ECGI targeted ablation for persistent AF not responding to pulmonary vein isolation: Results of a two-staged strategy (TARGET AF2).

Background: Mechanisms sustaining persistent atrial fibrillation (AF) remain unclear. Objectives: The study sought to evaluate both the clinical outcomes and response to ablation of potential drivers in patients with recurrent persistent AF recurrence following pulmonary vein isolation (PVI). Methods: A total of 100 patients with persistent AF of <2 years' duration underwent cryoballoon PVI (ECGI phenotyping of persistent AF based on driver burden and distribution to predict response to pulmonary vein isolation). Patients with documented recurrence of atrial arrhythmia within 12 months were recruited and underwent repeat PVI (if needed) followed by ablation of potential drivers (PDs) identified by electrocardiographic imaging (ECGI). PDs were defined as rotational activity >1.5 revolutions or focal activations. Cycle lengths were measured pre- and postablation. The primary outcome was freedom from atrial arrhythmia off antiarrhythmic drugs at 1 year as per guidelines. Results: Of 37 patients recruited, 26 had recurrent AF and underwent ECGI-guided ablation of PDs. An average of 6.4 ± 2.7 PDs were targeted per patient. The mean ablation time targeting PDs was 15.5 ± 6.9 minutes. An ablation response occurred in 20 patients (AF termination in 6, cycle length prolongation ≥10% in 14). At 1 year, 14 (54%) of 26 patients were free from arrhythmia, and 12 (46%) of 26 were off antiarrhythmic drugs. Considering the 96 patients who completed follow-up out of the original cohort of 100 patients undergoing cryoablation in this staged strategy, freedom from arrhythmia at 1 year following the last procedure was 72 (75%) of 96, or 70 (73%) of 96 off antiarrhythmic drugs. Conclusions: In patients with recurrent AF despite PVI, ECGI-guided ablation caused an acute response in a majority with reasonable long-term outcomes.

ECG-I phenotyping of persistent AF based on driver burden and distribution to predict response to pulmonary vein isolation (PHENOTYPE-AF).

BACKGROUND: This prospective trial sought to phenotype persistent atrial fibrillation (AF) based on AF mechanisms using electrocardiographic imaging (ECGI) mapping to determine whether this would predict long-term freedom from arrhythmia after pulmonary vein isolation (PVI). METHODS: Patients with persistent AF of <2 years duration underwent cryoballoon PVI. ECGI mapping was performed before PVI to determine potential drivers (PDs) defined as rotational activations completing ≥1.5 revolutions or focal activations. The coprimary endpoint was the association between (1) PD burden (defined as the number of PD occurrences) and (2) PD distribution (defined as the number of segments on an 18-segment model of the atria harboring PDs) with freedom from arrhythmia at 1-year follow up. RESULTS: Of 100 patients, 97 completed follow up and 52 (53.6%) remained in sinus rhythm off antiarrhythmic drugs. Neither PD burden nor PD distribution predicted freedom from arrhythmia (hazard ratio [HR]: 1.01, 95% confidence interval [CI]: 0.99-1.03, p = .164; and HR: 1.04, 95% CI: 0.91-1.17, p = .591, respectively). Otherwise, the burden of rotational PDs, rotational stability, and the burden of PDs occurring at the pulmonary veins and posterior wall all failed to predict arrhythmia recurrence (all p > .10). CONCLUSIONS: AF mechanisms as determined using ECGI mapping do not predict outcomes after PVI for persistent AF. Further studies using different methodologies to characterize AF mechanisms are warranted (NCT03394404).

Noninvasive electrocardiographic imaging-guided targeting of drivers of persistent atrial fibrillation: The TARGET-AF1 trial.

BACKGROUND: Mechanisms sustaining persistent atrial fibrillation (AF) remain uncertain. OBJECTIVES: The purpose of this study was to use electrocardiographic imaging (ECGI) mapping to guide localized driver ablation in patients with persistent AF. METHODS: Patients undergoing catheter ablation for persistent AF <2 years were included. Patients were enrolled consecutively between 2018 and 2020. ECGI mapping was used to identify focal and rotational potential drivers (PDs). PDs were ablated after pulmonary vein isolation (PVI). The ablation response and freedom from AF/atrial tachycardia (AT) at 1 year were assessed. RESULTS: Forty patients were enrolled. AF terminated with PVI in 8 patients, and 32 underwent ECGI-guided driver ablation. Average procedural duration was 228.8 ± 66.7 minutes, with a total radiofrequency delivery time of 38.9 ± 14.1 minutes. During 1 year of follow-up, the primary endpoint of freedom from AF/AT was achieved in 26 patients (65%). The secondary endpoint of freedom from AF was achieved in 30 patients (75%). AF termination was achieved in 20 of 40 patients (50%). The composite endpoint of an ablation response (AF termination or cycle length slowing ≥10%) occurred in 37 of 40 patients (92.5%). In total, 181 drivers (48 focal and 133 rotational) were ablated, with an ablation response achieved in 59 (32.6%). Focal drivers and drivers with a higher recurrence rate and greater temporal stability were more likely to be associated with an ablation response including AF termination (P <.001). CONCLUSION: ECGI-guided ablation plus PVI results in high freedom from AF during follow-up and an ablation response in a large proportion of patients. Using driver type and characteristics may facilitate a hierarchical ablation approach.

Driver characteristics associated with structurally and electrically remodeled atria in persistent atrial fibrillation.

Background: Recent studies suggest persistent atrial fibrillation (AF) is maintained by localized focal or rotational electrical activations termed drivers. Objective: The purpose of this study was to evaluate how left atrial (LA) dilation and time in AF impact persistent AF mechanisms. Methods: Patients with persistent AF <2 years underwent electrocardiographic image mapping. Potential drivers (PDs) were defined as rotational wavefront activity ≥1.5 revolutions or focal activations. Distribution of PDs was recorded using an 18-segment model. Results: One hundred patients were enrolled (age 61.3 ± 12.1 years). Of these patients, 47 were hypertensive, 14 had diabetes mellitus, and 10 had ischemic heart disease. AF duration was 8 [5-15] months. Median LA diameter was 39 [33-43] mm. Although LA dimensions did not correlate with overall PD burden or distribution, there was a modest correlation between increasing LA area (r = 0.235; P = .024) and LA volume (r = 0.216; P = .039) with proportion of PDs that were rotational. Although time in AF did not correlate with overall PD burden or distribution, there was a correlation between time in AF and the number of focal PDs (r = 0.203; P = .044). Female gender, increasing age, and hypertension also were associated with an increase in focal PDs. Conclusion: This is the first study to demonstrate different AF mechanisms in patient subgroups. Greater understanding of patient-specific AF mechanisms may facilitate a tailored approach to AF mapping and ablation.

The heart failure specialists of tomorrow: a network for young cardiovascular scientists and clinicians.

The "Heart failure specialists of Tomorrow" (HoT) group gathers young researchers, physicians, basic scientists, nurses and many other professions under the auspices of the Heart Failure Association of the European Society of Cardiology. After its foundation in 2014, it has quickly grown to a large group of currently 925 members. Membership in this growing community offers many advantages during, before, and after the 'Heart Failure and World Congress on Acute Heart Failure'. These include: eligibility to receive travel grants, participation in moderated poster sessions and young researcher and clinical case sessions, the HoT walk, the career café, access to the networking opportunities, and interaction with a large and cohesive international community that constantly seeks multinational collaborations.

Healthcare Workers Bioresource: Study outline and baseline characteristics of a prospective healthcare worker cohort to study immune protection and pathogenesis in COVID-19.

Background: Most biomedical research has focused on sampling COVID-19 patients presenting to hospital with advanced disease, with less focus on the asymptomatic or paucisymptomatic. We established a bioresource with serial sampling of health care workers (HCWs) designed to obtain samples before and during mainly mild disease, with follow-up sampling to evaluate the quality and duration of immune memory. Methods: We conducted a prospective study on HCWs from three hospital sites in London, initially at a single centre (recruited just prior to first peak community transmission in London), but then extended to multiple sites 3 weeks later (recruitment still ongoing, target n=1,000). Asymptomatic participants attending work complete a health questionnaire, and provide a nasal swab (for SARS-CoV-2 RNA by RT-PCR tests) and blood samples (mononuclear cells, serum, plasma, RNA and DNA are biobanked) at 16 weekly study visits, and at 6 and 12 months. Results: Preliminary baseline results for the first 731 HCWs (400 single-centre, 331 multicentre extension) are presented. Mean age was 38±11 years; 67% are female, 31% nurses, 20% doctors, and 19% work in intensive care units. COVID-19-associated risk factors were: 37% black, Asian or minority ethnicities; 18% smokers; 13% obesity; 11% asthma; 7% hypertension and 2% diabetes mellitus. At baseline, 41% reported symptoms in the preceding 2 weeks. Preliminary test results from the initial cohort (n=400) are available: PCR at baseline for SARS-CoV-2 was positive in 28 of 396 (7.1%, 95% CI 4.9-10.0%) and 15 of 385 (3.9%, 2.4-6.3%) had circulating IgG antibodies. Conclusions: This COVID-19 bioresource established just before the peak of infections in the UK will provide longitudinal assessments of incident infection and immune responses in HCWs through the natural time course of disease and convalescence. The samples and data from this bioresource are available to academic collaborators by application  https://covid-consortium.com/application-for-samples/.