Clinical impact of defibrillation testing at the time of implantable cardioverter-defibrillator insertion

Clinical impac o de ib illa ion es ing a he ime o implan able ca dio e e -de ib illa o inse ion Claudio Hadid1, Felipe A ienza1, Bo is S asbe g2, Ángel A enal1, Pablo Codne 2, Es eban González-To ecilla1, Tomás Da ino1, Tama a Pe cal1, Jesús Almend al1, Me cedes O iz1, Raphael Ma ins3, Nie es Ma inez-Alzamo a4, F ancisco Fe nandez A iles1 1Hospi al Gene al Uni e si a io G ego io Ma añón, Mad id, Spain 2Rabin Medical Cen e , Tel A i Uni e si y, Tel A i , Is ael 3CHU Nancy, F ance 4Uni e sidad Poli écnica de Valencia, Valencia, Spain Abs ac Backg ound: Ven icula ib illa ion is ou inely induced du ing implan able ca dio e e - -de ib illa o inse ion o assess de ib illa o pe o mance, bu his s a egy is expe iencing a p og essi e decline. We aimed o assess he e icacy o de ib illa o he apies and long- e m ou come in a coho o pa ien s ha unde wen de ib illa o implan a ion wi h and wi hou de ib illa ion es ing. Me hods: Re ospec i e obse a ional se ies o consecu i e pa ien s unde going ini ial de i- b illa o inse ion o gene a o eplacemen . We egis e ed spon aneous en icula a hy h- mias incidence and he apy e icacy, and mo ali y. Resul s: A o al o 545 pa ien s unde wen de ib illa o implan a ion (111 wi h and 434 wi hou de ib illa ion es ing). A e 19 ( ange 9–31) mon hs o ollow-up, he dea h a e pe obse a ion yea (4% s. 4%; p = 0.91) and he a e o pa ien s wi h de ib illa o - ea ed en- icula a hy hmic e en s pe obse a ion yea (wi h es : 10% s. wi hou es : 12%; p = 0.46) we e simila . The gene alized es ima ing equa ions-adjus ed i s shock p obabili y o success in pa ien s wi h es (95%; CI 88–100%) s. wi hou es (98%; CI 96–100%; p = 0.42) and he p opo ion o success ul an i achyca dia he apies (wi h es : 87% s. wi hou es : 80%; p = 0.35) we e simila be ween g oups. The e was no di e ence in he annualized a e o ailed i s shock pe pa ien and pe shocked pa ien be ween g oups (5% s. 4%; p = 0.94). Conclusions: In his obse a ional s udy, ha included an unselec ed popula ion o pa ien s wi h a de ib illa o , no di e ence was ound in o e all mo ali y, i s shock e icacy and a e o ailed shocks ega dless o whe he de ib illa ion es ing was pe o med o no . (Ca diol J 2015; 22, 3: 253–259) Key wo ds: implan able ca dio e e -de ib illa o , de ib illa ion es ing, en icula ib illa ion, de ib illa o shocks, mo ali y 253 www.ca diologyjou nal.o g ORIGINAL ARTICLE Ca diology Jou nal 2015, Vol. 22, No. 3, 253–259 DOI: 10.5603/CJ.a2014.0062 Copy igh © 2015 Via Medica ISSN 1897–5593 Add ess o co espondence: Felipe A ienza, MD, PhD, Ca diology Depa men , Hospi al Gene al Uni e si a io G ego io Ma añón, C/D Esque do, 46, 28007 Mad id, Spain, el: +34915868281, e-mail: [email p o ec ed] Recei ed: 17.07.2014 Accep ed: 21.07.2014 In oduc ion The assessmen o de ib illa ion e icacy has long been he s anda d o ca e du ing implan able ca dio e e -de ib illa o (ICD) inse ion, and is ecommended by ICDs manu ac u e s and scien- i ic guidelines [1, 2]. Howe e , his s a egy is cu en ly being ques ioned due o he high p ob- abili y o cu en de ices o success ully de ib il- la e en icula a hy hmias, he low incidence o spon aneous en icula ib illa ion (VF) (~10%) and he high e icacy o dedica ed an i achyca dia pacing (ATP) s a egies [2–8]. Mo eo e , de ib illa- ion es ing (DT) is no wi hou a isk, and compli- ca ions associa ed o VF induc ion, shock deli e y and anes hesia may occu [2, 3, 9–12]. Fo all hese easons, he p opo ion o pa ien s unde going any ype o DT, especially among p ima y p e en ion ICD implan a ion, is expe iencing a p og essi e decline in ou ine clinical p ac ice [12–15]. The p ospec i e, non- andomized SAFE-ICD s udy se- lec ed cen e s acco ding o hei common p ac ice o pe o ming o no pe o ming DT a implan a ion and ound no di e en ou come be ween g oups [8]. Howe e , ha s udy only included de-no o implan s and did no epo da a on ATP he apy. The pu pose o he p esen s udy was o as- sess he e icacy o ICD he apies (bo h shocks and ATP) and long- e m clinical ou come in a coho o consecu i e pa ien s, including de-no o implan s and gene a o eplacemen s, ha unde wen ICD implan a ion wi h (+) and wi hou (–) DT a he ime o ICD inse ion. Me hods We e ospec i ely e iewed he eco ds o a se ies o consecu i e pa ien s > 18 yea s old, in whom an ICD had been implan ed in wo e ia y-ca e eaching hospi als (Hospi al Gene al Uni e si a io G ego io Ma añón and Rabin Medical Cen e ) du ing a pe iod o 3 yea s, ollowing he implemen a ion o a non-DT policy a ou ins i u- ions. DT was ecommended in igh pec o al ICD implan a ion, R wa e signal < 5 mV o no able o be measu ed due o pacing, abandoned leads, implan ed elec onic de ices, ch onic ea men wi h amioda one and pa ien s wi h hype ophic ca diomyopa hy o channelopa hies. Howe e , he inal decision o es was le a he disc e ion o he ope a o . In case any ype o DT was conside ed necessa y de ib illa ion sa e y ma gin es ima ion was ou inely pe o med [16]. In he DT+ g oup, VF was induced by s anda d T-wa e shock o a 50-Hz bu s . A p o ocol o 2 de ib illa ions a 10 J below he maximum ou pu o he de ice was applied wi h a 5-min es pe iod be ween VF in- duc ions. I he i s shock ailed, bu he second was success ul, he pa ien was also conside ed o ha e adequa e DT. I he de ib illa ion a emp was unsuccess ul ce ain s a egies we e adop ed o o e come his si ua ion (i.e. igh en icula [RV] lead eposi ioning) and he p o ocol was epea ed. All pa ien s signed w i en in o med consen . All spon aneous achya hy hmic episodes wi h ICD s o ed elec og ams ha esul ed in en icula he apies we e e iewed by wo independen ob- se e s (C.H. and P.C.), o assess e icacy o he deli e ed he apy. Disag eemen s we e esol ed by consensus wi h a hi d obse e . All ICD implan a ions we e pe o med a he elec ophysiology labo a o y unde local anes hesia and conscious seda ion. Only pec o al implan a- ions wi h dual-coil shocking leads placed in he RV apex we e included in he s udy. Pa ien s e- cei ed high-ou pu (≥ 35 J) o s anda d ac i e can de ices manu ac u ed by Med onic (Minneapolis, MN, USA), Bos on Scien i ic (S . Paul, MN, USA) o Bio onik (Be lin, Ge many). De ice p og am- ming was pe o med acco ding o pa ien clinical s a us and le a he disc e ion o he esponsible physician, bu all shocks we e p og ammed a he highes a ailable ou pu o he de ice. Howe e , a s anda dized ATP p og amming in he as en- icula achyca dia (VT) zone was ecommended in all pa ien s [17]. Pa ien s we e i s ollowed 3 mon hs a e de ice implan a ion and e e y 6 mon hs he ea e . S a is ical analysis We used an app oxima e no mal es o he equali y o a es o sample size es ima ion, whe e a o al o 111 pa ien s in he DT+ g oup and 434 in he DT– g oup would be able o de ec an absolu e e o in mo ali y a es o 0.06, wi h 80% s a is ical powe and a signi icance le el o 5%. Con inuous a iables we e assessed o no mali y using he Wilk-Shapi o es . No mally dis ibu ed a iables a e exp essed as mean ± s anda d de ia ion, whe eas hose wi h nonpa ame ic dis ibu ion a e p esen ed as median and in e qua ile ange (IQR). Ca ego ical a iables a e epo ed as numbe and pe cen age. Compa isons o no mal con inuous baseline cha ac e is ics we e made using S uden ’s - es . In case o non-no mally dis ibu ed con- inuous a iables, nonpa ame ic es s we e used. Compa isons o ca ego ical a ia bles we e done us- ing he Fishe ’s exac es o c2 es , as app op ia e. 254 www.ca diologyjou nal.o g Ca diology Jou nal 2015, Vol. 22, No. 3 Incidence a es o dea h and a hy hmic e en s be ween he coho s o DT+ and DT– pa ien s we e compa ed using an app oxima e no mal es o he equali y o a es. The annualized a e o each a hy hmic episode ype pe pa ien mon h was calcula ed by di iding he o al numbe o episodes by ype by mon hs o ollow-up o each pa ien g oup (DT+ s. DT–), whe e he weigh assigned o each pa ien is he p opo ion o o e all ollow-up ha he pa ien con ibu ed o he agg e- ga e ollow-up [7]. Annualized a es o e en s pe pa ien in bo h coho s we e compa ed using he Gene alized Linea Model (GLZM) and he Wald c2 es . Gene alized es ima ing equa ions (GEE) me hod was used o compa e he e icacy o ICD he apies in he wo coho s, adjus ing o mul iple episodes pe pa ien [18]. Kaplan-Meie su i al cu es and log- ank es we e used o compa e su - i al be ween bo h g oups. Fo s a is ical analysis we used SPSS e sion 19.0 (SPSS Inc.; Chicago, IL). All p obabili y (p) alues we e 2-sided and s a is ical signi icance was es ablished a p < 0.05. Resul s We included 548 consecu i e pa ien s ha ep esen he o al numbe o ICD implan s pe - o med a he pa icipa ing cen e s du ing he inclusion pe iod a each si e, including gene a o eplacemen s. Pa ien s we e ollowed o a median o 19 mon hs (IQR 9–31). Th ee (0.68%) pa ien s could no be con ac ed and we e conside ed los o ollow-up and excluded om analysis. Table 1 shows he clinical cha ac e is ics o pa ien s in- cluded in he s udy. In 111 (20%) pa ien s, DT was pe o med a he ime o ICD implan a ion. DT+ pa ien s we e sligh ly younge , less likely o ecei e a ca diac esynch oniza ion he apy wi h de ib illa ion capabili ies (CRT-ICD) and mo e likely o be ea ed wi h an ia hy hmic d ugs and o ecei e a dual-chambe de ice. O he baseline clinical cha ac e is ics we e compa able be ween g oups. Pa ien s’ clinical ou comes Pa ien s in he DT+ g oup we e ollowed o a longe pe iod han DT– pa ien s (32 [18–45] s. 15 [9–26] mon hs; p < 0.001). A e adjus ing he e en a e by he ollow-up du a ion, he e was no signi ican di e ence in he dea h a e pe obse a- ion yea (DT+: 0.04 s. DT–: 0.04; p = 0.91) no in he a e o pa ien s wi h en icula a hy hmic e en s pe obse a ion yea (DT+: 0.10 s. DT–: 0.12; p = 0.46) (Table 2). Simila ly, he e was no di e ence in he a e o pa ien s wi h VF pe ob- se a ion yea and only a end owa ds a sligh ly highe a e o pa ien s wi h VT pe obse a ion yea in he DT– g oup. Table 1. Pa ien s’ baseline cha ac e is ics. Va iable DT+ (n = 111) DT– (n = 434) P Age [yea s] 67 (54–74) 68 (59–76) 0.03* Male 95 (86%) 360 (83%) 0.52** Hea disease e iology: Ischemic 80 (72%) 279 (64%) 0.12** Dila ed ca diomyopa hy 12 (11%) 77 (18%) 0.08** Channelopa hies 5 (4.5%) 10 (2.3%) 0.20** Hype ophic ca diomyopa hy 6 (5.4%) 22 (5%) 0.88** O he 8 (7%) 46 (10%) 0.28** Ejec ion ac ion £ 0.35 69/111 (62%) 300/413 (73%) 0.16** Indica ion seconda y p e en ion 69 (62%) 227 (52%) 0.08** De no o ICD implan a ion 95 (86%) 349 (80%) 0.22** Type o ICD: < 0.01** Single chambe 72 (65%) 270 (62%) NS*** Dual chambe 21 (19%) 44 (10%) 0.01*** CRT-ICD 18 (16%) 120 (28%) 0.01*** An ia hy hmic d ug he apy (amioda one) 38 (34%) 95 (22%) 0.01** Con inuous a iables a e exp essed as median and in e qua ile ange; *Mann-Whi ney U es . Sig 2-sided; **Pea son’s c2 es . Sig 2-sided; ***App oxima e no mal es o adjus ed esiduals. Sig. 2-sided; CRT-ICD — ca diac esynch oniza ion he apy wi h de ib illa ion capabili ies; DT — de ib illa ion es ing; ICD — implan able ca dio e e -de ib illa o ; NS — no signi ican www.ca diologyjou nal.o g 255 Claudio Hadid e al., ICD de ib illa ion es ing a implan ICD he apy equency and e icacy by DT g oup a implan Du ing he ollow-up pe iod, 109 (20%) pa- ien s expe ienced 449 en icula a hy hmic episodes ha equi ed ICD he apy. The absolu e p opo ion o shocked pa ien s was highe in he DT+ g oup (22% s. 11%; p < 0.01). Howe e , a e adjus ing o he ollow-up du a ion, he e was no di e ence in he annualized a e o pa ien s ecei ing shocks o ATP he apies, be ween DT+ s. DT– g oups (Table 2). As shown in Table 3, he e was no di e ence in he GEE-adjus ed i s shock p obabili y o success in pa ien s wi h DT+ (95%; CI 88–100%) s. DT– (98%; CI 96–100%; p = 0.42). The p opo ion o success ul ATP he apies was g ea e in he DT+ g oup, bu he di e ence was no signi ican (DT+: 87% s. DT–: 73%; p = NS). Fi e pa ien s had a ailed app op ia e i s shock: 2 pa ien s in he DT+ g oup and 3 in he DT– g oup (Table 4). This accoun s o 2.8% (5/179) o o al app op ia e ICD shocks deli e ed in he s udy and 0.9% (5/545) o pa ien s ollowed in he s udy. A e adjus ing o he di e ences in ollow-up du a ion, he e was no di e ence be ween g oups in he an- nualized a e o ailed i s shock pe pa ien (DT+: 0.01 s. DT–: < 0.01; p = 0.71) and pe shocked pa ien (DT+: 0.05 s. DT–: 0.04; p = 0.94). Table 4 shows he clinical cha ac e is ics o pa ien s wi h a ailed i s shock. In all cases, he second shock success ully e mina ed he en icula a hy hmia. Mo ali y Fo y (7.3%) pa ien s died du ing he ollow- -up: 13 in he DT+ g oup (6 non-sudden ca diac Table 2. Pa ien s’ clinical ou comes du ing ollow-up. Incidence a e (pa ien -yea obse a ion) DT+ (n = 11) DT– (n = 434) P Dea h 0.04 0.04 0.91 Pa ien s wi h en icula a hy hmic e en s: 0.10 0.12 0.46 Pa ien s wi h en icula ib illa ion 0.08 0.05 0.16 Pa ien s wi h en icula achyca dia 0.05 0.09 0.07 Pa ien s wi h he apies: 0.10 0.12 0.46 Shock 0.08 0.07 0.69 An i achyca dia pacing 0.05 0.07 0.16 App oxima e no mal es o equali y o a es. Sig. 2-sided; DT — de ib illa ion es ing Table 3. E icacy o app op ia e he apies o en icula a hy hmias. DT+ (n = 31) DT– (n = 78) P Success ul shocks 38 136 Failed shocks 2 3 Success ul shocks/ /shocks ± 95% 98% 0.42 Success ul ATP 79 196 Failed ATP 46 133 Success ul ATP/ATP ± 87% 80% 0.35 ± Gene alized es ima ing equa ions adjus men o accoun o mul- iple episodes; ATP — an i achyca dia pacing; DT — de ib illa ion es ing Table 4. Clinical cha ac e is ics o pa ien s wi h a ailed i s ICD shock. Case Gende Age E iology EF De ice Indica ion: P e en ion DT E en Zone AAD 2nd ICD shock 1 Male 70 Non-ischemic 0.15 CRT-ICD P ima y – M-VT VF Yes Success ul 2 Male 61 Ischemic 0.30 SC-ICD Seconda y – M-VT VF No Success ul 3 Male 60 Non-ischemic 0.20 SC-ICD Seconda y – P-VT VF No Success ul 4 Male 59 Ischemic 0.30 DC-ICD Seconda y + VF VF Yes Success ul 5 Male 65 Ischemic 0.25 SC-ICD Seconda y + VF VF Yes Success ul ICD — implan able ca dio e e -de ib illa o ; EF — ejec ion ac ion; Zone — ICD de ec ion zone; AAD — an ia hy hmic d ug he apy; SC-ICD — single-chambe ICD; DC-ICD — dual-chambe ICD; M-VT — monomo phic en icula achyca dia; P-VT — polymo phic en icula achyca dia; VF — en icula ib illa ion 256 www.ca diologyjou nal.o g Ca diology Jou nal 2015, Vol. 22, No. 3 dea hs; 4 non-ca diac dea hs; 2 sudden dea hs; 1 unknown cause) and 27 in he DT– g oup (11 non-sudden ca diac dea h; 11 non-ca diac dea h; 2 elec ical s o m; 3 unknown causes). Pa ien s dying due o elec ical s o m we e admi ed o he hospi al wi h incessan en icula a hy hmia ha was ea ed wi h mul iple app op ia e ICD dis- cha ges ha e mina ed he episodes wi h he i s shock in all ins ances, while he ICD was wo king p ope ly. One sudden dea h in he DT+ g oup oc- cu ed in 1 pa ien wi h hype ophic ca diomyo- pa hy. Unknown dea hs we e non-sudden and no shock deli e y occu ed. The e we e no dea hs ela ed o de ice ailu e o mal unc ion. Unadjus ed mo ali y a es we e highe in pa ien s wi h (12%) s. wi hou DT (6.2%; p = = 0.048). Howe e , a e adjus ing o he di e - ences in ollow-up du a ion, he e was no di e ence in he annualized a e o dea h in DT+ s. DT– pa- ien s (Table 2). As shown in Figu e 1, he e we e no signi ican di e ences in he obse ed su i al a es be ween DT+ s. DT– pa ien s (p = 0.9). Discussion This obse a ional s udy in an unselec ed popula ion o consecu i e pa ien s unde going ICD implan a ion ound simila shock e icacy and long- e m clinical ou come ega dless o whe he DT was pe o med o no . The e o e, in ou s udy, pe o ming DT did no p edic ICD pe o mance and had no clinical impac du ing he ollow-up. These esul s a e ep esen a i e o he o e all popula ion o pa ien s cu en ly unde going all ypes o ICD implan s a wo e ia y e e al cen e s, o all kinds o ICD indica ions, including ICD wi h CRT capabili ies and gene a o eplace- men s. Finally, hese esul s a e ep esen a i e o he clinical ou comes o he ansi ion om he adi ional DT s a egy o he non-DT s a egy o mos o he pa ien s. Clinical impac o DT ICD implan a ion is indica ed o educe all- cause mo ali y in pa ien s a isk. In he p esen s udy, we obse ed no di e ences in he o e all mo ali y a es i espec i e o whe he DT was pe o med o no . All-cause mo ali y a es we e simila in he RAFT pilo ial [19], bu lowe han lowe in o he s obse a ional o e ospec i e s udies [8, 20, 21]. Di e ences in pa ien cha ac- e is ics and ollow-up du a ion migh accoun o hese appa en disc epancies. Ne e heless, none o hese s udies we e powe ed o de ec ed di e - ences in all-cause mo ali y and sudden ca diac dea h. On he o he hand, in ag eemen wi h p io s udies, he e was no di e ence be ween g oups in he annualized a e o pa ien s wi h en icula a hy hmic episodes and he annualized a e o pa ien s ecei ing app op ia e shocks (8% s. 9%) [19–21]. ICD he apy e icacy in DT+ s. DT– pa ien s The e icacy o ICD o success ully de ib illa e induced VF a implan is conside ed an adequa e su oga e o ICD e icacy du ing ollow-up [22]. In he p esen s udy, i s shock e icacy was 97% and Figu e 1. Kaplan-Meie es ima es o su i al in pa ien s wi h (DT+) and wi hou (DT–) de ib illa ion es ing. www.ca diologyjou nal.o g 257 Claudio Hadid e al., ICD de ib illa ion es ing a implan only 5 episodes equi ed a second shock o suc- cess ully e mina e he a hy hmia, wi h no di e - ences be ween DT+ (95%) s. DT– (98%) g oups. This compa ison canno be assessed s a is ically due o he small numbe o unsuccess ul shocks. This a e o i s shock ailu e is in ag eemen o ha epo ed o spon aneous VF in pa ien s wi h DT (80–91%) o sa e y ma gin es ing (91%) a ICD implan a ion [2, 4, 5]. Simila ly, a signi ican p opo ion (80–87%) o VT/ as VT episodes we e success ully ATP- e mina ed wi hou shock deli - e y, ega dless o whe he DT was pe o med. This is consis en wi h p e ious s udies showing ha dedica ed ATP p og amming educe he need o shocks o e mina e VT/VF in a subs an ial numbe o pa ien s [7, 17, 23]. In addi ion, newe de ices a e able o deli e ATP du ing ene gy cha ge when ea ing a VF episode, in an a emp o e mina e a as VT de ec ed in he VF zone [24, 25]. In e es - ingly, we obse ed no i s shock ailu es ollowing ine ec i e ATP he apies, bo h in DT+ and DT– pa ien s, since all i s shocks we e p og ammed a maximum ene gy [23]. P io s udies P io e ospec i e [5, 20, 21], p ospec i e obse a ional [8] and small andomized [19] s udies ha e epo ed on he long- e m clinical ou come o non- es ed s. pa ien s unde going DT, mos ly in mixed popula ion o p ima y p e en ion and CRT-D pa ien s. Despi e di e ences in design, pa ien s’ cha ac e is ics and ollow-up du a ion, ou esul s a e in ag eemen wi h mos o hese s udies. Pi es and Johnson [5] epo ed a e ospec i e analysis o ICD pa ien s assigned o in aope a i e DT, limi ed de ib illa ion sa e y ma gin es ing o no DT in a non- andomized ashion, and ound no di e ence in shocks e icacy and sudden dea h a e, bu a highe o e all mo ali y in he non- es ed g oup. Bianchi e al. [21] e ospec i ely compa ed he clinical ou come o ICD ecipien s o p ima y p e en ion om cen e s ha ou inely pe o med DT o ha o pa ien s in whom no DT was pe - o med, and ound no di e ence in o al mo ali y, ca dio ascula mo ali y o sudden dea h a es be ween hose g oups. Simila ly, no di e ences in su i al ee o hea ansplan a ion o shock e icacy we e ound in a e ospec i e s udy o CRT-D pa ien s [20]. A small pilo sub-s udy o he RAFT ial, compa ed pa ien s wi h and wi hou DT in a andomized ashion and showed simila ICD he apy e icacy bu a non-signi ican 2- old inc eased all-cause mo ali y in pa ien s unde go- ing DT [19]. In he la ges s udy epo ed o da e, he SAFE-ICD s udy p ospec i ely ollowed 2,120 pa ien s om cen e s selec ed acco ding o hei s anda d implan a ion p ac ice and ound a simila long- e m ou come in pa ien s wi h DT s. wi hou DT du ing de no o implan s, in e ms pe iope a i e complica ions, ICD he apy e icacy and mo ali y [8]. Despi e he smalle sample size, ou s udy ag ees wi h he SAFE-ICD in hei p ospec i e, non- andomized na u e, and he lack o ou come di e ences be ween g oups. Howe e , in ou s udy, no pa ien s we e excluded du ing he ec ui men pe iod and all ypes o ICD implan s we e consid- e ed, including gene a o eplacemen s. Thus, ou s udy con i ms and u he expands he SAFE-ICD s udy esul s in pa ien s ha mos likely ep esen an unselec ed popula ion cu en ly unde going ICD implan a ion wi h ega ds o age, gende , indica- ion and de ice ype [14, 16]. Mo eo e , his is he i s s udy o p o ide de ailed analyses o he ou come o ICD he apies, bo h ATP and shocks, showing a simila i s shock e icacy in pa ien s ollowing ailed ATP he apy in pa ien s wi h and wi hou DT a implan . Since ATP he apy ailu e delays ime o shock and p olongs VF du a ion, a lowe shock e icacy could ha e been expec ed in his con ex [23, 26]. I is eassu ing o no e ha in ou s udy, all VT/VF episodes ollowing ailed ATP we e success ully con e ed when i s shock was p og ammed a maximum ene gy, ega dless DT was pe o med o no . Limi a ions o he s udy Ou s udy has se e al po en ial limi a ions. This is a non- andomized e ospec i e s udy wi h di e en ollow-up imes be ween g oups ha we e adjus ed by calcula ing annualized e en a es. Se- lec ion bias owa ds including pa ien s wi h lowe DT h esholds in he non- es ed g oup canno be excluded. Non- es ed pa ien s had lowe ejec ion ac ion and his di e ence may explain he highe a e o CRT implan a ion in his g oup. Second, as only dual-coil ICD leads we e implan ed, ou ind- ings should no be ex apola ed o pa ien s wi h single-coil leads. Thi d, ICD p og amming was no guided by he esul o DT in he es ed g oup and i s shocks we e se a maximum ene gy in bo h g oups. The emaining ICD pa ame e s se ings we e le a he physicians’ disc e ion and we e no a ailable o analyses. Ne e heless, he ecom- mended ATP p og amming s a egy was able o success ully e mina e a high p opo ion o ea ed episodes in p e ious s udies [7, 17, 26]. Finally, 3 pa ien s died o unknown causes, bu wi nesses’ e- po s easonably excluded a sudden cause o dea h. 258 www.ca diologyjou nal.o g Ca diology Jou nal 2015, Vol. 22, No. 3 Conclusions In his obse a ional s udy, ha included an unselec ed popula ion o consecu i e pa ien s unde going ICD implan a ion, pe o ming DT a he ime o ICD inse ion was no associa ed wi h imp o ed su i al, highe i s shock e icacy p obabili y o lowe a e o ailed ICD shocks as compa ed o he s a egy o wi hholding DT. Un il he esul s o andomized clinical ials become a ailable [22], he p esen s udy ques ions he need o sys ema ically pe o ming DT in he majo i y o pa ien s unde going ICD implan a ion. Con lic o in e es : D A ienza and P o . S asbe g a e on he Eu opean A iso y Boa d o Med onic. The es o he au ho s ha e no con lic s o in e es s o epo . Re e ences 1. Cu is AB, Ellenbogen KA, Hammill SC e al. 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