www.revportcardiol.org
Revista
Portuguesa
de
Cardiologia
Portuguese
Journal
of
Cardiology
ORIGINAL
ARTICLE
Importance
of
monitoring
zones
in
the
detection
of
arrhythmias
in
patients
with
implantable
cardioverter-defibrillators
under
remote
monitoring
Sílvia
Aguiar
Rosa
∗,
Pedro
Silva
Cunha,
Ana
Lousinha,
Bruno
Valente,
Ana
Sofia
Delgado,
Ricardo
Pimenta,
Manuel
Brás,
Madalena
Coutinho
Cruz,
Guilherme
Portugal,
André
Viveiros
Monteiro,
Mário
Oliveira,
Rui
Cruz
Ferreira
CardiologyDepartment,SantaMartaHospital,Lisbon,Portugal
Received5September2017;accepted13May2018 Availableonline24January2019
KEYWORDS Implantable cardioverter-defibrillator; Monitoringzone; Supraventricular arrhythmias; Ventricular arrhythmias; Clinicalpractice Abstract
Introduction:Implantablecardioverter-defibrillator(ICD)monitoringzones(MZ)provide pas-sivefeaturesthatdonotinterferewiththefunctioningofactivetreatmentzones.However,it isnotknownforcertainwhetherprogramminganMZaffectsarrhythmiadetectionbytheICD. TheaimofthepresentstudyistoassesstheclinicalrelevanceofMZinapopulationofpatients withICDs.
Methods:In thisretrospectiveanalysis ofpatients withICDs,withorwithoutcardiac resyn-chronizationtherapy,for primarypreventionunderremotemonitoring,theMZwasanalyzed andrecordedarrhythmiaswereassessedindetail.
Results:Atotalof221patientswerestudied(77%men;age64±12years).Meanejection frac-tionwas30±12%.Themeanfollow-upwas63±35months.Onehundredandseventy-fourMZ eventsweredocumentedin139patients(62.9%):74ofnon-sustainedventriculartachycardia (NSVT),42ofsupraventriculartachycardia,44ofatrialfibrillation/atrialflutter,andfivecases ofnoise.Amongthe137patientswhopresentedwitharrhythmiasintheMZ(excludingtwocases withnoisedetectiononly),22(16.1%)receivedappropriateshocksand/orantitachycardia pac-ing(ATP),whileoftheother84patients,15.5%receivedappropriateICDtreatment(p=NS).In patientswhopresentedwithNSVTintheMZ,15(20.5%)receivedappropriateshocksand/or ATP.InaccordancewiththeMZfindings,physiciansdecidedtochangeoutpatientmedication in41.7%ofallpatientsinwhomarrhythmiceventswerereported.
∗Correspondingauthor.
E-mailaddress:silviaguiarosa@gmail.com(S.AguiarRosa). https://doi.org/10.1016/j.repc.2018.05.015
0870-2551/©2018SociedadePortuguesadeCardiologia.PublishedbyElsevierEspa˜na,S.L.U.ThisisanopenaccessarticleundertheCC BY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Conclusion:VentricularandsupraventriculararrhythmiasarecommonfindingsintheMZofICD patients.ProgramminganMZisvaluableinthediagnosisofarrhythmiasandmaybeauseful toolinclinicalpractice.
©2018SociedadePortuguesadeCardiologia.PublishedbyElsevierEspa˜na,S.L.U.Thisisan openaccessarticleundertheCCBY-NC-NDlicense( http://creativecommons.org/licenses/by-nc-nd/4.0/). PALAVRAS-CHAVE Cardioversor desfibrilhador implantável; Zonade monitorizac¸ão; Arritmias supraventriculares; Arritmias ventriculares; Práticaclínica
Importânciadazonademonitorizac¸ãonadetec¸ãodearritmiasemportadoresde cardioversordesfibrilhadorimplantávelemprogramademonitorizac¸ãoremota
Resumo
Introduc¸ão: A zona de monitorizac¸ão (ZM) de cardioversor desfibrilhador implantável (CDI) permiteumafuncionalidadepassivaquenãointerferecomofuncionamentodaszonasde trata-mentoativo.Contudo,nãoéperfeitamenteconhecidoseaprogramac¸ãodeZMafetaadetec¸ão dearritmiaspeloCDI.OobjetivodopresenteestudoéavaliararelevânciaclínicadeZMnuma populac¸ãosubmetidaaimplantac¸ãodeCDI.
Métodos: Análiseretrospetivadedoentessubmetidosaimplantac¸ãodeCDI,comousem ter-apiaderessincronizac¸ãocardíaca,emprevenc¸ãoprimária,sobmonitorizac¸ãoremota.ZMfoi analisadaeasarritmiasdocumentadasavaliadasemdetalhe.
Resultados: Foramestudados221doentes(77%homens;64±12anos).Frac¸ãodeejec¸ãomédia foi30±12%.Operíododeseguimentomédiofoi63±35meses.Foramdocumentados174eventos naZM,em139doentes(62.9%):taquicardiaventricularnãosustentada(TVNS)---74, taquicar-diasupraventricular--- 42,fibrilhac¸ão/flutterauricular---44,ruído---5.Dos137doentesque apresentaramarritmianaZM(excluindodoiscasosdedetec¸ãoderuído),22(16,1%)receberam choquesapropriadosoupacingantitaquicardia(PAT),enquantoquedosrestantes84doentes, 15,5%receberamterapiasapropriadasdoCDI(p=NS).DosdoentesqueapresentaramTVNSna ZM,15(20,5%)receberamchoquesapropriadose/oupacinganti-taquicardia(PAT).Deacordo comosachadosemZM,omédicodecidiualteraraterapiaoraldeambulatórioem41,7%de todososdoentescomeventosarrítmicosreportados.
Conclusão:Arritmasventriculares esupraventricularessãoachadoscomunsnaZMdeCDI.A programac¸ãodeZMéimportantenodiagnósticodearritmiasepoderáserumelementoútilna práticaclínica.
©2018SociedadePortuguesadeCardiologia.PublicadoporElsevierEspa˜na,S.L.U.Este ´eum artigoOpen Accesssobumalicenc¸aCCBY-NC-ND( http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction
Implantablecardioverter-defibrillators(ICDs)arethe treat-ment of choice for primary prevention against sudden cardiac death.1 Arrhythmia therapy is delivered in the
form of antitachycardia pacing (ATP) or shock. An ICD is able to terminate potentially life-threatening ventricular arrhythmias, preventing syncope, hypotension and, most importantly,sudden cardiac death. Devicealgorithms and thresholds for detection and therapies are programmed according to age, indication and the underlying cardiac disease.2
Forlowerheartrates, monitoring zones(MZ),inwhich thedevicedoesnotdelivertherapybutmonitorstheheart rhythm,arecommonlyusedinclinicalpractice.MZprovide passive features that do not interfere with the function-ingofactivetreatment zones.MZ canalsoclassifyevents assupraventricularorventriculararrhythmias.3However,it
is not known for certain whether the programming of an MZaffectsarrhythmiadetectionbytheICDor theclinical managementofthesepatients.
The aim of the present study is to assess the benefit in clinical practice of MZ for treatment in a population ofpatientswithICDsorcardiacresynchronization therapy-defibrillator(CRT-D)devicesforprimaryprevention.
Methods
Thiswasaretrospectiveanalysisofpatientsimplantedwith anICDorCRT-Dforprimarypreventionatatertiarycenter between 2006 and 2015. Devices were implanted accord-ingtointernationalguidelines.4Patientswithindicationfor
implantationforsecondarypreventionwereexcluded. AllpatientswithaprogrammedMZwereconsideredfor the study. This zone wasprogrammed according to heart rate(140-170bpm)andpersistence(numberofconsecutive cycles>50). Therapyzoneswereprogrammed for 170-200 bpmfor30outof40cycles(ATPattemptsorshock),and>200 bpmfor12outof18cycles(ATPduringchargeorshock).
TheMZcriteriawerechangedaccordingtothe arrhyth-mia data obtained via the device during follow-up.
Table1 Baselinecharacteristicsofthestudypopulation.
Overallpopulation(n=221) EventsinMZ(n=139) NoeventsinMZ(n=82) p
Age,years 64±12 64.7±12.4 63.0±15.1 0.364 Male,n(%) 170(76.9%) 103(74.1%) 67(81.7%) 0.120 LVEF,% 30±12 27.6±11.0 33.5±12.0 0.002 Etiology,n(%) DCM 95(43.0%) 75(54.0%) 20(24.4%) 0.007 ICM 94(42.5%) 50(36.0%) 44(53.6%) 0.027 HCM 15(6.8%) 7(5.0%) 8(9.8%) 0.237
Primaryelectricalcardiacdisease 11(5.0%) 3(2.2%) 8(9.8%) 0.077
CHD 4(1.8%) 3(2.2%) 1(1.2%) 0.300 VHD 2(0.9%) 1(0.6%) 1(1.2%) 1.000 Device,n(%) <0.001 ICD 138(62.4%) 73(52.5%) 65(79.3%) Single-chamber 124(89.9%) 65(47.1%) 59(42.8%) Dual-chamber 14(10.1%) 8(5.8%) 6(4.3%) CRT-D 83(37.6%) 66(47.5%) 17(20.7%) Deviceprogramming,n(%) MZ140bpm/VT170bpm/VF210bpm 171(77.4%) 94(67.6%) 77(93.9%) MZ140bpm/VT170bpm/VF214bpm 50(22.6%) 45(32.4%) 5(6.1%)
CHD:congenitalheartdisease;CRT-D:cardiacresynchronizationtherapy-defibrillator;DCM:dilatedcardiomyopathy;HCM:hypertrophic cardiomyopathy;ICD:implantablecardioverter-defibrillator;ICM:ischemiccardiomyopathy;LVEF:leftventricularejectionfraction;MZ: monitoringzone;VHD:valvularheartdisease.
ATP-basedtherapywasactivatedonlyinpatientspresenting withslowVT(belowthecut-offof170bpm).
Allenrolledpatientsreceivedaremotemonitoring(RM) system. The RM equipment was provided at the first outpatientvisitafterICDorCRT-Dimplantationandreports werereviewedby trainedstaffunderthesupervisionof a seniorelectrophysiologist.
Initially a retrospective analysis was performed of MZ reports through the RM system and recorded arrhythmias were assessed in detail. In patients with single-chamber devices, atrial fibrillation (AF) detection was based on heart rate combined with absence of stability criteria, according to cycle length irregularity during the arrhyth-mia. Sinus tachycardia, supraventricular tachycardia and non-sustainedventriculartachycardia(NSVT)were differen-tiatedbytheonsetcriteriaandusingcomparisonwithnative QRScomplexmorphologyandcyclelength.Inpatientswith arrhythmiceventsdocumentedintheMZ,thedecisionofthe physicianattheoutpatientclinicvisitregardingthe treat-mentapproachwasanalyzed byreviewing patientfiles. A secondanalysisofMZreportsthroughRMsystemswasthen performedtodeterminetheimpactofchangesin medica-tion or invasive strategy onthe recurrence of arrhythmic events. For all patients, data were collected regarding arrhythmicevents,deviceprogrammingandappropriateand inappropriatetherapiesviaICDorCRT-D.
Statisticalanalysis
ThestatisticalanalysiswasperformedusingIBMSPSS Statis-tics,version19(IBMSPSS,Chicago,IL).Continuousvariables wereexpressedasmean±standarddeviationand categor-icalvariableswereexpressedaspercentage.Studygroups
werecomparedusingtheStudent’sttestorthe Wilcoxon-Mann-Whitneytest forcontinuousvariables,andPearson’s chi-squareor Fisher’sexact testfor categoricalmeasures, asappropriate.Ap-value<0.05wasconsideredstatistically significant.
Results
Duringthe study period, 898 patients underwentICD and CRT-Dimplantation,of whom221 receivedthe device for primarypreventionwithfacilitiesforRM.Thebaseline char-acteristics of the study population are shown in Table 1. Of the overall population, 77% were men,mean age was 64±12years, and mean left ventricular ejection fraction was 30±12%. Dilated and ischemic cardiomyopathy were themostcommonunderlyingconditions,followedby hyper-trophiccardiomyopathy,primaryelectricalcardiacdisease andcongenitalheartdisease.
Mean follow-up after implantation was63±35months, during which MZ data were collected. One hundred and seventy-four events were documented in the MZ in 139 patients (62.9% of the overall population) (Figure1). Supraventriculararrhythmiasaccounted for almosthalf of allfindings (49.4%), witha similarincidenceof supraven-tricular tachycardia and AF/atrial flutter. In 29 patients (20.9%), AF and other supraventricular arrhythmias were diagnosedbasedonelectrogramsfromsingle-chamberICDs. NSVToccurred in 74 patients (42.5% of all events) in the MZ.Onlyfiveeventswereduetonoise.RegardingICD ther-apydelivery,ofthe137patientswhopresentedarrhythmic eventsintheMZ(excludingtwopatientswithnoise detec-tiononly),22 (16.1%) receivedappropriateshocks and/or ATP, while in the other 84 patients without events in the
174 events documented in the MZ in 139 patients(62.9%) Supraventricular tachycardia n=42 Atrial fibrillation/flutter n=44 Non-sustained ventricular tachycardia n=74 Noise n=5
Figure1 Arrhythmiceventsdocumentedinthemonitoringzoneduringfollow-up.
Figure2 Comparison ofappropriatedevicetherapies between patientswith andwithoutarrhythmic eventsdetected inthe monitoringzone.
MZ, 15.5% received appropriate ICD therapies (p=0.908)
(Figure2). Inpatients withNSVTin theMZ thefrequency
of appropriateICD therapy was not significantlydifferent fromtheothers,with15patients(20.5%)receivingdevice therapy.
Inaccordancewiththe MZfindings,physicians decided tochange outpatient medication in 58 patients (41.7% of all patients in whom arrhythmic events were reported in the MZ), due to supraventricular arrhythmia in 24 cases and to ventricular tachycardia in 34. In the presence of NSVTin the MZ, theinitiation or titration of antiarrhyth-micdrugs(mainlybeta-blockersandamiodarone)wasbased onthepresenceofsymptomsand/orNSVTlengthand bur-den. Among these 58 subjects, six started beta-blockers, 11 started amiodarone, andeight (13.8%) started chronic oralanticoagulation.Thepreviouslyprescribed antiarrhyth-micdrugdosage wastitrated in44 patients.Beta-blocker dosagewasincreasedin41patientsandamiodarone/sotalol dosagewasincreasedinthreecases.Inadditionto optimiza-tionofmedicaltreatment,twopatientsunderwentablation ofsupraventricular arrhythmiasdetectedinthe MZ(atrial flutterandatrioventricularnodalreentranttachycardia)and threeunderwentatrioventricularjunctionablation due to AFwithrapidventricularresponse(andlowpercentageof biventricular pacing). Furthermore,internal cardioversion via the ICDwas performed in onepatient withpersistent
AF(Figure3).SincetherewasuncertaintywhethertheAF
burdenjustifiedoralanticoagulation, theinitiationofthis medicationwasbasedonthephysician’sdecision.However, inviewofthehighriskinthispopulation,patientspresenting
50% 3% 1% 32% 9% 5% Unchanged Ablation Internal cardioversion Start/increase beta-blocker Start/increase amiodarone Start oral anticoagulation
Figure3 Influenceofmonitoringzonereportsonthe treat-mentapproach.
AFepisodeslasting>5minwereprescribedanticoagulation therapy.
After optimization of medical therapy, 37 patients (63.8%) did not have recurrence of arrhythmic events in theMZ,70.8%inthesupraventriculararrhythmiasubgroup and55.6%intheventriculartachycardiasubgroup.Inthose with recurrence,16 individuals presented NSVTepisodes, fiveshowedsupraventriculartachycardiaandtwohad parox-ysmal AF. In three cases there was more than one type ofarrhythmia. Despitechangesinmedication,15 patients (25.9%)hadrecurrenceofthesamearrhythmia.
Among the 65 patients with NSVT, in whom antiar-rhythmic medication was increased, during a follow-up
of 10.0±7.5 monthsno appropriatetherapies were deliv-ered by the device, and more than half (55.6%) did not present recurrenceof documentedarrhythmiasin theMZ. Intheoverallpopulation,arrhythmiceventsintheMZwere detectedin62.9%,whichledtotreatmentchangesin27.1%, withaconsequent 17%decrease inthe arrhythmicevents detected in the MZ. There were no clinical or technical complicationsreportedinrelationtotheactivationofMZ.
Discussion
Programmingan MZforprimarypreventionin ICDpatients leads to the detection of symptomatic or asymptomatic arrhythmias,indicatingthatitmaybeauseful toolin the optimizationofmedicalandinterventionaltreatmentinthis population.
The benefits of RM in preventing hospital admis-sion for heart failure or cardiovascular death are well documented.5---7However,itsusefulness inoptimizationof
antiarrhythmictreatmenthasnotbeensoextensively stud-ied.As highlightedin thepresent study,RM enablesearly detection of new-onset or paroxysmal arrhythmias in the MZandhenceearlytherapeuticintervention.
In our sample, arrhythmic events were documentedin the MZ in 62.9% of patients. These findings had a sig-nificant impact on clinical practice, since in half of the patientsoutpatientmedicationwaschangedand/orablation wasperformed. This optimizationin patient management resulted in a considerable reduction in arrhythmicevents reportedintheMZ.
As previously reported, patients with cardiac devices presented a high incidence of atrial arrhythmias, evenin theabsenceofsymptoms.8Around50%ofICDcarrierscan
be expected to experience AF during the lifetime of the device.9Inourpopulation,new-onsetparoxysmalAF/atrial
flutter was found in a significant proportion of patients (20%),leadingtotheinitiationoforalanticoagulation.This incidence is similartodata reportedby Ricci etal., who foundanAFincidenceof26%inpacemaker/ICDpatients.10
SinceAF,evenifparoxysmalorasymptomatic,isassociated with a five-fold increase in the risk of ischemic stroke,11
recognitionoftheseepisodesandinitiationof anticoagula-tionmayprovideprotectionagainstthromboembolicevents suchasstroke.ProgramminganMZprovidesvaluable infor-mationonAFoccurrence,AFburdenandconsequentstroke risk. Thesecontinuous monitoring data(particularly when combinedwithRMsystems)can beof considerablevalue, sincemanyAFepisodeswithclinicallysignificant duration areasymptomatic.12Improvementsinuseofandadherence
tooralanticoagulationbasedoncontinuousICDmonitoring haverecentlybeendemonstrated.13
The impactofappropriateshocksonqualityoflifeand morbidityinICDpatientsremainsaconcern,14---16and
redu-cingtherateofshocktherapiesisarealchallengefor the ICDoutpatientclinic.Initiationortitrationof antiarrhyth-micdrugsinpatientswithNSVTdocumentedintheMZhas thepotentialtoreducetherateofshocksandATPdelivered topatients.Infact,inourpopulation,amongpatientswith NSVT whose antiarrhythmic medication was optimized no shocksorATPweredeliveredvia thedevice,and55.6%of thesepatients did notpresent recurrenceof documented
arrhythmias in the MZ. Since NSVT is associated with an increasedriskofdeathinbothischemic16andnon-ischemic
cardiomyopathy,17---19 its detection and consequent
thera-peuticoptimizationcanpotentiallyreduceICDtherapiesin thesepatients.
Itisalsoimportanttoemphasizethatinourstudy, regard-lessofthetypeofarrhythmiarecorded,analysisoftheMZ hadthepotentialtochange physicians’decisionsin27.1% ofcases,withanimpactonarrhythmiarecurrence.
TherehavebeenconcernsthatMZcanbeassociatedwith increasedriskofinappropriatedevicetherapy,20,21however
inourstudy onlytwopatients (0.9%)received inappropri-ate therapies due to AF withrapid ventricular response. This incidence is much lower than that described in the DetectSupraventricularTachycardiaStudy,inwhichtherate ofinappropriatedetectionofsupraventriculartachycardias was31%,22 or in astudy by van Rees etal. of a
prospec-tiveregistry,with13%ofinappropriateshocks.23 High-rate
cut-offprogramming fordetectionandtherapy in primary preventionhasbeen shown todecreasethisrate substan-tiallyto6.6%.24
Thepresentstudyshowedthatcontinuousrhythm mon-itoring by the cardiac device unmasks arrhythmias in asymptomaticandsymptomaticpatients,withanimpacton clinical management, leading toa significant decrease in arrhythmiceventsdetectedintheMZ.
Study
limitations
Thisisanobservationallong-termretrospectivestudywith the inherent limitations, including the absence of a con-trol group. The relatively small sample size results from thesingle-centernatureofthestudy.However,ourresults reflect a real-life long-term clinical practice experience basedonanRMprogram.
Conclusion
Detection of spontaneous ventricular and supraventricu-lararrhythmias arecommonfindings in a population with implantablecardiacdevicesfor primaryprevention witha programmedMZ.TheMZappearstobeofvalueinthe diag-nosis ofarrhythmias, andmay be auseful tool in clinical practice.Inourstudy,thetreatmentapproachwaschanged inabouthalfofthepatientsbasedonMZreports.Itisalso importanttoemphasizethatanticoagulationwasstartedin patientswithpreviouslyunknownparoxysmalAF,providing animportantmeasureinstrokeprevention.
Conflicts
of
interest
Theauthorshavenoconflictsofinteresttodeclare.
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