catheter ablation of atypical atrioventricular nodal ... file10.1161/circulationaha.116.024471 2...

10.1161/CIRCULATIONAHA.116.024471

1

Catheter Ablation of Atypical Atrioventricular

Nodal Reentrant Tachycardia

Running Title: Katritsis et al.;Atypical AVNRT Ablation

Demosthenes G. Katritsis, MD, PhD1,2; Joseph E. Marine, MD3; Fernando M. Contreras, MD1;

Akira Fujii, MD4; Rakesh Latchamsetty, MD5; Konstantinos C. Siontis, MD5;

George D. Katritsis, MBChB, BSc6; Theodoros Zografos, MD2; Roy M. John, MD4;

Lawrence M. Epstein, MD4; Gregory F. Michaud, MD4; Elad Anter, MD1; Ali Sepahpour, MD7;

Edward Rowland, MD7; Alfred E. Buxton, MD1; Hugh Calkins, MD3; Fred Morady, MD,5

William G. Stevenson, MD4; Mark E. Josephson, MD1

1Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA; 2Athens

Euroclinic, Athens, Greece; 3Johns Hopkins Hospital, Baltimore, MD; 4Brigham and Women’s

Hospital, Harvard Medical School, Boston, MA;5University of Michigan Health System, Ann

Arbor, MI; 6The Oxford University Clinical Academic Graduate School, Oxford, UK;7The Heart Hospital, London, UK

Address for Correspondence: Dr. D. KatritsisDivision of Cardiology Beth Israel Deaconess Medical Center185 Pilgrim Rd, Baker 4 Boston, MA 02215 Tel: +306944845505 Fax: +302106416535 Email: [email protected] or [email protected]

Journal Subject Terms: Arrhythmias

1Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MAMA;;; 2AtAtAthehehensnsns

Euroclinic, Athens, Greece; 3Johns Hopkins Hospital, Baltimore, MD; 4Brigham and Women’s

Hospital, Harvard Medical School, Boston, MA;5University of Michigan Health System, Ann

ArArArboboborrr, MMMI; 66TThe Oxford University Clinical AAcademic Gradduau te SSchool, Oxford, UK;777ThThThe ee HeHeart Hoospittaal, LoLoLondndononn, , UKUKK

Addddrereressssss fororr CCCorreresppondencncnce:e:e Dr. D. KaK tritsis


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Abstract

Background— Due to its low prevalence, data on atypical atrioventricular nodal reentrant

tachycardia (AVNRT) are scarce, and the optimal ablation method is not established. Our study

aimed at assessing the efficacy and safety of conventional slow pathway ablation, as applied for

typical cases, in atypical AVNRT.

Methods— We studied 2079 patients with AVNRT subjected to slow pathway ablation. In 113

patients, mean age 48.5±18.1 years, 68 female, atypical AVNRT or co-existent atypical and

typical AVNRT without other concomitant arrhythmia was diagnosed. Ablation data and outcomes

were compared to a group of age- and sex-matched control patients with typical AVNRT.

Results— Fluoroscopy and radiofrequency current delivery times were not different in the

atypical and typical groups, 20.3±12.2 vs 20.8±12.9 min (P=0.730) and 5.9±5.0 vs 5.5±4.5 min

(P=0.650), respectively. Slow pathway ablation was accomplished from the right septum in 110

patients, and from the left septum in 3 patients, in the atypical group. There was no need for

additional ablation lesions at other anatomical sites, and no cases of AV block were encountered.

Recurrence rates of the arrhythmia were 5.6% in the atypical (6/108 patients), and 1.8% in the

typical (2/111 patients) groups, in the next 3 months following ablation (P=0.167).

Conclusions— Conventional ablation at the anatomical area of the slow pathway is the therapy

of choice for symptomatic AVNRT, regardless of whether the typical or atypical form is present.

Key-words: arrhythmia; ablation; atrioventricular node; atypical, reentrant, tachycardia

P=0.650), respectively. Slow pathway ablation was accomplished from the right ssepepeptutuum m m ininin 1111011

patients, and from the left septum in 3 patients, in the atypical group. There was no nneedd foff r

additional ablation lesions at other anatomical sites, and no cases of AV block were encountered

Recurrererencncee e rararates ofofof the arrhythmia were 5.6% in tthehh atypical (6/108 patatients), and 1.8% in the

ypiicacacal (2/111 papapatiiieeents)s)s gggroror upupps,s,s, iiin n n thththe nenext 3 mmmono thths fooollllllowowowinining ababblalalatitionn (P=0=0=0.1616167)7)7).

Concncnclusions— CCCononveenntn ionananall l ablation att the annaatomomicalalal aaarerereaa a oof thehe slooww papaathway isisis — thhee theraapy

of chohohoiciciceee fooorr r sysysymppttomamatic AVAVAVNRNRNRT,T,T, regggarara dlesesesss off wwheheheththt errr tttheheh tttypppicicicala oorr atttypypypici alalal fffooro mm is presesent.


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Clinical Perspective

What is new?

Atypical AVNRT, regardless of the type, can be successfully ablated by targeting the

anatomic area of the slow pathway.

When a right septal approach is not successful, the anatomic area of the slow pathway

can be ablated from the left septum.

Higher septal lesions that may increase the risk of inadvertent AV block or lesions

within the coronary sinus os are not necessary for the ablation of atypical AVNRT.

It seems that the same slow pathway participates in both typical and atypical AVNRT.

What are the clinical implications?

Catheter ablation at the anatomical area of the slow pathway from the right or left

septum is the treatment of choice for atypical AVNRT.

This approach is not associated with an increased risk of inadvertent AV block.

The recurrence rate following ablation of atypical AVNRT may not be significantly

higher than that seen following ablation of typical AVNRT.

It seems that the same slow pathway participates in both typical and atyypipicacal AVAVA NRNRTT.

What araree thththe cliniccala implications?

CCaC ththeterer aaablblb aatioioon n n atat ttheheh ananatomiccall arreea ooff ththhee sllslowow ppattathwhwayay fromom tthehe rrrigigght ooor r r lelel ftft

ssepptumum is the trreatmennnt t t of cchoicee ffor atatyppicical AVNVNRTT.nnn

This approach is not associated with an increased risk of inadvertent AV block.


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Introduction

Atrioventricular nodal re-entrant tachycardia (AVNRT), represents the most common regular

arrhythmia encountered in clinical practice.1,2 A recent randomized trial, as well as observational

studies, have provided evidence that catheter ablation is the treatment of choice for symptomatic

patients, by substantially reducing hospitalization,3 improving quality of life,4-9 and reducing

costs.9-11

Approximately 6.4% of patients with AVNRT present with delayed retrograde atrial

activation, and these arrhythmias are characterized as atypical variants.12 Due to its low

prevalence, data on atypical AVNRT, as opposed to its typical counterpart, are scarce. Atypical

AVNRT has been identified as a predictor of lower ablation success rate,13 and the optimal

method of catheter ablation is not established. Although conventional slow pathway ablation has

been reported safe and effective for atypical AVNRT,14,15 in most published series ablation was

guided by identifying the slow pathway via consideration of retrograde atrial activation or other

techniques.16-22 These approaches, however, may result in energy delivery in the mid or superior

septum; 18,19,21,22 i.e. sites that are potentially associated with an increased risk of inadvertent

atrioventricular block.20,23

We hypothesized that since the slow pathway appears to be a component of the AVNRT

circuit regardless of typical or atypical characteristics,12,24,25 conventional slow pathway ablation

as applied for typical AVNRT, should be equally safe and effective in atypical cases. We have,

therefore, studied an extensive series of atypical AVNRT cases treated with anatomical slow

pathway ablation, and compared them to sex and age-matched patients who underwent ablation

for typical AVNRT.

AVNRT has been identified as a predictor of lower ablation success rate,r 13 and thehe oooptptptimimmalalal

method of catheter ablation is not established. Although conventional slow pathway ablation has

been reported safe and effective for atypical AVNRT,14,15 in most published series ablation was

guiddeeed by idennntititifyyyininng ththhee e slsllowww pppatatathwhwhwayy via conono sidederatititiononon oooff f rer trtrogogograradee atriaaall l acacactititivavv tionono ooor r r ototothehh r

echhhnnin ques.16-222 TTThehese aapproooaaca hes, howweever, mamam y reresuuultltlt iiinn n enneergyy ddelivveeryy y iini the mmmiid orr superirior

eptum; 18,19,21221 2,222 i.e. siites that are potentiially associai ted with an increased riskk of f inadvertent


5

Methods

Patients

Participating centers keep detailed databases of their patients subjected to catheter ablation and

these databases were searched for eligible patients. Data from adult patients with symptomatic

AVNRT, with at least one episode every 2 months, undergoing catheter ablation at Beth Israel

Deaconess Medical Center, Boston, MA, USA (2009-2015); Rhode Island Hospital, Providence,

RI, USA (1999-2001); Athens Euroclinic, Greece (2007-2015; the Heart Hospital, London, UK

(2009-2014); the Johns Hopkins Hospital, Baltimore, MD, USA (2011-2014); the University of

Michigan Health System, Ann Arbor, MI, USA (2009-2015); and the Brigham and Women’s

Hospital, Boston, MA, USA (2008-2015), were analyzed. All patients with a diagnosis of

atypical AVNRT subjected to catheter ablation were identified, and compared to age- and sex-

matched control patients with typical AVNRT. Controls were matched to atypical cases at each

participating center. We used an optimal matching algorithm to match each atypical AVNRT

case to a typical AVNRT case of the same age and sex, at each institution. When more than one

potential eligible controls were identified within an institution (same gender and age as the

atypical case), we selected the typical AVNRT control with procedure date closest to the atypical

AVNRT case. We did not specify a priori a matching caliper width for age, because we

anticipated that exact or nearly exact matches could be identified for each atypical AVNRT case.

Patients displaying characteristics of co-existent typical and atypical AVNRT were included in

the study, but patients with other arrhythmias such as atrial flutter or fibrillation that required

additional ablation were excluded. Patients who had been subjected to ablation for AVNRT in

the past were also excluded. Electrograms and ablation characteristics of patients were studied by

authors at participating institutes and, if needed, verified by the first and last author of this report.

Hospital, Boston, MA, USA (2008-2015), were analyzed. All patients with a diaggnonoosisisis s ofofof

atypical AVNRT subjected to catheter ablation were identified, and compared to age- and sex-

matched control patients with typical AVNRT. Controls were matched to atypical cases at each

partticiccipating ceceennntererer. WeWeWe uuusesed d d ananan opopoptitt mamal l matccchihh ngg algggorororititithmhmhm to o mamamatctch eae chhh aaatytytypipipicacc l AVAVAVNRNRNRTT T

caseee ttto a typicaaal l l AVAVNRNRT caaasses of the saamme ageee aandd sexexex,, atatat eacach innsstituttioonn.n WWWhen momom rre than onone

potential eligible controls were identified d wiithin an institution (same gender and age as the


6

All patients were studied in the post-absorptive state, under mild sedation, and after all

antiarrhythmic agents had been discontinued for more than 5 half-lives. No patient had received

amiodarone for the preceding three months. The study received approval from our institutional

review boards.

Definitions

AVNRT was diagnosed by fulfillment of established criteria during detailed atrial and

ventricular pacing maneuvers.26 Typical (slow-fast) AVNRT was defined by an atrial-His/His-

atrial ratio (AH/HA) >1, and HA interval 70 ms. Atypical AVNRT was defined by delayed

retrograde atrial activation with HA>70 ms. If the AH was <200 msec and the AH<HA, the

atypical form was characterized as fast-slow. If AH>200 ms and AH>HA, the atypical form was

considered slow-slow. Tachycardias with a prolonged AH interval >200 ms but AH<HA, or with

AH<200 ms and AH>HA, or with variable intervals during the same or different episodes, were

classified as indeterminate. Details of our methodology for measurements of intervals during

tachycardia have been described elsewhere.12,25

Mapping and Ablation

Anatomical slow pathway ablation was performed at each center according to standard

techniques.27-29 In brief, a conventional 4-mm ablation catheter was positioned at the inferior

(posterior) part of the tricuspid annulus until an A/V ratio of <1 was recorded, and the atrial

electrogram was delayed relatively to the atrial electrogram recorded at the His bundle. Care was

taken to keep the ablation catheter below the ostium of the coronary sinus (CS) as visualized in

the right anterior oblique (RAO) projection; mapping was not performed at the mid or anterior

septum (Figure 1). When multicomponent signals or separate, low-amplitude potentials were

obtained, radiofrequency (RF) current, 20-40W aimed at a temperature of 60oC, was delivered

atypical form was characterized as fast-slow. If AH>200 ms and AH>HA, the atyypipiicacacal l fofoformrmrm wwwas

considered slow-slow. Tachycardias with a prolonged AH interval >200 ms a but AH<HA, or with

AH<200 ms and AH>HA, or with variable intervals during the same or different episodes, were

classsisiified as innndddeteeermrr inininatatatee.e DeDeDetatatailillsss ofoo oouru methohohodoollogygygy fffororor mmmeaasusuurerer mementn s ofofof iiintntntererervav lsss dddurururinining g g

achhhyycy ardia haaaveveve bbeeenn ddescririribebb d elsewhwhere.12,2255

Mapping and Ablation


7

for up to 30 sec until a junctional rhythm with 1:1 retrograde ventriculo-atrial (VA) conduction

was elicited. If VA conduction was not seen, RF delivery was immediately stopped. Once

junctional rhythm with VA conduction was recorded, energy delivery was continued for 10-30

sec or until cessation of the junctional rhythm. Following ablation, arrhythmia induction with the

use of isoproterenol was attempted. End-points for ablation success were demonstration of RF-

induced junctional rhythm conducted to the atria, and non-inducibility of AVNRT with

programmed stimulation during isoproterenol challenge.

If RF-induction of junctional rhythm or non-inducibility of tachycardia could not be

accomplished from the right side of the septum, mapping at the corresponding part of the left

septum was undertaken. In some centers, additional lesions higher in the septum or in the roof of

the proximal coronary sinus were delivered before proceeding to left septal ablation. A mapping

electrode was retrogradely introduced through the noncoronary cusp of the aortic valve to record

a left-sided His bundle electrogram as described elsewhere.30,31 Since positioning of the left

septal catheter retrogradely through the non-coronary cusp inevitably results in mapping of the

anterior part of the septum, a trans-septal approach was used for introduction of the left-sided

ablation catheter and additional mapping of the posterior part of the septum (Figure 2). Mapping

of the inferior (posterior) part of the mitral annulus, below the left-sided His was performed with

the same principles as on the right septum. At the successful ablation site the atrial electrogram is

closer to this recorded by the CS rather than the His electrode. Thus, inadvertent AV block is

avoided following ablation either from the right or the left septum.29 Following successful

ablation, patients were discharged from hospital within 24 hours on aspirin and no

antiarrhythmic drugs. All patients were followed-up for an at least 3-month interval, and

repeated ablation was performed in case of recurrence of symptoms during that time. Patients

eptum was undertaken. In some centers, additional lesions higher in the septum oror iiinn n ththhe e rororoofofof of

he proximal coronary sinus were delivered before proceeding to left septal ablation. A mapping

electrode was retrogradely introduced through the noncoronary cusp of the aortic valve to record

a leeftftt-sided Hisiss bbbununundle e e eleleleeectc rooogrgrgramamam as dedescribeeed dd eelssewhwhwherere e.e.e.3033 ,31 SSiS ncncn e e popositiiionononinining g g ofo thehehe lllefefeft t t

eptpttalala catheter r reeretrroogrraddely thhrh ough thee nnon-cororo onnaary y y cucucuspsps iinenevittabbly reresuuulttts in mapapappiinng of thhee

anterior part of the septum, a trans-septal l approachh was used for introduction of the leftf -sidedd


8

with a diagnosis of AVNRT at repeat ablation, or patients who presented with a documented

tachycardia similar to the clinical one before ablation, were registered as failures.

Statistical analysis

Continuous, normally distributed variables are presented as mean ± standard deviation. Data

normality was analysed using the Kolmogorov-Smirnov test. In all cases the examined variables

followed the normal distribution and the Student’s t-test was used to analyse differences between

two groups, and the one-way ANOVA test to analyse differences between more than two groups.

Categorical data are expressed as frequencies (percentages) and were compared using Fisher's

exact test. All reported p-values were based on two-sided tests and were compared to a

significance level of 5%. Statistical calculations were performed on SPSS for Windows version

21 (IBM Corporation, Armonk, New York). A post hoc power analysis was performed to

estimate the achieved statistical power for the comparison of arrhythmia recurrence in the typical

and the atypical group using G*Power version 3.1.9.2 (Heinrich-Heine-Universität Düsseldorf,

Düsseldorf, Germany).32 Considering an alpha level of 0.05, and according to the sample size

used in the study and the observed difference, the present study achieved a power of 0.25. A total

sample size of 815 patients would be needed to achieve a power of 0.80 (Online appendix,

Figure 1). In exploratory analysis, the critical recurrence rate in the atypical group that the study

would be able to detect with a power of 0.80, was estimated to be 12.3% (Online appendix,

Figure 2).

ignificance level of 5%. Statistical calculations were performed on SPSS for Windnddowowows s s veveversrsrsioioionn

21 (IBM Corporation, Armonk, New York). A post hoc power analysis was performed to

estimate the achieved statistical power for the comparison of arrhythmia recurrence in the typical

and d thththe atypicalalal grororouppp uuusisisingngn GGG*P*P*Powowower vversionnn 333.11.99.2 (((HeHeHeinininrirr chh-HeHeH ini ee-U- niiiveveversrsrsitititätää Düsüsüsseseseldldldorororf,

Düssssssele dorf, Geeermrmr anany)).332 Cooonnsn idering g anan alphaaa llevveel ooof f f 0.00 05050 , aand aaccordrdinnng g g to the sssamampple sizee

used in the study and thhe observedd difference, thhe present study achievedd a power of 0.0 25. A tota


9

Results

Patients

In total, 2079 patients with AVNRT were studied at Beth Israel Deaconess Medical Center

(Boston, MA, USA), and Rhode Island Hospital (Providence, RI, USA) (n=287); Athens

Euroclinic, Greece (n=307); the Heart Hospital, London, UK (n=179); the Johns Hopkins

Hospital, Baltimore, MD, USA (n=271); the University of Michigan Health System, Ann Arbor,

MI, USA (n=621); and the Brigham and Women’s Hospital, Boston, MA, USA (n=414). Using

the criteria mentioned above, 113 patients (5.4%) had atypical AVNRT or co-existent atypical

and typical AVNRT and no other concomitant arrhythmia. The mean age of patients with

atypical AVNRT was 48.5±18.1 years (range 14 to79), and 68 patients (60%) were female. The

control group consisted of 113 patients with typical AVNRT, age- (48.6±17.3 years) and sex-

matched to the atypical AVNRT patients, on a one-to-one basis.

Electrophysiologic characteristics

Eighty-five out of the 113 patients (75.2%) had fast-slow AVNRT according to both the AH<HA

and AH<200 ms, and 14 patients (12.4%) slow-slow AVNRT. The remaining 14 patients (12.4

%) could not be reliably classified due to inconsistent AH and HA/AH patterns or variable

intervals. There were no significant differences in age and gender among the different atypical

AVNRT forms (P = 0.592, and P = 0.323, respectively). Twenty patients (8.9%) had co-existent

typical and atypical AVNRT during the electrophysiology study. Details of this group have been

presented elsewhere.25 Atypical AVNRT was induced by ventricular pacing or extrasystoles in

27 patients (Figure 3), or spontaneously during isoprenaline infusion in 11 patients. In the

remainder atypical AVNRT was induced by high right atrial (HRA) or CS pacing (Figures 4 and

5), and in 2 of them following an anterograde conduction jump (Figure 6). In 7 out of 98

atypical AVNRT was 48.5±18.1 years (range 14 to79), and 68 patients (60%) wereree fefefemamamalelele. ThThThe

control group consisted of 113 patients with typical AVNRT, age- (48.6±17.3 years) and sex-

matched to the atypical AVNRT patients, on a one-to-one basis.

Elecece trtrt ophysiololo oogo icicic chahaharararactc erererisisistititicscscs

Eighghghtytyt -five ouuutt t ofofo thhe 1113 pppaata ients (7(( 5..22%) haaadd faastt-ssslololoww w AVAVAVNRNRT T accocordrddinining to booto hh ththe AH<H<HA

and AHH<2000 ms, and 114 patients ((12.4%)% slow-slow AVNRT. The remaining 144 patients (12.2 44


10

patients with atypical AVNRT, earliest retrograde atrial activation was recorded by the His

bundle electrode. Four of these patients were classified as fast-slow, 2 as slow-slow, and one as

indeterminate. Electrophysiological characteristics during tachycardia are shown in Table 1.

Ablation characteristics

All but 3 patients underwent conventional, right-sided ablation at the anatomical area of the slow

pathway as described. This was successful without the need of additional lesions at other sites. In

3 patients a left-sided approach was successfully accomplished following unsuccessful right-

sided slow pathway ablation, as well as ablation lesions at higher septal sites, and, in one of

them, following unsuccessful additional lesions in the roof of the proximal coronary sinus.

Recorded electrograms by the left-sided ablation catheter at the successful site displayed the

same temporal relationships as those usually recorded by a right ablation catheter (Figure 1). In

one patient, both typical and atypical AVNRT was inducible following unsuccessful right septal

ablation, whereas in the remainder atypical only AVNRT was induced following unsuccessful

right septal ablation. Left septal ablation was needed for only one of the 7 patients in whom

earliest retrograde atrial activation was recorded by the His electrode. Fluoroscopy and RF times

are presented in Table 2. A junctional rhythm during RF ablation was noted in 110 (97%) and

111 (98%) patients in the atypical and typical groups, respectively (P=1.000). No cases of AV

block were encountered in the atypical AVNRT group. Three patients of the typical AVNRT

controls had transient AV block or PR prolongation that resolved by the next day following the

procedure (P=0.247).

Follow-up

Three-month follow-up was complete in 108 patients of the atypical group (96%), and recurrence

of symptomatic AVNRT was detected in 6 (5.6%) patients. Five of these patients had fast-slow

Recorded electrograms by the left-sided ablation catheter at the successful site dissplpllayayayededed ttthehehe

ame temporal relationships as those usually recorded by a right ablation catheter (Figure 1). In

one patient, both typical and atypical AVNRT was inducible following unsuccessful right septal

ablaatitition, wherreaeaeas ininin thehehe rrrememe aiaiaindndndererer aaatypipical onnnlylyly AAVNVNRTRTRT wwwasasas iindndducucu eded ffollooowiwiwingngng uuunsucucu cececessssssfufuful

ighhht tt septal ablalalatitt onon. LeLeft sepepeptal ablationon was nnneeededed fofoforrr ononlylly onee oof thhee 77 7 ppap tients inn whw om

earliest retrograde atriial activation was recordedd bby the His electrode. Flluoroscopy and d RF times


11

type, and one a slow-slow tachycardia. One patient had been subjected to both right and left

septal ablation. Repeat ablation was performed in 3 patients. In two of them right septal ablation

at the area of the slow pathway was unsuccessful, and a left-sided procedure, as previously

described, was necessary. Three patients refused repeated ablation and were treated with

medication. In the typical group, two patients were lost to follow-up, and recurrence was seen in

2 (1.8%) patients (P=0.167, for the percentages of recurrences in atypical vs typical AVNRT

ablation). No case of AV block was noted during follow-up in either the typical or the atypical

group.

Discussion

Our study represents the largest series of atypical AVNRT cases published. Results indicate that

conventional slow pathway ablation is generally a safe and effective method of ablation for

patients with AVNRT, regardless of the type. No cases of AV block were encountered, and

success and recurrence rates were similar for typical and atypical AVNRT ablation. We did not

find atypical AVNRT to be associated with a significantly higher rate of ablation failure, as

previously reported,5 and no significant difference in recurrence rates was detected between the

two groups, but the modest statistical power achieved in our study does not preclude the

possibility of a type II error. Anatomical slow pathway ablation, as described in our study, can be

accomplished without the need for additional pacing and other manoeuvers,33,34 and offers a safe

therapeutic approach for the management of these patients. In our extensive series, detailed

mapping and/or ablation attempts at the CS os or higher in the septal area were not necessary for

the elimination of this arrhythmia.

These results are in keeping with our previous observations that atypical AVNRT can be

induced by both atrial and ventricular extra-stimulation, and, rarely, may also be induced

Our study represents the largest series of atypical AVNRT cases published. Resulltstss iiindndndicicicatatate e thththat

conventional slow pathway ablation is generally a safe and effective method of ablation for

patients with AVNRT, regardless of the type. No cases of AV block were encountered, and

uccceeess and recucucurrrrenee ceee rrratatatese wwwererere e e sisisimiilalar for tytyt picacal annnd d d atatatypypypiccalall AAAVNVNRTR aaablblblatatatioioionn. WeWeWe dddididid nnnot

finddd aaatypical AVAVAVNRNRT to be aasa sociated wwith a sssiignnifficacaantntntlylyly hhhigiigherr rrate ooff ababablation fffaiailuurre, as

previously reported,d 55 and no signifif cant ddifference ini recurrence rates was detected between theh


12

following an anterograde conduction jump.12,25 The coexistence of both typical and atypical

types in the same patient, as well as the fact that spontaneous conversions from one type to

another may occur, also argue in favor of the concept that atypical and typical AVNRT may

share a common electrophysiological substrate. Although atypical AVNRT of the fast-slow type,

and typical AVNRT do not utilize the same limb for fast pathway conduction, in anatomical

models the arrhythmia circuit utilizes the same “slow” component that is most likely located in

the area of the posterior nodal extensions.35 Indeed, although there is much uncertainty about the

nature of the fast pathway, the evidence supporting the inferior nodal extensions as the anatomic

substrate of the slow pathway is strong.12,25 It was initially proposed that “fast-slow” AVNRT

utilises a posterior extension as the “slow” pathway, while the “fast” component comprised the

fast pathway of the typical form in the opposite direction,35 but this was refuted by subsequent

evidence.25 It seems more likely that all subforms of atypical AVNRT utilize the right and left

inferior extensions as the substrate of both components of their circuit (Figure 7).12 In this

context, both typical and atypical AVNRT, can be ablated by targeting the area of the slow

pathway either from the right or the left side. However, we have not been able to identify any

electrophysiological features that may predict the need for a left septal slow pathway ablation,

either for atypical or typical AVNRT. This is also the case for our patients with recurrences

following an apparently successful procedure.

Study limitations

The main limitation of our study is the low statistical power achieved for comparison of

recurrences in the typical and atypical AVNRT groups. Although we report the largest series of

atypical AVNRT cases, due to the low recurrence rates in the typical and atypical groups, a

larger sample size would be needed to establish equal effectiveness of slow pathway ablation in

utilises a posterior extension as the “slow” pathway, while the “fast” component cocompmpmpriririsesesed dd thththee e

fast pathway of the typical form in the opposite direction,35 but this was refuted by subsequent

evidence.25 It seems more likely that all subforms of atypical AVNRT utilize the right and left

nfeeririior extensisisioono s s s as tthehehe sssubububstststrararatetete ooof boboth commmpoponnentsss ofofof tttheheheir cciirircucuc it ((FiF guguurerere 777).).).12 Innn ttthihihisss

contntnteexe t, both tytytypipp cacal anand atypypypical AVNNRRT, caaan bee aablbllatatatededed bbyy targgeetingg tthee e ara ea of thhee sslow

pathway eithher from thhe right or theh left side. HoH wever, we have not been ablel to identiify any


13

typical and atypical AVNRT. However, even if there is a statistically significant difference, it is

likely of small magnitude and may not be as meaningful from a clinical standpoint, especially

considering the rarity of the recurrences. Second, our results have been derived by high volume

EP laboratories, and very experienced operators. Thus, whether our data can be generalized to

lower volume centers, is not known. Third, this is a retrospective collection of cases performed

by several operators in 7 different centers that participated. Still, all successful ablations were

performed by targeting the anatomic area of the slow pathway either from the right or the left

septum. Finally, a 3-month only follow-up was available for all patients, but in our experience,

AVNRT recurrences are very unlikely after the 3 first months post-ablation.

Conclusions

Atypical AVNRT can be safely and effectively treated by conventional slow pathway ablation.

Detailed mapping during tachycardia for ablation purposes, and targeting the higher septum or

the coronary sinus ostium, do not appear necessary for the ablation therapy of the vast majority

of AVNRT, whether typical or atypical.

Disclosures

None

Conclusions

Atypical AVNRT can be safely and effectively treated by conventional slow pathway ablation.

Detailed mapping during tachycardia for ablation purposes, and targeting the higher septum or

he coooronary sinininusss ooosttiuiuium,m,m ddo o nonot t apappeearar necessssas ryry forr ttthehe aablbb attioion nn ththererapa y y ofof ththhee e vav sttt mmmajaja ororititi y

of AVAVVNRT, wwhehehethheer ttyypicalall oor atypppicaal.


14

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uj wa a , Na a s , a as a S, a su o o , o s , c bo , a a .Visualization of the antegrade fast and slow pathway inputs in patients with slow-w-fafaaststsatrioventricular nodal reentrant tachycardia. Pacing Clin Electrophysiol. 2014;37::8787874-4-838383..21. Kaneko Y, Nakajima T, Irie T, Suzuki F, Ota M, Iijima T, Tamura M, Iizuka T, Tamura S,Saito A, Kurabayashi M. Successful ablation of atypical atrioventricular nodal reentrantachycardia from a noncoronary sinus of Valsalva. Int Heart J. 2014;55:84-6.JJ

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Table 1. Conduction intervals during typical and atypical AVNRT.

Atypical AVNRTn=113

Typical AVNRTn=113

P

CL (ms) 367.0±91.5 365.9±67.5 0.927AH (ms) 134.2±73.6 300.4±69.2 < 0.0001HA (His) (ms) 230.9±78.9 49.5±15.4 < 0.0001HA (pCS) (ms) 226.3±80.4 59.8±16.1 < 0.0001ERAA (His/CS) 7/91* 95/8**

*: no CS measurements in 15 patients, **: no CS measurements in 10 patients.CL: tachycardia cycle length; AH: atrial to His interval during tachycardia; HA (His): His to atrium interval on the His recording electrode; HA (pCS): His to atrium interval on the proximal coronary sinus recording electrode; ERAA: earliest retrograde atrial activation.

Table 2. Ablation characteristics.

Atypical AVNRTn=113

Typical AVNRTn=113

P

Fluoroscopy time (min) 20.112.2 20.8±12.9 0.730RF delivery time (min) 5.9±5.0 5.5±4.5 0.650Junctional rhythm during RF (pts) 110 111 1.000AV block (pts) 0 3 (transient) 0.247

RF: radiofrequency.

Atypical AVNRTn=113

Typical AVNRTn=113

PPP

Fluoroscopy time (min) 20.112.2 20.8±12.9 0.00 7737 00RF delivery time (min) 5.9±5.0 5.5±4.5 0.650Junctional rhythm during RF (pts) 110 111 1.000AV blooockck (((ptptpts) 0 3 (transientnt) 0.247

RF::: rrradiofrequenccyy.


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Figure Legends

Figure 1. Electrograms at the site of successful ablation Electrograms at the site of successful

ablation recorded from the right (left panel) and left (right panel) septal ablation catheters. HRA:

high right atrium; R His: His bundle recorded by the right septal electrode; L His: His bundle

recorded by the left septal electrode; R Abl: electrograms at the successful ablation site recorded

by the right septal ablation catheter; L Abl: electrograms at the successful ablation site recorded

by the left septal ablation catheter; CS: coronary sinus; I, aVF, V1, V6: 12-lead ECG leads.

Figure 2. Slow pathway mapping. Right- and left-sided mapping of the slow pathway in the

RAO and LAO projections. The left-sided ablation electrode has been introduced through a

trans-septal approach in order to map the infero-posterior septum. RAO; right anterior oblique

projection; LAO; left anterior oblique projection; L Abl: left septal ablation catheter; R Abl: right

septal ablation catheter; His: His bundle; CS: coronary sinus; RV: right ventricle; R His: His

bundle recording from the right septum; L His: His bundle recording from the left septum

Figure 3. Induction of atypical AVNRT by ventricular pacing. A few of our atypical cases had

induction by 1 to 2 response from the A, with first A blocking in the lower node and going up a

slow pathway, then down another slow pathway (the two inferior nodal inputs?) to initiate

atypical AVNRT. An alternative explanation might be simultaneous retrograde activation of both

a fast and a slow pathway, with the latter initiating the tachycardia. However, this is rather

unlikely considering the much prolonged VA time for activation of the second A following V

Figure 2. Slow pathway mapping. Right- and left-sided mapping of the slow pathwhwwayayay iiinnn thththe e e

RAO and LAO projections. The left-sided ablation electrode has been introduced through a

rans-septal approach in order to map the infero-posterior septum. RAO; right anterior oblique

projojjececection; LAAAOOO; lllefee t anananteteteririiorrr oooblblbliqiqiqueuu ppror jectioioion;n LL Ablblbl:: leleeftftft seppttatal ll aba lalationnn cccatatathehehetett r; RRR AAAblblbl::: rirr gh

eptpttalala ablation n ccac ththeteer; Hiss:s His bundllee; CS: cccoorononarrry y y sisisinnuss; RVV: righht venenentricle; R R R HHis: His

bundle recording ffrom the right septum; L HiH s: Hisi bundle recordini g from theh left septum


19

pacing compared to the VA time during tachycardia.HRA: high right atrium; His: His bundle;

CS: coronary sinus; RV: right ventricle; I, II, III, V1, V6: 12-lead ECG leads.

Figure 4. Induction of atypical AVNRT by atrial pacing. Induction of atypical, “slow-slow”

AVNRT by atrial pacing (same patient as in Figure 3).

Abbreviations as in Figure 3.

Figure 5. Induction of atypical AVNRT by atrial pacing.

Induction of the “fast-slow” form of atypical AVNRT by atrial pacing.


Figure 6. Induction of atypical AVNRT following anterograde conduction jump. Induction of

atypical AVNRT following an anterograde conduction jump during proximal CS pacing. In the

left panel, a S1S2 of 300 ms produces an AH=240 ms. In the right panel, a S1S2 of 290 ms results

in anterograde conduction jump (AH=300 ms) and induces tachycardia. HRA: high right atrium;

His: His bundle; CS: coronary sinus; RV: right ventricle; I, II, III, V1, V6: 12-lead ECG leads.


Figure 6. Induction of atypical AVNRT following anterograde conduction jump. Induction of

atypppicicical AVNRTRTRT fffoloo looowiwiwingngn aann n anananteteterorr grrada e condndnducttionnn jjjumumump p p duduririingngng pproroxix mamamal l l CSCSCS pppacinini g.g.g. IIIn n n thththe

eftt pppanel, a S111SSS22 ooff 30000 mss ppproduces anan AH=24242 0 mms... InInIn ttthehhe riightt ppaneel,, aa a SSS1S2 of 29292 00 mms ressuults

n anterograded condud ctioi n jump (AHA =3000 ms) andd induces tachyh cardia. HRA:A higi h riight atrium;


20

Figure 7. Proposed circuit of AVNRT. During typical AVNRT (slow-fast), right- or left-sided

circuits may occur with antegrade conduction through the inferior inputs and retrograde

conduction through the superior inputs (S) or the anisotropic atrionodal transitional area (AAT).

In atypical AVNRT conduction occurs anterogradely through one of the inferior inputs, left (LI)

or right (RI) and retrogradely through the other one. Depending on the orientation of the circuit

we may record the so-called fast-slow, slow-slow or inteterminate types.

FO: foramen ovale, CS: coronary sinus, TV: tricuspid valve.

Reproduced from Katritsis DG, Sepahpour A, Marine JE, Katritsis GD, Tanawuttiwat T, Calkins

H, Rowland E, Josephson ME. Atypical atrioventricular nodal reentrant tachycardia: prevalence,

electrophysiologic characteristics, and tachycardia circuit. Europace. 2015;17:1099-106, with

kind permission.

electrophysiologic characteristics, and tachycardia circuit. Europace. 2015;17:1099999-1-1-1060606, , wiwiwiththth

kind permission.

catheter ablation of atypical atrioventricular nodal ... file10.1161/circulationaha.116.024471 2...

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