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Three Part Question

In [patients who have undergone cardiac surgery] does [atrial pacing] decrease the incidence of [postoperative atrial fibrillation]?

Clinical Scenario

You are concerned to note that the incidence of postoperative atrial fibrillation in your unit is almost 40% after elective cardiac surgery. You have read a recent review that suggests that postoperative atrial pacing may protect patients against atrial fibrillation and as all patients receive right atrial wires in your unit intra-operatively this seems to be a simple opportunity to reduce the incidence of AF without the inherent complications of pharmacological prophylaxis. Thus you resolve to explore the literature further with a view to implementing a departmental policy for post-operative atrial pacing.

Search Strategy

Medline 1966-August 2004 and EMBASE 1980 to August 2004 using the OVID interface.
[exp Cardiac Pacing, Artificial/ OR exp Pacemaker, Artificial/ OR pacing.mp] AND [atrial.mp or biatrial.mp or bi-atrial.mp or bachman$.mp] AND [Atrial fibrillation.mp OR exp Atrial Fibrillation/ OR Atrial flutter.mp OR exp Atrial Flutter/ OR AF.mp OR supraventricular tachycardia.mp OR exp Tachycardia, Supraventricular/] AND [CABG.mp OR Coronary art$ bypass.mp OR Cardiopulmonary bypass.mp OR exp Cardiovascular Surgical Procedures/ OR exp Cardiac Surgical Procedures/ OR exp Coronary Artery Bypass/ OR Cardiac Surgery.mp]

Search Outcome

A total of 229 papers were found in Medline and exactly 229 papers were also found in Embase of which 14 were relevant. An additional 2 papers were found by checking reference lists.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Crystal et al 2002 Canada	10 trials found that investigated pacing in the prevention of AF, found from searching Medline, Embase, Cinhal up to April 2001 trials found from 9-100 patients in treatment groups.	Meta-analysis level 1a	Odds reduction of Biatrial pacing	Biatrial pacing reduces AF, OR 0.46 (95%CI 0.30-0.71) (744pts enrolled)
			Odds reduction of Right atrial pacing	Right atrial Pacing reduces AF, OR 0.68 (95%CI 0.39-1.19) (581 pts enrolled)
			Odds reduction of Left atrial pacing	Left Atrial Pacing reduces AF, OR 0.57 (95%CI 0.28-1.16) (148pts enrolled)
			Odds reduction for fixed and flexible pacing algorithms	Fixed Rate OR 0.58 (95%CI 0.32-1.02). Flexible pacing algorithm OR 0.62 (95%CI 0.38-1.01)
Debrunner et al 2004 Switzerland	80 patients with no previous history of AF undergoing valve surgery +/- CABG Control RA wires (lateral wall RA) n=40; Biatrial synchronous pacing (BAP) – RA (lateral wall RA); + LA (between insertion of pulmonary veins) wires Control group paced via RA for haemodynamic compromise if rate < 80 / min BAP group paced using algorithm 10bpm above intrinsic rate up to max 110/min from immediately postop to 72 hrs postop Telemetry / Holter ECG monitoring for 72 hours	PRCT level 1b	At least 2 mins of AF within first 72 hours of surgery confirmed by 2 independent physicians	18/40 (45%) control developed AF within first 3 days compared with 8/40 (20%) of BAP group (p=0.02). Differences more marked in subgroup analysis of 25 patients on preoperative beta-blockers – 1/14 paced versus 6/11 unpaced (p=0.0088). 12/18 control patients and 4/8 "paced group" who developed AF had persistent AF	52/80 male Not blinded Possible confounding effects of beta-blockade in 30% of patients
			complications	No complications / sequelae related to wire placement
			Use of anti-dysrhythmic therapy at discharge	All patient in sinus rhythm at discharge - 17/40 control and 7/40 "paced group" discharged on anti-dysrhythmic therapy (p=0.015)
Goette et al 2002 Germany	161 patients with no history of AF randomized pre-CPB 50/161 control – RA pacing wire placed but not used; 60/161 paced via lateral wall RA wire; 51/161 paced at Bachman Bundle –(functional biatrial pacing) AAI pacing immediately after surgery in two actively paced groups for 5 days @ 96 bpm	PRCT level 1b	occurrence of AF >= 1 minute measured by telemetry	Of 161 patients, 21/50 controls (42%); 29/60 RA pacing (48%); 19/51 Bachmann bundle pacing (37%) developed AF (intention to treat analysis). Differences between groups not statistically significant. 137 patients analysed according to pacing actually received (24 patients withdrawn from study for clinical reasons). 11/39 (28%) control, 25/54 (47%) RA paced and 11/44 (25%) Bachman Bundle-paced groups developed AF developed. Differences between groups versus control not statistically significant although comparison of incidence of AF in paced groups was, favouring Bachman-bundle pacing (p< 0.05). No sequelae related to pacing wires	Surgeon randomisation led to unequal group sizes 24 patients withdrawn from study for clinical reasons (11 control; 6 RA paced; 7 Bachman-bundle paced) Fixed pacing rate – loss of pacing @ intrinsic rates > 96 bpm 5 days pacing; 96 hours monitoring
Gerstenfeld et al 2001 USA	118 patients randomised to biatrial pacing (BAP) for 96 hours post-op 60 controls and 58 in BAP group Treatment and control group both given beta-blockers as tolerated Active group paced in AAI mode at 100 bpm	PRCT level 1b	AF > 10 mins	Control group 21/60 35%. BAP group 11/58 19% BAP (p<0.05). Incidence of AF in isolated AVR group 35% control versus 21% BAP (p=0.08). Beneficial effect of pacing greatest in those over 70 years – 55% control versus 25% BAP developed AF (p<0.05). No significant difference in incidence of AF for those aged < 70 years
Levy et al 2000 UK and Circulation 2000	130 CABG patients sinus rhythm. Biatrial group (n=65) 4 days DDD biatrial pacing at base rate 80 bpm using an atrial resynchronised algorithm Control (n=65) (DDD pacing with base rate 30 bpm) Temporary atrial epicardial leads placed lateral wall RA and Bachmann Bundle LA during surgery Pacing box functioned as Holter and was interrogated at end of study	Unblinded PRCT level 1b	Episode of AF lasting > 1 hour on pacemaker Holter	Biatrial pacing decreased monitored AF from 25/65 (38.5%) in control group to 9/65 (13.8%) (p=0.001). Biatrial pacing decreased any monitored or clinical AF from 26/65 (40%) in control group to 10/65 (15.4%). (p=0.001)	underpowered for ITU / hospital stay Biatrial pacing lead failure rate 20% All patients on beta-blockers had these withdrawn post-operatively.
			Clinically detected AF	Biatrial pacing decreased clinically detected AF from 21/65 (32.3%) in control group to 7/65 (10.8%) (p=0.002) during study period
			ITU and Hospital stay	Mean and median ICU and hospital stay NS, although those in control group who developed AF spent significantly more time in ITU and hospital than those who didn't (p 0.001 - 0.05).
			Postoperative complications	Serious complication rate decreased from 35 to 13 (p=0.001) in control versus paced group
Daoud et al 2000 USA	118 patients undergoing open heart surgery right atrial pacing at 45 bpm (RA-AAI; n=39), right atrial triggered pacing at a rate of >=10 bpm above native rate but not < 85 bpm (RA-AAT; n=38), simultaneous right and left atrial triggered pacing at rate >= 10 bpm above native rate but not < 85 bpm (Bi-AAT; n=41). Controls (n=39) (RA-AAI) at an inhibition rate of 45bpm Pacing achieved via temporary epicardial leads placed on anterior-superior RA and posterior-inferior LA between coronary sinus and right inferior pulmonary vein Pacing commenced within 12 hours of surgery and continues until 24 hours before discharge.	Double Blind PRCT Level 1b	Postoperative AF lasting more than 5 minutes detected on Holter and telemetric monitoring	4/41 (10%) Bi-AAT group developed AF, compared to 11/39 (28%) RA-AAI group (p=0.03 versus Bi-AAT) and 12/38 (32%) RA-AAT group (p=0.01 versus Bi-AAT). No statistical difference between incidence of AF with RA-AAI and RA-AAT groups (p=0.8). No complications related to presence of pacing wires.	Pacing wire failure (60% RA and 80% LA electrodes had failed by 5th postop day) Most patient beta-blocked Mixed group of patients – 100/118 CABG patients Delay in commencing pacing at beginning of study
Fan et al 2000 China	132 post-CABG patients with no history of AF randomised to receive overdrive atrial pacing via temporary epicardial pacing wires placed at the right atrial appendage and / or roof of left atrium at surgery. Four groups - 32pts Biatrial pacing (BiA); 33pts left atrial pacing (LA); 36pts right atrial pacing (RA); 31pts no pacing (Control) Pacing rate 90 bpm unless intrinsic rate higher than this in which case rate set at 10 bpm more. Max paced rate 120 bpm. Overdrive pacing continued for 5 days	PRCT level 1b	Incidence of postoperative atrial fibrillation lasting > 10 minutes or requiring urgent intervention assessed by continuous telemetry and daily ECG's	BiA group 4/32 12.5%. Left atrial group 12/33 36.4% Right Atrial group 12/36 33.3% Control group 13/31 41.9% (p<0.05 for BiA against all other groups)	Premature termination of pacing in 12 patients due to technical problems (raised pacing thresholds and / or poor sensing). Their data processed in an "intention-to-treat" analysis but no information on "spread" across 3 active treatment groups. 70% patients male Continued perioperative use of beta-blockade in 54% of patients. 12% had pre-operative Beta-blockers withdrawn.
			Length of hospital stay	Length hospital stay significantly less for BiA group (7.0 +/- 1.4 days) compared to Control group (9.6+/-4.2 days) p=0.003
Greenberg et al 2000 USA	154 patients undergoing cardiac surgery Excluded if in AF preop or were receiving anti-dysrhythmic therapy RA (posterior aspect RA) and LA (lateral wall just inferior to origin of right superior pulmonary vein) temporary epicardial leads inserted at surgery 4 patient groups – 40/154 right atrial pacing (RAP), 35/154 left atrial pacing (LAP), 31/154 biatrial pacing (BAP), 48/154 control (no pacing unless clinically indicated- pulse < 50 bpm) Paced commence as soon as possible post-op for 72 hours using rate of 100bpm, unless native rate was 80-89 (105bpm) or over 90bpm (110bpm) Continuous ECG and telemetry for 96 hours. ECG's reviewed by "blinded" medical staff	Single blinded PRCT level 1b	Postoperative atrial fibrillation lasting > 1 hour or resulting in haemodynamic compromise requiring electrical or chemical intervention	RAP group 3/40 (8%); LAP group 7/35 (20%) BAP group 8/31 (26%) control group 18/48 (37.5%). Incidence of AF decreased from 37.5% (control) to 17% (paced patients). P<0.005. RAP had 79% decrease in AF compared to Control (p=0.002) Post op AF decreased in LAP and BAP groups compared to control but not statistically significant	Technical limitations of BAP equipment used Beta blockers given to all patients so unable to separate effect of that from pacing – may have influenced overall rate 115/154 male; 88% patients undergoing CABG alone; remainder valves or combined procedure Difficulty maintaining pacing protocol for duration of study in all groups – RAP 10%, LAP 23%, BAP 33% - had problems maintaining pacing protocol. 19% of control patients also required therapeutic pacing for medical reasons Monitoring- used constant ECG monitoring with alarms rather than Holter
			Length of hospital stay (surgery to discharge)	Length of hospital stay decreased by 22% control versus paced groups (P=0.003); RAP versus control hosp stay p=0.01. No sequelae related to placement / removal of wires
Blommaert et al 2000 Belgium	96 consecutive post CABG patients haemodynamically stable in sinus rhythm without anti-dysrhythmics on 2nd POD. Treatment group paced via temporary epicardial wires placed high on the right atrium utilising dynamic overdrive pacing algorithm for 24 hours versus control (not paced) Dynamic pacing algorithm set to pace in AAI mode with rate of 80-125 bpm to stimulate at rate just above patient's own intrinsic rate All patients received pacing wires to high RA near sinus node and RV routinely	PRCT level 1b	Primary end-point was AF sustained for 15 minutes identified by Holter ECG. Data from ECG monitoring system reviewed by Cardiologist	Pacing group AF 5/48 (10%). Control group AF 13/48 (27%) (p=0.036). Duration of AF episodes comparable (p=0.27). Multivariate analysis showed this difference only relevant for patients with LV ejection fraction over 50% (rate of AF 6% in paced versus 26% in control group). No significant difference (p=0.27) in duration of AF episodes between groups	Small groups; mainly male (73/96) Concomitant use of beta-blockers in > 50% patients (but no statistical difference between groups) Day 2 chosen as time when incidence of AF at its highest but short monitoring period used so long term benefits cannot be commented on.
Chung et al 2000 USA	100 post-CABG patients not in AF / flutter at time of postop randomisation AAI group, n=51 pacing at least 10 beats / min more than resting native rate(paced rates 90-110 bpm) via temporary atrial and ventricular epicardial leads placed during surgery. Control group n=49 Control group could receive protective anti-bradycardia pacing in VVI mode at 60 bpm at discretion of attending physicians Commenced 1st postop day and continued to 4th postop day.	PRCT level 2b	Incidence of new AF / flutter in first 4 days post-CABG requiring pharmacological / electrical treatment.	AAI group AF 13/51 (25.5%). Control group 14/49 (28.6%) (p=0.90) by 4th. Atrial depolarization frequency significantly higher in control patients who developed AF compared to those who did not (p=0.023)	Lots of exclusions prior to randomisation – 172 recruited preop but 72 excluded prior to randomisation due to haemodynamic instability, rhythm disturbance (including development of AF) and lead failure Multiple problems in pacing group – [1] Pacing in AAI mode did not satisfactorily lead to overdrive pacing in ll subjects [2] 5/13 "Paced" subjects who developed AF by day 4 were not actually pacing at onset of AF on telemetry review [3] 13/51 paced patients did not complete protocol due to a number of reasons including failure of pacing system, sinus tachycardia > 110 bpm and other unspecified medical reasons. Trend towards higher perioperative inotrope use in control group AF only considered end-point if required treatment
			Incidence of AF / flutter at 7 days.	AAI group 14/51 (27.5%). Control group 14/49 (28.6%) unpaced had developed AF by Day 7 (p=0.90). Peak incidence of AF day 2 (non-paced) and day 3 (paced)
			Assessment of atrial ectopic activity by atrial premature depolarization (APD) frequency	APD frequency significantly higher in paced patients on 1st and 2nd postop days, and overall (p=0.041, 0.001 and 0.0001 respectively) compared to controls
Gerstenfeld et al 1999 USA	61 post CABG patients who were in preop sinus rhythm . Three groups – 21/61 no atrial pacing (NAP); 21/61 right atrial pacing (RAP); 19/91 biatrial pacing (BAP) Ventricular, RA (high lateral wall near SA node) and LA (posterior surface between right superior and inferior pulmonary veins) temporary epicardial leads attached during surgery to all patients RAP and BAP patients paced at lower rate of 100 bpm DDD for 96 hrs postop; NAP paced at 50 bpm via ventricular wires Holter + Telemetry monitoring	Single Blind PRCT level 1b	Onset of sustained AF or atrial flutter for more than 10 mins	Control group 7/21 (33%). Right atrial pacing 6/21 (29%). Biatrial pacing 7/19 (37%).(p>0.7). On-treatment analysis – NAP 36%, RAP 29%, BAP 33% ( p>0.4) Less AF in beta-blocked / paced subgroups – NAP 38%, RAP 15%, BAP 0% (p<0.05).	Small groups; 45/61 male Not all patients beta-blocked 4 control patients required pacing for clinical reasons Cross over of 1 BAP, 1 RAP and 1 NAP patient for clinical reasons Problem of fixed rate pacing in patients with fast native rates
			Complications	In 3 patients loss of atrial sensing led to the pacemaker apparently inducing AF by pacing during atrial repolarisation
Kurz et al 1999 Switzerland	21 cardiac surgery patients randomised to biatrial synchronous pacing (BSP) or control One wire on LA (posterior aspect between pulmonary veins) and 2 on RA (right atrial appendage).Wires placed at surgery Paced @ 10bpm at rate more than underlying rate up to max 110 bpm in AAI mode for 72 hours Control RA paced if clinically necessary Continuous rhythm monitoring	Aborted PRCT level 4	Occurrence of AF > 2 mins in first 72 hours postop. Interval between surgery and AF and duration of AF. Therapeutic interventions required	3/12 BSP completed study without developing AF. 6/12 BSP developed sensing failure due to deterioration of P wave amplitude leading to asynchronous atrial stimulation. 5/6 developed AF. 2/12 withdrawn due to excessive diaphragmatic stimulation. 1/12 withdrawn due to electrode dislocation causing LV stimulation. 2/9 controls developed AF.	Study aborted after only 21 patients of planned 200 due to excess incidence of AF in BSP groups
Orr W, Tsui SSL . 1999 UK	230 pts undergoing first-time CABG surgery with no prior history of AF Randomised to postop synchronised biatrial pacing via temporary epicardial wires placed on to posterior LA and RA during surgery or control AAI mode Treatment group paced within 4 hours to 96 hours post-op	PRCT level 1b	Episodes of AF > 30 mins or requiring treatment	Paced group 17.9%. Control group 33.9% (RR 0.53, p<0.0001). 89% of "paced" group successfully paced for 96 hours. No excess haemorrhage, infection or other sequelae	No details of exact pacing algorithm used No details of AF detection method
Schweikert RA, Grady TA. 1998 USA - abstract only	86 patients randomised to atrial pacing or control Atrial pacing algorithm using dual chamber rate responsive pacemaker with automatic mode-switching and overdrive facility to drive rate 80-130 bpm	PRCT level 2b	AF > 10 minutes requiring electrical or pharmacological intervention	Atrial pacing 11/43 (34%). Control group 11/43 (34%) (p=1.0)	No details of AF detection methods or placement of wires.
Au et al 2003 Hong Kong	52 patients undergoing CABG. Biatrial group (n=52) had wire attached to RA appendage and second wire onto roof of left atrium behind aorta. Control group (n=52) was a non randomized matched group Pacing at AAI rate 90bpm or 10bpm above native rhythm up to 140 bpm	Case Control Study, level 3b	Incidence of AF	Paced group 16/52 (30%). Control group 13/52 (25%). p=N/S. No differences in hospital stay or morbidity	This is not a PRCT but a case control study. Numbers are small
White et al (AFIST-II) 2003 USA	160 patients undergoing CABG or valve surgery. 2x2 factorial design comparing both Amiodarone and pacing at Bachmanns bundle. Amiodarone groups 1050mg Amiodarone iv given by 24hr infusion 6 hours post-surgery, followed by 400mg tds orally for 4 days Pacing groups Epicardial wires placed at Bachmanns bundle. Pacing started AAI mode, 6 hrs post-op at 80bpm rising to 110bpm to keep rhythm above native rate. Pacing stopped if native rhythm above 100bpm	PRCT level 1b	Onset of AF of more than 5 mins or causing haemodynamic compromise (pacing)	Pacing groups 20/73 (27%). Control groups 29/87 (33%). p= 0.523	53.8% stopped active pacing for a proportion of the study technical difficulties with pacing in 17% of patients
			Onset of AF of more than 5 mins or causing haemodynamic compromise (amiodarone)	Amiodarone groups 17/77 (22%). Control groups 32/83 (39%). p= 0.037

Comment(s)

Crystal et al performed a meta-analysis in 2002 that looked at pharmacological and pacing strategies for the reduction of AF after Cardiac Surgery. They identified 10 of the 13 completed trials that we identified by our search strategies. They found that Biatrial pacing significantly reduced the likelihood of AF with an Odds ratio of 0.46 (95%CI 0.30-0.71), which was a significant result. They also identified that right atrial and left atrial pacing reduced the odds of AF but that these results were not significant (RA pacing OR 0.68, 95%CI 0.39-1.19 and LA pacing OR 0.57, 95%CI 0.28-1.16). The reported studies varied markedly however in their protocols and pacing strategies, with definitions of AF from 1min of AF to 1 hour. In addition the placing of the wires varied, and the pacing strategies from fixed rates to complex flexible algorithms were used. A more recent review in this area identified 13 studies but did not perform an update of the meta-analysis (Archbold)-. We therefore elected to include all the individual trials in this topic so that all these various strategies could be compared. Debrunner in 2004 studied 80 patients undergoing valve surgery with or without CABG. Patients were randomized to Biatrial pacing with an algorithm to keep pacing >10bpm over the intrinsic rhythm for 3 days. Control patients received right atrial pacing with pacing set to 80bpm. They demonstrated a reduction in AF from 45% to 20% in the biatrial pacing group, although the administration of beta-blockers was not controlled in this study, and a large number of patients had beta-blockers withdrawn post-operatively. Goette et al randomized 161 patients with a history of AF undergoing cardiopulmonary bypass. They randomized the patients into 3 groups, controls who had right atrial pacing, which was only used if clinically indicated, a right atrial pacing group with active pacing for 5 days and biatrial pacing with wires placed at Bachmann's Bundle and active pacing used for 5 days. They found no statistically significant results although 24 patients were withdrawn from the study for clinical reasons. Gerstenfeld et al published 2 studies in 1999 and 2001, studying Biatrial pacing, right atrial pacing and controls in 61 patients, and later just comparing biatrial pacing with controls in 188 patients. In the smaller study no significant differences were found although there were only 6-7 occurrences of AF in each group. In their second larger study, the incidence of AF in the control group was 35% but in the biatrial pacing group the incidence was only 19%. On further analysis this difference was attributable only to patients over 70 years of age. Levy et al performed a large study in 130 patients undergoing first time CABG. Patients were randomized to biatrial pacing with wires in the right atrium and a second pair of wires at Bachmann's Bundle, set to pace at 80 bpm. The control group had a rate of AF of 40% but the biatrial paced group had an incidence of only 15%. This was significant for both monitored and clinically detected AF. Unfortunately the study protocol required all patients on beta-blockers pre-operatively to have these withdrawn post-operatively. Daoud published a study in Circulation in 2000 that compared control right atrial pacing, right atrial pacing at 85bpm or 10bpm above the intrinsic rhythm or biatrial pacing in a double blind fashion. The control group had an incidence of 28% and the right atrial pacing group had an incidence of 32% but the biatrial pacing group had an incidence of only 10%. This was a statistically significant finding. Of note 60% of right atrial wires and 80% of left atrial wires failed by the 5th post-operative day. Fan et al in 2000 published a study in Circulation that randomized 137 patients to 4 groups, Biatrial, Right atrial, left atrial and a control group. The protocol was a fixed rate of 90pbm with the rate increased to 10bpm above the underlying rhythm up to 120bpm for 5 days. They found that the incidence of AF in the biatrial pacing group was 12.5% but the incidence in the RA, LA and control groups were 36%, 33% and 42% respectively. Thus they concluded that Biatrial pacing was significantly superior to the other 3 strategies. In addition they found that adequate pacing was possible in all patients for the full 5-day duration of the study. Greenberg et al studied 154 patients, randomizing them to right atrial, left atrial, biatrial pacing and a control group. Pacing was set to 100bpm, if the native rhythm was over 80, rate was increased to either 105 or 110bpm, for 3 days. Assessment of ECG recordings was by blinded cardiologists. They found that the incidence of AF was 8% in the right atrial pacing group, which was significantly lower than left atrial pacing 20%; Biatrial pacing 26% or control 37.5%. Unfortunately they had considerable problems with the left atrial and biatrial pacing, with 23% and 33% of patients unable to maintain pacing either due to diaphragmatic pacing or high thresholds. Blommaert et al investigated 96 patients undergoing CABG, randomized to a control group or a right atrial wire group. They used a novel programmed dynamic pacing strategy where the pacemaker had a lower rate of 80 bpm but if the native rhythm rose above this, the pacemaker automatically increased the rate up to a rate of 125bpm, but kept the rhythm just above that of the native rhythm. This strategy was started on day 2 and continued for 24 hours. The control group had an incidence of AF of 27% compared to an incidence of 10% in the pacing group (p=0.036). Chung et al studied 100 patients who were at least 6 hours post elective CABG. 49 patients received AAI pacing at 90bpm or 10bpm above the native rhythm up to a rate of 110bpm for 4 days. They found that the rate of AF was 26% for the AF group and the incidence in the control group was 29%, which was a non-significant finding. In addition they found that there was a significant increase in the atrial ectopic frequency in the paced group. This study had several problems in the pacing group. 11 patients did not have successful overdrive pacing, and 5 of the 13 patients who went into AF in this group were not actually receiving pacing at the onset of AF. In 1999 Kurz et al set out to perform a randomized controlled trial in 200 patients, randomized to biatrial pacing with a single wire in the left atrium and two wires on the right atrium. However they had considerable problems in the pacing group mainly due to sensing failure in 50% of studied patients. In 5 or the 6 patients with pacing failure, this induced atrial fibrillation. In addition 2 patients were withdrawn due to excessive diaphragmatic stimulation and one withdrawn as a wire dislocated and started to cause ventricular stimulation. Schweikert published an abstract in the Journal of the American College of Cardiology. They used atrial pacing with advanced overdrive pacing capabilities to study 86 patients undergoing CABG. They found that there were 11 patients in each group that developed AF and thus concluded that right atrial pacing does not prevent AF. Orr et al performed a study in 230 patients, randomized to biatrial pacing or controls. They found that the incidence of AF was 17.9% in the biatrial pacing group compared to an incidence of 33.9% in the control group, which was a highly significant result. Au et al performed a small case-control study that showed no difference between biatrial pacing and controls in two groups of 52 patients. This study was however very small and non-randomized. The AFIST-II trial performed a 2x2 factorial design study in 160 patients looking at both post-operative Amiodarone prophylaxis and also Atrial Pacing at Bachmann's Bundle. They used a pacing rate of 80bpm increasing to 110bpm, but pacing was stopped if the native rhythm increased to above 100bpm. While they showed a significant improvement in AF for amiodarone, they showed no benefit for atrial pacing. The Pacing groups had an incidence of 27% and the control groups had an incidence of 33%. They also had many problems with the pacing algorithm, as 54% of patients had pacing stopped for a period during the trial including 17% stopped due to technical difficulties with the wires. Thus in summary, of the 11 biatrial pacing studies (including 2 that used Bachmann's Bundle pacing), 6 found significant benefit and 5 found no significant benefit. We combined these results using the DerSimonian and Laird Random Effects Model. This showed that there was a significant benefit to biatrial pacing with an odds ratio of 0.51 (95%CI 0.36-0.72). Of the 8 right atrial pacing studies, 2 found a significant benefit and 6 found no benefit. When the results were again combined by meta-analysis no benefit was found. While there is a significant benefit to biatrial pacing, several of the papers reported technical difficulties, with loss of sensing, diaphragmatic pacing and LV pacing which led to a number of patients being withdrawn from their respective studies. Thus if biatrial pacing is used, much care must be used when placing the wires. In addition there were many different algorithms for pacing, although most seemed to pace at 80-90bpm, raising this higher if the native rhythm went above 80bpm. Also the number of days that pacing was used varied. AF incidence generally peaked around day 2, thus 3-5 days of pacing may be prudent.

Clinical Bottom Line

Right atrial pacing is of no benefit but biatrial pacing significantly reduces the incidence of Atrial fibrillation.

References

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2. Debrunner M. Naegeli B. Genoni M. Turina M. Bertel O. Prevention of atrial fibrillation after cardiac valvular surgery by epicardial, biatrial synchronous pacing. [Clinical Trial. Journal Article. Randomized Controlled Trial]. European Journal of Cardio-Thoracic Surgery 2004:25(1):16-20.
3. Goette A. Mittag J. Friedl A. Busk H. Jepsen MS. Hartung WM. Huth C. Klein HU. Pacing of Bachmann's bundle after coronary artery bypass grafting. [Clinical Trial. Journal Article. Randomized Controlled Trial] Pacing & Clinical Electrophysiology 2002:25(7):1072-8.
4. Gerstenfeld EP. Khoo M. Martin RC. Cook JR. Lancey R. Rofino K. Vander Salm TJ. Mittleman RS. Effectiveness of bi-atrial pacing for reducing atrial fibrillation after coronary artery bypass graft surgery. Journal of Interventional Cardiac Electrophysiology 2001:5(3):275-83.
5. Levy T. Fotopoulos G. Walker S. Rex S. Octave M. Paul V. Amrani M. Randomized controlled study investigating the effect of biatrial pacing in prevention of atrial fibrillation after coronary artery bypass grafting. Circulation 2000:102(12):1382-7.
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9. Blommaert D. Gonzalez M. Mucumbitsi J. Gurne O. Evrard P. Buche M. Louagie Y. Eucher P. Jamart J. Installe E. De Roy L. Effective prevention of atrial fibrillation by continuous atrial overdrive pacing after coronary artery bypass surgery. Journal of the American College of Cardiology 2000:35(6):1411-5.
10. Chung MK Augostini RS Asher CR Pool DP Grady TA Zikri M Buehner SM Weinstock M McCarthy PM. Ineffectiveness and potential proarrhythmia of atrial pacing for atrial fibrillation prevention after coronary artery bypass grafting. Annals of Thoracic Surgery 2000: 69(4):1057-63.
11. Gerstenfeld EP Hill MR French SN Mehra R Rofino K Vander Salm TJ Mittleman RS. Evaluation of right atrial and biatrial temporary pacing for the prevention of atrial fibrillation after coronary artery bypass surgery, Journal of the American College of Cardiology 1999:33(7):1981-8.
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13. Orr W, Tsui SSL . Synchronised biatrial pacing after coronary artery bypass surgery. Pacing and Clinical Electrophysiology 1999;22:755.
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16. White CM, Caron MF, Kalus JS, Rose H, Song J, Reddy P, Gallagher R, Kluger J. Atrial fibrillation Suppression Trial II. Intravenous plus oral amiodarone, atrial septal pacing, or both strategies to prevent post-cardiothoracic surgery atrial fibrillation, (AFIST-II). Circulation 2003;108 Suppl 1: II200-6
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