Human Atrial Fibrillation Initiates via Organized Rather Than Disorganized Mechanisms

Schricker, Amir; Lalani, Gautam; Krummen, David E.; Rappel, Wouter‐Jan; Narayan, Sanjiv M.

doi:10.1161/circep.113.001289

Cited by 49 publications

(48 citation statements)

References 29 publications

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“…7 Conversely, if electrodes are too closely spaced, calculated wave propagation may fall within measurement error. For instance, for atrial conduction velocity in AF patients of 40 cm/sec, 31,59 reported errors in assigning onset time in AF (≈5-10 ms) translate to a distance of 2-4 mm (=40×0.005 to 40×0.010). Closer electrode separation than this will be attempting to identify circuits within measurement noise, and will have less confidence.…”

Section: Areas For Technical Improvement In Source-guided Ablation Of Afmentioning

confidence: 99%

The continuous challenge of AF ablation: From foci to rotational activity

Narayan

Vishwanathan

Kowalewski

et al. 2017

Revista Portuguesa de Cardiologia (English Edition)

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Pulmonary vein isolation (PVI) is central to ablation approaches for atrial fibrillation (AF), yet many patients still have arrhythmia recurrence after one or more procedures despite the latest technology for PVI. Ablation of rotational or focal sources for AF, which lie outside the pulmonary veins in many patients, is a practical approach that has been shown to improve success by many groups. Localized sources lie in atrial regions shown mechanistically to sustain AF in optical mapping and clinical studies of human AF, as well as computational and animal studies. Because they arise in localized atrial regions, AF sources may explain central paradoxes in clinical practice -such as how limited ablation in patient specific sites can terminate persistent AF yet extensive anatomical ablation at stereotypical locations, which should extinguish disordered waves, does not improve success in clinical trials. Ongoing studies may help to resolve many controversies in the field of rotational sources for AF. Studies now verify rotational activation by multiple mapping approaches in the same patients, at sites where ablation terminates persistent AF. However, these studies also show that certain mapping methods are less effective for detecting AF sources than others. It is also recognized that the success of AF source ablation is technique dependent. This review article provides a mechanistic and clinical rationale to ablate localized sources (rotational and focal), and describes successful techniques for their ablation as well as pitfalls to avoid. We hope that this review will serve as a platform for future improvements in the patient-tailored ablation for complex arrhythmias.

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Section: Areas For Technical Improvement In Source-guided Ablation Of Afmentioning

confidence: 99%

The continuous challenge of AF ablation: From foci to rotational activity

Narayan

Vishwanathan

Kowalewski

et al. 2017

Revista Portuguesa de Cardiologia (English Edition)

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“…26 This has been the basis of physiological filtering employed in FIRM mapping to separate principal components from noise. 27 …”

Section: Separating Local From Far-field Activationmentioning

confidence: 99%

Role of Rotors in the Ablative Therapy of Persistent Atrial Fibrillation

Schricker¹,

Zaman²,

Narayan³

2015

Arrhythmia &Amp; Electrophysiology Review

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Catheter ablation is more effective than pharmacological therapy for the secondary prevention of patients with paroxysmal 1,2 and persistent 3,4 atrial fibrillation (AF) and has an emerging role in the primary prevention of paroxysmal AF. 5,6 Nevertheless, in randomised clinical trials (RCTs) its success in treating patients with paroxysmal AF is 40-60 % for a single procedure and 70 % for multiple procedures at one year, 1,2 and results for persistent AF are lower. 7,8 Thus, there is an urgent unmet need to improve our understanding of mechanistic targets for AF in each patient, to match recent advances in ablation energy delivery and catheter positioning.This report reviews mechanistic data on human AF, mapping technologies that provide the opportunity to reconcile fundamental mechanisms in individual patients and their therapeutic application. Atrial Fibrillation MechanismsAF is initiated by triggers predominantly near the pulmonary veins (PV), 9 with increasingly recognised sites outside the PVs. [10][11][12] To improve success, ablation to eliminate AF triggers should thus also target non-PV triggers, although they are transient and difficult to locate. Another potential ablative target is the mechanistic cascade by which triggers initiate AF, yet this is relatively unstudied. We recently showed -using wide-area mapping during spont aneous and induced AF -that the first cycles of AF after a trigger exhibit a single organised re-entrant spiral wave or focal driver (see Figure 1) that subsequently disorganises. 13 Remarkably, these AF-initiating mechanisms may be relatively spatially fixed for each patient -even for different triggers from both atria -separated by 2.1 ± 1.7 cm from trigger sites (see Figure 1). 13 Thus, AF initiation is likely to be a two-step mechanistic process, in which 1) a trigger initiates an organised spiral wave or focal source at patient-specific anatomical sites that 2) lead rapidly to disorganisation to produce the classical AF phenotype. This begs the question of whether AF maintenance is driven by self-sustaining disorganisation, or whether disorganisation is actually sustained by localised AF drivers (rotors or focal drivers).Self-sustaining disorganisation was traditionally considered the mechanism of AF maintenance. This mechanism is supported by computational models in which multiple wavelets sustain AF if there is enough room in the atrium ('critical mass'), 14 proposals that dissociation between the epicardium and endocardium may be contributory 15 and plaque recordings from the atria of patients in the operating room showing re-entry without apparent organisation. Limitations to these studies are that fibrillatory maps are based upon recordings that poorly represent local activation;16 only small areas of the atria were mapped (<10-20 %) and while these studies show that disorganisation exists they did not test if it self-sustains. The success of widespread ablation or Maze surgery supports the concept of self-sustaining disorganisation, but are also consistent with coinci...

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“…1 Maria Niespialolwska-Steuden*, 2 Vias Markides, 3 Osita Okafor, 3 Mohamed Farag, 3 Nikolaos Spinthakis, 3 Monika Cisecka, 2 Diana Adrienne Gorog, 2 Background Atrial fibrillation (AF) is the most frequent sustained cardiac arrhythmia and a major cause of morbidity and mortality. Catheter ablation is a potentially curative treatment.…”

Section: Improvement In Endogenous Thrombolytic Status Following Succmentioning

confidence: 99%

54 Improvement in Endogenous Thrombolytic Status following Successful Ablation of Atrial Fibrillation

Niespialolwska-Steuden

Markides

Okafor

et al. 2015

Heart

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BackgroundAtrial fibrillation (AF) is the most frequent sustained cardiac arrhythmia and a major cause of morbidity and mortality. Catheter ablation is a potentially curative treatment. The effect of ablation on global thrombotic status is still uncertain.MethodsA cohort of 34 patients (71% male, aged 63+/-17y) with persistent AF was recruited prior to ablation procedure. The mean CHA2DS2VASC score was 2+/-2 and all the patients were treated with warfarin or novel anticoagulant agents. Global Thrombotic Test (GTT), a point of care blood test measuring markers of thrombogenicity, occlusion time (OT) and lysis time (LT) (in seconds) was utilised. OT reflects platelet reactivity. LT relates to the activity endogenous thrombolysis. As per other studies, increase in OT or shortening of LT has got a potentially prognostic value indicative of reduction in thrombotic risk.ResultsAt 3 month follow up 20% of patients reversed back to AF. Their OT and LT values remained unchanged in comparison to prior to the ablation: LT med 2005s; IQR [1231;2692] vs. 2848s [2038;3873], P=NS. However 80% of patients remained in SR. Successful elimination of arrhythmia in this group was reflected by reduction in LT (2025s; [1661;2475] vs. 1425s [1060;1893], P = 0.001), but no change in OT. There was a significant difference in LT values between patients who were in SR and those in AF at the time of the follow up (1425s [1060; 1893] vs. 2848 [2038;3873], P = 0.003). Patients anticoagulated with warfarin, had similar INR values at baseline and follow up (2.3+/-0.3).ConclusionOur study demonstrated that successful ablation of persistent AF improves parameters of thrombogenicity and may potentially improve a long term prognosis. That observation should be confirmed by larger studies.

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Human Atrial Fibrillation Initiates via Organized Rather Than Disorganized Mechanisms

Cited by 49 publications

References 29 publications

The continuous challenge of AF ablation: From foci to rotational activity

The continuous challenge of AF ablation: From foci to rotational activity

Role of Rotors in the Ablative Therapy of Persistent Atrial Fibrillation

54 Improvement in Endogenous Thrombolytic Status following Successful Ablation of Atrial Fibrillation

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