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The intramyocardial aspect of the left ventricular summit (LVS) can be mapped by advancing a unipolar guidewire into septal perforator branches of the anterior interventricular vein.The purpose of this study was to differentiate between ventricular premature depolarizations (VPDs) with a basal superior intraseptal (SIS) site of origin and those originating from the epicardial LVS using septal intramyocardial mapping.A retrospective cohort of patients with suspected LVS VPDs who underwent SIS unipolar mapping were reviewed for their clinical characteristics, mapping findings, and procedural outcomes.SIS mapping was successful in 44 of 47 cases (93.6%). VPD origin was SIS (defined as earliest activation from the intraseptal wire) in 20 patients (45.5%; median 23 ms pre-QRS). Procedure success was similar in patients with (group 1) and without (group 2) SIS origin (84% vs 87.5%, respectively; P = .842). Of the 10 patients in group 1 without presystolic endocardial activation, 5 (11.3% of all 44 cases) were successfully ablated from the left ventricular endocardium by using an anatomical approach targeting the endocardium closest to the earliest intraseptal activation site.A significant proportion (45.5%) of VPDs that appear to arise from the left ventricular summit can be demonstrated to have a SIS origin using septal perforator venous mapping. A significant minority (11.3%) of these can be ablated from the endocardium by targeting from an anatomic vantage point closest to the earliest intraseptal activation site. The described strategy may help differentiate true LVS VPDs from those with SIS sites of origin.

Cardiac resynchronization therapy (CRT) using biventricular pacing has limited efficacy in patients with heart failure (HF) and right bundle branch block (RBBB). Left bundle branch area pacing (LBBAP) is a novel physiologic pacing option. OBJECTIVE The aim of the study was to assess the feasibility and outcomes of LBBAP in HF patients with RBBB and reduced left ventricular systolic function, and indication for CRT or ventricular pacing. METHODS LBBAP was attempted in patients with left ventricular ejection fraction (LVEF) = 5% increase in ejection fraction) to LBBAP were assessed. RESULTS LBBAP was attempted in 121 patients and successful in 107 (88%). Patient characteristics included age 74 +/- 12 years, female 25%, ischemic cardiomyopathy 49%, and ejection fraction 35% +/- 9%. QRS axis at baseline was normal in 24%, left axis 63%, right axis 13%. LBBAP threshold and R-wave amplitudes were 0.8 +/- 0.3 V@ 0.5 ms and 10 +/- 9 mV at implant and remained stable during mean follow-up of 13 +/- 8 months. LBBAP resulted in narrowing of QRS duration (156 +/- 20 ms to 150 +/- 24 ms (P = .01) with R-wave peak times in V-6 of 85 +/- 16 ms. LVEF improved from 35% +/- 9% to 43% +/- 12% (P,.01). Clinical and echocardiographic response was observed in 60% and 61% of patients, respectively. Female sex and reduction in QRS duration with LBBAP were predictive of echocardiographic response and super-response. CONCLUSION LBBAP is a feasible alternative to deliver CRT or physiologic ventricular pacing in patients with RBBB, HF, and LV dysfunction.

Left bundle branch area pacing (LBBAP) has been performed exclusively using lumen-less pacing leads (LLL) with fixed helix design. This registry study explores the safety and feasibility of LBBAP using stylet-driven leads (SDL) with extendable helix design in a multicenter patient population. This study prospectively enrolled consecutive patients who underwent LBBAP for bradycardia pacing or heart failure indications at eight Belgian hospitals. LBBAP was attempted using SDL (Solia S60; Biotronik) delivered through dedicated delivery sheath (Selectra3D). Implant success, complications, procedural, and pacing characteristics were recorded at implant and follow-up. The study enrolled 353 patients (mean age 76 ± 39 years, 43% female). The mean number of implants per center was 25 (range: 5-162). Overall, LBBAP with SDL was successful in 334/353 (94%), varying from 93% to 100% among centers. Pacing response was labeled as left bundle branch pacing in 73%, whereas 27% were labeled as myocardial capture. Mean paced QRS duration and stimulus to left ventricular activation time measured 126 ± 21 ms and 74 ± 17. SDL-LBBAP resulted in low pacing thresholds (0.6 ± 0.4 V at 0.4 ms), which remained stable at 12 months follow-up (0.7 ± 0.3, p = .291). Lead revisions for SDL-LBBAP occurred in 5 (1.4%) patients occurred during a mean follow up of 9 ± 5 months. Five (1.4%) septal coronary artery fistulas and 8 (2%) septal perforations occurred, none of them causing persistent ventricular septal defects. The use of SDL to achieve LBBAP is safe and feasible, characterized by high implant success in low and high volume centers, low complication rates, and stable low pacing thresholds.

This study sought to analyze the impact of the American College of Cardiology, American Heart Association, and Heart Rhythm Society (ACC/AHA/HRS) guidelines for cardiac resynchronization therapy with defibrillator (CRT-D) update on utilization and efficacy of CRT-D.In September 2012, the ACC/AHA/HRS guidelines for CRT-D were modified to include left bundle branch block (LBBB) as a Class I indication.The IBM Watson MarketScan Database was queried between January 1, 2003, and December 31, 2018, for CRT-D implants or upgrades. The primary outcome was heart failure (HF) hospitalization following left ventricular lead implant. Secondary outcomes included all-cause mortality and device-related lead revision.A total of 27,238 patients were analyzed: 18,384 pre-update and 8,854 post-update. Mean age was 69 ± 11 years, 73% men, and 98% with history of HF hospitalization. The proportion of patients with LBBB increased from 29% to 55% (P 0.001) after the update. Patients receiving CRT-D post-update demonstrated a greater prevalence of comorbidities, including atrial fibrillation (47% vs 40%; P 0.001), diabetes mellitus (45% vs 39%; P 0.001), chronic kidney disease (24% vs 15%; P 0.001), and HF hospitalization in the year before CRT-D (40% vs 37%; P 0.001). Despite greater baseline comorbidities, HF hospitalization significantly declined post-update (HR: 0.89; P 0.001). Multivariate predictors of reduced HF hospitalization included angiotensin receptor neprilysin inhibitor prescription (HR: 0.48; P 0.001) and presence of LBBB (HR: 0.71; P 0.001). All-cause mortality was not significantly different between the 2 groups, and fewer lead revisions were noted post-update (0.6% vs 1.7%; P 0.001).The revised 2012 guidelines led to an increased proportion of LBBB patients receiving CRT-D at the population-level. This change was associated with reduced HF hospitalization, despite broadening therapy to patients with more comorbid conditions.

Background Catheter ablation strategies for ventricular fibrillation (VF) and polymorphic ventricular tachycardia (PMVT) are not established when spontaneous triggers are rare or absent. Objective The purpose of this study was to report the feasibility and efficacy of a novel empiric ablation strategy of pacemapping to stored implantable cardioverter-defibrillator (ICD) template electrograms (SITE) of the clinical premature ventricular contraction (PVC) trigger. Methods Fifteen patients with drug-refractory VF/PMVT receiving defibrillator shocks without identifiable and mappable PVC triggers were prospectively analyzed. The protocol incorporated systematic pacemapping from known arrhythmogenic sites (moderator band/right ventricular [RV] papillary muscles, left conduction system/Purkinje network, outflow tracts) with real-time comparison between the paced ICD electrogram (EGM) morphology and SITE. Results Regions within the left Purkinje network yielded the best pacemap match for the SITE of the clinical PVC trigger in 55% of ablation targets (left posterior fascicle 6, left septal fascicle 1, left anterior fascicle 5), followed by the RV moderator band region in 14% (n = 3), RV papillary muscles in 13% (n = 3), periaortic region in 14% (n = 3), and left ventricular anterolateral papillary muscle in 4% (n = 1). Freedom from ICD therapies off antiarrhythmic drug (AAD) was 64% at 6 months and 48% at 12 months. Shock burden was reduced from 4 (2–6) to 0 (0–1) (P = .001), and use of AADs was reduced from 2 (1–2) to 0 (0–1) (P = .001). Conclusion In the absence of a mappable trigger, an empiric strategy of interrogating the Purkinje network, papillary muscles, and outflow tract regions by pacemap matching with SITE of the clinical PVC is feasible to guide ablation. A significant reduction in VF/PMVT therapy burden and AAD utilization was observed after a single procedure.

Left bundle branch block (LBBB) is not just a simple electrocardiogram alteration. The intricacies of this general terminology go beyond simple conduction block. This review puts together current knowledge on the historical concept of LBBB, clinical significance, and recent insights into the pathophysiology of human LBBB. LBBB is an entity that affects patient diagnosis (primary conduction disease, secondary to underlying pathology or iatrogenic), treatment (cardiac resynchronization therapy or conduction system pacing for heart failure), and prognosis. Recruiting the left bundle branch with conduction system pacing depends on the complex interaction between anatomy, site of pathophysiology, and delivery tools.

Background The classical paradigm of scar-related reentrant ventricular tachycardia (VT) features a circuit with a double loop figure-of-eight (F8) activation pattern. Objective The purpose of this study was to interrogate VT circuits with F8 activation patterns by entrainment mapping to differentiate an active loop from a passive loop. Methods Sixty VT circuits with >90% of tachycardia cycle length delineated in high resolution were retrospectively analyzed in 55 patients (nonischemic 49%). A pseudo-F8 VT circuit was defined as a double loop activation pattern driven by a single loop mechanism with a passive loop that yields a long postpacing interval (postpacing interval − tachycardia cycle length ≥ 30 ms). Results Single loop activation patterns were observed in 33% (n = 20). Of 40 circuits with F8 patterns by activation mapping, 20 were studied with entrainment mapping, where a passive loop was identified by a long postpacing interval in 50%. In 6 circuits where entrainment mapping was performed from both outer loop regions, all demonstrated asymmetric responses to entrainment, confirming a single loop mechanism. Entrainment from both lateral margins of the common pathway (n = 7) demonstrated an asymmetric response in 29%. In all pseudo-F8 circuits (n = 10), the shorter loop functioned as the active loop and ablation targeting the active loop side of the isthmus resulted in VT termination with a single radiofrequency application. Conclusion In a selected cohort, single loop mechanisms are more prevalent than double loop reentry in reentrant human VT. Half of VT circuits with double loop activation patterns can be demonstrated to be sustained by a single active loop mechanism by entrainment mapping. Ablation targeting the shorter active loop resulted in rapid termination during radiofrequency application.

As clinicians have gained experience in treating patients with the novel SARS-CoV-2 (COVID-19) virus, mortality rates for patients with acute COVID-19 infection have decreased. The Centers for Disease Control (CDC) has identified the African American population as having increased risk of COVID-19 associated mortality, however little is known about echocardiographic markers associated with increased mortality in this patient population. We aimed to compare the clinical and echocardiographic features of a predominantly African American patient cohort hospitalized with acute COVID-19 infection during the first (March–June 2020) and second (September–December 2020) waves of the COVID-19 pandemic, and to investigate which parameters are most strongly associated with composite all-cause mortality. We performed consecutive transthoracic echocardiograms (TTEs) on 105 patients admitted with acute COVID-19 infection during the first wave and 129 patients admitted during the second wave. TTE parameters including left ventricular ejection fraction (LVEF), left ventricular global longitudinal strain (LVGLS), right ventricular global longitudinal strain (RVGLS), right ventricular free-wall strain (RVFWS), and right ventricular basal diameter (RVBD) were compared between the two groups. Clinical and demographic characteristics including underlying co-morbidities, biomarkers, in-hospital treatment regimens, and outcomes were collected and analyzed. Univariable and multivariable analyses were performed to determine variables associated with all-cause mortality. There were no significant differences between the two waves in terms of age, gender, BMI, or race. Overall all-cause mortality was 35.2% for the first wave compared to 14.7% for the second wave (p

Background Although His bundle pacing (HBP) has been shown to improve left ventricular ejection fraction (LVEF), its impact on mitral regurgitation (MR) remains uncertain. Objectives The aim of this study was to evaluate change in functional MR after HBP in patients with left ventricular (LV) systolic dysfunction. Methods Paired echocardiograms were retrospectively assessed in patients with reduced LVEF (

Background While advances in the characterization of the structural substrate in arrhythmogenic right ventricular cardiomyopathy (ARVC) have been made, the ventricular tachycardia (VT) circuit remains incompletely described. Objective The purpose of this study was to delineate the reentrant VT circuit with simultaneous epicardial and endocardial mapping (SEEM) in ARVC. Methods Twenty-three consecutive patients with ARVC and VT underwent SEEM at 4 centers between 2014 and 2020. Retrospective analysis was performed on combined isochronal activation maps. Results Of the 30 VT circuits, 24 were delineated with SEEM (956 [341–1843] endocardial points and 1763 [882–3054] epicardial points). The apex and outflow tract rarely harbored VT circuits, with 50% distributed in the inferior wall and 43% in the free wall. The entire tachycardia cycle length was recorded from the epicardium in 71% of circuits. In all circuits, a large proportion of the tachycardia cycle length was recorded from the epicardium relative to the endocardium. Localized epicardial reentry was observed in 35% of patients (14 mm × 15 mm), which was associated with smaller endocardial low voltage area (39 cm2 vs 104 cm2; P = .002) and preserved right ventricular ejection fraction (35% vs 25%; P = .046) compared with those with larger circuit dimensions. Seventy percent of termination sites were achieved from the epicardium. Conclusion High-resolution recordings from both myocardial surfaces confirm a consistent predominance of epicardial participation during reentry in ARVC. Only the perivalvular inflow region of the “triangle of dysplasia” had a strong propensity to harbor VT circuits, with the greatest proportion located in the inferior wall. Localized epicardial reentry may be a manifestation of earlier stage disease with a relative paucity of endocardial substrate.

A 45-year-old man with stage IV melanoma presented with incessant nonsustained wide complex tachycardia. He was found to have a right ventricular intracardiac metastasis that created a nidus for ventricular tachycardia refractory to multiple therapeutic interventions. The patient underwent catheter ablation for this rare indication, with successful arrhythmia control by direct ablation over the tumor surface. (Level of Difficulty: Advanced.), Central Illustration