Focal atrial tachycardia

1. P-Wave Morphology in
Focal Atrial Tachycardia:
An Updated Algorithm to Predict Site of Origin
Journal Reading
07/12/2022
Alfin Ridha Ramadhan

3. Intro
• Focal atrial tachycardia (AT) is a relatively uncommon cause of
supraventricular tachycardia
• Foci do not occur randomly throughout the atria but tend to cluster
(Particular anatomic locations characterized by changes in fiber orientation
or localized automaticity)
• In 2006, we developed a P-wave morphology (PWM) algorithm that was
highly accurate (93%) in diagnosing the location of focal AT
• There has been a greater appreciation of the close proximity of anatomic
sites in the paraseptal (PS) region and the potential spatial limitations of
PWM. In addition, the noncoronary cusp (12) has been recognized as a
location

4. Method
•67 patients who underwent first-time RF ablation for focal PS/midline AT
•Patients with multiple changing AT morphologies, or if the P-wave could not be unencumbered from the T
wave, were excluded.
Population
•RA: right septum defined as the region of the fossa ovalis and septum primum
•Perinodal: earliest activation recorded in the proximal His-bundle electrode with RFA successful within 1 cm
of this region
•3) CS ostium 4) septal TA (5)
•Left atrium: superior mitral annulus (SMA), left septum, Non Coronary cusp
Anatomic
Definition
•1) positive (+): if there was a positive deviation from the isoelectric baseline;
•2) negative (-): if there was a negative deviation
•3) isoelectric (iso) arbitraril defined when there was no P-wave deviation from baseline of >= 0.05 mV
•4) biphasic: if there were both positive and negative (+/- or -/+) deflections from baseline.
P-wave
morphology.

5. Method• Catheter ablation was generally performed under conscious sedation
• Antiarrhythmic drug therapy was withheld for 5 doses before the ablation procedure.
• decapolar catheter was positioned in the CS, proximal bipole at CS Os. Quadripolar at the His
position
Procedure
• 3D electroanatomic mapping systems, either Ensite (Abbott Medical) or CARTO (Biosense
Webster)
• PS location -> when earliest activation times were located in the septal region with the atrial
electrogram at the His location equal to or ahead of P-wave onset
Mapping
AT
• use of irrigated and nonirrigated ablation catheters
• Maximum power was set at 50 W for nonirrigated and 30 W for irrigated
• Success -> absence of tachycardia or ectopy 30 min following ablation despite infusion of
isoproterenol (up to 6 mg/min) and burst atrial pacing.
RF
Ablation

6. Method• Clinic visits and/or telehealth consultation.
• Data regarding antiarrhythmic drug continuation, and arrhythmia recurrence were
collected
Follow
Up
• Based on the results of the midline/PS AT study cohort and after reviewing
descriptions of foci originating from the left septum and noncoronary cusp
• The updated P-wave algorithm was prospectively applied by 3 blinded assessors
Revision
PWM
algorithm
• Alfred Hospital Human Research and Ethics Committee (project number: 67283, local
reference number: Project 484/20).
Ethical
Approve

7. •67 pt (midline focal AT who underwent successful RF
ablation between 2006 and 2019)
•The mean age was 55.2+-15.1 years (61.2% women).
•Coexistent arrhythmias 13 (19.4%): AVNRT in 5, AF in
5,ventricular ectopy in 1.
Baseline
•The average RF time was 5.4 +-5 min and
fluoroscopy time of 12.5 +- 8 min
•Acute procedural success for the clinical AT was
achieved in 67 (100%)
•3 patients presented with recurrent AT arising from
the same anatomic location. In 2 patients with
perinodal AT, transient AV block was
•seen in 1 and transient PR interval prolongation in 1.
No other major complications were observed.
Procedural
Result

9. Revision to P wave Algorithm
• The number of arms of PWM in lead V1 was reduced from 5 to 4.
• Lead I was used to discriminate between left PV (LPV)/LAA and right PV (RPV) focal
AT.

10. Prospective Validation
• consisted of 30 patients with focal AT who underwent successful RF ablation.
• The mean age was 53.4 +- 15 years, with 63% women and normal cardiac dimensions
Population
Revised
Algorithm
• AT originated from the RA in 10 (33.3%): crista terminalis in 6, TA in 3, and right atrial appendage
(RAA) in 1.
• AT originated from the LA in 9 (30%): LPV/LAA in 2, and RPVs in 7.
• AT originated from the PS region in 11 (36.7%): CS os in 4, left septum in 2, right septum in 1,
noncoronary cusp in 2, perinodal region in 1, and SMA in 1.
Anatomic
Location
• 3 blinded assessors:
• Assessor 1 correctly identified 29 (97%) of 30 AT cases,
• Assessor 2 correctly identified 27 (90%) of 30 AT cases,
• Assessor 3 identified 28 (93%) of 30 AT cases
P-wave
Algorithm
Prediction

13. Discussion
• Kistler et al ATs were classified as either right or left sided.
Paraseptal AT was not used as a clinical entity
• Ouyang et al  focal AT arising from the noncoronary cusp, which
had not been previously appreciated as a source for AT.
• Additional studies highlighted the significant overlap in PWMs at
these sites due to their close anatomic proximity
• Present study reviewed the PWM from 67 patients with PS AT and
could not reliably separate individual sites on the basis of PWM
• A biphasic (-/+ or iso/+) or isoelectric P-wave in lead V1 was present
in 96% of PS AT and was incorporated into the revised algorithm

14. • The 2006 algorithm  point mapping was based on the manual
detection of the earliest local activation time using the large
dedicated bipole of the ablation catheter, without the availability of
3D electroanatomic mapping
• Mapping of atrial arrhythmias evolved significantly, from the
availability of 3D EAM, to point-by-point mapping, to multielectrode
mapping (MEM) using multipolar catheters with smaller electrodes
and closer interelectrode spacing

15. • In 2011, Qian et al  developed a P-wave algorithm to predict the
site of origin for focal AT based on a derivation cohort of 61 patients
with a high proportion from the CS ostium (36%). Similar findings a
positive P-wave in lead V1 was highly sensitive (95%) for a left-sided
AT

17. Study Limitation
• The revised algorithm does not include uncommon but potential sites
of focal AT, such as the ligament of Marshall or posterior left atrial
wall.
• The predictive value of the algorithm ideally needs to be validated at
these other sites.
• The patient cohort in which the updated algorithm was prospectively
evaluated against was relatively small.

18. Conclusion
• The 2021 PWM algorithm offers a simplified and accurate method of
determining the site of origin for focal AT.
• Prospective evaluation of the updated algorithm in a
contemporaneous population identified the correct location in 93%.

19. Thank You