Bednarek, Jacek

Lelakowski, Jacek

Majewski, Jacek

Małecka, Barbara

Ząbek, Andrzej

Cardiology Journal

English

Jagiellonian Univeristy Repository

83www.cardiologyjournal.orgORIGINAL ARTICLECardiology Journal2007, Vol. 14, No. 1, pp. 83–86Copyright © 2007 Via MedicaISSN 1507–4145Address for correspondence: Jacek Lelakowski, MD, PhDDepartment of ElectrocardiologyInstitute of Cardiology Jagiellonian UniversityCollegium Medicum in John Paul II HospitalPradnicka 80, 31–202 Cracow, PolandTel: +48 12 614 22 77, fax: +48 12 633 23 99e-mail: jlelakow@szpitaljp2.krakow.plReceived: 6.09.2006 Accepted: 23.11.2006Pacemaker dependency afterpacemaker implantationJacek Lelakowski, Jacek Majewski, Jacek Bednarek, Barbara Małecka and Andrzej ZąbekDepartment of Electrocardiology, Institute of Cardiology, Jagiellonian University,Collegium Medicum in John Paul II Hospital, Cracow, PolandAbstractBackground: Pacemaker dependency (PD) can be defined as the risk of serious injury ordeath from sudden pacemaker failure, an event more dangerous than progressive rate de-crease. The aim of this study was to evaluate the incidence of PD during long-term follow-upafter pacing system implantation.Methods and Results: The study included 3638 patients (mean age 65.3 ± 10.2 years).Indications for pacing were sick sinus syndrome (SSS) in 1315 patients, atrioventricularblock (AVB) in 1482, AVB and SSS in 478 and atrial fibrillation (AF) with bradycardia in363 patients. The mean follow-up was 4.8±1.8 years. Pacemaker dependency was defined asthe absence of an intrinsic rhythm of 30 beats/min during back-up pacing and after switchingoff the pacemaker. If any significant symptoms of bradycardia developed or if the underlyingrhythm did not appear (asystole > 5 s) the pacing was restarted. Pacemaker dependency  wasobserved in 76 (2.1%) of the 3638 patients. In this subgroup pacing indications were SSS in8 (0.6%) of 1315 patients, AVB in 52 (3.5%) of 1482, SSS and AVB in 15 (3.1%) of 478 andAF with bradycardia in 1 (0.3%) of 363. Patients with AVB had a significantly higher inci-dence of PD than patients with SSS or AF (p < 0.001, p < 0.005, respectively). A total of139 patients suffered from myocardial infarction and 106 patients had a temporary pacing priorto pacemaker implantation. The majority of these patients were pacemaker dependent (p < 0.001).Conclusions: In our study PD occurred very rarely, being found in 2.1% of all patients.Patients with AVB have a significantly higher incidence of PD than patients with SSS or AF.Temporary pacing prior to pacemaker implantation and previous myocardial infarction indi-cate patients at risk of PD development. (Cardiol J 2007; 14: 83–86)Key words: pacemaker dependency, escape rhythm, sick sinus syndrome,atrioventricular block, atrial fibrillationIntroductionDuring long-term follow-up a considerablenumber of permanent pacemaker patients showa spontaneous heart rhythm faster than the basic rateof the pacemakers. However, in approximately 40%of patients continuous pacemaker-induced rhythm isobserved at consecutive follow-up examinations.These pacemaker-dependent patients, whohave no intrinsic or escape rhythm, may develop84Cardiology Journal 2007, Vol. 14, No. 1www.foliacardiologica.eucomplications (syncope, serious injury or even sud-den death) under conditions of electromagnetic in-terference, lead dysfunction or battery depletion.During the original pacemaker implantation itis often difficult to assess the reliability of the es-cape rhythm and thus to predict the developmentof pacemaker dependency during long-term follow-up[1–9].The purpose of the present study was to ex-amine pacemaker dependency (PD) in paced pa-tients during long-term follow-up and to evaluatethe difference between patients with and withoutescape rhythm as well as to define clinical factorsthat can predict a higher incidence of PD.MethodsA total of 3638 consecutive paced patients wereenrolled in the present study (1709 men, 1929 wom-en). Only patients in whom the pacemaker could beprogrammed and turned off were selected. Themean age of the population at examination was 65.3 ±± 10.2 years (range 23–95 years). The patients hadundergone pacemaker implantation at the Depart-ment of Electrocardiology from 17 years down to1 year before the study (mean follow-up was 4.8 ±± 1.8 years between 1998 and 2005). The study wasa retrospective one. The indication for permanentpacing was syncope or symptomatic bradycardiacaused by atrioventricular block (AVB) in 1482 pa-tients, sick sinus syndrome (SSS) in 1315, AVB andSSS in 478 and atrial fibrillation (AF) in 363 patients.A total of 2046 patients had coronary artery disease(CAD), 1615 had arterial hypertension (AH) and725 patients had heart failure (HF). The other 462 pa-tients had no structural heart disease. Myocardialinfarction was suffered by 139 patients and 106 pa-tients had temporary pacing prior to pacemakerimplantation. In all, 1455 patients had DDD pacing,156 had VDD pacing, 1845 had VVI pacing and182 patients had AAI pacing. Patients were exclud-ed if they had undergone AV junctional radiofrequen-cy ablation or if they had had a pacemaker implantedbecause of bradyarrhythmia within 6 months of acutemyocardial infarction or cardiac surgery and thesepatients will be analysed in a subsequent study. Ourpatients were treated with ß-adrenergic blockersand other anti-arrhythmic drugs. The drugs wereused chronically or intermittently. The sex distri-bution, mean age and mean duration of follow-up foreach group are shown in Table 1.After giving their informed consent, these pa-tients were placed in a supine position and moni-tored continuously while the pacemaker (DDD andVDD Æ VVI) was programmed with the pacing ratedecreased by 10 beats/min every 2 min down to thelowest programmable rate (30 beats/min), whichwas continued for 30 s. Afterwards the pacemakerwas switched off. If any significant symptoms ofbradycardia developed or if the underlying rhythmdid not appear, producing a ventricular asystolelonger than 5 s [8], the pacing was restarted. In thisevent, the patient was defined as pacemaker-de-pendent. The examination was performed by a car-diologist, technician and specially trained nurse.An ECG was recorded with a standard record-er at a paper speed of 25 mm/s and an amplificationof 1 mV/cm. A defibrillator and resuscitation equip-ment were on hand for immediate use. There wereno serious or life-threatening complications in thestudy group.The c2 test was used to evaluate the effect ofsex, aetiology, coronary artery disease, artery hy-pertension, heart failure, myocardial infarction andtemporary pacing on pacemaker dependency. Thedifference between patients with and without es-cape rhythm was evaluated by using an independ-ent t-test. A p value of 0.05 or less was consideredsignificant.ResultsTable 1 shows the sex distribution, mean age,and mean duration of follow-up among patients withAVB in relation to those with SSS, AVB and SSSand AF with bradycardia.Table 1. Sex distribution, age and follow-up duration in relation to pacing indication. Groups andoverall population (n = 3638).Pacing indication AVB SSS SSS and AVB AF/bradytachycardia All patients(N = 1482)  (N = 1315)  (N = 478)  (N = 363)  (N = 3638)Men/women 637/845 740/575 225/253 107/256 1709/1929Age (years) 67.8±9.8 65.8±10.2 66.4±11.0 60.9±9.4 65.3±10.2Follow-up (years) 4.5±1.4 4.9±1.8 4.7±1.7 4.9±2.3 4.8±1.8SSS — sick sinus syndrome; AVB — atrioventricular block; AF — atrial fibrillation85Jacek Lelakowski et al., Pacemaker dependency after pacemaker implantationwww.foliacardiologica.euOf 3638 pacemaker patients 3562 (97.9%) pa-tients presented intrinsic or escape rhythms at rates> 30 beats/min and 76 (2.1%) developed PD withno intrinsic rhythm. Among the four indications forpermanent pacemaker implantation were rates ofPD development of 52 (3.5%) of 1482 patients withAVB, 8 (0.6%) of 1315 with SSS, 15 (3.1%) of 478with SSS and AVB, and 1 (0.3%) of 363 patients withAF and bradycardia (Table 2).There were no statistically significant differ-ences in sex, age, prevalence of CAD, AH, HF ormean follow-up duration among the various pacingindication groups and pacemaker-dependent andnon-dependent patients.The incidence of PD was significantly higheramong patients with AVB than patients with SSSand AF (p < 0.001 and p < 0.005 respectively).As shown in Table 3, AVB and SSS patientswho had had temporary pacing before pacemakerimplantation or who had undergone myocardial in-farction had a significantly higher incidence of PD(p < 0.001).DiscussionThe definition of PD has long been a source ofcontroversy and confusion. Duncan-Fraser et al. [1]reported their experience from June 1983 onwards,performing routine standardised dependency riskscoring on an active clinical population of 1800 pa-tients with some 25 models of pacemakers from5 different manufactures. A patient was classifiedas 1+ when an intrinsic rhythm exceeded the pacedrate of 70 beats/min, as 2+ when an intrinsicrhythm was visible with rate slowing or competi-tion, as 3+ when there was no spontaneous escapeor an escape rate between 30 and 50 beats/min andas 4+ when there was no spontaneous escape oran escape rate < 30 beats/min. They reported thatdependency risk scoring is a useful parameter ofassessment in any paced patient and provides reli-able and safe timing for pulse generator replace-ment. They further concluded that knowledge ofa patient’s dependency status has allowed them toset realistic surveillance schedules, to improve pa-tient flow within the clinic, to utilise physician timeto best advantage and to funnel highly dependentpatients to a programming room with resuscitationequipment.In the study published by Behrens et al. [9] fourclasses of PD are distinguished (class I — 5 s ofasystole, class II — 2–5 s of asystole with escapeby complete heart block, class III — escape by lesserdegrees of AVB, ventricular ectopy with sinus brady-cardia equal to or below 30 beats/min, class IV —escape by sinus rhythm of 40 beats/min or more).Classes III and IV were deemed non-dependent.After implantation of a permanent pacemaker,the escape rhythm may be suppressed and whenpacing is stopped a significant percentage of thepatients fail to develop an effective escape rhythm[2, 3, 5, 7]. This effect depends on the pacing rateand duration [5]. The pacemaker-dependent pa-tients may, with a sudden loss of pacing, be at sig-nificant risk of developing syncope, serious injuryor even sudden death [2, 3, 5, 7].The 2.1% of PD after pacemaker implantationin our study was relatively low compared to the in-cidence observed in previous studies, ranging be-tween 5% and 30% [2, 3, 7]. The difference may beattributed to variation between studies in the defi-nition of PD. The definition of Staessen et al. [2]includes the absence of any ventricular escaperhythm within 4 s of successful pacemaker inhibi-tion and irregular ventricular escape rhythms withpauses of 4 s or more. The other definition of PD,that of Glikson et al. [4], is an underlying rhythmbelow 50 beats/min. Nagatomo et al. [7] defined PDas the absence of an escape rhythm for at least 30 safter gradual slowing of the pacing rate to 30 beats/minwithout turning off the pacemaker.Table 3. Comparison between temporary pacingand myocardial infarction with and without escaperhythm.Group of patients Temporary Old myocardialpacing infarctionOverall 106 (2.9%) 139 (3.8%)— 3638 (100%)With escape 48 (1.3%) 95 (2.6%)— 3562 (97.9%)Without escape  58 (76.3%)*   44 (57.8%)*— 76 (2.1%)*p < 0.001 between two valuesTable 2. Number (%) of patients with pacemakerdependency according to pacing indication.Pacing indication Pacemaker dependencyAVB (N = 1482) 52 (3.5%)SSS (N = 1315) 8 (0.6%)SSS and AVB (N = 478) 15 (3.1%)AF/bradycardia (N = 363) 1 (0.3%)See Table 1 for explanation of abbreviations. SSS vs. AF/bradycardia:p = NS; AVB vs. SSS: p < 0.001; SSS vs. SSS and AVB: p < 0.001;AVB vs. AF/bradycardia: p < 0.001; SSS and AVB vs. AF/bradycardia:p < 0.00586Cardiology Journal 2007, Vol. 14, No. 1www.foliacardiologica.euOur definition, based on the absence of an es-cape or intrinsic rhythm for 30 s during temporaryback-up pacing at a rate of 30 beats/min and afterswitching off the pacemaker, identified the highestrisk pacemaker-dependent patients who sufferStokes-Adams attacks, serious injuries or suddendeath if pacing suddenly fails. Therefore a gradualslowing of the pacing rate and afterwards the ces-sation of pacing used in the present study seems tobe the best method for evaluating PD [7]. It mayindicate accidental serious pacing failure and reflectthe number of patients prone to asystole or severebradycardia.As observed in previous works [2, 3, 7], thepatients in the present study with AVB had a high-er incidence of pacemaker dependency during fol-low-up than patients with SSS or AF. The main find-ing of our study is that the patients with temporarypacing prior to pacemaker implantation and withprevious myocardial infarction showed a higher fre-quency of pacemaker dependency. Knowledge ofthe absence of spontaneous ventricular activity ina pacemaker patient has important clinical implica-tions. Malfunction of the pacemaker system shouldbe detected early in these patients and this can beachieved by increasing follow-up frequency [2, 3, 7].It has been clearly established in the past (like-wise as in our study) that there were no differenc-es in age, sex, baseline heart disease (CAD, AH,HF) or previous coronary artery surgery betweenpatients with and without escape rhythm [2–4, 6–8].However, Rosenheck et al. [3, 5] underlined thatpatients without a reliable escape rhythm havea longer history of conduction disorder, a slower in-traventricular conduction (a paced QRS wider than180 ms), and are frequently treated with anti-ar-rhythmic agents. In our retrospective study we didnot analyse drug administration and so were una-ble to assess the potential influence of pharmaco-therapy on PD. However Nagatomo et al. [7] showno correlation between drug administration and thepresence or absence of an intrinsic rhythm duringlong-term follow-up. The incidence of pacemakeror electrode malfunction was found in 1.3% and 6%patients respectively [1]. These patients are at highrisk if PD does occur.ConclusionsIn our study the prevalence of PD was relative-ly low (2.1%). The incidence of PD after deviceimplantation was dependent on the pacing indica-tion and was more common in patients with AVBthan in patients with SSS or AF. Temporary pacingprior to pacemaker implantation and previous my-ocardial infarction indicate patients at risk of devel-oping pacemaker dependency.References1. Duncan-Fraser J, Cameron DA, Radvansky E, Gold-man B. Dependency risk score: usefulness duringa pulse generator recall. In: Gomez FP (ed.) Cardiac pac-ing, electrophysiology, tachyarrhythmias. Futura MediaServices, Mount Kisco, New York, 1985: 1130–1133.2. Staessen J, Ector H, De Geest H. The underlyingheart rhythm in patients with an artificial cardiacpacemaker. PACE, 1982; 5: 801–807.3. Rosenheck S, Bondy C, Weiss AT et al. Comparisonbetween patients with and without reliable ventricularescape rhythm in the presence of long standing com-plete atrioventricular block. PACE, 1993; 16: 272–276.4. Glikson M, Dearani JA, Hyberger LK, Schaff HV,Hammil SC, Hayes DL. Indications, effectiveness,and long-term dependency in permanent pacing aftercardiac surgery. Am J Cardiol, 1997; 80: 1309–1313.5. Rosenheck S, Bondy C, Weiss AT, Gotsman MS.The effect of overdrive pacing rate and duration on ven-tricular escape rhythms in patients with chronic com-plete atrioventricular block. PACE, 1994; 17: 213–221.6. Fedman S, Glikson M, Kaplinsky E. Pacemaker de-pendency after coronary artery bypass. PACE, 1992;15: 2037–2040.7. Nagatomo T, Abe H, Kikuchi K, Nakashima Y. Newonset of pacemaker dependency after permanentpacemaker implantation. PACE, 2004; 27: 475–479.8. Deharo JC, Mansourati J, Graux P et al. Long-termpacemaker dependency after radiofrequency ablationof the atrioventricular junction. Am. Heart J, 1997;133: 580–584.9. Behrens M, Klementowicz P, Andrews C, Ausubel K,Furman S. Pacemaker dependency following cessa-tion of pacing. PACE, 1985; 8: 288 (abstract).

Pacemaker dependency after pacemaker implantation

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Pacemaker dependency after pacemaker implantation

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