely cause sudden death. Electrophysiological study with catheter ablation is often warranted to confirm the diagnosis, to provide further evidence for the absence of ventricular scar or other disease, and often to cure the arrhythmia. Ablation is also an option for symptomatic nonsustained VT and frequent ventricular ectopy in these patients.1 The appearance of the VT on ECG often suggests its likely cause and associated heart disease (Figure 1). Monomorphic VT has the same QRS complex from beat to beat, indicating repetitive ventricular activation from a structural substrate or focus that can be targeted for ablation. Most are due to reentry through regions of ventricular scar.7 Figure 1. ECG types of VT and most common causes are shown with characteristic ECG features of selected VTs. LBBB indicates left bundle-branch block; LVOT, LV outflow tract; RBBB, right bundle-branch block; L, left; and R, right. Polymorphic VTs have a changing ventricular activation sequence that can be due to …

A Leadless Intracardiac Transcatheter Pacing System

BACKGROUND A leadless intracardiac transcatheter pacing system has been designed to avoid the need for a pacemaker pocket and transvenous lead. METHODS In a prospective multicenter study without controls, a transcatheter pacemaker was implanted in patients who had guideline-based indications for ventricular pacing. The analysis of the primary end points began when 300 patients reached 6 months of follow-up. The primary safety end point was freedom from system-related or procedure-related major complications. The primary efficacy end point was the percentage of patients with low and stable pacing capture thresholds at 6 months (≤2.0 V at a pulse width of 0.24 msec and an increase of ≤1.5 V from the time of implantation). The safety and efficacy end points were evaluated against performance goals (based on historical data) of 83% and 80%, respectively. We also performed a post hoc analysis in which the rates of major complications were compared with those in a control cohort of 2667 patients with transvenous pacemakers from six previously published studies. RESULTS The device was successfully implanted in 719 of 725 patients (99.2%). The Kaplan-Meier estimate of the rate of the primary safety end point was 96.0% (95% confidence interval [CI], 93.9 to 97.3; P<0.001 for the comparison with the safety performance goal of 83%); there were 28 major complications in 25 of 725 patients, and no dislodgements. The rate of the primary efficacy end point was 98.3% (95% CI, 96.1 to 99.5; P<0.001 for the comparison with the efficacy performance goal of 80%) among 292 of 297 patients with paired 6-month data. Although there were 28 major complications in 25 patients, patients with transcatheter pacemakers had significantly fewer major complications than did the control patients (hazard ratio, 0.49; 95% CI, 0.33 to 0.75; P=0.001). CONCLUSIONS In this historical comparison study, the transcatheter pacemaker met the prespecified safety and efficacy goals; it had a safety profile similar to that of a transvenous system while providing low and stable pacing thresholds. (Funded by Medtronic; Micra Transcatheter Pacing Study ClinicalTrials.gov number, NCT02004873.).

EHRA/HRS/APHRS expert consensus on ventricular arrhythmias.

Christian Torp Pedersen (EHRA Chairperson, Denmark), G. Neal Kay (HRS Chairperson, USA), Jonathan Kalman (APHRS Chairperson, Australia), Martin Borggrefe (Germany), Paolo Della-Bella (Italy), Timm Dickfeld (USA), Paul Dorian (Canada), Heikki Huikuri (Finland), Youg-Hoon Kim (Korea), Bradley Knight (USA), Francis Marchlinski (USA), David Ross (Australia), Frédéric Sacher (France), John Sapp (Canada), Kalyanam Shivkumar (USA), Kyoko Soejima (Japan), Hiroshi Tada (Japan), Mark E. Alexander (USA), John K. Triedman (USA), Takumi Yamada (USA), and Paulus Kirchhof (Germany)

Multiple atrial macro–re-entry circuits in adults with repaired congenital heart disease: entrainment mapping combined with three-dimensional electroanatomic mapping

OBJECTIVES We sought to characterize re-entry circuits causing intra-atrial re-entrant tachycardias (IARTs) late after the repair of congenital heart disease (CHD) and to define an approach for mapping and ablation, combining anatomy, activation sequence data and entrainment mapping. BACKGROUND The development of IARTs after repair of CHD is difficult to manage and ablate due to complex anatomy, variable re-entry circuit locations and the frequent co-existence of multiple circuits. METHODS Forty-seven re-entry circuits were mapped in 20 patients with recurrent IARTs refractory to medical therapy. In the first group (n = 7), ablation was guided by entrainment mapping. In the second group (n = 13), entrainment mapping was combined with a three-dimensional electroanatomic mapping system to precisely localize the scar-related boundaries of re-entry circuits and to reconstruct the activation pattern. RESULTS Three types of right atrial macro-re-entrant circuits were identified: those related to a lateral right atriotomy scar (19 IARTs), the Eustachian isthmus (18 IARTs) or an atrial septal patch (8 IARTs). Two IARTs originated in the left atrium. Radiofrequency (RF) lesions were applied to transect critical isthmuses in the right atrium. In three patients, the combined mapping approach identified a narrow isthmuses in the lateral atrium, where the first RF lesion interrupted the circuit; the remaining circuits were interrupted by a series of RF lesions across a broader path. Overall, 38 (81%) of 47 IARTs were successfully ablated. During follow-up ranging from 3 to 46 months, 16 (80%) of 20 patients remained free of recurrence. Success was similar in the first 7 (group 1) and last 13 patients (group 2), but fluoroscopy time decreased from 60 +/- 30 to 24 +/- 9 min/procedure, probably related to the increasing experience and ability to monitor catheter position non-fluoroscopically. CONCLUSIONS Entrainment mapping combined with three-dimensional electroanatomic mapping allows delineation of complex re-entry circuits and critical isthmuses as targets for ablation. Radiofrequency catheter ablation is a reasonable option for treatment of IARTs related to repair of CHD.

Subxiphoid Surgical Approach for Epicardial Catheter-Based Mapping and Ablation in Patients With Prior Cardiac Surgery or Difficult Pericardial Access

Background—Percutaneous epicardial mapping and ablation are successful in some patients with ventricular epicardial reentry circuits but may be impossible when pericardial adhesions are present, such as from prior cardiac surgery. The purpose of this study was to evaluate the feasibility of direct surgical exposure of the pericardial space to allow catheter epicardial mapping and ablation in the electrophysiology laboratory when percutaneous access is not feasible. Methods and Results—In 6 patients with prior cardiac surgery or failed percutaneous pericardial access, a subxiphoid pericardial window was attempted. In all 6 patients, manual lysis of adhesions exposed the epicardial surface of the heart through a small subxiphoid incision and allowed placement of an 8F sheath into the pericardial space under direct vision. Access to the diaphragmatic surface of the heart with ablation catheters was achieved in all patients, and catheter manipulation to the lateral and anterior walls was possible in 4 patients. Three-dimensional electroanatomic voltage maps revealed low-amplitude regions in the inferior or posterior left ventricular epicardium. A total of 16 ventricular tachycardias were induced, and 14 were abolished by radiofrequency ablation. Ablation was limited by intrapericardial defibrillator patches adherent to the likely target region in 2 patients. All patients had chest pain consistent with pericarditis early after the procedure that resolved within a few days. There were no other complications. Conclusions—A direct surgical subxiphoid epicardial approach in the electrophysiology laboratory is feasible for patients with difficult pericardial access who require ablation of epicardial arrhythmia foci.

Identification of the Ventricular Tachycardia Isthmus After Infarction by Pace Mapping

Background—Ventricular tachycardia (VT) isthmuses can be defined by fixed or functional block. During sinus rhythm, pace mapping near the exit of an isthmus should produce a QRS similar to that of VT. Pace mapping at sites proximal to the exit may produce a similar QRS with a longer stimulus-to-QRS interval (S-QRS). The aim of the study was to determine whether a VT isthmus could be identified and followed by pace mapping. Methods and Results—Left ventricular pace mapping during sinus rhythm was performed at 819 sites in 11 patients with VT late after infarction, and corresponding CARTO maps were reconstructed. An isthmus site was defined by entrainment and/or VT termination by ablation. Pace-mapping data were analyzed from the identified isthmus site and from sites at progressively increasing distances from this initial isthmus site. Sites where pace mapping produced the same QRS with different S-QRS delays were identified to attempt to trace the course of the isthmus. In 11 patients, 13 confluent low-voltage infarct regions were present. In all these regions, parts of VT isthmuses were identified by pace mapping. In 11 of 13 of the identified isthmus parts, the QRS morphology of the pace map matched a VT QRS. In 10 of 11 patients, radiofrequency ablation rendered clinical VTs noninducible. Successful ablation sites were localized within an isthmus identified by pace mapping in all of these 10 patients. Conclusions—VT isthmuses can be identified and part of their course delineated by pace mapping during sinus rhythm. This method could help target isthmus sites for ablation during stable sinus rhythm.