Trial Outcomes & Findings for Characterising the Stable and Dynamic Left Atrial Substrate in Atrial Fibrillation (NCT NCT04229472)

NCT ID: NCT04229472

Last Updated: 2025-08-19

Results Overview

Mean and distribution of left atrial voltage amplitude across the whole chamber and by segments with lower limit of normal defined as the upper 95% value within the segment with the lowest mean amplitude at long pacing cycle length.

Recruitment status

COMPLETED

Study phase

NA

Target enrollment

31 participants

Primary outcome timeframe

During ablation procedure

Results posted on

2025-08-19

Participant Flow

Participant milestones

Participant milestones
Measure	Normal Subject Control Group High density mapping of left atrial voltages in patients with supraventricular tachycardia	Atrial Fibrillation Group High density mapping of left atrial voltages	AcQMap Atrial Fibrillation Group High density mapping of left atrial voltages and AcQMap propagation patterns alongside cardiac MRI
Overall Study STARTED	0	20	11
Overall Study COMPLETED	0	19	10
Overall Study NOT COMPLETED	0	1	1

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Race and Ethnicity were not collected from any participant.

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Normal Subject Control Group High density mapping of left atrial voltages in patients with supraventricular tachycardia	Atrial Fibrillation Group n=19 Participants High density mapping of left atrial voltages	AcQMap Atrial Fibrillation Group n=10 Participants High density mapping of left atrial voltages and AcQMap propagation patterns alongside cardiac MRI	Total n=29 Participants Total of all reporting groups
Sex: Female, Male Female	—	5 Participants n=19 Participants	4 Participants n=10 Participants	9 Participants n=29 Participants
Sex: Female, Male Male	—	14 Participants n=19 Participants	6 Participants n=10 Participants	20 Participants n=29 Participants
Race and Ethnicity Not Collected	—	—	—	0 Participants Race and Ethnicity were not collected from any participant.
Ablation Type De novo	—	19 Participants n=19 Participants	6 Participants n=10 Participants	25 Participants n=29 Participants
Ablation Type Redo	—	0 Participants n=19 Participants	4 Participants n=10 Participants	4 Participants n=29 Participants
Age, Continuous	—	65 Years STANDARD_DEVIATION 10 • n=19 Participants	64 Years STANDARD_DEVIATION 9 • n=10 Participants	64 Years STANDARD_DEVIATION 10 • n=29 Participants
Body Mass Index	—	30 kg/m2 STANDARD_DEVIATION 5 • n=19 Participants	31 kg/m2 STANDARD_DEVIATION 5 • n=10 Participants	30 kg/m2 STANDARD_DEVIATION 5 • n=29 Participants

PRIMARY outcome

Timeframe: During ablation procedure

Population: It was not possible to maintain sinus rhythm during recordings at long pacing cycle lengths in all patients.

Mean and distribution of left atrial voltage amplitude across the whole chamber and by segments with lower limit of normal defined as the upper 95% value within the segment with the lowest mean amplitude at long pacing cycle length.

Outcome measures

Outcome measures
Measure	Atrial Fibrillation Group n=9 Participants High density mapping of left atrial voltages	AcQMap Atrial Fibrillation Group n=8 Participants High density mapping of left atrial voltages	AcQMap Atrial Fibrillation Group High density mapping of left atrial voltages and AcQMap propagation patterns alongside cardiac MRI
To Define the Normal Range of Voltage Amplitude	2.00 mV Standard Deviation 2.39	1.92 mV Standard Deviation 2.37	—

SECONDARY outcome

Timeframe: During ablation procedure

A change in electrogram morphology from normal to abnormal (defined as ≥3 deflections lasting ≥50ms) between long and short pacing cycle length in regions of low (\<0.5mV), intermediate (0.5-lower limit of normal defined from control group) and normal (defined from control group results) voltage amplitude.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: During ablation procedure

Difference in single vector conduction velocity at long and short cycle lengths in regions of low, intermediate and normal voltage.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: During ablation procedure

Difference in voltage amplitude by each method in sinus rhythm.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: During ablation procedure

Population: This secondary aim could not be achieved as the cardiac MRI images were too poor to collect measurement values for the pre-specified outcome measure. Therefore, data will never be obtained in the future.

Difference in electrogram voltage amplitude at long and short cycle length in regions with and without late gadolinium enhancement on cardiac MRI.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: During ablation procedure

Population: This secondary aim could not be achieved as the cardiac MRI images were too poor to collect measurement values for the pre-specified outcome measure. Therefore, data will never be obtained in the future.

Difference in proportion of abnormal electrograms \>50ms duration and \>3 deflections at long and short cycle length in regions with and without late gadolinium enhancement on cardiac MRI.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: During ablation procedure

Population: This secondary aim could not be achieved as the cardiac MRI images were too poor to collect measurement values for the pre-specified outcome measure. Therefore, data will never be obtained in the future.

Difference in conduction velocities at long and short cycle length in regions with and without late gadolinium enhancement on cardiac MRI.

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: During ablation procedure

Population: Due to recruitment challenges during the COVID-19 pandemic, we were unable to enroll normal subjects as initially planned.

A change in electrogram morphology from normal to abnormal (defined as ≥3 deflections lasting ≥50ms), between long and short pacing cycle length.

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: During ablation procedure

Population: Due to recruitment challenges during the COVID-19 pandemic, we were unable to enroll normal subjects as initially planned.

A change in electrogram voltage amplitude between long and short pacing cycle length.

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: During ablation procedure

Population: Due to recruitment challenges during the COVID-19 pandemic, we were unable to enroll normal subjects as initially planned.

A change in electrogram duration (in ms) between long and short pacing cycle length.

Outcome measures

Outcome data not reported

Adverse Events

Normal Subject Control Group

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Atrial Fibrillation Group

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

AcQMap Atrial Fibrillation Group

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Timothy R Betts

Oxford University Hospitals NHS Foundation Trust

Phone: +44 (0)1865 220256

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place