Signal-Averaged P Wave in Patients With Wolff-Parkinson-White Syndrome After Successful Radiofrequency Catheter Ablation

Transcription

1 1310 JACC Vol. 26, No. 5 Sgnal-Averaged P Wave n Patents Wth Wolff-Parknson-Whte Syndrome After Successful Radofrequency Catheter Ablaton IVAN G. MAIA, MD, FERNANDO E. S. CRUZ FILHO, MD, MARCIO L. A. FAGUNDES, MD, SILVIA H. BOGHOSSIAN, MD, LUTGARDE VANHEUSDEN, RN, ROBERTO M. SA, MD, PAULO Ro de Janero, Brazl A. G. ALVES, MD Objectves. We attempted to establsh a relaton between the atral conducton tme assessed by the sgnal-averaged P wave electrocardogram and epsodes of paroxysmal atral fbrllaton n patents wth the Wolff.Parknson-Whte syndrome. Background. The ncdence of paroxysmal atral fbrllaton s hgher n patents wth the Wofl'-Parknson-Whte syndrome than n normal persons. However, the role of ntraatral conducton delay n precptatng the dsorganzaton of atral rhythm s not completely understood. Methods. The total duraton of the sgnal-averaged P wave and the P wave n standard lead II was evaluated after successful radofrequency catheter ablaton n 28 patents wth the Wolff- Parknson-Whte syndrome. The data obtaned from 17 patents (61%) wth a documented hstory of pror paroxysmal atral fbrllaton (group 1) were compared wth those obtaned from 11 patents (39%) wthout a hstory of atral fbrllaton (group 2). Both groups were further compared wth a normal control populaton. Results. The mean -+ SD sgnal-averaged P wave duraton n group 1 was ms (range to 171.0). Fourteen patents (82%) n ths group showed a P wave duraton > ms. In group 2, the sgnal-averaged P wave duraton was _ ms (range to 136.0). Only one patent n ths group (9%) showed a P wave duraton > ms (p < 0.000, group 1 vs. group 2). The sgnal-averaged P wave duraton n the control group was _ ms (range to 129.5; p < 0.000, group 1 vs. the control group; p < 0.454, group 2 vs. the control group). The P wave duraton n lead II was _ ms n group 1 and 9227, ms n group 2 (p < 0.949). Usng a cutoff value of < ms for a normal sgnal-averaged P wave duraton, the method had a senstvty and specfcty and postve and negatve predctve values of 82%, 91%, 93% and 77%, respectvely, for dentfyng patents wth clncal paroxysmal atral fbrllaton. Conclusons. In the current study, the sgnal-averaged P wave showed a prolonged ntraatral conducton tme n patents wth the Wolff-Parknson-Whte syndrome and paroxysmal atral fbrllaton. These patents can be dfferentated from those wth the pre-exctaton syndrome wthout clncal atral fbrllaton as well as from normal subjects. The prolonged ntraatral conducton tme may serve as an atral substratum for development and mantenance of the fbrllatory state. (J Am CoU Cardo11995;26:1310-4) Patents wth the Wolff-Parknson-Whte syndrome have a hgher ncdence of spontaneous paroxysmal atral fbrllaton than that of normal persons (1). If the propertes of the accessory pathway allow rapd conducton, paroxysmal atral fbrllaton can be a potentally lfe-threatenng arrhythma (2). Recent work has demonstrated the clncal utlty of the sgnal-averaged P wave electrocardogram (ECG) n studyng atral actvaton conducton tmes. These studes (3,4) reported that a prolonged sgnal-averaged P wave duraton s assocated wth hgh senstvty and specfcty for dentfyng patents at rsk for the development of paroxysmal atral fbrllaton. However, ablty to obtan the sgnal-averaged P wave duraton n patents wth the Wolff-Parknson-Whte syndrome s lm- From the Hosptal Pr6-Cardaco and Hosptal de Cardologa de Laranjeras. Ro de Janero, Brazl. Manuscrpt receved February. I. 1995; revsed manuscrpt receved June , accepted June 7, Address for correspondence: Dr. Ivan G. Maa. Rua Raul Kennedy 81. Ro de Janero Brazl CEP (I. ted by the presence of the delta wave. When ventrcular pre-exctaton exsts, the delta wave can conceal the end of the P wave, affectng the correct determnaton of P wave duraton. Ths problem does not occur after successful radofrequency ablaton of the anomalous pathway or durng normal conducton n cases of ntermttent pre-exctaton. In these two stuatons, the dsappearance of the delta wave allows a precse assessment of P wave duraton. The purpose of ths study was to evaluate, usng the sgnal-averaged P wave ECG, the ntraatral conducton tme of patents wth the pre-exctaton syndrome who had prevously undergone successful radofrequency catheter ablaton. We compared the fndngs n patents wth and wthout documented epsodes of paroxysmal atral fbrllaton and n a control group of normal subjects. Methods Patent selecton. We prospectvely analyzed the sgnalaveraged P wave ECG of 28 consecutve patents wth the 1995 by the Amercan College of Cardt~logy /95/$ (95)00317-W

2 JACC Vol. 26, No. 5 MAIA ET AL SIGNAL-AVERAGED P WAVE IN WOLFF-PARKINSON-WHITE SYNDROME Table 1. Indvdual Patent Data P Wave Duraton (ms) yv~/~ ~ m ~ A J L.L_L_LL_L~ Pt. Age (yr)/ AP Arrhy Sgnal- No. Gender Ste Type Averaged Lead I1 1" 22/M R RT, PAF * 58/M R RT, PAF /M R RT /M L RT, PAF /M L RT, PAF /M L RT /F L RT /F R RT I/F L RT ll 1.0 9(} /M L RT, PAF /M L RT /F L RT /M L RT, PAF /F L RT /M L RT, PAF /q 7 R RT /M L RT, PAF /'1:: R RT /F L RT, PAF /M L RT, PAF /I= R RT, PAF /M R RT, PAF /M L RT, PAF /F L RT /M L RT, PAF /M L RT, PAF /M L RT, PAF /M L RT, PAF *Recurrent paroxysmal atral fbrllaton (PAF). AP = anomalous pathway; Arrhy - paroxysmal supraventrcular tachycarda: F = female; L = left; M = male; Pt - patent; R = rght; RT - atroventrcular recprocatng tachycarda. Wolff-Parknson-Whte syndrome, wth a fxed degree of ventrcular pre-exctaton, who underwent radofrequency ablaton. There were 18 men and 10 women wth a mean age _+ SD of 34.6 _ years; 20 patents had a left-sded and 8 had a rght-sded accessory pathway. Group 1 comprsed 17 patents (61%; 15 men, 2 women; mean age years) wth prevous documented epsodes of paroxysmal atral fbrllaton. In ths group, 13 patents had a left-sded anomalous pathway. Group 2 comprsed 11 patents (39%; 8 women, 3 men; mean age years) wthout clncal atral fbrllaton; 7 of these 11 patents had a left-sded accessory pathway. The results n these two groups were compared wth the results obtaned n an age-matched normal control group of 12 patents (7 women, 5 men; mean age 33.1 _ years). To preclude left atral enlargement, we excluded from the study patents wth any of the followng condtons: 1) congestve heart falure, 2) systemc hypertenson (blood pressure ->160/90 mm Hg), 3) prevous myocardal nfarcton, 4) congental heart dsease, 5) cardomyopathy, 6) systemc dseases. All patents who met these entry crtera had a left atral sze <4.0 cm by echocardography and were wthdrawn from all II ","v~'~-~ ~. ~,'~, ~ ' ~ ' v ' ~ ~ n ~ I I!,,, v.r~r,--,,,'.-~.~.-.-.v~- L~L.J~" Fgure I. Demonstraton of anomalous pathway ablaton durng atra] fbrllaton. Despte successful ablaton, the atral tachyarrhythma perssts. RF... ndcates the applcaton of radofrequency energy. antarrhythmc medcatons at least 5 half-lves before the ablaton and the sgnal-averaged procedures. Indvdual data are shown n Table 1. Accessory pathway ablaton. Radofrequency catheter ablaton protocols were approved by the Scentfc Board of our nsttutons. Wrtten nformed consent was obtaned from all patents. For left-sded anomalous pathways, the procedure was performed by usng the retrograde arteral approach, wth the catheter postoned on the ventrcular sde of the mtral annulus. Energy was delvered at stes that recorded the shortest atroventrcular (AV) tmes. The predctor of success was the nterval between the onset of the local ventrcular electrogram and the onset of the delta wave n the surface ECG, wth or wthout anomalous pathway potentals, recorded n at least fve smlar pre-excted beats. For rght-sded accesso W pathways, a transvenous femoral approach was used and ablaton was performed at the atral aspect of the trcuspd annulus. In fve patents the ablaton was performed durng paroxysmal atral fbrllaton (5) wthout nterrupton of the atral tachyarrhythma (Fg. 1). Successful ablaton was acheved n all 28 patents studed wth the averaged P wave method. The data from the ablaton procedures n groups 1 and 2 were compared. Standard ECG methodology. For each patent, a standard 12-lead ECG was recorded mmedately before the sgnalaveraged P wave. The records were obtaned at a paper speed of 25 mm/s and a sgnal sze of 10 mm/mv. The total P wave duraton was manually measured n lead II. Sgnal-averaged methodology. The sgnal-averaged P wave was recorded accordng to the method proposed by Gudera and Stenberg (3) usng the Predctor II system from Corazonx Corporaton. The recordngs were performed between the 7th and the 14th day after the ablaton procedure to allow atral functonal recovery tme after paroxysmal atral fbrllaton and cardoverson (6). An orthogonal lead system dentcal to that used n ventrcular sgnal-averaged ECGs was used (7). The QRS complex was used as the trgger of the sgnal-averagng process. To expose the P wave, the fducal pont was shfted to the rght at a 450-ms wndow. The sgnal was dgtzed at a frequency of 2,000 samples/s wth 16-bt accuracy. A snus P wave template was manually selected, wth a correlaton coef-

3 1312 MAIA ET AL. JACC Vol. 26, No. 5 SIGNAL-AVERAGED P WAVE IN WOLFF-PARKINSON-WHITE SYNDROME L2 - Ildere AbkNom I.,2 - After A~;~,~ ]Scale:uv 20.0 I - ~. 1~o.oo Comtre4 Groap 5o oo.v WPW Syndrome wkdkoet - Paroxysmal Atral Fbrllaton I---- 4s.oo! A ' 8 I j r 4o.oo t p-wave []mrotm,: I IdL0 ms ~.0o! 3s.oo I0.00 ',,!0.00! ' fl, : ~ 218,o.oo~, l :, ',:' I,], 5.00 "~; l" :1 I ~s.oo 50.ooj I ZS.0O P-Wave Dmnttkm: ms '~, ', [ z0.oo~ f, ] uv WPW Syldrome Wth so. 1 Paroxysmal Atral Fbrllaton - F 45.~- C ~.oo P-Wave Drotkm: ms 25,00 I ! 1 t IB go ' go Fgure 2. Examples of the sgnal-averaged P wave n the control group (A) and n patents wth the Wolff-Parknson-Whte (WPW) syndrome wthout and wth paroxysmal atral fbrllaton (B and C, respectvely). The upper panel shows the correspondng P wave n lead II (L2) before and after catheter ablaton. fcent of 99%. The correlaton wndow wdth was 25 ms, wth <0.3-~V nose at the end of the procedure. To mprove the vsualzaton of the low ampltude components of the atral actvaton, a least square ft flter wth a wndow wdth of 100 ms was appled to the averaged output. P wave onset and offset were determned manually as the frst atral deflecton from the baselne nose level and the return of the atral sgnal to the baselne level, respectvely. The X, Y and Z fltered leads were combned nto a P vector magntude. The total P wave duraton, n ms, was manually determned from the P vector magntude. Sgnal-averaged P wave analyss. The sgnal-averaged P waves were prospectvely analyzed n blnded fashon; two dfferent physcans revewed the data wthout knowledge of prevous clncal paroxysmal atral fbrllaton. Follow-up. All patents were carefully followed up durng outpatent clnc vsts, when symptoms that mght ndcate atral fbrllaton recurrence were nvestgated. Long-term ablaton success was consdered acheved f no evdence of recurrences of the clncal arrhythma or a return of preexctaton were dagnosed. Statstcal analyss. Data arc presented as mean value _+ 1 SD. One-way analyss of varance was used for group comparsons. Sgnfcance refers to a value of p < The P wave duraton from the vector magntude was used to determne the senstvty, specfcty, and postve and negatve predctve values of the sgnal-averaged P wave for dentfyng patents wth clncal paroxysmal atral fbrllaton. Results Baselne clncal data and radofrequency ablaton characterstcs. The groups wth (group 1) and wthout (group 2) clncal atral fbrllaton dd not dffer n age, ste of accessory pathway, number of radofrequency applcatons requred (4.45 _ vs , p < 0.330) or total delvered energy ( _ vs W, respectvely, p < 0.235). P wave duraton n standard lead II. P wave duraton n lead li ranged from 85.0 to ms (mean ) n group 1 and from 80.0 to 100 ms (mean _+ 7.86) n group 2 (p < 0.949). Three patents n group 1 (Cases 1, 25 and 28) and one patent n group 2 (Case 24) showed notched P waves. Sgnal-averaged P wave analyss. P wave duraton n group 1 ranged from to ms (mean 14t.94 _+ 9.47); 14 patents (82%) n ths group had values >135.0 ms. P wave duraton n group 2 ranged from 1tl.0 to ms (mean _+ 8.72), only one patent (9%) had a value >135.0 ms. In the control group, P wave duraton ranged from to ms (mean _ 4.49). Examples of the sgnalaveraged P wave are shown n Fgure 2 and the results are expressed graphcally n Fgure 3. The P wave duraton comparsons between groups 1 and 2 reached statstcal sgnfcance (p < 0.000) as dd the comparsons between group 1 and the control group (p < 0.000). There were no statstcal dfferences between group 2 and the control group (p < 0.454). To assess the consequences of radofrequency applcaton over the atral tssue, we examned the results of the sgnalaveraged P wave duraton consderng only the 20 patents wth a left-sded anomalous connecton who underwent energy delvery, on the ventrcular sde of the mtral annulus. Among patents wth a left-sded connecton n group 1, P wave duraton ranged from to ms (mean _ 5.12);

4 JACC Vol. 26, No. 5 MAIA ET AL SIGNAL-AVERAGED P WAVE IN WOLFF-PARKINSON-WHITE SYNDROME Fgure 3. Sgnal-averaged P wave duraton n the three study groups. A normal P wave duraton was consdered to be <135.0 ms. Group 1 = 17 patents wth the Wolff-Parknson-Whte syndrome wth paroxysmal atral fbrllaton; Group 2 = 11 patents wth the Wolff-Parknson-Whte syndrome wthout paroxysmal atral fbrllaton; Control = 12 patents wthout the Wolff-Parknson-Whte syndrome ~AVE DUR~:rlON (ms) f $! GROUP 1 GROUP 2 CONTROL among those n group 2, t ranged from to ms (mean _+ 8.73) (p < 0.002). Wth a cutoff value for normal P wave duraton of <135.0 ms, the senstvty, specfcty and postve and negatve predctve values of the method were 82%, 91%, 93% and 77% respectvely, for dentfyng patents wth clncal paroxysmal atral fbrllaton. P wave n lead II and sgnal-averaged P wave. In all patents, P wave duraton after sgnal averagng was sgnfcantly longer than P wave duraton measured n standard lead II. In group 1, the ncrease n P wave duraton ranged from 43.5 to 62.0 ms (mean _+ 5.82). In group 2, t ranged from 21.0 to 42.0 ms (mean ) (p < 0.000). In the control group, t ranged from 25.0 to 42.0 ms (mean ) (p < 0.000, group 1 versus control group; p < 0.567, group 2 versus control group). Follow-up. After a mean follow-up nterval of 8 months (range 2 to 18), three patents (18%) from group 1 had documented recurrent paroxysmal atral fbrllaton; the respectve P wave duraton n these patents was 150.5, and ms (Table 1). There were no arrhythma recurrences n group 2. Dscusson The clncal ncdence rate of paroxysmal atral fbrllaton n patents wth Wolff-Parknson-Whte syndrome has been reported (1) to range from 12% to 32%. However, the reasons for ths hgh rate are not clear. It has been suggested (8) that the assocaton of mechancal factors such as atral stretch, hypoxema and AV recprocatng tachycarda may be precptatng factors. Other studes (9,10) have suggested that fast retrograde conducton over an anomalous pathway or the presence of atral premature beats durng orthodromc recprocatng tachycarda may be precptatng factors for the development of acute epsodes of atral fbrllaton. These two stuatons could nduce atral actvaton durng ncomplete recovery of the atral tssue, leadng to the ntaton of ntraatral reentry, and subsequent atral fbrllaton. The de- creased ncdence of paroxysmal atral fbrllaton reported after surgcal (11) or catheter (12) elmnaton of the accessory pathway conducton suggests partcpaton of such conducton n the geness of ths atral tachyarrbythma. All these fndngs support the hypothess that the anomalous pathway medated the epsodes of atral fbrllaton. However, after successful elmnaton of the anomalous connecton, some patents may stll have spontaneous sustaned epsodes of atral fbrllaton wth no evdence of accessory pathway conducton, even after adenosne nfuson. In the present study, the ncdence of recurrent paroxysmal atral fbrllaton after radofrequency ablaton was 17.6%, a fact suggestng that the accessory pathway s not always the man cause of atral fbrllaton. Furthermore, as observed n our patents, successful ablaton of the accessory pathway, performed durng paroxysmal atral fbrllaton, does not result n termnaton of the fbrllatory epsodes (Fg. 1), even after 60 ran of the procedure. Thus, the anomalous pathway s probably responsble for ntaton of the acute epsodes of atral fbrllaton but not for ther mantenance. Intraatral conducton dsturbances have been demonstrated (9) n patents wth the Wolff-Parknson-Whte syndrome and paroxysmal atral fbrllaton assessed by electrophysologc studes. Some patents wth ventrcular preexctaton exhbt ECG P wave morphologc dsturbances, and the causes of such alteratons have been extensvely dscussed (13). In several patents, the P waves are dstnctly notched, suggestng the presence of ntraatral conducton dsturbances. Thus, as prevously dscussed, t s very possble that the anomalous pathway plays a role n the ntaton of atral fbrllaton by rapd retrograde conducton of the electrcal mpulse durng AV recprocatng tachycarda so that t reaches the atra durng the vulnerable perod. However, not only the presence of the anomalous connecton tself but the assocated delayed conducton n the atral tssue could facltate and perpetuate reentry (10). The delayed ntraatral conducton tme represents an mportant factor precptatng acute epsodes of atral fbrllaton (14). It has been demonstrated (15) that the nducblty of

5 1314 MAIA ET AL. JACC Vol. 26, No. 5 SIGNAL-AVERAGED P WAVE IN WOLFF-PARKINSON-WHITE SYNDROME atral fbrllaton before and after radofrequency ablaton of the anomalous pathway s ndependent of the presence of the accessory connecton and smlar to that n the general populaton. Thus, supportng the results obtaned from electrophysologc studes (10), our data strongly suggest the presence of delayed atral actvaton n patents wth the Wolff- Parknson-Whte syndrome and paroxysmal atral fbrllaton. Usng a more senstve technque to study atral actvaton tme, we observed a hgher ncdence of conducton delay n these patents. In addton, no patent had an enlarged left atrum as assessed by echocardography. Thus, t s nterestng to speculate that, from the same anatomc substratum (conducton delay), the epsodes of atral fbrllaton would be more frequent n patents wth the Wolff-Parknson-Whte syndrome than n the general populaton because the presence of the accessory pathway tself could facltate ntaton of the fbrllatory state. The conducton delay n the atral tssue would further allow perpetuaton of atral reentry and the fbrllatory mechansms. Ths hypothess s supported by the greater ncrease n P wave duraton seen n patents n group I than n group 2 when the sgnal-averaged P wave and the P wave n lead II were compared (50.15 ± 5.88 vs ± 5.35 ms, p < 0.000). These fndngs suggest that n patents wth paroxysmal atral fbrllaton, the mparment n atral conducton s hghlghted by the low ampltude sgnals that are detected by the averagng process. Lmtatons of the study. One could argue the consequences of radofrequency applcaton at the AV groove and ts possble mplcatons for the results observed here. However, the majorty of patents had a left-sded connecton and consequently the energy was delvered at the ventrcular nserton of the pathway, durng a retrograde aortc approach. Radofrequeney lesons are small (4 to 5 ram, dependng on the tp of the catheter used durng the procedure) (16) and could not nterfere wth P wave duraton. Indeed, all patents enrolled n ths study underwent a Doppler echocardographc study before and after the ablaton n whch no valvular nsutfcency was dagnosed. In addton, the results obtaned when we analyzed only patents wth a left-sded anomalous pathway were almost the same as those observed n the total group, and there were no correlatons n ether group between P wave duraton and the number of radofrequency applcatons or the amount of energy delvered. Clncal mplcatons. To date, wth clncal paroxysmal atral fbrllaton has developed n 3 of 17 patents after ablaton; all 3 patents had a P wave duraton > ms, thus reflectng the accuracy of the sgnal-averaged P wave method for detectng patents lkely to have ths type of atral arrhyth- ma. Unfortunately, the method has lmted clncal applcaton, because the delta wave overshadows the correct measurement of P wave duraton. However, as a nonnvasve procedure, t can contrbute to the understandng of the complex mechansms nvolved n the geness of paroxysmal atral fbrllaton. References 1. Campbell RWF, Smth RA, Gallagher J J, Prchett EL, Wallace AG. Atral fbrllaton n the preexctaton syndrome. Am J Cardol 1977;40: Montoya PT, Brugada P, Smeets J, et al. Ventrcular fbrllaton n the Wolff-Parknson-Whte syndrome. Eur Heart J 1991;12: Gudera SA, Stenberg JS. The sgnal-averaged P wave duraton: a rapd and nonnvasve marker of rsk of atral fbrllaton. J Am Col Cardol 1993;21: l. 4. Stenberg JS, Zelenkofske S, Wong S-C, et al. Value of the P-wave sgnal-averaged ECG for predctng atral fbrllaton after cardac surgery. Crculaton 1993;88: Cruz Flho FES, Fagundes MLA, Boghossan S, et al. lmportfnca clnca da ndca~'ao precoce da terap6utca ablatva em pacentes corn sndromc de Wolff-Parknson-Whte e fbrlaq~to atral, corn ou sem parada cardoresprat6ra. Rev Soc Cardol Ro de Janero 1994;7: Mannng WJ, Slverman DI, Katz SE, et al. Impared left atral mechancal functon after cardoverson: relaton to the duraton of atral fbrllaton. J Am Col Cardol 1994;23: Brethardt G. Can ME, EI-Sherf N, et al. Standards for analyss of ventrcular late potentals usng hgh-resoluton or sgnal-averaged electrocardography: a statement by a task force commttee of European Socety of Cardology, the Amercan Heart Assocaton and the Amercan College of Cardology. J Am Col Cardol 1991;17: Mclntosh HD, Kong Y, Morrs JJ. Hemodynamc effects of supraventrcular arrhythmas. Am J Med 1964;37: Garca-Coso F, Benson DW, Anderson RF, et al. Onset of atral fbrllaton durng antdrome tachycarda. Assocaton wth sudden cardac arrest and ventrcular fbrllaton n a patent wth Wolff-Parknson-Whte syndrome. Am J Cardol 1982;50: Fujmura O, Klen GJ, Yee R, Sharma AD. Mode of onset of atral fbrllaton n the Wolff-Parknson-Whte syndrome: how mportant s the accessory pathway? J Am Col Cardol 1990;15: Sharma A, Klen G, Guraudon G, ctal. Atral fbrllaton n patents wth Wolff-Parknson-Whte syndrome: ncdence after surgcal ablaton of the accessory pathway. Crculaton 1985;72: Hassaguerre M, Fscher M, Labbe T, et al. Frequency of recurrent atral fbrllaton after catheter ablaton of overt accessory pathways. Am J Cardol 1991 ;69: Sherf L. Neufcld HN. The Pre-exctaton Syndrome: Facts and Theores. New York: Yorke Medcal Books, 1978: Coso FG, Palacos J, Vdal JM, et al. Electrophysology studes n atral fbrllaton. Slow conducton of premature mpulses: a possble manfestaton of the background for reentry. Am 1 Cardol 1983;51: Kalbflesch S J, El-Atass R, Calkns H, et al. Inducblty of atral fbrllaton before and after radofrequency catheter ablaton of accessory atroventrcular connectons. J Cardovasc Electrophysol 1993;4: Hanes DE. The bophyscs and pathophysology of leson formaton durng radofrequency catheter ablaton. In Zpes DP, Jalfe J, edtor. Cardac Electrophysology. From Cell to Bedsde. Phladelpha: Saunders, 1995: