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Background: The mechanisms underlying atrial fibrillation (AF) remain controversial. We developed Representation of Electrical Tracking or Origin-Mapping to characterize activation wavefronts by direction and uniformity, accumulating data as an orbital plot and analyzed as frequency histograms. We applied this technique to patients undergoing AF ablation to determine if AF activation is random. Methods: Patients undergoing persistent AF ablation were recruited, and an AFocusII was positioned at multiple left atrial locations and kept steady for 1 minute to collect electrograms. The AFocusII was returned to the original site and position after >10 minutes for a repeat 1-minute data collection. Data were exported to custom Representation of Electrical Tracking or Origin-Mapping software, and 30 seconds consecutive time windows at each location were studied using frequency histograms of wavefronts. R50 (the range in degrees containing 50% of the total activation) was used as a method to enable statistical comparisons of activation patterns. Electrogram characterization into categories of complex fractionated atrial electrograms by Ensite Precision was subjected to similar analysis. Results: Consecutive 30 seconds segments were studied at 161 locations in 18 pts. Mean overlap between frequency histograms was 79.5%±7.7 (95% CI, 78.3–80.7). Nine patients underwent delayed mapping at the same location, and mean overlap between the first 30 seconds and >10 minute interval was 73%±11.8 and 71.9%±13.6 for consecutive 30-second segments. Stability was confirmed using R50 (Bland-Altman mean difference: 0.87°; limits of agreement: −34.0 to 36.0; r =0.005; P =0.95). A greater variance in R50 was observed between different locations within a patient than the variance within the same locations (intraclass correlation=0.765; P P r =0.36, P Conclusions: There appears to be preferential activation patterns during persistent AF indicating spatiotemporal stability. This has important implication to our mechanistic understanding of persistent AF.

Background— The activation pattern of localized reentry (LR) in atrial tachycardia remains incompletely understood. We used the ultra–high density Rhythmia mapping system to study activation patterns in LR. Methods and Results— LR was suggested by small rotatory activations (carousels) containing the full spectrum of the color-coded map. Twenty-three left-sided atrial tachycardias were mapped in 15 patients (age: 64±11 years). 16 253±9192 points were displayed per map, collected over 26±14 minutes. A total of 50 carousels were identified (median 2; quartiles 1–3 per map), although this represented LR in only n=7 out of 50 (14%): here, rotation occurred around a small area of scar ( Conclusions— The activation pattern of LR is of small stable rotational activations (carousels), and this drove 30% (7/23) of our postablation atrial tachycardias. However, this appearance is most often pseudo-reentrant and must be differentiated by interpretation of electrograms in the candidate circuit and activation in the wider surrounding region.

Automated external defibrillators (AEDs) in public spaces have saved countless cardiac arrest victims.1 They rely on rhythm detection algorithms with high specificity for recognizing ventricular arrhythmia when used appropriately. AED diagnostics can be difficult to retrieve once the patient has arrived in hospital, with patient management decisions often made in their absence. We present a case where retrieval of an AED download was critical to manage. An 18-year-old Afro-Caribbean semiprofessional basketball player collapsed for the first time while slowing down after a sprint in the middle of a match at a local gymnasium. This was his first collapse episode. He had no past medical history or family history of sudden death. First responders were unable to detect a peripheral pulse, and bystander cardiopulmonary resuscitation (CPR) was commenced by one of his teammates. A Zoll AED Plus was available and applied in under 2 minutes, promptly advising shock delivery. Having received a 120 J …

Background— The optimal ablation strategy for persistent atrial fibrillation (AF) remains unclear. Methods and Results— This multicentre randomized study compared circumferential pulmonary vein ablation+linear ablation (control arm) versus circumferential pulmonary vein ablation+linear ablation+complex fractionated atrial electrogram (CFAE) ablation (CFAE arm) in patients with persistent AF. Circumferential pulmonary vein ablation was performed followed by roof and mitral isthmus ablation, before CFAE ablation in the CFAE arm. Ablation strategy was maintained at the first redo procedure. Sixty-five patients were recruited in each arm. The mean age was 61±10 years, 75% were men, median AF duration was 2 years, 42% had long-lasting persistent AF, 68% had associated cardiovascular disease, mean left atrial dimension was 46±6 mm, and median CHA 2 DS 2 -VASc score was 2. Ablation and procedure times were significantly longer in the CFAE arm (70±20 versus 55±17; 201±35 versus 152±45 minutes; P P =0.29) and multiprocedural success (CFAE: 51/65 [78%] versus control: 52/65 [80%]; P =1.0) were not significantly different. At the first redo procedure, patients in the CFAE arm had a higher incidence of organized atrial tachycardia/flutter (24/33 [73%] versus 11/31 [35%]; P =0.005) and gap-related macro–re-entrant flutter (8/33[24%] versus 1/31[3%]; P =0.03). Early recurrence of atrial arrhythmia was an independent predictor of late recurrence. Conclusions— CFAE ablation did not confer incremental benefit when performed in addition to circumferential pulmonary vein ablation and linear ablation. It was associated with a higher incidence of gap-related flutter. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT01711047.