Mortality and Incidence of Atrial Fibrillation in Paced Patients

Mortality and AF Incidence in Paced Patients. This review presents and discusses available data from randomized controlled trials on the prognosis of pacemaker patients, especially the incidences of atrial fibrillation (AF) and death, the impact of pacing mode selection, and the impact of AF on prognosis. The incidence of AF is several times higher in paced patients than in the nonpaced population. The annual incidences of AF and chronic AF are at least 5% and 3%, respectively, after pacemaker implantation. Mean lifetime cumulative incidences of AF and chronic AF can be estimated at approximately 30% to 40% and 20%, respectively. The most important predictors of AF are brady‐tachy syndrome, sick sinus syndrome, and selection of VVI(R) pacing mode. The expected lifespan in paced patients is shorter than in the age‐matched nonpaced population. One of the factors decreasing lifespan in paced patients most likely is the high incidence and prevalence of AF. In patients with sick sinus syndrome, VVI pacing significantly increases AF and mortality compared with AAI pacing. In a mixed population of patients with bradycardia, DDD(R) pacing causes AF less often than does VVI(R) pacing. Survival does not differ between these pacing modes within the first 3.5 years after pacemaker implantation. At the present time, AAI(R) should be the preferred pacing mode in patients with sick sinus syndrome, and DDD(R) should be used for other patients without chronic AF for prevention of AF. It is not clear whether prevention of AF will improve survival of paced patients.     

Influence of Cardiac Pacing Mode on Left Atrial Appendage Flow Velocity: Implication to Systemic Embolism During VVI Pacing

Previous studies have shown that the incidence of thromboembolism is higher in patients with single-chamber ventricular demand (VVI) pacemakers than in patients with dual-chamber (DDD) pacemakers. However, data on left atrial appendage flow velocity in pacing patients are limited. To investigate the influence of the pacing mode on the left atrial appendage flow velocity, we studied 19 patients with permanent DDD pacemakers and measured the left atrial appendage flow velocity by transesophageal echocardiography at baseline (during DDD pacing) and after switching to VVI pacing. The indications for pacemaker implantation were second- and third-degree atrioventricular block (AVB group, n = 11) and sick sinus syndrome (SSS group, n = 8). Compared with the DDD pacing mode, there was a significant decrease in the left atrial appendage flow velocity during VVI pacing in both the SSS group (43 ± 14 vs 23 ± 7 cm / sec, P < 0.05) and the AVB group (59 ± 18 vs 41 ± 18 cm / sec, P < 0.05). In eight patients with persistent retrograde ventriculoatrial conduction during VVI pacing, the left atrial appendage flow velocity was markedly decreased (from 43 ± 16 to 25 ± 9 cm / sec, P < 0.05). In five (63%) of the eight patients, left atrial appendage flow velocity was less than 25 cm/sec. A reduction in left atrial appendage flow velocity when switching from DDD to VVI pacing may account for an increased risk of thrombus formation in the left atrial appendage (an increased thromboembolic risk in patients in sinus rhythm with VVI pacemakers).     

Comparison of atrial and VVI pacing modes in symptomatic sinus node dysfunction without associated tachyarrhythmias

The natural course of patients with symptomatic sinus node dysfunction who did not have associated tachyarrhythmias before pacemaker implantation was compared after VVI and atrial pacemaker implantation. Between April 1981 and June 1989, forty-seven such patients (mean age 52 + 13 years) received VVI pacemakers and forty patients (mean age 54 + 13 years) received AAI or DDD pacemakers. Baseline clinical characteristics and severity of sinus node dysfunction were comparable in the two groups. Over a follow up of 10 to 96 months (mean 49.2 + 26 months), 11 (23.4%) VVI patients were in functional class II or more compared to 2 (5%) atrially paced patients (p less than 0.01). Other complication rates were also higher in the VVI group as compared to AAI group viz. atrial fibrillation (21.2% vs 2.5% p less than 0.01) and stroke (10.6% vs 2.5%) though the number of deaths (14.9% vs 10%) was not significantly different in the two groups. Two patients in atrial paced group and one patient in VVI group developed first degree heart block. There was no incidence of second or third degree heart block. Transient loss of atrial sensing occurred in 3 patients and atrial lead displacement in 2 cases, but overall incidence of lead related problems was low and comparable in both groups. Thus atrial pacing is superior to ventricular pacing in sinus node dysfunction and risk of developing high grade atrioventricular block on follow up is low.     

起搏术后心房颤动的影响因素及心房颤动与心钠素的关系

目的观察心脏起搏术后发生心房颤动(简称房颤)的影响因素及房颤与血心钠素(ANP)的关系。方法选择安装心脏起搏器的患者103例进行随访,分析房颤与年龄、起搏方式、心律失常类型、左房内径(LAD)、左室射血分数(LVEF)和血ANP的关系。结果①65岁以下患者房颤发生率低于65岁以上组(P<0.05)。②VVI组房颤发生率高于DDD组(P<0.05)。③慢快综合征组房颤发生率较缓慢型病窦综合征和房室传导阻滞组高(P<0.05)。④VVI房颤组术后LAD增大、LVEF下降(P<0.05),VVI房颤组术后与DDD组比较有差异(P<0.05)。⑤VVI房颤组和VVI窦性心律组ANP浓度较DDD组高(P<0.05);各组不同心功能级别(NYHA)之间ANP浓度随着心功能级别的加重而升高。结论长期心脏起搏术后房颤的发生可能与年龄大、VVI起搏、病窦综合征(慢快型)、LAD增大、LVEF降低及ANP浓度升高相关。     

Left atrial appendage function during DDD and VVI pacing.

OBJECTIVE: To examine, using transoesophageal echocardiography, the possible disturbances of left atrial appendage function during VVI and DDD pacing in patients with a normal atrium paced with a dual chamber system. DESIGN: Randomised controlled trial. SETTING: Tertiary care centre. PATIENTS: 22 patients (mean age 68 (SD 6) years) who had been paced with dual chamber pacemakers for at least six months. Exclusion criteria were valvar disease, cardiomyopathy, hypertension, and diabetes mellitus. INTERVENTIONS: All patients underwent a transoesophageal echocardiographic evaluation of left atrial appendage function under DDD and VVI modes in random order. Measurements were made after at least two months' pacing in each mode. MAIN OUTCOME MEASURES: Echocardiographic indices of left atrial appendage flow under both pacing modes. RESULTS: All 22 patients had higher emptying and filling flow velocities under DDD than under VVI mode. The filling and emptying flow velocity integrals were also significantly higher under DDD mode (P < 0.001, P = 0.019). CONCLUSIONS: Left atrial appendage function, as reflected in indices of emptying and filling assessed by transoesophageal echocardiography, is significantly different with DDD than with VVI pacing. This may explain the higher incidence of thromboembolic episodes in patients paced under VVI mode.     

Benefits of dual chamber pacing in sick sinus syndrome

The effects of DDD (fully automatic) and VVI (ventricular demand) pacing modes on exercise tolerance, symptom diary cards, and Holter monitoring were investigated in a randomised double blind crossover study of 16 patients who had had DDD pacemakers implanted because of frequent syncope. Eight patients presented with sick sinus syndrome and, with one exception, retrograde atrioventricular conduction and eight age and sex matched patients presented with 2:1 or complete atrioventricular block. Maximal symptom limited exercise in those with atrioventricular block was significantly higher after one month of DDD pacing than after VVI pacing. In those with sick sinus syndrome, however, maximal effort tolerance was not significantly different for the two pacing modes. In all but one patient with sick sinus syndrome sinus rhythm developed during exercise in VVI pacing. For both VVI and DDD modes maximal atrial rates were significantly lower in those with sick sinus syndrome. Palpitation and general wellbeing were significantly improved during DDD pacing in the eight patients with sick sinus syndrome. Shortness of breath was improved by DDD pacing in the eight patients with atrioventricular block but not in those with sick sinus syndrome. Holter monitoring showed that sick sinus syndrome patients remained in paced rhythm, either DDD or VVI, for most of the 24 hour period. DDD pacing was better than VVI pacing in sick sinus syndrome with retrograde atrioventricular conduction. Despite their ability to show sinus rhythm and inhibit their pacemakers on exercise patients with sick sinus syndrome are just as likely to have symptomatic benefit from DDD pacing as patients with atrioventricular block.     

Benefits of dual chamber pacing in sick sinus syndrome.

The effects of DDD (fully automatic) and VVI (ventricular demand) pacing modes on exercise tolerance, symptom diary cards, and Holter monitoring were investigated in a randomised double blind crossover study of 16 patients who had had DDD pacemakers implanted because of frequent syncope. Eight patients presented with sick sinus syndrome and, with one exception, retrograde atrioventricular conduction and eight age and sex matched patients presented with 2:1 or complete atrioventricular block. Maximal symptom limited exercise in those with atrioventricular block was significantly higher after one month of DDD pacing than after VVI pacing. In those with sick sinus syndrome, however, maximal effort tolerance was not significantly different for the two pacing modes. In all but one patient with sick sinus syndrome sinus rhythm developed during exercise in VVI pacing. For both VVI and DDD modes maximal atrial rates were significantly lower in those with sick sinus syndrome. Palpitation and general wellbeing were significantly improved during DDD pacing in the eight patients with sick sinus syndrome. Shortness of breath was improved by DDD pacing in the eight patients with atrioventricular block but not in those with sick sinus syndrome. Holter monitoring showed that sick sinus syndrome patients remained in paced rhythm, either DDD or VVI, for most of the 24 hour period. DDD pacing was better than VVI pacing in sick sinus syndrome with retrograde atrioventricular conduction. Despite their ability to show sinus rhythm and inhibit their pacemakers on exercise patients with sick sinus syndrome are just as likely to have symptomatic benefit from DDD pacing as patients with atrioventricular block.     

Inducibility of atrial fibrillation during atrioventricular pacing with varying intervals: role of atrial electrophysiology and the autonomic nervous system

INTRODUCTION: Patients receiving VVI pacemakers have a higher incidence of paroxysmal atrial fibrillation (AF) than those receiving DDD pacemakers. However, the mechanism behind the difference is not clear. The purpose of this study was to investigate whether atrial electrophysiology and the autonomic nervous system play a role in the occurrence of AF during AV pacing. METHODS AND RESULTS: The study population consisted of 28 patients who had (group I, n = 15) or did not have (group II, n = 13) AF induced by a single extrastimulus during pacing with different AV intervals. Atrial pressure, atrial size, atrial effective refractory periods, and atrial dispersion were evaluated during pacing with different AV intervals. Twenty-four-hour heart rate variability and baroreflex sensitivity also were examined. Atrial pressure, atrial size, effective refractory periods in the right posterolateral atrium and distal coronary sinus, and atrial dispersion increased as the AV interval shortened from 160 to 0 msec. During AV pacing, group I patients had greater minimal (52+/-17 vs 25+/-7 msec; P < 0.005) and maximal (76+/-16 vs 36+/-9 msec; P < 0.005) atrial dispersion than group II patients. The differences in atrial size and atrial dispersion among different AV intervals were greater in patients with AF than in those without AF. Baroreflex sensitivity (6.6+/-1.7 vs 3.9+/-1.0; P < 0.00005), but not heart rate variability, was higher in patients with AF than in those without AF. CONCLUSION: Abnormal atrial electrophysiology and higher vagal reflex activity can play important roles in the genesis of AF in patients receiving pacemakers.     

心脏起搏患者心房颤动和脑栓塞发生率的长期随访

为了解起搏患者心房颤动 (AF)和脑栓塞 (CE)的发生率及其影响因素 ,12 5例起搏患者术后每 6～ 12个月随访一次 ,随访时暴露自身心律并记录术后CE事件。 12 5例患者随访 5 .88± 0 .34(1.5～ 2 4.6 )年。术前AF总的发生率为 2 8% (35 / 12 5 ) ,术后为 40 % (5 0 / 12 5 ) ,其中术后新发生持续性AF(CAF) 15 % (18/ 12 0 )、阵发性AF(PAF) 5 .5 %(5 / 90 )。影响AF发生的因素 :①起搏方式 :VDD患者未见AF发生 ,AAI、VVI和DDD三种起搏方式间AF发生率无显著性差异。②术前存在PAF者 ,术后CAF发生率明显升高 ,达 2 6 .7% (8/ 30 )。③心律失常类型 :慢 快综合征患者术后CAF的发生率 30 .3% (10 / 33)显著高于缓慢性病窦综合征 6 .4% (3/ 47)和房室阻滞 11.1% (5 / 45 )患者 (P均<0 .0 5 )。④年龄 :6 0岁以上患者中CAF的发生率显著高于 6 0岁以下患者 (P <0 .0 5 )。术后CE发生率为 5 .6 % ,伴AF者显著高于不伴AF者 (P <0 .0 1) ,而未见起搏方式对其影响。结果提示 :在起搏随访时应重视对AF的检出及治疗 ,避免由此造成的起搏功能障碍、起搏并发症和CE ,并充分考虑基础心律失常类型、起搏方式和年龄可能产生的影响。     

VVI与DDD起搏对病窦综合征患者远期疗效的比较

比较VVI与DDD起搏方式对病窦综合征患者的临床疗效。研究病窦综合征患者212例,按不同起搏方式分为两组:VVI组105例、DDD组107例。研究终点:①在每次预定的随访中,以标准12导联ECG、Holter及心电监护诊断心房颤动(简称房颤);②卒中:当患者有大于24h脑缺血事件而产生神经系统症状或24h内死于脑血管事件,可确诊为卒中;③死亡:心血管事件死亡。患者出院后1,3,6个月定期随访,以后每隔半年随访一次。随访时,记录标准12导联ECG存档。每例患者至少有一份ECG,部分患者做Holter,了解有无阵发性房颤及术后发生持续性房颤的时间,患者的症状及体征。结果:①与VVI组比较,DDD组房颤发生率明显降低(10.3%vs24.8%,P<0.05);②VVI组患者6例出现脑卒中(5.7%),而DDD组无1人发生脑卒中,两组差异有显著性(P<0.05);③VVI组共有3例在术后3,4年发生慢性充血性心力衰竭,最后死于恶性心律失常,而DDD组患者均无因心力衰竭住院,随访至今无死亡。DDD组11例房颤均在2年内发生,其中第1年7例,而VVI组有26例房颤发生的时间较为弥散,2年内发生8例(30.8%),其余在3~8年内陆续发生。结论:病窦综合征患者安装双腔起搏器治疗发生房颤和脑卒中的机率明显减少。     

Cost benefit analysis of single and dual chamber pacing for sick sinus syndrome and atrioventricular block: An economic sensitivity analysis of the literature

The benefits of dual (DDD) over single chamber pacing (VVI)have been demonstrated in haemodynamics, exercise capacity,quality of life and reduced complications in atrioventncularblock and sick sinus syndrome. The literature was reviewed to provide complication rates fordual and VV1 pacing. Cost calculations were based on UnitedKingdom 1991 prices. Over a 10-year period, a computer modelcalculated the incidence and prevalence of atrial fibrillation,stroke, permanent disability, heart failure and mortality insix patient categories: sick sinus syndrome paced VVI, sicksinus syndrome upgraded to DDD, sick sinus syndrome paced DDDfrom outset, atrioventricular block paced VYI and those upgradedto DDD and atrio ventricular block paced initially DDD. Calculationswere based on intention to treat. The 10 year survival with DDD vs YVI pacing was 71% vs 57% insick sinus syndrome and 61% vs 51%, respectively, in atrioventricularblock. In both indications the prevalence of heart failure inthe 10 year survivors was 600 lower with DDD pacing. In sicksinus syndrome patients paced VVI, 36% had severe disabilitywhile only 8% experienced this with DDD pacing. For atrioventricularblock the figures were, respectively, 22% vs 3%. The differencein 10 year cumulative cost between VVI and DDD is 13 times thepurchase price of a VVI pulse generator for sick sinus syndromeand 7 times for atrioventricular block. In the third year afterimplantation the cumulative costs of DDD were lower than forVVI for both indications. Dual chamber pacing for both indications, sick sinus syn dromeand atrioventricular block, is both clinically and cost effective.     

Clinical significance of prolonged P wave width after right atrial appendage pacing in sick sinus syndrome.

The present study investigated both the clinical significance of atrial fibrillation (AF) before right atrial appendage (RAA) pacing and the influence of prolonged P wave on AF occurrence in RAA-paced patients with sick sinus syndrome (SSS). Fifty-seven patients (age 68+/-10 years; 19 men, 38 women) with SSS who underwent RAA pacing were divided into 2 groups: 23 patients without AF before pacing (I + II; Rubenstein I or II) and 34 patients with AF before pacing (III; Rubenstein III). The P wave duration in intrinsic rhythm and with RAA pacing were measured on the standard electrocardiography in leads II and V(1) with the use of a digitizing tablet. Group III was further subdivided into 2 groups: 20 patients (IIIb) with a paced P wave >130 ms in both leads II and V(1) and the other 14 patients (IIIa). The duration of the intrinsic P wave in leads II and V(1) was significantly greater in group III than in group I + II (119+/-20 vs 108+/-21 ms, p=0.0417, 106+/-16 vs 95+/-21 ms, p=0.0258, respectively). During the follow-up of 40+/-21 months, AF recurrence was significantly higher in group IIIb than in groups IIIa and I + II (17/20 vs 5/14 vs 2/23 p<0.0001). A few occurrences of AF were observed by conventional RAA pacing in patients without AF before pacing. However, SSS with AF before pacing caused a significant intra-atrial conduction disturbance and a high incidence of AF recurrence after implantation of RAA pacing, especially in patients with a prolonged paced P wave, in whom new pacing modalities may be needed to shorten paced P wave duration and prevent AF.     

Acute short-term effect of VVI pacing mode on P wave dispersion in patients with dual chamber pacemakers

The acute or chronic effect of VVI pacing on P wave duration in the same patient with dual chamber pacemaker has not been studied before. Hence, with the purpose of determining whether VVI pacing increases dispersion of atrial refractoriness, we undertook a comparative study with the aid of a simple noninvasive approach, namely P wave dispersion (PWD) determined from surface electrocardiogram in the same patients who were implanted with dual chamber pacemakers. Pmax duration calculated in VVI paced mode was significantly higher than in VDD paced mode (121+/-21 vs. 111+/-17 ms, P=0.021). PWD (33+/-15 vs. 40+/-23 ms, P=0.062) did not demonstrate any significant difference between VDD and VVI paced modes, respectively. In conclusion, the findings of our study suggest that short-term VVI pacing itself does not have any direct effect on PWD in patients with dual chamber pacemakers. Different pacing modes in the long term might be responsible for altering PWD and the occurrence of atrial fibrillation while affecting the autonomic nervous system.     

Deleterious effects of long-term single-chamber ventricular pacing in patients with sick sinus syndrome: the hidden benefits of dual-chamber pacing.

Nine hundred fifty patients who received three modes of primary pacemaker systems (581 dual-chamber universal [DDD], 84 atrioventricular-sequential ventricular-inhibited [DVI] and 285 ventricular-inhibited [VVI]) over 12 years were studied retrospectively to determine the effect of pacing mode on patient longevity and the subsequent development of chronic atrial fibrillation or flutter. All patients were followed up continuously for 7 to 8 years. Patients were classified according to indication for permanent pacing (sick sinus syndrome or other indication), age at pacemaker implantation (less than or equal to 70 or greater than 70 years) and history of atrial tachyarrhythmia. Fourteen percent of patients developed atrial fibrillation at some time during the study period. Of those, 4% had a DDD pacemaker, 8% had a DVI pacemaker and 19% had a VVI pacemaker. At 7 years, atrial fibrillation was significantly more frequent in the VVI group than in the DDD and DVI groups. In patients with sick sinus syndrome, the incidence rate was even higher in the VVI group but approximately the same in the DDD and DVI groups. Patients in the VVI and DVI groups who had had previous atrial tachyarrhythmia had a significantly higher incidence of atrial fibrillation at 7 years than did those in the DDD group. During the entire period there were 130 deaths in the study group, including 22% of patients with a DDD pacemaker, 38% of those with a DVI pacemaker and 50% of those with a VVI pacemaker. Patient survival at 7 years was lower in the VVI group than in the DDD or DVI groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

不同起搏方式对病窦综合征患者远期效果的影响

为了解不同起搏方式对病窦综合征特别是慢－快综合征患者心功能及房性心律失常的影响，利用超声心动图、体表心电图及Ｈｏｌｔｅｒ检查，对２１１例病窦综合征患者采用自身对照方法进行回顾性分析。结果发现：生理性起搏（ＡＡＩ／ＤＤＤ）组术后左室射血分数（ＬＶＥＦ）、心输出量（ＣＯ）明显增加（ＡＡＩ：５３．５±６．１％ｖｓ４７．２±７．８％，４．９５±０．５７Ｌ／ｍｉｎｖｓ４．２０±０．６２Ｌ／ｍｉｎ；ＤＤＤ：５２．５±６．８％ｖｓ４４．３±０．１％，５．１２±０．７１Ｌ／ｍｉｎｖｓ４．４１±０．３８Ｌ／ｍｉｎ；Ｐ均＜０．０１），左房内径（ＬＡＤ）无明显变化；ＤＤＤ组Ｅ／Ａ比值明显增加（０．９８±０．０９ｖｓ０．８７±０．１５，Ｐ＜０．０１），ＡＡＩ组Ｅ／Ａ比值呈增加趋势（Ｐ＝０．０５７）。房性心律失常发生率明显减少（１５．９％ｖｓ５０％，Ｐ＜０．０１）。非生理性起搏（ＶＶＩ）组术后ＬＶＥＦ、ＣＯ明显下降（４４．１±４．７％ｖｓ４８．３±４．３％，３．７７±０．４２Ｌ／ｍｉｎｖｓ４．１７±０．８５Ｌ／ｍｉｎ，Ｐ均＜０．０１），ＬＡＤ明显增大（３９．２６±２．３７ｍｍｖｓ３６．８１±２．３５ｍｍ，Ｐ＜０．０１），Ｅ／Ａ比值呈?     

Left atrial appendage function in patients with different pacing modes

Many studies suggest that patients who receive a ventricular pacemaker have a higher incidence of systemic thromboembolism compared to patients receiving a physiological pacemaker. However, the exact mechanism regarding the etiology of thromboembolism remains unclear. We evaluated the left atrial appendage (LAA) functions, using multiplane transesophageal echocardiography (TEE), in patients with different pacing modes. In order to evaluate the ejection fraction (EF), peak emptying (V(E)) and filling (V(F)) flow velocities of the LAA by TEE, we studied 31 patients (mean age 63+/-18.5 years) who had been paced for 5.0+/-2.9 years. Patients with atrial fibrillation, left ventricular dysfunction and mitral valve disease were excluded. The pacing indications were complete atrioventricular block (AVB) in 19 patients (9 VVI, 10 VDD or DDD) and sick sinus syndrome (SSS) in 12 patients (5 VVI, 7 DDD). Mean EF, V(E) and V(F) of the LAA were significantly lower in all patients with ventricular pacing (25.5+/-15.6%, 30.4+/-15.6 cm/s and 29. 1+/-19.2 cm/s, respectively) compared to those with physiologic pacing (48.5+/-16.9%, 59.6+/-16.3 cm/s, 57.9+/-18.5 cm/s, respectively) (P<0.01 in all). When patients were further classified with respect to underlying heart disease whether they had SSS or AVB, all measurements of the LAA (EF, V(E) and V(F)) in both subgroup of patients with SSS and AVB were found significantly lower in those with ventricular pacing than in those with physiologic pacing (Tables 3 and 4). This decrease, especially in LAA flow, was much greater in those with SSS (Mean V(E) and V(F) <20 cm/s). In a patient paced with VVI for SSS, a thrombus was detected within the LAA cavity. In conclusion, these results suggest that the pacing modality appeared to influence the LAA functions in paced patients. Patients with asynchronous ventricular pacing modes had a significantly higher incidence of depressed LAA functions than did patients with physiological pacing, especially more marked in patients with sick sinus syndrome. This may be a factor responsible for increased risk of thrombus formation and thromboembolic events in this patient population.     

Dual chamber pacing: how many patients remain in DDD mode over the long term?

OBJECTIVE--DDD pacing is better than VVI pacing in complete heart block and sick sinus syndrome but is more expensive and demanding. In addition, some patients have to be programmed out of DDD mode and this may have an important impact on the cost-effectiveness of DDD pacing. The purpose of this study was to determine how many patients remain in DDD mode over the long term (up to 10 years). DESIGN--A retrospective analysis of the outcome over 10 years of consecutive patients who had their pacemakers programmed initially in DDD mode. SETTING--A district general hospital. PATIENTS--249 patients with DDD pacemakers. Sixty two patients (24.9%) had predominantly sick sinus syndrome and 180 (72.3%) had predominantly atrioventricular conduction disease. Mean (range) complete follow up for this group of patients was 32 months (1-10 years). RESULTS--Cumulative survival of DDD mode was 83.5% at 60 months. Atrial fibrillation was the commonest reason for abandonment of DDD pacing. Atrial fibrillation developed in 30 patients (12%), with atrial flutter in three (1.2%). Loss of atrial sensing or pacing, pacemaker mediated tachycardia, and various other reasons accounted for reprogramming out of DDD mode in eight patients (3.2%). Overall, an atrial pacing mode was maintained in 91% and VVI pacing was needed in only 9%. CONCLUSIONS--With careful use of programming facilities and appropriate secondary intervention, most patients with dual chamber pacemakers can be maintained successfully in DDD or an alternative atrial pacing mode until elective replacement, although atrial arrhythmia remains a significant problem. There are no good reasons, other than cost, for not using dual chamber pacing routinely as suggested by recent guidelines and this policy can be achieved successfully in a district general hospital pacing centre.     

Pacemaker selection: time for a rethinking of complex pacing systems?

Evidence from randomized trials indicates that the clinical benefits of dual-chamber (DDD) pacing are modest: (i) no significant differences exist between physiological pacing and single-chamber pacing in mortality and stroke; (ii) ventricular desynchronization resulting from chronic right-ventricular pacing in DDD mode, induces a significantly increased incidence of atrial fibrillation (AF) and heart failure hospitalizations; (iii) AF pacing prevention and therapy algorithms have shown a modest to minimal or absent efficacy; (iv) the widespread use of physiological pacemakers is not an economically attractive strategy. Thus, these data provide a reliable body of evidence on which to make more rationale clinical decisions for individual patients and policy decisions for health costs saving. The cheaper single-chamber AAI(R) or VVI(R) has been shown to satisfy both conditions in most cases of sinus node disease and AV block.     

Permanent cardiac pacing and thromboembolic risk in elderly patients

In patients undergoing permanent cardiac pacing, the maintenance of atrial contractility is important to ensure adequate ventricular filling and to guarantee an optimal ventricular ejection capacity. The appropriate pacing mode, assuring a suitable mechanical atrioventricular coupling, prevents the onset of atrial fibrillation and contributes to reduction of the risk of subsequent systemic and pulmonary thromboembolic episodes. We examined 461 patients (266 males and 195 females, aged between 52 and 97 years, average age 76.5 +/- 18) paced for conduction disturbances of various degrees and etiology. Of them, 323 patients received ventricular demand pacemaker (VVI group, average age 77.9 years); 138 underwent dual chamber pacing (DCP group, average age 75.2 years), 117 of the latter received universal demand pacing (DDD) and 21 atrial synchronous ventricular demand pacing (VDD). The patients were subsequently divided into two age-groups: Group A (/= 75 years, 287 patients). According to pacing mode and successive development of stable atrial fibrillation (AF), we analysed the occurrence of systemic and/or pulmonary thromboembolic episodes and the incidence of fatal events. During our study, performed from January 1986 to August 1993, 70 embolic episodes were observed in the VVI group and six in the DCP group. Eighty-four patients with VVI units developed AF during follow-up, compared with only five patients in the DCP group. Our data indicate that VVI patients have a higher incidence of AF, embolic complications and cerebrovascular mortality, in comparison with the DCP group. VVI pacing should be avoided, especially in older patients, when atrial rhythmical activity is present.