Direct or Coincidental Elimination of Stable Rotors or Focal Sources May Explain Successful Atrial Fibrillation Ablation

Q: What are the key findings of this study?

Direct or coincidental ablation of stable AF sources achieved 80.3% freedom from AF compared to 18.2% when sources were missed (p<0.001) at a median 273 days.

Q: What is the clinical evidence from this study?

Study design: Cohort. Population: Atrial fibrillation (paroxysmal, persistent, and longstanding persistent) (n=94). Intervention: Direct (FIRM-guided) or coincidental (conventional anatomical) ablation passing through stable AF rotors or focal sources vs. Ablation missing all stable AF sources (no-source ablation). Primary outcome: Freedom from AF after a single procedure (<1% burden on continuous implanted ECG monitors or AF <30 seconds on intermittent monitors) (p=<0.001).

Q: What does this research mean for the field?

Elimination of stable atrial fibrillation rotors and focal sources, whether by direct targeted ablation or coincidental conventional lesion delivery, significantly predicts long-term freedom from atrial fibrillation. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.CHALLENGES_CONSENSUS.

Q: What question did this study set out to answer?

To determine whether direct or coincidental ablation of patient-specific stable electrical rotors and focal sources explains long-term freedom from atrial fibrillation.

Sanjiv M. Narayan; David E. Krummen; Paul Clopton; Kalyanam Shivkumar; John M. Miller

doi:10.1016/j.jacc.2013.03.021

April 4, 2013Journal of the American College of CardiologyOpen Access

Direct or Coincidental Elimination of Stable Rotors or Focal Sources May Explain Successful Atrial Fibrillation Ablation

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Key result

Eliminating stable AF sources links to ~62-point higher freedom from AF vs. missing them.

P<0.001
n=94

Why the study?

It was unclear why conventional anatomical AF ablation is effective in some patients yet ineffective in others with similar profiles. This study examined whether direct or coincidental ablation of stable AF rotors or focal sources explains long-term freedom from AF.

Does direct or coincidental catheter ablation of stable AF rotors and focal sources improve long-term freedom from atrial fibrillation compared to ablation that misses all sources?

Key Points

To determine whether direct or coincidental ablation of patient-specific stable electrical rotors and focal sources explains long-term freedom from atrial fibrillation.
In the prospective non-randomized CONFIRM trial, 107 consecutive ablation cases were assigned in a 1:2 fashion to targeted source ablation via Focal Impulse and Rotor Modulation (FIRM) followed by conventional ablation, or conventional ablation alone.
Electroanatomic ablation lesion maps were co-registered with FIRM maps to assess whether delivered lesions intersected identified AF sources in n=94 patients completing follow-up (71.2% persistent AF).
Ablation lesions intersected AF sources directly in 100% of FIRM cases (34/34) and coincidentally in 45% of conventional cases (27/60; p<0.05).
Over a median follow-up of 273 days (IQR 138–636), freedom from AF was 80.3% (49/61) when sources were ablated versus 18.2% (6/33; recurrence 81.8%) when sources were missed (p<0.001).
Freedom from AF was 87.9% (29/33) when all sources were ablated, 66.7% (8/12) when some sources were ablated, and 16.7% (4/24) when no sources were ablated (p<0.001).

Study Design

Type

Cohort (n=94)

Blinding

Blinded outcome/map assessment (Electroanatomic and FIRM maps were analyzed per patient blinded to demographics, outcomes or assignment)

Randomization

Non-randomized, assigned 2:1 to FIRM-blinded (conventional) ablation alone or FIRM-guided ablation

Structured PICO

Does direct or coincidental catheter ablation of stable AF rotors and focal sources improve long-term freedom from atrial fibrillation compared to ablation that misses all sources?

P

Population

94 adults (≥21 years, predominantly male VA population) with drug-refractory paroxysmal or persistent atrial fibrillation (71.2% persistent) and identified stable AF sources, followed for a median of 273 days after a single ablation procedure.

I

Intervention

Ablation passing through ≥1 stable AF rotor or focal source (n=61), achieved either directly via real-time Focal Impulse and Rotor Modulation (FIRM) mapping guidance (15-30 seconds RF delivery at 25-35 W with 3.5 mm irrigated tip or 40-50 W with 8 mm tip in heart failure, covering ≈2 cm² source area for ≤3 sources) followed by conventional ablation (n=34), or coincidentally during conventional anatomic ablation alone (n=27).

C

Comparator

Ablation missing all identified stable AF rotors or focal sources (no-source ablation, n=33) during conventional wide-area circumferential pulmonary vein isolation (with left atrial roof line in persistent AF).

O

Outcome

Freedom from AF after a single procedure over median 273 days (IQR 138-636) follow-up, defined as <1% burden on continuous implanted ECG monitors or AF <30 seconds on quarterly intermittent external Holter/event monitors.hard clinical

Main Result

Absolute Event Rate: 80.3% vs 18.2%

p-value: p=<0.001

Limitations

Non-randomized design
Lower use of implanted ECG monitors in conventional ablation patients (26.1% vs 88.2% in FIRM-guided), potentially missing intermittent arrhythmia recurrences
Lack of contact force sensing or MRI to verify effective lesion delivery at each source site
Relatively small numbers of at-risk patients at longer follow-up periods
Predominantly male VA population
Lower use of continuous implanted ECG monitors in conventional ablation patients (26.1% vs 88.2% in FIRM-guided), reducing accuracy of follow-up
Lack of contact force sensing or magnetic resonance imaging to verify effective ablation at each site

Implication

This on-treatment analysis of the CONFIRM trial demonstrates that eliminating patient-specific stable AF rotors or focal sources—whether directly via FIRM mapping or coincidentally via anatomical lesion sets—strongly predicts single-procedure freedom from AF.

Abstract

Objective: We hypothesized that ablation of recently described stable AF sources, either directly by Focal Impulse and Rotor Modulation (FIRM) or coincidentally when anatomical ablation passes through AF sources, may explain long term freedom of AF. Background: It is unclear why conventional anatomical AF ablation can be very effective in some patients yet ineffective in others with similar profiles. Methods: The CONFIRM trial prospectively revealed stable AF rotors or focal sources in 98/101 subjects with AF at 107 consecutive ablation cases. In 1:2 fashion, subjects received targeted source ablation (FIRM) then conventional ablation, or conventional ablation alone. We determined if ablation lesions on electroanatomic maps passed through AF sources on FIRM maps. Results: Subjects who completed followup (n=94, 71.2% persistent AF) each showed 2.3±1.1 concurrent AF rotors or focal sources, that lay near pulmonary veins (22.8%), left atrial roof (16.0%), and elsewhere in left (28.2%) and right (33.0%) atria. AF sources were ablated directly in 100% FIRM cases and coincidentally (e.g. left atrial roof) in 45% conventional cases (p<0.05). During 273 days (median, IQR 138–636) after 1 procedure, AF was absent in 80.3% of patients if sources were ablated but recurred in 81.8% of patients if sources were missed (p<0.001). Freedom from AF was highest if all sources were ablated, intermediate if some sources were ablated, and lowest if no sources were ablated (p<0.001). CONCLUSIONS: Elimination of stable AF rotors and focal sources may explain freedom from AF after diverse approaches to ablation. Patient-specific AF source distributions are consistent with the reported success of specific anatomical lesion sets, and of widespread ablation. These results support targeting AF sources to reduce unnecessary ablation, and motivate studies on FIRM-only ablation.

Discussion

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Cite This Study

Narayan et al. (2013) conducted a cohort in Atrial fibrillation (paroxysmal, persistent, and longstanding persistent) (n=94). Direct (FIRM-guided) or coincidental (conventional anatomical) ablation passing through stable AF rotors or focal sources vs. Ablation missing all stable AF sources (no-source ablation) was evaluated on Freedom from AF after a single procedure (<1% burden on continuous implanted ECG monitors or AF <30 seconds on intermittent monitors) (p=<0.001). Direct or coincidental ablation of stable AF sources achieved 80.3% freedom from AF compared to 18.2% when sources were missed (p<0.001) at a median 273 days.

synapsesocial.com/papers/6adad15af2cd537cba5cc4c0 https://doi.org/10.1016/j.jacc.2013.03.021

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Direct or Coincidental Elimination of Stable Rotors or Focal Sources May Explain Successful Atrial Fibrillation Ablation

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

Direct or Coincidental Elimination of Stable Rotors or Focal Sources May Explain Successful Atrial Fibrillation Ablation

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

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