Safety and efficacy of AAIR pacing in selected patients with sick sinus syndrome.

BACKGROUND: The DANPACE study suggested implanting dual-pacing dual-sensing dual-response rate-adaptive (DDDR) pacemakers in patients with sick sinus syndrome, even though 90.7% of their atrial-pacing atrial-sensing inhibited-response rate-adaptive (AAIR) group did not require upgrade. Most centers implant DDDR pacemakers due to risk of future atrioventricular (AV) block. Given that AAIR pacemakers are less expensive, have one less lead with potentially one less point of complication, we question whether DDDR pacemakers are superior to AAIR pacemakers. We aim to describe long-term outcomes of AAIR implants. METHODS: Patients presenting to the Grey Nuns Hospital in Edmonton, Canada from 1990 to 2012 with sick sinus syndrome without AV block had AAIR pacemakers implanted. Outcomes that were measured over the follow-up time included need for ventricular lead reoperation, incidence of AV block and incidence of sudden cardiac death from AV block. RESULTS: During this period, 330 patients presented with sick sinus syndrome. Eighty-seven (26.4%) patients met criteria for and received AAIR pacemakers. Seventy-eight (91.8%) did not require upgrade over mean follow-up of 10.6 ±â€Š0.6 years. Amongst this group, 31 patients (39.7%) were alive, whereas 47 (60.3%) were deceased at end of follow-up due to other comorbidities. No sudden deaths were attributable to AV block. Only 7 patients (8.2%) required ventricular lead reoperation: 2 (2.4%) presented urgently with symptomatic AV block; 3 (3.5%) had atrial fibrillation requiring beta-blockade; 1 (1.2%) had atrial lead dislodgment; and 1 (1.2%) was electively upgraded at battery end-of-life. CONCLUSIONS: This study looks at safety of AAIR pacemakers with only 2.4% of patients developing AV block requiring urgent upgrade. Approximately 91.8% of patients remained with their original AAIR pacemakers (mean follow-up 10.6 vs 5.4 years in DANPACE). Our findings are similar to the DANPACE study but our conclusions are different as we believe AAIR pacing should be considered for selected patients with sick sinus syndrome without AV block.

A 19-year study on pacemaker-related infections: a claim for using postoperative antibiotics.

BACKGROUND: Although the incidence of pacemaker-related infection (PMINF) is low, it necessitates removal of the pacing system. There is currently no consensus on antibiotics during implantation. METHODS: A prospective database on patients undergoing pacemaker surgery from 1991 to 2009 was reviewed to determine factors associated with PMINF. Specifically, three eras of antibiotic use were compared to elucidate the effect of antibiotics on PMINF: no antibiotics, perioperative antibiotics, and peri- plus postoperative antibiotics. RESULTS: There were 3,253 procedures with PMINF identified in 46 (1.4%) patients. Over 19 years, PMINF incidence fell from 3.6% (no antibiotics) to 2.9% (perioperative antibiotics), to 0.4% (peri- plus postoperative antibiotics). On univariate analysis, the following were associated with PMINF: nonuse of postoperative antibiotics (3.0% vs 0.4%, P < 0.001), year of implant (P < 0.001), repeat procedures (2.3% vs 1%, P = 0.006), nonuse of perioperative antibiotics (3.6% vs 1.3%, P = 0.027). With postoperative antibiotics, rates were significantly reduced in new implants (1/1,289 = 0.1% vs 22/967 = 2.3%, P < 0.001) and repeat procedures (7/692 = 1.0% vs 16/305 = 5.2%, P < 0.001). On multivariate analysis, the following were significant (standardized coefficients denote relative importance): postoperative antibiotics (0.776), repeat procedures (0.508), year of implant (0.142), perioperative antibiotics (0.088). CONCLUSIONS: The PMINF rate is reduced significantly by perioperative antibiotics with a further significant reduction with postoperative antibiotics. However, the reduction in PMINF rate could be a result of changes in practice in the different time eras. This study suggests consideration of perioperative followed by postoperative antibiotics to minimize pacemaker infections.

Myocardial deformation analysis in contrast echocardiography: first results using two-dimensional cardiac performance analysis.

BACKGROUND: Contrast echocardiography (CE) provides closer agreement with magnetic resonance imaging (MRI) for left ventricular (LV) volumes and ejection fraction (EF) than noncontrast echocardiography. However, the feasibility and role of myocardial deformation analysis on contrast echocardiographic images have not been well established. The aim of this study was to assess the feasibility of deformation analysis on CE using a new software tool that provides simultaneous measurements for LV volumes and EF. METHODS: Data from 52 patients who were recruited for the Alberta Heart Failure Etiology and Analysis Research Team Study (34 men; mean age, 64 ± 9 years) and underwent CE and MRI were considered. Contrast bolus injections were administered for optimal endocardial definition. Offline LV volume analysis was performed by standard manual tracing. A single frame was traced manually for two-dimensional (2D) cardiac performance analysis (CPA), which automatically calculated LV volumes, EF, and global longitudinal strain (GLS). Volumes obtained with 2D CPA were compared with those measured with standard CE and MRI. GLS from noncontrast echocardiographic recordings was also calculated with 2D CPA and compared with CE-derived and MRI-derived GLS. RESULTS: Tracing of contrast echocardiographic images with 2D CPA was possible in 49 out of 52 patients, and measurements correlated well with standard CE and MRI (EF: r = 0.93, P < .001, and r = 0.85, P < .001, respectively). Mean GLS from noncontrast echocardiographic and contrast echocardiographic recordings was -13.4 ± 5.8 and -15.3 ± 4.64, respectively (P = .056), and the latter correlated well with MRI-derived GLS (r = 0.78 vs 0.81, respectively). CONCLUSIONS: Simultaneous volumetric and deformation analysis on contrast echocardiographic recordings is feasible and reproducible. While volumes and EF obtained with the new software compare well with those obtained from standard CE and MRI, GLS from CE shows a good correlation with strain measured with MRI.

The world survey of cardiac pacing and cardioverter-defibrillators: calendar year 2005 an International Cardiac Pacing and Electrophysiology Society (ICPES) project.

BACKGROUND: A worldwide cardiac pacing and implantable cardioverter-defibrillator (ICD) survey was undertaken for calendar year 2005 and compared to a similar survey conducted in 2001. RESULTS: There were contributions from 43 countries: 16 from Europe, 13 from the Asia Pacific region, four from the Middle East and Africa, and 10 from the Americas. The United States had the largest number of cardiac pacemaker implants (223,425). Virtually all countries showed increases in implant numbers over the 4 years. High-degree atrioventricular block and sick sinus syndrome remain the major indications for implantation of a cardiac pacemaker, although indications data were not available for large implanting regions such as Europe, Australia, and the United States. There remains a high percentage of VVI(R) pacing in the developing countries, although compared to the 2001 survey, virtually all countries had increased the percentage of DDDR implants, together with a fall in single-lead VDD implants. Pacing leads were predominantly transvenous, bipolar, and passive fixation. There was, however, an increased use of active fixation leads in both the atrium and ventricle. All countries surveyed showed a significant rise in the use of ICDs with the largest implanter being the United States (119,121) with 401 new implants per million population. CONCLUSIONS: Although the numbers of participating countries have fallen, there still remains a group of loyal enthusiastic survey coordinators. Recruitment of new coordinators will hopefully continue in order to obtain a fully global experience of cardiac pacing and ICD usage.

Clinical experience with pacemaker pulse generators and transvenous leads: an 8-year prospective multicenter study.

BACKGROUND: Pacemakers have improved the lives of patients worldwide. Unfortunately, the medical community has had little independent information regarding the performance of these vital medical devices. OBJECTIVES: The purpose of this study was to examine the reasons pacemaker pulse generators and transvenous leads were removed from service. We evaluated the causes and major adverse clinical events associated with device end-of-service life behavior and how they were detected and managed. METHODS: Pulse generator and lead data were entered prospectively using a web-based format. Normal battery depletion was signified by the elective replacement indicator appearing >3 years after implant. Lead failure was a device defect causing pacing, sensing, or fixation malfunction, high threshold, or abnormal impedance. Major adverse clinical events were death, angina, heart failure, syncope, and perioperative surgical complications. RESULTS: From 1998 to 2006, 2,652 pulse generator and 615 leads were removed from service. The average pulse generator was implanted for 7.3 +/- 3.1 years (range <1 day to 26 years). The majority of pulse generators (n = 2,317 [87%]) were replaced for normal battery depletion. Severe and accelerated battery depletion, manufacturers' advisories, and electronic or connector defects accounted for 13% of pulse generator removals. The proportion of pulse generators removed from service as a result of manufacturers' advisories, electronic failure, and housing defects were 4%, 2%, and 1%, respectively. Models with rate response capability had shorter battery longevities than those without rate response capability. Major adverse clinical events due to pulse generator end-of-service life behavior were related to electronic and connector defects, and both normal and severe battery depletion. Median time to lead failure was 7.2 +/- 5.2 years. Insulation defects caused the majority of lead failures, and most of these leads used polyurethane materials. Lead failure was associated with a 16% incidence of major adverse clinical events. No major adverse clinical events occurred when impending lead failure was detected at routine follow-up. Lead extraction was associated with a 5.6% complication rate, including one death. CONCLUSION: Overall pulse generator performance was satisfactory. Differences in battery longevity were observed among models. In some patients, elective replacement indicators signifying normal battery depletion resulted in major adverse clinical events. Pacemaker follow-up effectively identified pulse generator end-of-service life and often detected impending lead failure, thus avoiding major adverse clinical events. Long-term studies are needed to assess chronic lead performance so that appropriate clinical management strategies, including recommendations for lead extraction, can be developed.

Pacemaker longevity: are we getting what we are promised?

BACKGROUND: Although pacemaker manufacturers provide projections on longevity, these projections cannot be relied upon due to the assumptions of output parameters being far in excess of those programmed in clinical practice. OBJECTIVE: The purpose of this review was to compare the actual longevity to the calculated longevity of pacemakers based on battery cell characteristics taking into account individual programmed parameters, mode, degree of usage, and percent pacing. This was also compared to the manufacturers' own projected longevities. METHODS: Patients who had a pacemaker replaced between 1998 and 2003 were included (n = 124). Cell characteristics were obtained from manufacturers and programmed parameters were obtained at each visit. Stepwise calculations were done for each visit to find current drain during each interval, and then were used in a weighted average to find the total average lifetime current drain. This was subsequently used to find a calculated longevity for each pacemaker to be compared to the actual longevity observed. RESULTS: The pacemakers lasted 491+/-92 days (mean+/-SEM) less than calculated. There was also a difference between dual- and single-chamber devices (though not statistically significant). Moreover, it was found that there were significant differences between manufacturers. CONCLUSIONS: There appears to be a significant discrepancy between calculated and actual longevities, confirming that battery depletion occurs earlier than expected. This suggests that current drain expended for ancillary functions may be considerable. Another factor may be pre-implantation drain. Vigilance with programming of outputs, modes, sensors, heart rates, and ancillary functions could potentially extend longevity and postpone/obviate the need for costly repeat surgery with its attended risk of complications. Furthermore, the differences between manufacturers seem to parallel the clinical impressions.

Cardiac pacing device therapy for atrial dysrhythmias: how does it work?

Atrial fibrillation (AF) is the most common dysrhythmia in North America. Paroxysmal or persistent AF affects an estimated 2.8 million individuals, causes significant morbidity, and is associated with 1 billion dollars in healthcare costs each year in the United States. An aging population, the prevalence of hypertension, and the emergence of heart failure as the final common pathway of heart disease finds us in an age where the incidence of AF is ever increasing and the management challenges are indeed an expanding clinical problem. Although guidelines for selection of the appropriate pacing mode have been published, device therapy for the control of AF and paroxysmal AF is an emerging clinical management strategy. In 2001 The American College of Cardiology (ACC)/American Heart Association (AHA) published a document to revise the 1998 guidelines for device therapy, and even now these guidelines require elucidation and inclusion for the use of cardiac pacing device therapy for the control of atrial dysrhythmia. Choosing a complex system, in particular for the patient with persistent and symptomatic atrial dysrhythmia, is a most intricate challenge for the healthcare professional and the healthcare system. Rate dependent effects on refractoriness, reduction of ectopy, remodeling of the substrate, and prevention of pauses have been described as the potential mechanisms responsible for the rhythmic control effect attributed to atrial pacing. However, while permanent cardiac pacing is required for patients with symptomatic bradycardia with atrioventricular block and AF, the concept of pacing for the primary prevention of AF is novel. Pacing algorithms, single site, biatrial, and dual-site atrial pacing and site-specific pacing have all been studied as substrate modulators to prevent recurrent atrial dysrhythmia.A dilemma exists surrounding the primary approach for the control of symptomatic AF with rapid ventricular response. The question remains: should it be to maintain the sinus rhythm or to control the ventricular response rate to the AF and anticoagulate? Variations in the population studied, differences in the pacing algorithms and protocols, and a lack of definitive end points account for the variable results of the studies completed thus far. With the current data available, it appears that for individuals with sinus node dysfunction and paroxysmal AF in combination with a bradyarrhythmia indication for pacing, suppression algorithms may play an additive role with full atrial pacing in the management and reduction of episodes and burden of paroxysmal AF. The goal of these therapies is to reduce the symptoms and hopefully decrease the healthcare costs associated with paroxysmal and persistent AF with uncontrolled ventricular response.

The world survey of cardiac pacing and cardioverter defibrillators: calendar year 2001.

A worldwide cardiac pacing and ICD survey was undertaken for calendar year 2001. Fifty countries, 22 from Europe, 16 from the Asia Pacific region, 3 from the Middle East and Africa, and 9 from the Americas contributed to the survey. The United States had by far the largest number of cardiac pacemaker implants, although Germany had the highest new implants per million population. Virtually all countries that participated in the 1997 survey showed significant increases in implant numbers over the 4 years. High degree atrioventricular block and sick sinus syndrome remain the major indications for implantation of a cardiac pacemaker with < 2% biventricular pacing in those countries that implanted such systems in 2001. There remains a high percentage of VVIR pacing in the developing countries with only a few countries using substantial numbers of single lead VDD and AAIR systems. There has been an increase in the use of DDDR systems in most countries since the 1997 survey. Pacing leads were predominantly transvenous, bipolar, and passive fixation. There was an increased use of active-fixation leads in the atrium. There was a significant rise in the use of ICDs with the largest usage occurring in the United States. A group of enthusiastic survey coordinators has now been established. Recruitment of new countries will hopefully continue to obtain a fully global experience of cardiac pacing and ICD usage.

Evaluation of the appropriateness of pacemaker mode selection in bradycardia pacing: how closely are the ACC/AHA guidelines followed?

Although guidelines for selection of the appropriate pacing mode have been published, little data is available on how closely these are followed in the clinical setting. All 738 patients (men 412, women 326; age 73.4 +/- 0.46 years; range 19-101 years) who underwent pacemaker implantation from 1996 to 2000 were reviewed to determine if the appropriate mode was selected based on the ACC/AHA guidelines with the data collected prospectively. Demographic, investigational, and implantation data including the presence of sinus disease and/or atrioventricular block, diagnosis, indication for pacing, ACC/AHA class indication for device therapy, recommended ACC/AHA mode, implanted mode, and reason for not using the recommended mode were entered into an SPSS data base. Of 738 patients, 708 were cross-tabulated for a match to the guidelines of which 358 (50.6%) had a mode selected that did not conform. The reasons were advanced physical disability (16%), physician choice without identifiable reason (21%), rate modulation selected without identifiable indication (16%), DDD implanted instead of VDD (25%), advanced age (9%), rare need for pacing (6%), a need for specific device features (5%), and unstable stimulation thresholds or difficult venous access (2%). In the treatment of bradyarrhythmias, deviation from the ACC/AHA indicated mode occurred in a substantial proportion of pacing system implantations. However, in many, the deviation appeared appropriate considering the patient's clinical status. Nevertheless, in a smaller proportion of patients the deviation appeared inappropriate requiring rectification. The two outstanding categories were: (1) elderly denied a dual chamber system with no clinical explanation and (2) selection of rate-modulated devices without any indication of chronotropic incompetence.

Postpacemaker implant pericarditis: incidence and outcomes with active-fixation leads.

Pericarditis has been noted as a potential complication of pacemaker implantation. This study evaluated the risk of developing pericarditis following pacemaker implantation with active-fixation atrial leads. Included were 1,021 consecutive patients (mean age 73.4+/-0.4 years, range 16-101 years; 45.2% women) undergoing new pacemaker system implantation between 1991 and 1999 who were reviewed for the complication of pericarditis. The incidence and outcomes of postimplantation pericarditis in patients receiving active-fixation atrial leads were compared to those not receiving these leads. Of 79 patients who received active-fixation atrial leads, 4 (5%) developed pericarditis postpacemaker implantation. Of 942 patients with passive-fixation atrial leads or no atrial lead (i.e., a ventricular lead only), none developed pericarditis postoperatively (P < 0.001). Of patients receiving active-fixation ventricular leads only (n = 97), none developed pericarditis. No complications were apparent at the time of implantation in patients who developed pericarditis. Pleuritic chest pain developed between 1 and 28 hours postoperatively. Three patients had pericardial rubs without clinical or echocardiographic evidence of tamponade. They were treated conservatively with acetylsalicylic acid or ibuprofen and their symptoms resolved without sequelae in 1-8 days. One patient (without pericardial rub) died due to cardiac tamponade on postoperative day 6. Postmortem examination revealed hemorrhagic pericarditis with no gross evidence of lead perforation. Pericarditis complicates pacemaker implantation in significantly more patients who receive active-fixation atrial leads. It may be precipitated byperforation of the atrial lead screw through the thin atrial wall. Patients developing postoperative pericarditis should befollowed closely due to the risk of cardiac tamponade.