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PLoS One. 2019 Apr 3;14(4):e0212903. doi: 10.1371/journal.pone.0212903. eCollection 2019.

Multicentre randomised trial comparing contact force with electrical coupling index in atrial flutter ablation (VERISMART trial).

Author information

Department of Cardiology, Leeds Teaching Hospitals NHS Trust, Leeds General Infirmary, Leeds, United Kingdom.
Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom.
Department of Cardiology, Barts Health NHS Trust, St Bartholomew's Hospital, London, United Kingdom.



Electrical coupling index (ECI) and contact force (CF) have been developed to aid lesion formation during catheter ablation. ECI measures tissue impedance and capacitance whilst CF measures direct contact. The aim was to determine whether the presence of catheter / tissue interaction information, such as ECI and CF, reduce time to achieve bidirectional cavotricuspid isthmus block during atrial flutter (AFL) ablation.


Patients with paroxysmal or persistent AFL were randomised to CF visible (range 5-40g), CF not visible, ECI visible (change of 12%) or ECI not visible. Follow-up occurred at 3 and 6 months and included a 7 day ECG recording. The primary endpoint was time to bidirectional cavotricuspid isthmus block.


114 patients were randomised, 16 were excluded. Time to bidirectional block was significantly shorter when ECI was visible (median 30.0 mins (IQR 31) to median 10.5mins (IQR 12) p 0.023) versus ECI not visible. There was a trend towards a shorter time to bidirectional block when CF was visible. Higher force was applied when CF was visible (median 9.03g (IQR 7.4) vs. 11.3g (5.5) p 0.017). There was no difference in the acute recurrence of conduction between groups. The complication rate was 2%, AFL recurrence was 1.1% and at 6 month follow-up, 12% had atrial fibrillation.


The use of tissue contact information during AFL ablation was associated with reduced time taken to achieve bidirectional block when ECI was visible. Contact force data improved contact when visible with a trend towards a reduction in the procedural endpoint. trial identifier: NCT02490033.

Conflict of interest statement

This study received a research grant from a commercial source, Biosense Webster. Biosense Webster had no involvement in the trial design, analysis of the results or drafting of the manuscript. Dr Prapa Kanagaratnam has received speaker fees from Medtronic. Dr Gordon Begg and Dr James O’Neill have received fellowships from Abbott. Dr Muzahir Tayebjee has received research/travel grants from Abbott, Biosense Webster, Medtronic and Boehringer Ingelheim. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

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