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.

Electrocardiographic optimization techniques in resynchronization therapy.

Cardiac resynchronization therapy (CRT) is a cornerstone of therapy for patients with heart failure, reduced left ventricular (LV) ejection fraction, and a wide QRS complex. However, not all patients respond to CRT: 30% of CRT implanted patients are currently considered clinical non-responders and up to 40% do not achieve LV reverse remodelling. In order to achieve the best CRT response, appropriate patient selection, device implantation, and programming are important factors. Optimization of CRT pacing intervals may improve results, increasing the number of responders, and the magnitude of the response. Echocardiography is considered the reference method for atrioventricular and interventricular (VV) intervals optimization but it is time-consuming, complex and it has a large interobserver and intraobserver variability. Previous studies have linked QRS shortening to clinical response, echocardiographic improvement and favourable prognosis. In this review, we describe the electrocardiographic optimization methods available: 12-lead electrocardiogram; fusion-optimized intervals (FOI); intracardiac electrogram-based algorithms; and electrocardiographic imaging. Fusion-optimized intervals is an electrocardiographic method of optimizing CRT based on QRS duration that combines fusion with intrinsic conduction. The FOI method is feasible and fast, further reduces QRS duration, can be performed during implant, improves acute haemodynamic response, and achieves greater LV remodelling compared with nominal programming of CRT.

Integrating new approaches to atrial fibrillation management: the 6th AFNET/EHRA Consensus Conference.

There are major challenges ahead for clinicians treating patients with atrial fibrillation (AF). The population with AF is expected to expand considerably and yet, apart from anticoagulation, therapies used in AF have not been shown to consistently impact on mortality or reduce adverse cardiovascular events. New approaches to AF management, including the use of novel technologies and structured, integrated care, have the potential to enhance clinical phenotyping or result in better treatment selection and stratified therapy. Here, we report the outcomes of the 6th Consensus Conference of the Atrial Fibrillation Network (AFNET) and the European Heart Rhythm Association (EHRA), held at the European Society of Cardiology Heart House in Sophia Antipolis, France, 17-19 January 2017. Sixty-two global specialists in AF and 13 industry partners met to develop innovative solutions based on new approaches to screening and diagnosis, enhancing integration of AF care, developing clinical pathways for treating complex patients, improving stroke prevention strategies, and better patient selection for heart rate and rhythm control. Ultimately, these approaches can lead to better outcomes for patients with AF.

Cardiac magnetic resonance-aided scar dechanneling: Influence on acute and long-term outcomes.

BACKGROUND: Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) provides tissue characterization of ventricular myocardium and scar that can be depicted as pixel signal intensity (PSI) maps. OBJECTIVE: To assess the possible benefit of guiding the ventricular tachycardia (VT) substrate mapping by integrating these PSI maps into the navigation system. METHODS: In total, 159 consecutive patients (66 ± 11 years old, 151 men [95%]) with scar-related left ventricular (LV) VT were included. VT substrate ablation used the scar dechanneling technique. A CMR-aided ablation using the PSI maps was performed in 54 patients (34%). Procedural data as well as acute and long-term outcomes were compared with those of the remaining 105 patients (66%). RESULTS: Mean procedure duration and fluoroscopy time were 229 ± 67 minutes and 20 ± 9 minutes, respectively, without significant differences between groups. Both the number of radiofrequency (RF) applications and RF delivery time were lower in the CMR-aided group (28 ± 18 applications vs 36 ± 18 applications, P = .037, and 19 ± 12 minutes vs 27 ± 16 minutes, P = .009, respectively). After substrate ablation, monomorphic VT inducibility was lower in the CMR-aided than in the control group (17 [32%] vs 53 [51%] patients, P = .022). After a mean follow-up period of 20 ± 19 months, patients from the CMR-aided group had a lower recurrence rate than those in the control group (10 patients [18.5%] vs 46 patients [43.8%], respectively, P = .002; log-rank P = .017). Multivariate analysis found that CMR-aided ablation (hazard ratio, 0.48 [95% Confirdence Interval (CI) 0.24-0.96], P = .037) was an independent predictor of recurrences. CONCLUSION: CMR-aided scar dechanneling is associated with a lower need for RF delivery, higher noninducibility rates after substrate ablation, and a higher VT-recurrence-free survival.

Left atrial fibrosis quantification by late gadolinium-enhanced magnetic resonance: a new method to standardize the thresholds for reproducibility.

AIMS: Identification of left atrial (LA) fibrosis through late gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) remains controversial due to the heterogeneity and lack of reproducibility of proposed methods. Our aim is to describe a normalized, reproducible, standardized method to evaluate LA fibrosis through LGE-CMR. METHODS AND RESULTS: Electrocardiogram- and respiratory-gated 3-Tesla LGE-CMR was performed in 10 healthy young volunteers and 30 patients with atrial fibrillation (AF): 10 with paroxysmal AF, 10 with persistent AF, and 10 with a previous AF ablation procedure. Local image intensity ratio (IIR) of the LA was calculated as the absolute pixel intensity to mean blood pool intensity ratio. The healthy atrial tissue threshold was defined in young healthy volunteers (upper limit of normality set at IIR tissue mean plus 2 SDs). Dense atrial scarring was characterized in patients with previous radiofrequency-induced scarring (post-AF ablation patients). Validation groups consisted of patients with paroxysmal and persistent AFs. The upper limit of normal IIR was 1.20; IIR values higher than 1.32 (60% of mean maximum pixel intensity in post-ablation patients) were considered dense scar. Image intensity ratio values between 1.2 and 1.32 identified interstitial fibrosis. Patients with paroxysmal and persistent AFs had less atrial fibrotic tissue compared with post-ablation patients. Endocardial bipolar voltage was correlated to IIR values. CONCLUSIONS: An IIR of 1.2 identifies the upper limit of normality in healthy young individuals. An IIR of >1.32 defines dense atrial fibrosis in post-ablation patients. Our results provide a consistent, comparable, and normalized tool to assess atrial arrhythmogenic substrate.

Circumferential pulmonary vein ablation: does use of a circular mapping catheter improve results? A prospective randomized study.

BACKGROUND: The best method for performing atrial fibrillation (AF) ablation is still under debate. The importance of using a circular mapping (CM) catheter for assessing isolation of the pulmonary vein (PV) antrum on the outcome of the procedure has not been clearly established. OBJECTIVE: The purpose of this study was to evaluate whether use of a CM catheter improves the arrhythmia-free proportion after circumferential pulmonary vein ablation (CPVA). METHODS: A series of 146 consecutive patients (83% males, age 53 +/- 10 years, 53% paroxysmal AF) were randomized to two ablation strategies. In both groups, ipsilateral PV encirclement was performed until disappearance or dissociation of the local electrogram within the surrounded area. In the first group, only the radiofrequency catheter was used to both map and ablate (CPVA group, n = 73). In the other group, a CM catheter was added to assess the electrical activity of the PV antrum (CPVA-CM group, n = 73). An ablation line along the left atrial roof was also created in all patients. RESULTS: Procedural and fluoroscopic times were longer in the CPVA-CM group (P <.05). Severe procedure-related complications occurred in 1 (1.4%) patient in the CPVA group and in 3 (4.1%) patients in the CPVA-CM group (P = .317). After mean follow-up of 9 +/- 3 months, 31 (42.5%) patients in the CPVA group and 47 (64.4%) patients in the CPVA-CM group were arrhythmia-free without antiarrhythmic medication (P = .008). CONCLUSION: Use of a CM catheter to ensure isolation of the PV antrum improved the success of CPVA but increased some procedural requirements.