Same-day discharge after atrial fibrillation ablation under a nurse-coordinated standardized protocol.

AIMS: Same-day discharge (SDD) after atrial fibrillation (AF) ablation is an effective means to spare healthcare resources. However, safety remains a concern, and besides structural adaptations, SDD requires more efficient logistics and coordination. Therefore, in this study, we implement a streamlined, nurse-coordinated SDD programme following a standardized protocol. METHODS AND RESULTS: As a dedicated SDD coordinator, a nurse specialized in ambulatory cardiac interventions was in charge of the full SDD protocol, including eligibility, patient flow, in-hospital logistics, patient education, and discharge as well as early post-discharge follow-up by smartphone-based virtual visits. Patients planned for AF ablation were considered eligible if they had a left ventricular ejection fraction (LVEF) ≥35%, with basic support at home and accessibility of the hospital within 60 min also forming a part of the eligibility criteria. A total of 420 consecutive patients were screened by the SDD coordinator, of whom 331 were eligible for SDD. The reasons for exclusion were living remotely (29, 6.9%), lack of support at home (19, 4.5%), or LVEF <35% (17, 4.0%). Of the eligible patients, 300 (91%) were successfully discharged the same day. There were no major post-SDD complications. Rates of unplanned medical attention (19, 6.3%) and 30-day readmission (5, 1.6%) were extremely low and driven by femoral access-site complications. These were significantly reduced upon the introduction of compulsory ultrasound-guided punctures after the initial 150 SDD patients (P = 0.0145). Standardized SDD coordination resulted in efficient workflows and reduced the total workload of the medical staff. CONCLUSION: Same-day discharge after AF ablation following a nurse-coordinated standardized protocol is safe and efficient. The concept of ambulatory cardiac intervention nurses functioning as dedicated coordinators may be key in the future transition of hospitals to SDD. Ultrasound-guided femoral puncture virtually eliminated relevant femoral access-site complications in our cohort and should therefore be a prerequisite for SDD.

Non-invasive detection of slow conduction with cardiac magnetic resonance imaging for ventricular tachycardia ablation.

AIMS: Non-invasive myocardial scar characterization with cardiac magnetic resonance (CMR) has been shown to accurately identify conduction channels and can be an important aid for ventricular tachycardia (VT) ablation. A new mapping method based on targeting deceleration zones (DZs) has become one of the most commonly used strategies for VT ablation procedures. The aim of the study was to analyse the capability of CMR to identify DZs and to find predictors of arrhythmogenicity in CMR channels. METHODS AND RESULTS: Forty-four consecutive patients with structural heart disease and VT undergoing ablation after CMR at a single centre (October 2018 to July 2021) were included (mean age, 64.8 ± 11.6 years; 95.5% male; 70.5% with ischaemic heart disease; a mean ejection fraction of 32.3 ± 7.8%). The characteristics of CMR channels were analysed, and correlations with DZs detected during isochronal late activation mapping in both baseline maps and remaps were determined. Overall, 109 automatically detected CMR channels were analysed (2.48 ± 1.15 per patient; length, 57.91 ± 63.07 mm; conducting channel mass, 2.06 ± 2.67 g; protectedness, 21.44 ± 25.39 mm). Overall, 76.1% of CMR channels were associated with a DZ. A univariate analysis showed that channels associated with DZs were longer [67.81 ± 68.45 vs. 26.31 ± 21.25 mm, odds ratio (OR) 1.03, P = 0.010], with a higher border zone (BZ) mass (2.41 ± 2.91 vs. 0.87 ± 0.86 g, OR 2.46, P = 0.011) and greater protectedness (24.97 ± 27.72 vs. 10.19 ± 9.52 mm, OR 1.08, P = 0.021). CONCLUSION: Non-invasive detection of targets for VT ablation is possible with CMR. Deceleration zones found during electroanatomical mapping accurately correlate with CMR channels, especially those with increased length, BZ mass, and protectedness.

Novel systematic processing of cardiac magnetic resonance imaging identifies target regions associated with infarct-related ventricular tachycardia.

AIMS: There is lack of agreement on late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) imaging processing for guiding ventricular tachycardia (VT) ablation. We aim at developing and validating a systematic processing approach on LGE-CMR images to identify VT corridors that contain critical VT isthmus sites. METHODS AND RESULTS: This is a translational study including 18 pigs with established myocardial infarction and inducible VT undergoing in vivo characterization of the anatomical and functional myocardial substrate associated with VT maintenance. Clinical validation was conducted in a multicentre series of 33 patients with ischaemic cardiomyopathy undergoing VT ablation. Three-dimensional LGE-CMR images were processed using systematic scanning of 15 signal intensity (SI) cut-off ranges to obtain surface visualization of all potential VT corridors. Analysis and comparisons of imaging and electrophysiological data were performed in individuals with full electrophysiological characterization of the isthmus sites of at least one VT morphology. In both the experimental pig model and patients undergoing VT ablation, all the electrophysiologically defined isthmus sites (n = 11 and n = 19, respectively) showed overlapping regions with CMR-based potential VT corridors. Such imaging-based VT corridors were less specific than electrophysiologically guided ablation lesions at critical isthmus sites. However, an optimized strategy using the 7 most relevant SI cut-off ranges among patients showed an increase in specificity compared to using 15 SI cut-off ranges (70 vs. 62%, respectively), without diminishing the capability to detect VT isthmus sites (sensitivity 100%). CONCLUSION: Systematic imaging processing of LGE-CMR sequences using several SI cut-off ranges may improve and standardize procedure planning to identify VT isthmus sites.

Catheter Ablation of Ventricular Tachycardia in Ischemic Heart Disease: What Is Known and New Perspectives.

PURPOSE OF THE REVIEW: This review aims to evaluate current evidence regarding ventricular tachycardia ablation in patients with ischemic heart disease and explore novel approaches currently developing to improve procedural and long-term outcomes. RECENT FINDINGS: Recently published trials (PARTITA, PAUSE-SCD, and SURVIVE-VT) have demonstrated the prognostic benefit of prophylactic ventricular tachycardia ablation compared to current clinical practice. Advanced cardiac imaging provides a valuable pre-procedural evaluation of the arrhythmogenic substrate, identifying ablation targets non-invasively. Advanced cardiac mapping techniques allow to better characterize arrhythmogenic substrate during ablation procedure. Emerging technologies like pulsed field ablation and ultra-low temperature cryoablation show promise in ventricular tachycardia ablation. Advancements in mapping techniques, ablation technologies, and pre-procedural cardiac imaging offer promise for improving ventricular tachycardia ablation outcomes in ischemic heart disease.

Late onset of two concurrent and dissociated arrhythmias in a transplanted heart.

A 53-year-old patient with a history of heart transplant is referred for atrial tachycardia ablation. Two dissociated concomitant rhythms are observed: a focal atrial tachycardia in the donor atrium and atrial fibrillation in the remaining recipient atrium.

Myocardial scarring and recurrence of ventricular arrhythmia in patients surviving an out-of-hospital cardiac arrest.

INTRODUCTION: Prediction of recurrent ventricular arrhythmia (VA) in survivors of an out-of-hospital cardiac arrest (OHCA) is important, but currently difficult. Risk of recurrence may be related to presence of myocardial scarring assessed with late gadolinium enhancement cardiac magnetic resonance (LGE-CMR). Our study aims to characterize myocardial scarring as defined by LGE-CMR in survivors of a VA-OHCA and investigate its potential role in the risk of new VA events. METHODS: Between 2015 and 2022, a total of 230 VA-OHCA patients without ST-segment elevation myocardial infarction had CMR before implantable cardioverter-defibrillator implantation for secondary prevention at Copenhagen University Hospital, Rigshospitalet, and Hospital Clínic, University of Barcelona, of which n = 170 patients had a conventional (no LGE protocol) CMR and n = 60 patients had LGE-CMR (including LGE protocol). Scar tissue including core, border zone (BZ) and BZ channels were automatically detected by specialized investigational software in patients with LGE-CMR. The primary endpoint was recurrent VA. RESULTS: After exclusion, n = 52 VA-OHCA patients with LGE-CMR and a mean left ventricular ejection fraction of 49 ± 16% were included, of which 18 (32%) patients reached the primary endpoint of VA. Patients with recurrent VA in exhibited greater scar mass, core mass, BZ mass, and presence of BZ channels compared with patients without recurrent VA. The presence of BZ channels identified patients with recurrent VA with 67% sensitivity and 85% specificity (area under the ROC curve (AUC) 0.76; 95% CI: 0.63-0.89; p < .001) and was the strongest predictor of the primary endpoint. CONCLUSIONS: The presence of BZ channels was the strongest predictor of recurrent VA in patients with an out of-hospital cardiac arrest and LGE-CMR.

Magnetic resonance detection of advanced atrial cardiomyopathy increases the risk for atypical atrial flutter occurrence following atrial fibrillation ablation.

AIMS: Recurrence of arrhythmia after catheter ablation of atrial fibrillation (AF) in the form of atypical atrial flutter (AFL) is common among a significant number of patients and often requires redo ablation with limited success rates. Identifying patients at high risk of AFL after AF ablation could aid in patient selection and personalized ablation approach. The study aims to assess the relationship between pre-existing atrial cardiomyopathy and the occurrence of AFL following AF ablation. METHODS AND RESULTS: We analysed a cohort of 1007 consecutive AF patients who underwent catheter ablation and were included in a prospective registry. Patients who did not have baseline cardiac magnetic resonance imaging and late gadolinium enhancement (LGE-CMR) or did not experience any recurrences were excluded. A total of 166 patients were included gathering 56 patients who underwent re-ablation due to AFL recurrences and 110 patients who underwent re-ablation due to AF recurrences (P = 0.11). A multiparametric assessment of atrial cardiomyopathy was based on basal LGE-CMR, including left atrial (LA) volume, LA sphericity, and global and segmental LA fibrosis using semiautomated post-processing software. Out of the initial cohort of 1007 patients, AFL and AF occurred in 56 and 110 patients, respectively. An age higher than 65 [odds ratio (OR) = 5.6, 95% confidence interval (CI): 2.2-14.4], the number of previous ablations (OR = 3.0, 95% CI: 1.2-7.8), and the management of ablation lines in the index procedure (OR = 2.5, 95% CI: 1.0-6.3) were independently associated with AFL occurrence. Furthermore, several characteristics assessed by LGE-CMR were identified as independent predictors of AFL recurrence after the index ablation for AF, such as enhanced LA sphericity (OR = 1.3, 95% CI: 1.1-1.6), LA global fibrosis (OR = 1.03, 95% CI: 1.01-1.07), and increased fibrosis in the lateral wall (OR = 1.03, 95% CI: 1.01-1.04). CONCLUSION: Advanced atrial cardiomyopathy assessed by LGE-CMR, such as increased LA sphericity, global LA fibrosis, and fibrosis in the lateral wall, is independently associated with arrhythmia recurrence in the form of AFL following AF ablation.

Scar conducting channel characterization to predict arrhythmogenicity during ventricular tachycardia ablation.

AIMS: Heterogeneous tissue channels (HTCs) detected by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) are related to ventricular arrhythmias, but there are few published data about their arrhythmogenic characteristics. METHODS AND RESULTS: We enrolled 34 consecutive patients with ischaemic and non-ischaemic cardiomyopathy who were referred for ventricular tachycardia (VT) ablation. LGE-CMR was performed prior to ablation, and the HTCs were analyzed. Arrhythmogenic HTCs linked to induced VT were identified during the VT ablation procedure. The characteristics of arrhythmogenic HTCs were compared with those of non-arrhythmogenic HTCs. Three patients were excluded due to low-quality LGE-CMR images. A total of 87 HTCs were identified on LGE-CMR in 31 patients (age:63.8 ± 12.3 years; 96.8% male; left ventricular ejection fraction: 36.1 ± 10.7%). Of the 87 HTCs, only 31 were considered arrhythmogenic because of their relation to a VT isthmus. The HTCs related to a VT isthmus were longer [64.6 ± 49.4 vs. 32.9 ± 26.6 mm; OR: 1.02; 95% CI: (1.01-1.04); P < 0.001] and had greater mass [2.5 ± 2.2 vs. 1.2 ± 1.2 grams; OR: 1.62; 95% CI: (1.18-2.21); P < 0.001], a higher degree of protectedness [26.19 ± 19.2 vs. 10.74 ± 8.4; OR 1.09; 95% CI: (1.04-1.14); P < 0.001], higher transmurality [number of wall layers with CCs: 3.8 ± 2.4 vs. 2.4 ± 2.0; OR: 1.31; 95% CI: (1.07-1.60); P = 0.008] and more ramifications [3.8 ± 2.0 vs. 2.7 ± 1.1; OR: 1.59; 95% CI: (1.15-2.19); P = 0.002] than non-arrhythmogenic HTCs. Multivariate logistic regression analysis revealed that protectedness was the strongest predictor of arrhythmogenicity. CONCLUSION: The protectedness of an HTC identified by LGE-CMR is strongly related to its arrhythmogenicity during VT ablation.

Stepwise application of ECG and electrogram-based criteria to ensure electrical resynchronization with left bundle branch pacing.

AIMS: To define a stepwise application of left bundle branch pacing (LBBP) criteria that will simplify implantation and guarantee electrical resynchronization. Left bundle branch pacing has emerged as an alternative to biventricular pacing. However, a systematic stepwise criterion to ensure electrical resynchronization is lacking. METHODS AND RESULTS: A cohort of 24 patients from the LEVEL-AT trial (NCT04054895) who received LBBP and had electrocardiographic imaging (ECGI) at 45 days post-implant were included. The usefulness of ECG- and electrogram-based criteria to predict accurate electrical resynchronization with LBBP were analyzed. A two-step approach was developed. The gold standard used to confirm resynchronization was the change in ventricular activation pattern and shortening in left ventricular activation time, assessed by ECGI. Twenty-two (91.6%) patients showed electrical resynchronization on ECGI. All patients fulfilled pre-screwing requisites: lead in septal position in left-oblique projection and W paced morphology in V1. In the first step, presence of either right bundle branch conduction delay pattern (qR or rSR in V1) or left bundle branch capture Plus (QRS ≤120 ms) resulted in 95% sensitivity and 100% specificity to predict LBBP resynchronization, with an accuracy of 95.8%. In the second step, the presence of selective capture (100% specificity, only 41% sensitivity) or a spike-R <80 ms in non-selective capture (100% specificity, sensitivity 46%) ensured 100% accuracy to predict resynchronization with LBBP. CONCLUSION: Stepwise application of ECG and electrogram criteria may provide an accurate assessment of electrical resynchronization with LBBP (Graphical abstract).

Non-invasive assessment of pulmonary vein isolation durability using late gadolinium enhancement magnetic resonance imaging.

AIMS: Electrical reconnection of pulmonary veins (PVs) is considered an important determinant of recurrent atrial fibrillation (AF) after pulmonary vein isolation (PVI). To date, AF recurrences almost automatically trigger invasive repeat procedures, required to assess PVI durability. With recent technical advances, it is becoming increasingly common to find all PVs isolated in those repeat procedures. Thus, as ablation of extra-PV targets has failed to show benefit in randomized trials, more and more often these highly invasive procedures are performed only to rule out PV reconnection. Here we aim to define the ability of late gadolinium enhancement (LGE)-magnetic resonance imaging (MRI) to rule out PV reconnection non-invasively. METHODS AND RESULTS: This study is based on a prospective registry in which all patients receive an LGE-MRI after AF ablation. Included were all patients that-after an initial PVI and post-ablation LGE-MRI-underwent an invasive repeat procedure, which served as a reference to determine the predictive value of non-invasive lesion assessment by LGE-MRI.: 152 patients and 304 PV pairs were analysed. LGE-MRI predicted electrical PV reconnection with high sensitivity (98.9%) but rather low specificity (55.6%). Of note, LGE lesions without discontinuation ruled out reconnection of the respective PV pair with a negative predictive value of 96.9%, and patients with complete LGE lesion sets encircling all PVs were highly unlikely to show any PV reconnection (negative predictive value: 94.4%). CONCLUSION: LGE-MRI has the potential to guide selection of appropriate candidates and planning of the ablation strategy for repeat procedures and may help to identify patients that will not benefit from a redo-procedure if no ablation of extra-PV targets is intended.

Management of Ventricular Arrhythmias in Heart Failure.

PURPOSE OF REVIEW: Despite substantial progress in medical and device-based heart failure (HF) therapy, ventricular arrhythmias (VA) and sudden cardiac death (SCD) remain a major challenge. Here we review contemporary management of VA in the context of HF with one particular focus on recent advances in imaging and catheter ablation. RECENT FINDINGS: Besides limited efficacy of antiarrhythmic drugs (AADs), their potentially life-threatening side effects are increasingly acknowledged. On the other hand, with tremendous advances in catheter technology, electroanatomical mapping, imaging, and understanding of arrhythmia mechanisms, catheter ablation has evolved into a safe, efficacious therapy. In fact, recent randomized trials support early catheter ablation, demonstrating superiority over AAD. Importantly, CMR imaging with gadolinium contrast has emerged as a central tool for the management of VA complicating HF: CMR is not only essential for an accurate diagnosis of the underlying entity and subsequent treatment decisions, but also improves risk stratification for SCD prevention and patient selection for ICD therapy. Finally, 3-dimensional characterization of arrhythmogenic substrate by CMR and imaging-guided ablation approaches substantially enhance procedural safety and efficacy. VA management in HF patients is highly complex and should be addressed in a multidisciplinary approach, preferably at specialized centers. While recent evidence supports early catheter ablation of VA, an impact on mortality remains to be demonstrated. Moreover, risk stratification for ICD therapy may have to be reconsidered, taking into account imaging, genetic testing, and other parameters beyond left ventricular function.

Variables affecting the quality of anticoagulation in atrial fibrillation patients newly initiating vitamin K antagonists: insights from the national and multicentre SULTAN registry.

AIMS: Vitamin K antagonists (VKAs) are effective drugs reducing the risk for stroke in atrial fibrillation (AF), but the benefits derived from such therapy depend on the international normalized ratio (INR) maintenance in a narrow therapeutic range. Here, we aimed to determine independent variables driving poor anticoagulation control [defined as a time in therapeutic range (TTR) <65%] in a 'real world' national cohort of AF patients. METHODS AND RESULTS: The SULTAN registry is a multicentre, prospective study, involving patients with non-valvular AF from 72 cardiology units expert in AF in Spain. At inclusion, all patients naïve for oral anticoagulation were started with VKAs for the first time. For the analysis, the first month of anticoagulation and those patients with <3 INR determinations were disregarded. Patients were followed up during 1 year. A total of 870 patients (53.9% male, the mean age of 73.6 ± 9.2 years, mean CHA2DS2-VASc and HAS-BLED of 3.3 ± 1.5 and 1.4 ± 0.9, respectively) were included in the full analysis set. In overall, 7889 INR determinations were available. At 1-year, the mean TTR was 63.1 ± 22.1% and 49.2% patients had a TTR < 65%. Multivariate Cox regression analysis showed that coronary artery disease [odds ratio (OR) 1.81, 95% confidence interval (CI) 1.14-2.87; P = 0.012] and amiodarone use (OR 1.54, 95% CI 1.01-2.34; P = 0.046) were independently associated with poor quality of anticoagulation (TTR <65%). CONCLUSION: This study demonstrated that the quality of anticoagulation in AF patients newly starting VKAs is sub-optimal. Previous coronary artery disease and concomitant use of amiodarone were identified as independent variables affecting the poor quality of VKA therapy during the first year.

Late gadolinium enhancement-MRI determines definite lesion formation most accurately at 3 months post ablation compared to later time points.

AIMS: Neither the long-term development of ablation lesions nor the capability of late gadolinium enhancement (LGE)-MRI to detect ablation-induced fibrosis at late stages of scar formation have been defined. We sought to assess the development of atrial ablation lesions over time using LGE-MRI and invasive electroanatomical mapping (EAM). METHODS AND RESULTS: Ablation lesions and total atrial fibrosis were assessed in serial LGE-MRI scans 3 months and >12 months post pulmonary vein (PV) isolation. High-density EAM performed in subsequent repeat ablation procedures served as a reference. Serial LGE-MRI of 22 patients were analyzed retrospectively. The PV encircling ablation lines displayed an average LGE, indicative of ablation-induced fibrosis, of 91.7% ± 7.0% of the circumference at 3 months, but only 62.8% ± 25.0% at a median of 28 months post ablation (p < 0.0001). EAM performed in 18 patients undergoing a subsequent repeat procedure revealed that the consistent decrease in LGE over time was owed to a reduced detectability of ablation-induced fibrosis by LGE-MRI at time-points > 12 months post ablation. Accordingly, the agreement with EAM regarding detection of ablation-induced fibrosis and functional gaps was good for the LGE-MRI at 3 months (κ .74; p < .0001), but only weak for the LGE-MRI at 28 months post-ablation (κ .29; p < .0001). CONCLUSION: While non-invasive lesion assessment with LGE-MRI 3 months post ablation provides accurate guidance for future redo-procedures, detectability of atrial ablation lesions appears to decrease over time. Thus, it should be considered to perform LGE-MRI 3 months post-ablation rather than at later time-points > 12 months post ablation, like for example, prior to a planned redo-ablation procedure.

Conduction system pacing vs. biventricular pacing in patients with ventricular dysfunction and AV block.

BACKGROUND: It is unknown whether His-Purkinje conduction system pacing (HPCSP), as either His bundle or left bundle branch pacing, could be an alternative to cardiac resynchronization therapy (BiVCRT) for patients with left ventricular dysfunction needing ventricular pacing due to atrioventricular block. The aim of the study is to compare the echocardiographic response and clinical improvement between HPCSP and BiVCRT. METHODS: Consecutive patients who successfully received HPCSP were compared with a historical cohort of BiVCRT patients. Patients were 1:1 matched by age, LVEF, atrial fibrillation, renal function and cardiomyopathy type. Responders were defined as patients who survived, did not require heart transplantation and increased LVEF ≥5 points at 6-month follow-up. RESULTS: HPCSP was successfully achieved in 92.5% (25/27) of patients. During follow-up, 8% (2/25) of HPCSP patients died and 4% (1/25) received a heart transplant, whereas 4% (1/25) of those in the BiVCRT cohort died. LVEF improvement was 10% ± 8% HPCSP versus 7% ± 5% BiVCRT (p = .24), and the percentage of responders was 76% (19/25) HPCSP versus 64% (16/25) BiVCRT (p = .33). Among survivors, the percentage of patients who improved from baseline II-IV mitral regurgitation (MR) to 0-I MR was 9/11 (82%) versus 2/8 (25%) (p = .02). Compared to those with BiVCRT, patients with HPCSP achieved better NYHA improvement: 1 point versus 0.5 (OR 0.34; p = .02). CONCLUSION: HPCSP in patients with LVEF ≤45% and atrioventricular block improved the LVEF and induced a response similar to that of BiVCRT. HPCSP significantly improved MR and NYHA functional class. HPCSP may be an alternative to BiVCRT in these patients. (Figure 1. Central Illustration). [Figure: see text].

Septal flash correction with His-Purkinje pacing predicts echocardiographic response in resynchronization therapy.

BACKGROUND: His-Purkinje conduction system pacing (HPCSP) has been proposed as an alternative to Cardiac Resynchronization Therapy (CRT); however, predictors of echocardiographic response have not been described in this population. Septal flash (SF), a fast contraction and relaxation of the septum, is a marker of intraventricular dyssynchrony. METHODS: The study aimed to analyze whether HPCSP corrects SF in patients with CRT indication, and if correction of SF predicts echocardiographic response. This retrospective analysis of prospectively collected data included 30 patients. Left ventricular ejection fraction (LVEF) was measured with echocardiography at baseline and at 6-month follow-up. Echocardiographic response was defined as increase in five points in LVEF. RESULTS: HPCSP shortened QRS duration by 48 ± 21 ms and SF was significantly decreased (baseline 3.6 ± 2.2 mm vs. HPCSP 1.5 ± 1.5 mm p < .0001). At 6-month follow-up, mean LVEF improvement was 8.6% ± 8.7% and 64% of patients were responders. There was a significant correlation between SF correction and increased LVEF (r = .61, p = .004). A correction of ≥1.5 mm (baseline SF - paced SF) had a sensitivity of 81% and 80% specificity to predict echocardiographic response (area under the curve 0.856, p = .019). CONCLUSION: HPCSP improves intraventricular dyssynchrony and results in 64% echocardiographic responders at 6-month follow-up. Dyssynchrony improvement with SF correction may predict echocardiographic response at 6-month follow-up.

Cardiac magnetic resonance to predict recurrences after ventricular tachycardia ablation: septal involvement, transmural channels, and left ventricular mass.

AIMS: Ventricular tachycardia (VT) substrate-based ablation has an increasing role in patients with structural heart disease-related VT. VT is linked to re-entry in relation to myocardial scarring with areas of conduction block (core scar) and areas of slow conduction [border zone (BZ)]. VT substrate can be analysed by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR). Our study aims to analyse the role of LGE-CMR in identifying predictors of VT recurrence after ablation. METHODS AND RESULTS: We analysed 110 consecutive patients who underwent VT ablation from 2013 to 2018. All patients underwent a preprocedural LGE-CMR, and in 94 patients (85.5%), the CMR was used to aid the ablation. All LGE-CMR images were semi-automatically processed using dedicated software to detect scarring and conducting channels. After a median follow-up of 2.7 ± 1.6 years, the overall VT recurrence was 41.8% with an implantable cardioverter-defibrillator shock reduction from 43.6% to 28.2% before and after ablation, respectively. The amount of BZ (26.6 ± 13.9 vs. 19.6 ± 9.7 g, P = 0.012), the total amount of scarring (37.1 ± 18.2 vs. 29 ± 16.3 g, P = 0,033), and left ventricular (LV) mass (168.3 ± 53.3 vs. 152.3 ± 46.4 g, P < 0.001) were associated with VT recurrence. LGE septal distribution [62.5% vs. 37.8%; hazard ratio (HR) 1.67 (1.02-3.93), P = 0.044], channels with transmural path [66.7% vs. 31.4%, HR 3.25 (1.70-6.23), P < 0.001], and midmural channels [54.3% vs. 27.6%, HR 2.49 (1.21-5.13), P = 0.013] were related with VT recurrence. Multivariate analysis showed that the presence of septal LGE [HR 3.67 (1.60-8.38), P = 0.002], transmural channels [HR 2.32 (1.15-4.72), P = 0.019], and LV mass [HR 1.01 (1.005-1.019), P = 0.002] were independent predictors of VT recurrence. CONCLUSION: Pre-procedural LGE-CMR is a helpful and feasible technique to identify patients with high risk of VT recurrence after ablation. LV mass, septal LGE distribution, and transmural channels were predictive factors of post-ablation VT recurrence.

Proximity to the descending aorta predicts regional fibrosis in the adjacent left atrial wall: aetiopathogenic and prognostic implications.

AIMS: Left atrial (LA) fibrosis is present in patients with atrial fibrillation (AF) and can be visualized by magnetic resonance imaging with late gadolinium enhancement (LGE-MRI). Previous studies have shown that LA fibrosis is not randomly distributed, being more frequent in the area adjacent to the descending aorta (DAo). The objective of this study is to analyse the relationship between fibrosis in the atrial area adjacent to the DAo and the distance to it, as well as the prognostic implications of this fibrosis. METHODS AND RESULTS: Magnetic resonance imaging with late gadolinium enhancement was obtained in 108 patients before AF ablation to analyse the extent of LA fibrosis and the distance DAo-to-LA. A high-density electroanatomic map was performed in a subgroup of 16 patients to exclude the possibility of an MRI artifact. Recurrences after ablation were analysed at 1 year of follow-up. The extent of atrial fibrosis in the area adjacent to the DAo was inversely correlated with the distance DAo-to-LA (r = -0.34, P < 0.001). This area had the greatest intensity of LGE [image intensity ratio (IIR) 1.14 ± 0.15 vs. 0.99 ± 0.16; P < 0.001] and also the lowest voltage (1.07 ± 0.86 vs. 1.54 ± 1.07 mV; P < 0.001) and conduction velocity (0.65 ± 0.06 vs. 0.96 ± 0.57 mm/ms; P < 0.001). The extent of this regional fibrosis predicted recurrence after AF ablation [hazard ratio (HR) 1.02, 95% CI 1.01-1.03; P = 0.01], however total fibrosis did not (HR = 1.01, 95% CI 0.97-1.06, P = 0.54). CONCLUSIONS: Atrial fibrosis was predominantly located in the area adjacent to the DAo, and increased with the proximity between the two structures. Furthermore, this regional fibrosis better predicted recurrence after AF ablation than total atrial fibrosis.

Accuracy of left atrial fibrosis detection with cardiac magnetic resonance: correlation of late gadolinium enhancement with endocardial voltage and conduction velocity.

AIMS: Myocardial fibrosis is a hallmark of atrial fibrillation (AF) and its characterization could be used to guide ablation procedures. Late gadolinium enhanced-magnetic resonance imaging (LGE-MRI) detects areas of atrial fibrosis. However, its accuracy remains controversial. We aimed to analyse the accuracy of LGE-MRI to identify left atrial (LA) arrhythmogenic substrate by analysing voltage and conduction velocity at the areas of LGE. METHODS AND RESULTS: Late gadolinium enhanced-magnetic resonance imaging was performed before ablation in 16 patients. Atrial wall intensity was normalized to blood pool and classified as healthy, interstitial fibrosis, and dense scar tissue depending of the resulting image intensity ratio. Bipolar voltage and local conduction velocity were measured in LA with high-density electroanatomic maps recorded in sinus rhythm and subsequently projected into the LGE-MRI. A semi-automatic, point-by-point correlation was made between LGE-MRI and electroanatomical mapping. Mean bipolar voltage and local velocity progressively decreased from healthy to interstitial fibrosis to scar. There was a significant negative correlation between LGE with voltage (r = -0.39, P < 0.001) and conduction velocity (r = -0.25, P < 0.001). In patients showing dilated atria (LA diameter ≥45 mm) the conduction velocity predictive capacity of LGE-MRI was weaker (r = -0.40 ± 0.09 vs. -0.20 ± 0.13, P = 0.02). CONCLUSIONS: Areas with higher LGE show lower voltage and slower conduction in sinus rhythm. The enhancement intensity correlates with bipolar voltage and conduction velocity in a point-by-point analysis. The performance of LGE-MRI in assessing local velocity might be reduced in patients with dilated atria (LA diameter ≥45).

Optimized single-point left ventricular pacing leads to improved resynchronization compared with multipoint pacing.

BACKGROUND: Multipoint pacing (MPP) in cardiac resynchronization therapy (CRT) activates the left ventricle from two locations, thereby shortening the QRS duration and enabling better resynchronization; however, compared with conventional CRT, MPP reduces battery longevity. On the other hand, electrocardiogram-based optimization using the fusion-optimized intervals (FOI) method achieves more significant reverse remodeling than nominal CRT programming. Our study aimed to determine whether MPP could attain better resynchronization than single-point pacing (SPP) optimized by FOI. METHODS: This prospective study included 32 consecutive patients who successfully received CRT devices with MPP capabilities. After implantation, the QRS duration was measured during intrinsic rhythm and with three pacing configurations: MPP, SPP-FOI, and MPP-FOI. In 14 patients, biventricular activation times (by electrocardiographic imaging, ECGI) were obtained during intrinsic rhythm and for each pacing configuration to validate the findings. Device battery longevity was estimated at the 45-day follow-up. RESULTS: The SPP-FOI method achieved greater QRS shortening than MPP (-56 ± 16 vs. -42 ± 17 ms, p < .001). Adding MPP to the best FOI programming did not result in further shortening (MPP-FOI: -58 ± 14 ms, p = .69). Although biventricular activation times did not differ significantly among the three pacing configurations, only the two FOI configurations achieved significant shortening compared with intrinsic rhythm. The estimated battery longevity was longer with SPP than with MPP (8.1 ± 2.3 vs. 6.3 ± 2.0 years, p = .03). CONCLUSIONS: SPP optimized by FOI resulted in better resynchronization and longer battery duration than MPP.

Very high pacing thresholds during long-term follow-up predicted by a combination of implant pacing threshold and impedance in leadless transcatheter pacemakers.

BACKGROUND: Micra transcatheter pacemaker system (TPS) usually achieves low implant pacing threshold (IPT). However, IPT may increase in some patients during follow-up. AIM: To apply implant parameters in predicting long-term occurrence of very high pacing threshold (VHPT) in patients with Micra-TPS. METHODS: A cohort of 110 consecutive patients implanted with a Micra-TPS from 2014 to 2018 was evaluated at discharge and at 1, 12, 24, 36, and 48 months follow-up. VHPT was defined as greater than 2 V/0.24 ms. VHPT predictors were identified. RESULTS: Micra-TPS was implanted successfully in 108 patients (98.2%). During a mean follow-up of 24 ± 16 months, 18 patients (16.7%) died of causes nonpacemaker-related, and 4 (3.8%) developed VHPT. Patients with VHPT had higher IPT and lower implant impedance than patients with non-VHPT: 1 ± 0.31 vs 0.55 ± 0.29 V/0.24 ms (P = .003) and 580 ± 59 vs 837 ± 232 Ω (P = .03), respectively. IPT and impedance had excellent discriminative power to predict VHPT (area under the curve: 0.85 ± 0.07 and 0.91 ± 0.05, respectively). Negative predictive value (NPV) of IPT ≤ 0.5 V/0.24 ms was 100%; positive predictive value (PPV) was 8% throughout follow-up. Implant impedance ≤ 600 Ω had NPV of 99% throughout follow-up, whereas PPV varied: 16%, 21%, 16%, and 28% at 1, 12, 24, and 36 months, respectively. Sequential combination of IPT greater than 0.5 V/0.24 ms and impedance ≤ 600 Ω improved PPV to 25%, 35%, 27%, and 44%, respectively, whereas NPV remained 99% throughout follow-up. CONCLUSION: Despite favorable long-term electrical performance of Micra-TPS, a small percent of patients developed VHPT during follow-up. A sequential combination of IPT and impedance could allow the implanter to identify patients who will develop VHPT during long-term follow-up.