Ebstein's anomaly: an electrophysiological perspective.

Ebstein's anomaly of the tricuspid valve (EA) is an uncommon congenital cardiac malformation. It can present with atrioventricular tachycardia (AVRT), atrioventricular nodal re-entrant tachycardia (AVNRT), atrial arrhythmias, and rarely with ventricular tachycardia. The 12-lead electrocardiogram (ECG) is critically important and often diagnostic even prior to an electrophysiology study (EPS). Due to its complex anatomy, it poses particular challenges for mapping and ablation, even for an experienced electrophysiologist. In this review, we aim to provide insight into the electrophysiological perspective of EA and an in-depth analysis of the various arrhythmias encountered in diverse clinical scenarios.

Emergency out-of-hours catheter ablation for ventricular arrhythmia storm: a UK and Australian experience.

AIMS: There are limited data on emergency catheter ablation (CA) for ventricular arrhythmia (VA) storm. We describe the feasibility and safety of performing emergency CA in an out-of-hours setting for VA storm refractory to medical therapy at 2 tertiary hospitals. METHODS AND RESULTS: Twenty-five consecutive patients underwent out-of-hours (5pm-8am [weekday] or Friday 5pm-Monday 8am [weekend]) CA for VA storm refractory to anti-arrhythmic drugs and sedation. Baseline and procedural characteristics along with outcomes were compared to 91 consecutive patients undergoing weekday daytime-hours (8am-5pm) CA for VA storm. More patients undergoing out-of-hours CA had a left ventricular ejection fraction ≤35% (68% vs. 42%, P = 0.022), chronic kidney disease (60% vs. 20%, P < 0.001), and presented following a resuscitated out-of-hospital cardiac arrest (56% vs. 5%, P < 0.001), compared to the daytime-hours group. During median follow-up (377 [interquartile range 138-826] days), both groups experienced similar survival free from recurrent VA and VA storm. Survival free from cardiac transplant and/or mortality was lower in the out-of-hours group (44% vs. 81%, P = 0.007), but out-of-hours CA was not independently associated with increased cardiac transplant and/or mortality (hazard ratio 1.34, 95% confidence interval 0.61-2.96, P = 0.47). Of the 11 patients in the out-of-hours group who survived follow-up, VA-free survival was 91% and VA storm-free survival was 100% at 1-year after CA. CONCLUSION: Out-of-hours CA may occasionally be required to control VA storm and can be safe and efficacious in this scenario. During follow-up, cardiac transplant and/or mortality is common but undergoing out-of-hours CA was not predictive of this composite endpoint.

Mortality after catheter ablation of structural heart disease related ventricular tachycardia.

BACKGROUND: There is a paucity of data describing mortality after catheter ablation of ventricular tachycardia (VT). OBJECTIVES: We describe the causes and predictors of cardiac transplant and/or mortality following catheter ablation of structural heart disease (SHD) related VT. METHODS: Over 10-years, 175 SHD patients underwent VT ablation. Clinical characteristics, and outcomes, were compared between patients undergoing transplant and/or dying and those surviving. RESULTS: During 2.8 (IQR 1.9-5.0) years follow-up, 37/175 (21%) patients underwent transplant and/or died following VT ablation. Prior to ablation, these patients were older (70.3 ± 11.1 vs. 62.1 ± 13.9 years, P = 0.001), had lower left ventricular ejection fraction ([LVEF] 30 ± 12% vs. 44 ± 14%, P < 0.001), and were more likely to have failed amiodarone (57% vs. 39%, P = 0.050), compared to those that survived. Predictors of transplant and/or mortality included LVEF≤35% (HR 4.71 [95% CI 2.18-10.18], P < 0.001), age ≥ 65 years (HR 2.18 [95% CI 1.01-4.73], P = 0.047), renal impairment (HR 3.73 [95% CI 1.80-7.74], P < 0.001), amiodarone failure (HR 2.67 [95% CI 1.27-5.63], P = 0.010) and malignancy (HR 3.09 [95% CI 1.03-9.26], P = 0.043). Ventricular arrhythmia free survival at 6-months was lower in the transplant and/or deceased, compared to non-deceased group (62% vs. 78%, P = 0.010), but was not independently associated with transplant and/or mortality. The risk score, MORTALITIES-VA, accurately predicted transplant and/or mortality (AUC: 0.872 [95% CI 0.810-0.934]). CONCLUSIONS: Cardiac transplant and/or mortality after VT ablation occurred in 21% of patients. Independent predictors included LVEF≤35%, age ≥ 65 years, renal impairment, malignancy, and amiodarone failure. The MORTALITIES-VA score may identify patients at high-risk of transplant and/or dying after VT ablation.

Efficacy and safety of catheter ablation as first-line therapy for the management of ventricular tachycardia.

BACKGROUND: Ventricular tachycardia (VT) is associated with significantly increased morbidity and mortality. Catheter ablation (CA) in line with an implantable cardioverter-defibrillator (ICD) is highly effective in VT management; however, it is unknown if CA should be considered as first-line therapy. The aim of this study is to verify the efficacy and safety of CA as first-line therapy for the first VT presentation (as adjunctive to ICD insertion), compared to initial ICD insertion and anti-arrhythmic drug (AAD) therapy. METHODS: Data from patients with the first presentation for VT from January 2017 to January 2021 was reviewed. Patients were classified as "ablation first" vs "ICD first" groups and compared the clinical outcomes between groups. RESULTS: One hundred and eighty-four consecutive patients presented with VT; 34 underwent CA as first-line therapy prior to ICD insertion, and 150 had ICD insertion/AAD therapy as first-line. During the median follow-up of 625 days, patients who underwent CA as first-line therapy had significantly higher ventricular arrhythmia (VA)-free survival (91% vs 59%, log-rank P = 0.002) and composite of VA recurrence, cardiovascular hospitalization, transplant, and death (84% vs 54%, log-rank P = 0.01) compared to those who did not undergo CA. Multivariate analysis revealed that first-line CA was the only protective predictor of VA recurrence (hazard ratio (HR) 0.20, P = 0.003). There were 3 (9%) peri-procedural complications with no peri-procedural deaths. CONCLUSION: Real-world data supports the efficacy and safety of CA as first-line therapy at the time of the first VT hospitalization, compared to the initial ICD implant and AAD therapy.

Correlation of spatial patterns of endocardial pace mapping to underlying scar topography in patients with scar-related ventricular tachycardia.

INTRODUCTION: Endocardial pace mapping (PM) can identify conducting channels for ventricular tachycardia (VT) circuits in patients with structural heart disease (SHD). Recent findings show the temporal and spatial pattern of PM may aid identification of the surface harboring VT isthmii. The specific correlation of PM patterns to scar topography has not been examined. OBJECTIVE: To correlate the pattern of endocardial PMs to underlying scar topography in SHD patients with VT. METHODS: Data from patients undergoing VT ablation from August 2018 to February 2022 were reviewed. RESULTS: Sixty-three patients with SHD-related VT (mean age 65 ± 14 years) with 83 endocardial PM correlation maps were analysed. Two main correlation patterns were identified, an "abrupt-change correlation pattern (AC-pattern)" and "centrifugal-attenuation correlation pattern (CA-pattern)." AC-pattern had lower scar ratio (unipolar/bipolar % scar area; 1.1 vs. 1.5, p < .001), had longer maximal stimulus-QRS intervals (97.5 vs. 68 ms, p = .002), and higher likelihood of endocardial dominant scar (11/21 [52%] vs. 3/38 [8%], p < .001) than CA-pattern seen on intracardiac echocardiography (ICE). In contrast, CA-pattern was more likely to have epicardial dominant scar or mid-intramural scar on ICE (epicardial dominant scar; CA-pattern: 12/38 [32%] vs. AC-pattern: 1/21 [5%], p = .02, mid-intramural scar; CA-pattern: 15/38 [39%] vs. AC-pattern: 1/21 [5%], p = .005). CONCLUSIONS: The spatial pattern of endocardial PM in SHD-related VT directly correlates with scar topography. AC-pattern is associated with endocardial dominant scar on ICE with lower scar ratio and longer stimulus-QRS intervals, whereas CA-pattern is strongly associated with epicardial dominant or mid-intramural scar with higher scar ratio and shorter stimulus-QRS intervals.

A Prospective, Multicentre Randomised Controlled Trial Comparing Catheter Ablation Versus Antiarrhythmic Drugs in Patients With Structural Heart Disease Related Ventricular Tachycardia: The CAAD-VT Trial Protocol.

IMPORTANCE: Randomised trials have shown that catheter ablation (CA) is superior to medical therapy for ventricular tachycardia (VT) largely in patients with ischaemic heart disease. Whether this translates to patients with all forms and stages of structural heart disease (SHD-e.g., non-ischaemic heart disease) is unclear. This trial will help clarify whether catheter ablation offers superior outcomes compared to medical therapy for VT in all patients with SHD. OBJECTIVE: To determine in patients with SHD and spontaneous or inducible VT, if catheter ablation is more efficacious than medical therapy in control of VT during follow-up. DESIGN: Randomised controlled trial including 162 patients, with an allocation ratio of 1:1, stratified by left ventricular ejection fraction (LVEF) and geographical region of site, with a median follow-up of 18-months and a minimum follow-up of 1 year. SETTING: Multicentre study performed in centres across Australia. PARTICIPANTS: Structural heart disease patients with sustained VT or inducible VT (n=162). INTERVENTION: Early treatment, within 30 days of randomisation, with catheter ablation (intervention) or initial treatment with antiarrhythmic drugs only (control). MAIN OUTCOMES, MEASURES, AND RESULTS: Primary endpoint will be a composite of recurrent VT, VT storm (≥3 VT episodes in 24 hrs or incessant VT), or death. Secondary outcomes will include each of the individual primary endpoints, VT burden (number of VT episodes in the 6 months preceding intervention compared to the 6 months after intervention), cardiovascular hospitalisation, mortality (including all-cause mortality, cardiac death, and non-cardiac death) and LVEF (assessed by transthoracic echocardiography from baseline to 6-, 12-, 24- and 36-months post intervention). CONCLUSIONS AND RELEVANCE: The Catheter Ablation versus Anti-arrhythmic Drugs for Ventricular Tachycardia (CAAD-VT) trial will help determine whether catheter ablation is superior to antiarrhythmic drug therapy alone, in patients with SHD-related VT. TRIAL REGISTRY: Australian New Zealand Clinical Trials Registry (ANZCTR) TRIAL REGISTRATION ID: ACTRN12620000045910 TRIAL REGISTRATION URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=377617&isReview=true.

Comparison of the arrhythmogenic substrate for ventricular tachycardia in patients with ischemic vs non-ischemic cardiomyopathy - insights from high-density, multi-electrode catheter mapping.

PURPOSE: The purpose of this study was to compare the differences of arrhythmogenic substrate using high-density mapping in ventricular tachycardia (VT) patients with ischemic (ICM) vs non-ischemic cardiomyopathy (NICM). METHODS: Data from patients presenting for VT ablation from December 2016 to December 2020 at Westmead Hospital were reviewed. RESULTS: Sixty consecutive patients with structural heart disease (ICM 57%, NICM 43%, mean age 66 years) having catheter ablation of scar-related VT with pre-dominant left ventricular involvement were included. ICM was associated with larger proportion of dense scar area (bipolar; 19 [12-29]% vs 6 [3-10]%, P < 0.001, unipolar; 20 [12-32]% vs 11 [7-19]%, P = 0.01) compared with NICM. However, the scar ratio (unipolar dense scar [%]/bipolar dense scar [%]) was significantly higher in NICM patients (1.2 [0.8-1.7] vs 1.7 [1.3-2.3], P = 0.003). Larger scar area in ICM was paralleled by higher proportion of complex electrograms (6 [2-13] % vs 3 [1-5] %, P = 0.01), longer and wider voltage based conducting channels, higher incidence of late potential-based conducting channels, longer VT cycle-length (399 ± 80 ms vs 359 ± 68 ms, P = 0.04) and greater maximal stimulation-QRS interval among sites with good pace-map correlation (75 [51-99]ms vs 48 [31-73]ms, P = 0.02). Ventricular arrhythmia (VA) storm was more highly prevalent in ICM than NICM (50% vs 23%, P = 0.03). During the follow-up period, NICM had a significantly higher cumulative incidence for the VA recurrence than ICM (P = 0.03). CONCLUSIONS: High-density multi-electrode catheter mapping of left ventricular arrhythmogenic substrate of NICM tends to show smaller dense scar area and higher scar ratio, compared with ICM, suggestive the extent of epicardial/intramural substrate, with paucity of substrate targets for ablation, which results in the worse outcomes with ablation.

Impact of sex on clinical, procedural characteristics and outcomes of catheter ablation for ventricular arrhythmias according to underlying heart disease.

BACKGROUND: Women are under-represented in many key studies and trials examining outcomes of catheter ablation (CA) for ventricular arrhythmias (VA). We compared characteristics between men and women undergoing their first catheter ablation for VA at a single centre over 10 years. METHODS: The clinical, procedural characteristics and outcomes of 287 consecutive patients (male = 182, female = 105), undergoing their first CA at our centre over 10 years were compared according to sex and underlying heart disease. RESULTS: In the ablation population, women were younger, had fewer co-morbidities, were less likely to have ischemic cardiomyopathy (ICM) and VA storm and were more likely to have idiopathic VA and premature ventricular complexes as the indication for ablation (P < 0.05 for all). Amongst idiopathic and non-ischemic cardiomyopathy (NICM) subgroups, baseline characteristics were similar; amongst ICM, women were younger and had higher numbers of drug failure pre-ablation (P = 0.05). Women were similar to men in all procedural characteristics, acute procedural success and complications, regardless of underlying heart disease. At median follow-up of 666 days, VA-free survival, overall mortality and survival free of death or transplant were comparable in both groups. Sex was not a predictor of these outcomes, after accounting for clinical and procedural characteristics. CONCLUSION: Women represented 36% of the real-world population at our centre referred for CA of VA. There are key differences in clinical features of women versus men referred for VA ablation. Despite these differences, VA ablation in women can be accomplished with similar success and complication rates to men, regardless of underlying heart disease.

Correlation of exit sites of inducible ventricular tachycardia post-ST elevation myocardial infarction on electrophysiology study, with region of infarct.

BACKGROUND: Ventricular arrhythmia (VA) is the most common cause of sudden cardiac death post-ST elevation myocardial infarction (STEMI). Ventricular tachycardia (VT) may be inducible in electrophysiology studies (EPS) early (<40 days) post-STEMI. Whether it originates from the infarct site remains unknown. We examined the correlation between inducible VT and infarct location post-STEMI. AIMS: To investigate the correlation between inducible VT and infarct location post-STEMI. METHODS: We retrospectively analysed 46 patients from 2005 to 2017 with STEMI who underwent early programmed ventricular stimulation through EPS (>48 h post-STEMI and <40 days from admission). Gated heart pool scans were used to visualise infarct scar regions, and VT exit sites were derived from induction 12-lead electrocardiography. Patients were followed up for primary outcomes of recurrent VA and all-cause mortality. RESULTS: Forty-six patients were included for analysis, with 50 uniquely induced VT exit sites. Mean left ventricular ejection fraction was 30 ± 8.7% and 22% had impaired right ventricular ejection fraction. Mean time from presentation to EPS was 16 ± 31.3 days. Of the induced VT, 44 (88%) were from within scar and scar-border regions, whereas 6 (12%) of the induced VT were found to be remote to imaging-derived scar. Over a median follow-up period of 75 months, 6 (13%) patients died, and 7 (15%) patients had recurrent VA. No deaths occurred in patients with remote VT. CONCLUSION: The majority of early inducible post-infarct VT arises from acute myocardial scar; however, a small portion arises from sites remote from scars with a possible focal aetiology.

Early Catheter Ablation Versus Initial Medical Therapy for Ventricular Tachycardia Storm.

BACKGROUND: Ventricular tachycardia (VT) storm is associated with significantly increased morbidity, mortality, and exponential healthcare utilization. Although catheter ablation (CA) may be curative, there are limited data directly comparing outcomes of early CA with initial medical therapy. METHODS: We compared outcomes of patients presenting with VT storm treated with initial CA versus those treated with initial medical therapy during their first storm presentation in an observational study. Retrospective data from the host institution from January 2014 to April 2020 of 129 patients with their first VT storm presentation were analyzed (58 underwent initial CA, 71 underwent treatment with initial medical therapy). Outcomes were compared in follow-up. RESULTS: Median time to initial CA was 6 days. Over a median follow-up of 702 days, patients who underwent initial CA compared with those treated with initial medical therapy had significantly less: (i) VA recurrence (43% versus 92%; P=0.002); (ii) VT storm recurrence (28% versus 73%; P<0.001); (iii) composite end point of death, heart transplant, VT storm recurrence, and VT-related hospitalization (47% versus 89%; P=0.002); (iv) iatrogenic complications (at 12 months: 17% versus 45%; P<0.001); (v) cardiovascular-related hospitalizations (50% versus 89%; P=0.01); (vi) total number of hospitalizations (median 1 versus 4; P<0.001); and (vi) cumulative days in hospital (median 0.5 versus 18; P<0.001). There were no intraprocedural deaths in patients treated with early CA. CONCLUSION: In an observational setting in which patients presenting with storm, early CA appears superior to initial medical therapy in terms of VT recurrence, storm recurrence, iatrogenic complications, cardiovascular hospitalizations, and cumulative days in hospital in follow-up.

Intracardiac echocardiography techniques to identify ventricular arrhythmia substrate.

Intracardiac echocardiography (ICE) is increasingly used to facilitate catheter ablation of ventricular arrhythmias (VA). It allows intraprocedural recognition of myocardial substrate, optimization of catheter-tissue contact, identification of anatomical barriers to ablation, and early recognition of complications. In the era where the 3-dimensionality of substrate for VA is increasingly recognized, ICE is invaluable in identifying scar topography in the endocardial, midmyocardial, and epicardial layers. ICE assists in identifying endocavitary structures that are a common source of VA in idiopathic and structural heart disease. Furthermore, as substrate imaging of the right ventricle has not been optimized with other imaging modalities, ICE offers a unique opportunity to visualize substrate in this chamber. Real-time substrate identification can be particularly useful where there are contraindications to use of other imaging modalities or the images are obscured by artefact in the presence of cardiac device leads. In this review we provide a step-by-step guide in the techniques used to image ventricular arrhythmia substrate with ICE. We also discuss the benefits and limitations of this technique in comparison to other imaging modalities.

The Role of Contemporary Wearable and Handheld Devices in the Diagnosis and Management of Cardiac Arrhythmias.

Cardiac arrhythmias are associated with significant morbidity, mortality and economic burden on the health care system. Detection and surveillance of cardiac arrhythmias using medical grade non-invasive methods (electrocardiogram, Holter monitoring) is the accepted standard of care. Whilst their accuracy is excellent, significant limitations remain in terms of accessibility, ease of use, cost, and a suboptimal diagnostic yield (up to ∼50%) which is critically dependent on the duration of monitoring. Contemporary wearable and handheld devices that utilise photoplethysmography and the electrocardiogram present a novel opportunity for remote screening and diagnosis of arrhythmias. They have significant advantages in terms of accessibility and availability with the potential of enhancing the diagnostic yield of episodic arrhythmias. However, there is limited data on the accuracy and diagnostic utility of these devices and their role in therapeutic decision making in clinical practice remains unclear. Evidence is mounting that they may be useful in screening for atrial fibrillation, and anecdotally, for the diagnosis of other brady and tachyarrhythmias. Recently, there has been an explosion of patient uptake of such devices for self-monitoring of arrhythmias. Frequently, the clinician is presented such information for review and comment, which may influence clinical decisions about treatment. Further studies are needed before incorporation of such technologies in routine clinical practice, given the lack of systematic data on their accuracy and utility. Moreover, challenges with regulation of quality standards and privacy remain. This state-of-the-art review summarises the role of novel ambulatory, commercially available, heart rhythm monitors in the diagnosis and management of cardiac arrhythmias and their expanding role in the diagnostic and therapeutic paradigm in cardiology.

Catheter Ablation for Ventricular Tachycardia in Ischaemic Versus Non-Ischaemic Cardiomyopathy: A Systematic Review and Meta-Analysis.

BACKGROUND: There are differences in substrate and ablation approaches for ventricular tachycardia (VT) in ischaemic (ICM) and non-ischaemic cardiomyopathy (NICM). OBJECTIVE: To perform a systematic review and meta-analysis comparing clinical and procedural characteristics/outcomes of VT ablation in ICM versus NICM. METHODS: Electronic databases were searched for comparative studies reporting outcomes of VT ablation in patients with ICM and NICM. Primary outcomes were acute procedural success, VT recurrence and long-term mortality. Meta-analyses were performed using random-effects modelling. RESULTS: Thirty-one (31) studies (7,473 patients; 4,418 ICM and 3,055 NICM) were included. Patients with ICM were significantly older (67.0 vs 55.3 yrs), more commonly male (89% vs 79%), had lower left ventricular ejection fraction (29% vs 38%) were less likely to undergo epicardial access (11% vs 36%) and were more likely to require haemodynamic support during ablation (relative risk [RR] 1.30; 95% CI 1.01-1.69). Acute procedural success (i.e. non-inducibility of VT) was higher in the ICM cohort (RR 1.10, 95% CI 1.05-1.15). Recurrence of VT at follow-up was significantly lower in the ICM cohort (RR 0.77; 95% CI 0.70-0.84). Peri-procedural mortality, incidence of procedural complications and long-term mortality were not significantly different between the cohorts. CONCLUSIONS: NICM and ICM patients undergoing VT ablation are fundamentally different in their clinical characteristics, ablation approaches, acute procedural outcomes and likelihood of VA recurrence. VT ablation in NICM has a lower likelihood of procedural success with increased risk of VA recurrence, consistent with known challenging arrhythmia substrate.

Cardiac Society of Australia and New Zealand (CSANZ) Position Statement on the Follow-Up of Cardiovascular Implantable Electronic Devices 2022.

Recognising the need for a national approach for the recommended best practice for the follow-up of implanted cardiac rhythm devices to ensure patient safety, this document has been produced by the Cardiac Society of Australia and New Zealand (CSANZ). It draws on accepted practice standards and guidelines of international electrophysiology bodies. It lays out methodology, frequency, and content of follow-up, including remote monitoring; personnel, including physician, allied health, nursing and industry; paediatric and adult congenital heart patients; and special considerations including magnetic resonance imaging scanning, perioperative management, and hazard alerts.

Influence of respiration and tissue contact on ventricular substrate identification during high density mapping: Results from an ovine infarct model.

INTRODUCTION: Multielectrode mapping (MEM) and automated point collection are important enhancements to substrate mapping in ventricular tachycardia ablation. The effects of tissue contact and respiration on electrogram voltage with differing depolarization wavefronts with MEM catheters are unclear. METHODS: Bipolar and unipolar voltages were collected from control (n = 5) and infarcted (n = 7) animals with a multispline MEM catheter. Electro-anatomic maps were created in sinus rhythm, and right and left ventricular pacing. Analysis was performed across three collections: standard settings (SS), respiratory-phase gating (RG), and electrode-tissue proximity (TP). Comparison was made to scar detected by cardiac MRI (cMRI). RESULTS: Compared to SS and RG acquisition, median bipolar and unipolar voltages were higher using TP, regardless of the depolarization wavefront. In infarct animals, bipolar voltages were 30.7%-50.5% higher for bipolar and 8.7%-13.8% higher on unipolar voltages with TP, compared to SS. The effect of RG on bipolar and unipolar voltages was minimal. Percentage of local abnormal ventricular activities was not impacted by acquisition settings or wavefront direction in infarct animals. Compared with cMRI defined scar, all three acquisition settings overestimated scar area using standard voltage-based cutoffs. RG improved the low voltage area concordance with MRI by 1.6%-5.1% whereas TP improved by 5.9%-8.4%. CONCLUSIONS: High density voltage mapping with a MEM catheter is influenced by point collection settings. Tissue contact filters reduced low voltage areas and improved agreement with cMRI fibrosis in infarcted ovine hearts. These findings have critical implications for optimizing filter settings for high density substrate mapping in the left ventricle.

The response to cardiac resynchronization therapy in LMNA cardiomyopathy.

AIMS: Cardiac implantable electronic device (CIED) therapy is fundamental to the management of LMNA cardiomyopathy due to the high frequency of atrioventricular block and ventricular tachyarrhythmias. We aimed to define the role of cardiac resynchronization therapy (CRT) in impacting heart failure in LMNA cardiomyopathy. METHODS AND RESULTS: From nine referral centres, LMNA cardiomyopathy patients who underwent CRT with available pre- and post-echocardiograms were identified retrospectively. Factors associated with CRT response were identified (defined as improvement in left ventricular ejection fraction [LVEF] ≥5% 6 months post-implant) and the associated impact on the primary outcome of death, implantation of a left ventricular assist device or cardiac transplantation was assessed. We identified 105 patients (mean age 51 ± 10 years) undergoing CRT, including 70 (67%) who underwent CRT as a CIED upgrade. The mean change in LVEF ∼6 months post-CRT was +4 ± 9%. A CRT response occurred in 40 (38%) patients and was associated with lower baseline LVEF or a high percentage of right ventricular pacing prior to CRT in patients with pre-existing CIED. In patients with a European Society of Cardiology class I guideline indication for CRT, response rates were 61%. A CRT response was evident at thresholds of LVEF ≤45% or percent pacing ≥50%. There was a 1.3 year estimated median difference in event-free survival in those who responded to CRT (p = 0.04). CONCLUSION: Systolic function improves in patients with LMNA cardiomyopathy who undergo CRT, especially with strong guideline indications for implantation. Post-CRT improvements in LVEF are associated with survival benefits in this population with otherwise limited options.

Clinical, electroanatomic and electrophysiologic characterization and outcomes of catheter ablation for ventricular tachycardia following valvular intervention.

INTRODUCTION: Ventricular tachycardia (VT) can occur following valvular interventions. There are limited data describing substrate and ablation approaches in such patients. We sought to describe the clinical, electrophysiologic, electroanatomic features and catheter ablation outcomes of patients with VT following aortic and/or mitral valve intervention. METHODS: Over 12-years, consecutive patients with aortic valve replacement (AVR) and/or mitral valve replacement (MVR) or repair, undergoing VT ablation, were identified from two centers. Clinical and procedural parameters and outcomes are described. RESULTS: Twenty-three patients (age 66 ± 14years, 78% male, left ventricular ejection fraction 37 ± 16%), with prior AVR (mechanical n = 6, bioprosthetic n = 2, transcatheter n = 1), MVR (mechanical n = 5, bioprosthetic n = 1), mitral valve repair (n = 6) and both mechanical AVR and MVR (n = 2), underwent VT ablation. Sixteen had concurrent ischemic cardiomyopathy, 10 with prior bypass surgery. Left ventricular access was obtained in 21/23 (91%) patients (transseptal n = 14, retrograde aortic n = 5, transapical n = 2), with perivalvular scar identified in 17/21 (81%). Re-entrant VT isthmi involved the perivalvular regions in 12/23 (52%) patients, and regions remote from the valve in the remainder; 9% had nonscar-related VT. Intramural substrate was ablated from adjacent chambers in 5/23 (22%) patients and with half-normal saline irrigation in 8/23 (35%) patients. There were no instances of catheter entrapment. Following final ablation, VA-free survival was 78% at 13-months. CONCLUSION: Only half of VT circuits following valvular interventions involve the valve regions themselves, while the remainder involves unrelated regions. Catheter ablation is safe and efficacious at treating VT following valvular intervention, but novel strategies may be required.