Targeting Wavefront Discontinuity Lines for Scar-Related Ventricular Tachycardia Ablation: A Novel Functional Substrate Ablation Approach.

BACKGROUND: The boundaries of critical isthmuses for re-entrant ventricular tachycardia (VT) are formed by wave-front discontinuities (fixed lines of block, slow propagation, and rotational propagation) seen during baseline rhythm. It is unknown whether wavefront discontinuities can be automatically identified and targeted for ablation using electroanatomic mapping systems. OBJECTIVES: The purpose of this study was to assess the electrophysiologic characteristics of automatically projected wavefront discontinuity lines (WADLs) and outcomes of an ablation strategy targeting WADLs in a mixed cohort of VT patients. METHODS: Late activation substrate maps were analyzed from 1 or more baseline rhythm wavefronts. WADLs were identified using the Carto Extended Early Meets Late module. Number, total length, and distance to critical VT sites were measured. VT recurrence and VT-free survival were followed. RESULTS: In total, 49 patients underwent 52 ablations with 71 unique substrate maps analyzed (18.8% epicardial; 62.0% right ventricular paced, 28.2% sinus rhythm, 9.9% left ventricular paced). A total of 28 VT critical sites were identified in 24 patients. WADLs were present in 49 of 71 (69.0%) maps. WADLs were present regardless of cardiomyopathy etiology, mapping wavefront, or surface. At a WADL threshold of 30%, 73.9% of critical VT sites were in close proximity (≤15 mm) to a WADL. VT-free survival was 62% at 1 year, with a competing risk model estimating a 1-year risk of VT recurrence of 23%. CONCLUSIONS: WADLs can be automatically projected in a majority of patients in a mixed cohort of cardiomyopathy etiology, mapped wavefronts, and myocardial surfaces mapped. Targeting WADLs results in low rate of VT recurrence at 1 year.

Hybrid ablation for persistent/long-standing persistent atrial fibrillation: a meta-analysis and trial sequential analysis of randomized controlled trials.

The efficacy and safety of hybrid ablation (HA) for patients with non-paroxysmal atrial fibrillation (AF) remain unclear. PubMed, Embase, Cochrane, and ClinicalTrials.gov were searched for randomized controlled trials (RCTs) comparing HA (endo-epicardial ablation) versus endocardial ablation (EA) for patients with persistent/long-standing persistent AF. Risk ratios (RRs) and 95% confidence intervals (CIs) were pooled. Our meta-analysis included 3 RCTs comprising 358 patients, of whom 233 (65.1%) were randomized to HA. Compared with EA, HA reduced the recurrence of atrial tachyarrhythmias (RR 0.53; 95% CI 0.41-0.69; p < 0.01) but had no subgroup interaction according to AF type (p = 0.90). There was no significant difference in major adverse events (RR 1.22; 95% CI 0.46-3.25; p = 0.68). Trial sequential analysis indicates that the observed effects can be deemed conclusive. In conclusion, in patients with persistent/long-standing persistent AF, HA substantially reduced the recurrence of atrial tachyarrhythmias. Notably, patients with long-standing persistent AF may benefit more from this ablation strategy.

The Spatial Ventricular Gradient Is Associated With Inducibility of Ventricular Arrhythmias During Electrophysiology Study.

BACKGROUND: Myocardial electrical heterogeneity is critical for normal cardiac electromechanical function, but abnormal or excessive electrical heterogeneity is proarrhythmic. The spatial ventricular gradient (SVG), a vectorcardiographic measure of electrical heterogeneity, has been associated with arrhythmic events during long-term follow-up, but its relationship with short-term inducibility of ventricular arrhythmias (VAs) is unclear. OBJECTIVE: This study was designed to determine associations between SVG and inducible VAs during electrophysiology study. METHODS: A retrospective study was conducted of adults without prior sustained VA, cardiac arrest, or implantable cardioverter-defibrillator who underwent ventricular stimulation for evaluation of syncope and nonsustained ventricular tachycardia or for risk stratification before primary prevention implantable cardioverter-defibrillator implantation. The 12-lead electrocardiograms were converted into vectorcardiograms, and SVG magnitude (SVGmag) and direction (azimuth and elevation) were calculated. Odds of inducible VA were regressed by logistic models. RESULTS: Of 143 patients (median age, 69 years; 80% male; median left ventricular ejection fraction [LVEF], 47%; 52% myocardial infarction), 34 (23.8%) had inducible VAs. Inducible patients had lower median LVEF (38% vs 50%; P < .0001), smaller SVGmag (29.5 vs 39.4 mV·ms; P = .0099), and smaller cosine SVG azimuth (cosSVGaz; 0.64 vs 0.89; P = .0007). When LVEF, SVGmag, and cosSVGaz were dichotomized at their medians, there was a 39-fold increase in adjusted odds (P = .002) between patients with all low LVEF, SVGmag, and cosSVGaz (65% inducible) compared with patients with all high LVEF, SVGmag, and cosSVGaz (4% [n = 1] inducible). After multivariable adjustment, SVGmag, cosSVGaz, and sex but not LVEF or other characteristics remained associated with inducible VAs. CONCLUSION: Assessment of electrical heterogeneity by SVG, which reflects abnormal electrophysiologic substrate, adds to LVEF and identifies patients at high and low risk of inducible VA at electrophysiology study.

Correlation Between Functional Substrate Mapping and Cardiac Computed Tomography-Derived Wall Thinning for Ventricular Tachycardia Ablation.

BACKGROUND: Functional substrate mapping during baseline rhythm can identify arrhythmogenic tissue during ventricular tachycardia (VT) ablation. Wall thinning and wall thickness channels (WTCs) derived from computed tomography angiography have been shown to correlate with low voltage and VT isthmuses. The correlation between functional substrate mapping, wall thinning, and WTCs in patients with infarct- or non-infarct-related cardiomyopathies (ICM and NICM, respectively) has not been previously described. OBJECTIVES: The purpose of this study was to correlate cardiac CTA-derived myocardial wall thinning with functional VT substrate mapping using isochronal late activation mapping. METHODS: In 34 patients with ICM or NICM undergoing VT ablation who had a preprocedure computed tomography angiography, myocardial wall thinning was segmented in layers of 1 to 5 mm. Areas of wall thinning and WTCs were then spatially correlated with deceleration zones (DZs) from registered left ventricular endocardial isochronal late activation maps. RESULTS: In 21 ICM patients and 13 NICM patients, ICM patients had greater surfaces areas of wall thinning (P < 0.001). In ICM patients, 94.1% of primary DZs were located on areas of wall thinning, compared to 20% of DZs in NICM patients overall but 50% if there was any wall thinning present. Fifty-nine percent of DZs in ICM patients and 56% of DZs in NICM patients were located near WTCs. The positive predictive value for WTC in localizing DZs was 22.5% and 37.8% in ICM and NICM patients, respectively. CONCLUSIONS: Wall thinning is highly sensitive for functional substrate in ICM patients. WTCs had modest sensitivity for functional substrate but low positive predictive value for identifying DZs in ICM and NICM patients. These findings suggest that wall thinning may facilitate more efficient mapping in ICM patients, but WTCs are insufficient to localize wavefront discontinuities.

Incidence, Treatment, and Outcomes of Symptomatic Device Lead-Related Venous Obstruction.

BACKGROUND: The incidence and clinical impact of lead-related venous obstruction (LRVO) among patients with cardiovascular implantable electronic devices (CIEDs) is poorly defined. OBJECTIVES: The objectives of this study were to determine the incidence of symptomatic LRVO after CIED implant; describe patterns in CIED extraction and revascularization; and quantify LRVO-related health care utilization based on each type of intervention. METHODS: LRVO status was defined among Medicare beneficiaries after CIED implant from October 1, 2015, to December 31, 2020. Cumulative incidence functions of LRVO were estimated by Fine-Gray methods. LRVO predictors were identified using Cox regression. Incidence rates for LRVO-related health care visits were calculated with Poisson models. RESULTS: Among 649,524 patients who underwent CIED implant, 28,214 developed LRVO, with 5.0% cumulative incidence at maximum follow-up of 5.2 years. Independent predictors of LRVO included CIEDs with >1 lead (HR: 1.09; 95% CI: 1.07-1.15), chronic kidney disease (HR: 1.17; 95% CI: 1.14-1.20), and malignancies (HR: 1.23; 95% CI: 1.20-1.27). Most patients with LRVO (85.2%) were managed conservatively. Among 4,186 (14.8%) patients undergoing intervention, 74.0% underwent CIED extraction and 26.0% percutaneous revascularization. Notably, 90% of the patients did not receive another CIED after extraction, with low use (2.2%) of leadless pacemakers. In adjusted models, extraction was associated with significant reductions in LRVO-related health care utilization (adjusted rate ratio: 0.58; 95% CI: 0.52-0.66) compared with conservative management. CONCLUSIONS: In a large nationwide sample, the incidence of LRVO was substantial, affecting 1 of every 20 patients with CIEDs. Device extraction was the most common intervention and was associated with long-term reduction in recurrent health care utilization.

Lead-Related Venous Obstruction in Patients With Implanted Cardiac Devices: JACC Review Topic of the Week.

Cardiac implantable electronic device implantation rates have increased in recent decades. Venous obstruction of the subclavian, brachiocephalic, or superior vena cava veins represents an important complication of implanted leads. These forms of venous obstruction can result in significant symptoms as well as present a barrier to the implantation of additional device leads. The risk factors for the development of these complications remain poorly understood, and diagnosis relies on clinical recognition and cross-sectional imaging. Anticoagulation remains the mainstay of treatment, and thrombus debulking, lead extraction, venoplasty, and stenting are all important therapeutic interventions. This review provides a multidisciplinary-based approach to the evaluation and management of cardiac implantable electronic device lead-associated venous obstruction.

Arrhythmia in Cardiac Sarcoidosis.

Cardiac sarcoidosis (CS) is a complex disease that can manifest as a diverse array of arrhythmias. CS patients may be at higher risk for sudden cardiac death (SCD), and, in some cases, SCD may be the first presenting symptom of the underlying disease. As such, identification, risk stratification, and management of CS-related arrhythmia are crucial in the care of these patients. Left untreated, CS carries significant arrhythmogenic morbidity and mortality. Cardiac manifestations of CS are a consequence of an inflammatory process resulting in the myocardial deposition of noncaseating granulomas. Endomyocardial biopsy remains the gold standard for diagnosis; however, biopsy yield is limited by the patchy distribution of the granulomas. As such, recent guidelines have improved clinical diagnostic pathways relying on advanced cardiac imaging to help in the diagnosis of CS. To date, corticosteroids are the best studied agent to treat CS but are associated with significant risks and limited benefits. Implantable cardioverter-defibrillators have an important role in SCD risk reduction. Catheter ablation in conjunction with antiarrhythmics seems to reduce ventricular arrhythmia burden. However, the appropriate selection of these patients is crucial as ablation is likely more helpful in the setting of a myocardial scar substrate versus arrhythmia driven by active inflammation. Further studies investigating CS pathophysiology, the pathway to diagnosis, arrhythmogenic manifestations, and SCD risk stratification will be crucial to reduce the high morbidity and mortality of this disease.

Lead-associated Superior Vena Cava Syndrome.

Superior vena cava (SVC) syndrome is a rare complication associated with transvenous cardiac implantable electronic devices that may present with a variety of manifestations. Various strategies such as transvenous lead extraction, anticoagulation, venoplasty, and stenting have been used to treat this condition, but the optimal management protocols have yet to be defined. Subcutaneous implantable cardioverter-defibrillator (ICD) (S-ICD) therapy can be an alternative option to a transvenous system for those who require future ICD surveillance. We present a case of lead-associated SVC syndrome where thoracic venous congestion due to SVC obstruction influenced preimplant S-ICD QRS vector screening. Following treatment of venous obstruction, QRS amplitude may change and patients who were not initially S-ICD candidates may later become eligible.

Outcomes following implantable cardioverter-defibrillator generator replacement in adults: A systematic review.

Randomized trials inform the use of implantable cardioverter-defibrillators (ICDs) for prevention of sudden cardiac death, yet management of patients considering ICD generator replacement procedures remains largely dependent on clinical judgment. Thus, we performed a systematic review of all studies evaluating outcomes associated with ICD generator replacement. We queried PubMed, Embase, Web of Science, and the Cochrane Database of Systematic Reviews for relevant studies with a prespecified search and adjudication strategy (PROSPERO registration number CRD42018100818) to evaluate outcomes including (1) survival; (2) clinical complications (eg, infection, hematoma); or (3) incidence of ICD therapy. From 1607 unique titles, 37 studies met inclusion criteria, describing outcomes for 238,949 patients. Procedural mortality was rare, but complications including reoperation (median 4.57%; range 0.38%-10.31%), infections (median 2.01%; range 0.03%-9.27%), and hematoma (median 1.22%, range 0.17%-2.53%) were observed in a small fraction of patients. Appropriate ICD therapy after generator replacement was common (median rate 23.03%; range 10.9%-31.4%), with an overall annualized event rate of 8.52% at median duration of follow-up of 32.4 months. Appropriate ICD therapy continued to occur at a significant annual rate even in patients who no longer met implantation criteria (5.27%) and in patients who never previously received ICD therapy (4.87%). This analysis of published observational data regarding ICD generator replacement procedures identifies relatively low risks of procedural complications and clinically meaningful rates of appropriate ICD therapies. These estimates may guide clinical decisions and inform the design of definitive trials.

Intraprocedural volume imaging of the left atrium and pulmonary veins with rotational X-ray angiography: implications for catheter ablation of atrial fibrillation.

INTRODUCTION: The use of preprocedural CT or MR imaging to generate patient-specific cardiac anatomy greatly facilitates catheter ablation of the left atrium and pulmonary veins (LA-PVs) to treat atrial fibrillation (AF). This report details the accuracy and utility of an intraprocedural means to generate 3-D volumetric renderings of the LA-PV anatomy: contrast-enhanced rotational X-ray angiography (3DRA). METHODS AND RESULTS: Preprocedural CT or MR imaging and intraprocedural rotational angiography was performed in 42 patients undergoing AF ablation procedures. Initially, pulmonary artery (PA) bolus-chase contrast injections were performed (20 mL, 20 mL/s) to establish pulmonary transit time and cardiac isocentering. Depending on cardiac size, either a single PA injection (80-100 mL, 20 mL/s) or two separate dedicated left/right PA branch injections were performed (60 mL each, 20 mL/s). For the latter, the two volumes of the left/right portions of the LA-PVs were registered and fused. LA-PV 3DRA images were assessed qualitatively and quantitatively in comparison with CT/MR images. The majority of the 3DRA acquisitions (71%) were deemed at least "useful" in delineating the LA-PV anatomy. The LA appendage was delineated in 57% of the cases. A blinded quantitative comparison of PV ostial diameters resulted in an absolute difference of only 2.7 +/- 2.3 mm, 2.2 +/- 1.8 mm, 2.4 +/- 2.2 mm, and 2.2 +/- 2.3 mm for the left-superior, left-inferior, right-superior, and right-inferior PVs, respectively. The feasibility for registering the 3DRA image with real-time electroanatomical mapping was also demonstrated. CONCLUSION: Intraprocedural contrast-enhanced rotational angiography provides volumetric 3-D images of the LA-PVs of comparable diagnostic value to dedicated preprocedural CT/MR imaging.

Relation of the Mitral Annular Plane Systolic Excursion to Risk for Intervention in Initially Asymptomatic Patients With Aortic Stenosis and Preserved Systolic Function.

Aortic valve intervention (AVI) in patients with a severe aortic stenosis (AS) and a preserved left ventricular ejection fraction (LVEF) is controversial. Mitral annular plane systolic excursion (MAPSE) is an easily acquired metric of left ventricular longitudinal shortening. We sought to investigate if an asymptomatic decrease in MAPSE preceded the need for AVI in asymptomatic patients with AS and a preserved LVEF. In this retrospective cohort study, we identified 205 consecutive patients (56% male, 73 ± 11 years) with at least a moderate AS and a normal LVEF who underwent a serial outpatient transthoracic echocardiography (TTE) from 2006 to 2013. Apical TTE images were reviewed and (the average of septal, lateral, anterior, and inferior) MAPSE was measured. We examined the association of change in MAPSE with aortic valve area and LVEF over time and used time-varying Cox models to examine the risk of AVI. MAPSE correlated with aortic valve area (Spearman r = 0.18, p = 0.02) and decreased with subsequent TTE, whereas LVEF was "maintained." For each 1-mm reduction in MAPSE, the age- and gender-adjusted hazard ratio (HR) for AVI was 1.15 (95% confidence interval [CI] 1.01 to 1.31, p = 0.04). A MAPSE decrease of >2 mm/TTE was significantly associated with an increased risk of AVI, with an adjusted HR of 1.95 (95% CI 1.04 to 3.66, p = 0.04), whereas a MAPSE decrease of >1.5 mm/year trended toward an association with an increased risk of AVI (HR 1.61, 95% CI 0.95 to 2.74, p = 0.08). In conclusion, in asymptomatic patients with at least a moderate AS and a preserved LVEF, an asymptomatic decrease in MAPSE was associated with the clinical need for AVI despite ongoing preservation of LVEF.