Prevalence of typical atrial flutter with circuit posterior to the superior vena cava

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Slide 1 : Prevalence of typical atrial flutter with reentry circuit posterior to the superior vena cava Use of entrainment at the atrial roof A variant of typical atrial flutter ? Maury Philippe, MD, Duparc Alexandre, MD Hébrard Aurélien, MD Delay Marc, MD Cardiology, University Hospital Rangueil, Toulouse, France
Slide 2 : ? Electrophysiological studies in man have provided significant evidence suggesting that the mechanism of typical atrial flutter (AF) is based on a large macro-reentry located in the right atrium ? 240 to 340 beats/minute ? predominantly negative saw-tooth waves pattern in the inferiors leads ? counter-clockwise right atrial activation around the tricuspid annulus surrounding a central obstacle formed by the inferior vena cava and still incompletely defined adjacent areas of functional block ? Successful RF ablation of the cavo-tricuspid isthmus (CTI) Ricard P et al., Europace 2002
Slide 3 : ? CTI = lower turn-around of the circuit precise delineation of the upper turn around ? has been somewhat disregarded Historically : empirically believed to be located in front of the SVC ¤ typical counter-clockwise AF with circuits sometimes posterior to the SVC Shah D, et al. Circulation 1997 ¤ “lower loop reentry” involving only the inferior part of the right atrium Cheng J, et al. Circulation 1999 But the real prevalence of such types of circuit variants is unknown
Slide 4 : Aim of the study : to prospectively evaluate the prevalence of patients presenting with counter-clockwise typical AF with common ECG feature who share in fact a more posterior / lower superior turn-around of the reentry circuit using entrainment at the right atrial roof Methods : we prospectively included 50 consecutive patients referred for 1st RF ablation of typical counter-clockwise AF (typical negative saw tooth wave pattern in inferior leads) CTI-dependent AF = successfully cured by CTI RF-ablation - one quadripolar catheter at the low lateral right atrium - one roving RF catheter for entrainment at the CTI and at the atrial roof (AR) CTI-PPI and AR-PPI were determined after transient AF entrainment 10 ms shorter than AF cycle length
Slide 5 : RAO LAO Atrial Roof SVC SVC Atrial Roof appendage This particular location was reached in each patient at 12 o’clock in LAO view after the RF catheter was placed in the superior vena cava, then curved before drawn back till the tip falls in the atrium. The catheter tip was then deflected and pushed against the atrial roof, providing a satisfactory fluoroscopic location in both RAO and LAO views and a good contact attested by stable and tall local electrograms
Slide 6 : Local capture could be achieved in all patients Entrainment never stopped AF or changed AF pattern or cycle length nor induced AFib or atypical AF in any patient Differences between AF cycle length (AFCL) and PPI at the CTI (CTI-PPI) and at the AR (AR-PPI) were then calculated AR was considered to be outside of the circuit when differences between AFCL and AR-PPI > 30 ms (Morton JB et al. JACC 2002) (Triedman JK et al., Circulation 2001) In case of CTI-PPI significantly longer than AFCL (despite AF was CTI-dependent) AR was suspected not to belong to the circuit if AR-PPI was > 10 ms longer than CTI-PPI
Slide 7 : Results : Gender 46 males (92 %) Age 68 ± 9 yo (40 to 83) Underlying heart disease 38 pts (76 %) - ischemic 14 pts - valvular 8 pts - post-hypertensive 3 pts - dilated cardiomyopathy 5 pts - cor pulmonale 3 pts - pericardial disease 2 pts - mixed 3pts Previous cardiac surgery 15 pts (30 %) Preserved LVEF 34 pts (68 %) LVEF (when altered) 0.36 ± 0.11 (0.2 to 0.5) Previous atrial fibrillation 21 pts (42 %) Anti-arrhythmic drug 34 pts (68 %) - acute amiodarone 17 pts - chronic amiodarone 16 pts - sotalol 1 pt
Slide 8 : RF ablation was successful in all patients with termination of AF during RF application at the CTI and achievement of complete bidirectional CTI block in each AFCL 250 ± 29 ms (210 to 325) CTI-PPI – AFCL 9 ± 12 ms (0 to 45) AR-PPI – AFCL 20 ± 23 ms (0 to 90) (p = 0.005) CTI-PPI - AFCL was < 30 ms in 46 pts AR-PPI - AFCL was > 30 ms in 12 pts (26 %) (55 ± 15 ms, 35 to 90). In the latter 4 pts, AR-PPI never exceeded CTI-PPI by > 10 ms 24 % of patients presenting with ECG feature of typical AF present with a “posterior” variant of the reentry circuit Should we have choose a cut-off value of 20 ms (Saoudi N et al., Eur Heart J 2001) the proportion of “posterior” AF would then have been 34 % (17/50)
Slide 9 :
Slide 10 : Correlation between clinical or electro-physiological variables and presentation with common or “posterior” form of typical AF (cut off 30 ms) Common AF (n = 38) Posterior AF (n = 12) p age 68 ± 9 67 ± 7 NS AFCL (ms) 248 ± 28 255 ± 33 NS CTI-PPI – AFCL (ms) 10 ± 12 5 ± 9 NS males 34 (89 %) 12 (100 %) NS preserved LVEF 26 (68 %) 8 (66 %) NS EF (if altered) 0.38 ± 0.11 0.27 ± 0.05 0.07 heart disease 28 (73 %) 10 (83 %) NS Previous cardiac surgery 11 (29 %) 4 (25 %) NS atrial fibrillation 17 (44 %) 4 (33 %) NS anti-arrhythmic drugs 25 (65 %) 9 (75 %) NS chronic amiodarone 11 (29 %) 5 (41 %) NS recurrences 2 (5 %) 0 (0 %) NS AF recurred in 2 patients (4 %) over a mean follow-up of 13 ± 6 months No recurrence after a second procedure
Slide 11 : Table II b : correlations between the type of AF (common versus posterior with cut-off value 20 ms) and clinical and electrophysiological variables. Common AF (n = 33) Posterior AF (n = 17) p age 69 ± 9 66 ± 8 NS AFCL (ms) 251 ± 30 253 ± 34 NS CTI-PPI – AFCL (ms) 11 ± 14 7 ± 9 NS males 30 (90 %) 16 (94 %) NS preserved LVEF 23 (71 %) 10 (59 %) NS EF (if altered) 0.38 ± 0.11 0.33 ± 0.12 NS heart disease 24 (72 %) 14 (82 %) NS atrial fibrillation 13 (39 %) 7 (41 %) NS cardiac surgery 10 (30 %) 5 (29 %) NS anti-arrhythmic drugs 21 (63 %) 12 (70 %) NS chronic amiodarone 10 (30 %) 5 (29 %) NS recurrence 2 (6 %) 0 (0 %) NS
Slide 12 : Specific features of the « posterior » form of typical AF ? Descending atrial activation at the low lateral right atrium in all cases Terminal positive deflection in inferior leads was lacking in 4 cases diphasic +/- pattern was present in 5 cases in V1
Slide 13 : Discussion activation was described to propagate along the Bachmann bundle from the high septum to the right atrial roof before descending along the sulcus terminalis (Puech P, et al. Arch mal Coeur 1970) multiple intra-cardiac recordings : activation was shown to cross in front of the SVC (Chauvin M, et al. Arch mal Coeur 1982) constant regular counterclockwise activation displayed by duodecapolar circular catheter when placed along the anterosuperior portion of the atrium adjacent to the tricuspid ring (Poty H, et al., Circulation 1996 ) historically … However no entrainment was performed in those studies
Slide 14 : Using tridimensional activation mapping … in 14/17 patients with typical counter-clockwise AF activation front crossed the anterior root of the SVC fusing around the SVC in 3 cases (17 %) with a posterior propagation slightly earlier than that of the anterior limb (Shah D, et al. Circulation 1997) (Shah D, et al. Circulation 1997)
Slide 15 : in 7/7 patients with counter-clockwise AF the activation wavefront was shown to propagate both anterior and posterior to the SVC before fusing and proceeding down the anterior right atrial wall (Rodriguez LM, et al. Circulation 2001) However no entrainment was performed in those studies (Rodriguez LM, et al. Circulation 2001)
Slide 16 : Using entrainment in 13 pts, exacts PPI from sites close to the tricuspid annulus anterior to the SVC (Kalman JM ,et al. Circulation 1996) in 13 patients entrainment from the high posterior right atrium did not change activation sequence between high septum, AR and the high antero-lateral wall - AF occurs consistently cranial to the SVC - complete and constant postero-lateral line of block between both VC (Arribas F,et al. PACE 1997)
Slide 17 : Posterior by-passing the AR by transverse activation across the crista terminalis : medial to lateral conduction in 85 % of patients with typical AF by pacing from the postero-inferior right inter-atrial wall (Anselme F, et al. JCE 2004) - trans-crista conduction in the great majority of patients when rapidly paced from the posterior wall (Arenal A, et al. Circulation 1999) - after complete bidirectional CTI block by RF ablation in patients with typical AF medio-lateral transverse crista terminalis conduction in 58 % during CS pacing (Yang Y, et al. PACE 2005) - earliest breakthrough along the anterior tricuspid annulus happen in two third of patients in the low lateral part during CS pacing and in a more superior area in the remaining case or were multiple in a few cases (Yang Y, et al. PACE 2005)
Slide 18 : The “lower loop reentry “ in 6/28 (22 %) patients with typical counter-clockwise AF, spontaneous or induced faster AF with early breakthrough at the lower lateral right atrium and with collision of counter-clockwise and clockwise activations occurring at a more higher level on the lateral wall However LLR short lasting and self limited (Cheng J, et al. Circulation 1999) Counter-clockwise LLR with variable (and sometimes high) wavefront breaks have been retrospectively found in 19 of 372 consecutive patients (5 %) referred for RF ablation of unselected right AF Stables, spontaneous and sustained (Bochoeyer A, et al. Circulation 2003) (Yang Y, et al. Circulation 2001)
Slide 19 : Clinical implications: Ablation at the AR would represent an optional solution when abnormalities prevent access to the CTI from the IVC - occluded IVC - occluded vena cava filter - complete azygos continuation Usefulness of this solution is however questionable in view of our results because of the existence of by-passing of the AR and of probable conduction across the crista terminalis in a significant proportion of cases Furthermore, linear ablation at the AR with complete local conduction block would reveal or leave a posterior loop alone
Slide 20 : LIMITATIONS OF THE STUDY † No analysis of further entrainment criteria has been made † No entrainment was performed at the high posterior wall just above the posterior aspect of the SVC opening † bystander posterior wave front or double loop can not be excluded when AR PPI is short † Multipolar electrode catheter were not used : activation at the high lateral right atrium could not be determined † Reverse-typical clockwise AF were not included † angiographic delineation of the AR was not performed † Pacing at high output could have captured distant areas closer to the circuit † Half of our patients were on amiodarone at the time of the procedure Amiodarone has been shown to increase PPI in the circuit (Fatemi M et al., JCE 2005) but would have increase PPI both at the AR and CTI † 17 patients with an atrial rate > 260 ms have been included, most of them were under amiodarone This could have introduced a referral bias however patients in this study were consecutively and prospectively included Furthermore, there was no significant difference in the proportion of posterior form of AF whether or not chronic amiodarone had been prescribed
Slide 21 : Conclusions PPI measured at the atrial roof were longer than AF cycle length (or longer than CTI PPI when prolonged PPI at the CTI) in 24 to 36 % of patients referred for RF ablation of typical counter-clockwise AF In around a quarter to a third of patients presenting with ECG feature of typical AF the atrial roof is not part of the circuit Those patients present with a “posterior” variant of the reentry circuit Precise location of the posterior by-pass deserves further studies

 


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