Pacemaker Patients Research Articles

Abstract 15185: Risk Factors for Sudden Death in Chagas Cardiomyopathy

Introduction: Sudden death (SD) is an important cause of death in Chagas Cardiomyopathy patients. We aim to identify associated factors for its occurrence in Chagas Cardiomyopathy patients requiring pacemaker (PM). Methods: We prospectively evaluated 527patients included in the PACINCHAGAS Study - Risk Stratification in Pacemaker Patients with Chagas Cardiomyopathy, which primary objective is to create a risk score to predict death in this population.The patients are submitted to an extent questionnaire which included clinical (NYHA class, symptoms, comorbidities and medications) functional (electrocardiography, holter and echocardiography) and electronic variables (burden of pacing and arrhythmias).Patients withat least 6 months of follow-up were included in this analysis. Results: The cohort included 337 (63.9%) females, the mean age was 62.6±12.0 years and 64.3% were in NYHA class I. Indication for PM implantation was atrioventricular block, sick sinus syndrome, atrial fibrillation with slow ventricular response and unknown in 72.7%; 20.7%; 4.7% and 1.9%, respectively. The mean time of PM was 11.6±9.0years. During a mean follow-up of 1.8±0.6 years, 74 (14.0%) patients died; 25 deaths (33.8%) were due to heart failure, 23 (31.0%)weresudden (9.7%), 8(10.9%) were due to other cardiovascular causes, and 11 (14.8%) were due to non-cardiovascular causes. The cause of death could not be determined in seven patients (9.5%).Univariate analysis shows that patients with SD were younger (57.1 versus 62.8years, P=0.033), have higher duration of QRS (172.8 versus 155.8msec, P=0.013), lower ejection fraction (38.7% versus 48.7%, P=0.002), higher left ventricular diastolic diameter (60.0 versus 48.7mm, P=0.001), higher systolic arterial pulmonary pressure (41.8 versus 34.9mmHg, P=0.038) and higher rate of segmental wall-motion abnormality (57.9% versus 23.3%, P=0.002. Advanced functional class and non-sustained ventricular tachycardia were not associated to SD. Conclusions: We found that lower age, higher QRS duration and presence of echocardiographic abnormalities were associated to sudden death in PM users with Chagas Cardiomyopathy.

Abstract 14972: Sub-clinical Atrial Fibrillation in Elderly Primary Care Patients Without Clinical Atrial Fibrillation

Introduction: Sub-clinical AF has been reported in 10% of pacemaker patients (≥ 6 minutes, with 3 months of monitoring) and 16% of patients following cryptogenic stroke (≥ 30 seconds, with 1 month of monitoring). It is unknown how common sub-clinical AF is among other patient groups, including the elderly. These data are needed to give context to the detection of sub-clinical AF in clinical practice. Methods: We prospectively investigated the prevalence of sub-clinical AF among individuals ≥ 80 years, without known AF or symptoms of arrhythmia, attending primary care clinics. Subjects had a history of hypertension and at least one of the following: diabetes, BMI ≥ 30, sleep apnea, smoking, coronary disease, heart failure or left ventricular hypertrophy. Patients were recruited from 7 Ontario family practice clinics (n=119) and one general medicine clinic (n=10). Patients underwent 30 days of continuous, non-invasive ambulatory ECG monitoring using a device with automatic AF detection (Vitaphone 3100). The primary outcome was a composite of atrial flutter (AFL) or AF ≥ 6 minutes in duration. Those without AF were invited to complete an additional 30 days of monitoring. Results: Of 129 patients screened and consented, 100 patients initiated monitoring for an average monitoring duration of 36± 21 days. The mean (SD) age was 84 ± 3 years and systolic blood pressure was 138 ± 17 mmHg; 50% had coronary disease, 28% had diabetes and 6% had heart failure. Only 4% had a history of prior stroke. Thirty days of monitoring was completed by 57% of patients and 31% completed an additional 30 days. AFL or AF ≥ 30 seconds duration was documented in 19/100 patients; ≥ 6 minutes in 15; ≥ 30 minutes in 12; ≥ 6 hours in 8 and ≥ 24 hours in 2. Shorter episodes of atrial tachycardia lasting less than 30 seconds were observed in 47 patients. Conclusions: In this prospective, outpatient study, using non-invasive ECG monitoring, we found AFL or AF ≥ 6 minutes in 15% of elderly individuals with stroke risk factors. This high background prevalence of AFL/AF among elderly patients suggests a possible role for AF screening in this population; but also should be taken into consideration when interpreting the prevalence of AFL/AF in other populations.

Infection control in implantation of cardiac implantable electronic devices: current evidence, controversial points, and unresolved issues.

A significant increase in the implantation of cardiac implantable electronic devices (CIEDs) is evident over the past years, while there is evidence for a disproportionate increase in CIED-related infections. The cumulative probability of device infection seems to be higher in implantable cardioverter defibrillator and in cardiac resynchronization therapy patients compared with permanent pacemaker patients. Given that more than a half of CIED infections are possibly related to the operative procedure, there is a need for effective periprocedural infection control. However, many of the current recommendations are empirical and not evidence-based, while questions, unresolved issues, and conflicting evidence arise. The perioperative systemic use of antibiotics confers significant benefit in prevention of CIED infections. However, there are no conclusive data regarding the specific value of each agent in different clinical settings, the value of post-operative antibiotic treatment as well as the optimal duration of therapy. The merit of local pocket irrigation with antibiotic and/or antiseptic agents remains unproved. Of note, recent evidence indicates that the application of antibacterial envelopes into the device pocket markedly decreases the infection risk. In addition, limited reports on strict integrated infection control protocols show a dramatic reduction in infection rates in this setting and therefore deserve further attention. Finally, the relative impact of particular factors on the infection risk, including the type of the CIED, patients' individual characteristics and comorbidities, should be further examined since it may facilitate the development of tailored prophylactic interventions for each patient.

Effectiveness of Ventricular Intrinsic Preference (VIP™) and Ventricular AutoCapture (VAC) algorithms in pacemaker patients: Results of the validate study

BackgroundSeveral past clinical studies have demonstrated that frequent and unnecessary right ventricular pacing in patients with sick sinus syndrome and compromised atrio-ventricular conduction (AVC) produces long-term adverse effects. The safety and efficacy of two pacemaker algorithms, Ventricular Intrinsic Preference™ (VIP) and Ventricular AutoCapture (VAC), were evaluated in a multi-center study in pacemaker patients. MethodsWe evaluated 80 patients across 10 centers in India. Patients were enrolled within 15 days of dual chamber pacemaker (DDDR) implantation, and within 45 days thereafter were classified to either a compromised AVC (cAVC) arm or an intact AVC (iAVC) arm based on intrinsic paced/sensed (AV/PV) delays. In each arm, patients were then randomized (1:1) into the following groups: VIP OFF and VAC OFF (Control group; CG), or VIP ON and VAC ON (Treatment Group; TG). Subsequently, the AV/PV delays in the CG groups were mandatorily programmed at 180/150ms, and to up to 350ms in the TG groups. The percentage of right ventricular pacing (%RVp) evaluated at 12-month post-implantation follow-ups were compared between the two groups in each arm. Additionally, in-clinic time required for collecting device data was compared between patients programmed with the automated AutoCapture algorithm activated (VAC ON) vs. the manually programmed method (VAC OFF). ResultsPatients randomized to the TG with the VIP algorithm activated exhibited a significantly lower %RVp at 12 months than those in the CG in both the cAVC arm (39±41% vs. 97±3%; p=0.0004) and the iAVC arm (15±25% vs. 68±39%; p=0.0067). In-clinic time required to collect device data was less in patients with the VAC algorithm activated. No device-related adverse events were reported during the year-long study period. ConclusionsIn our study cohort, the use of the VIP algorithm significantly reduced the %RVp, while the VAC algorithm reduced in-clinic time needed to collect device data.

Assessing access to MRI of patients with magnetic resonance-conditional pacemaker and implantable cardioverter defibrillator systems: the Really ProMRI study design.

Despite the fact that magnetic resonance (MR)-conditional pacemaker and lead systems have been introduced more than 5 years ago, it is still not clear whether they have actually facilitated the access of pacemaker patients to this important diagnostic tool. Factors limiting MR scans in daily practice in patients with MR-conditional cardiac implantable electronic device (CIED) systems may be related to organizational, cultural and sometimes legal aspects. The Really ProMRI registry is an ongoing survey designed to assess the annual rate of MR examinations in patients with MR-conditional implants, with either pacemakers or implantable cardioverter defibrillators, and to detect the main factors limiting MRI. The primary endpoint of the Really ProMRI registry is to assess the current access to MRI of patients with MR-conditional pacemaker or implantable cardioverter defibrillator systems during normal practice. Data in the literature reported a 17% annual incidence of medical conditions requiring MRI in CIED patients. The Really ProMRI registry has been designed to detect 4.5% absolute difference with an 80% statistical power, by recruiting 600 patients already implanted with MR-conditional CIED implant. Patients will be followed up for 1 year, during which they will be asked to refer any prescription, execution or denial of an MR examination by patient questionnaires and original source documents. The ongoing Really ProMRI registry will assess the actual rate of and factors limiting the access to MRI for patients with MR-conditional CIEDs.

Non-invasive focus localization, right ventricular epicardial potential mapping in patients with an MRI-conditional pacemaker system - a pilot study.

BackgroundWith the advent of magnetic resonance imaging (MRI) conditional pacemaker systems, the possibility of performing MRI in pacemaker patients has been introduced. Besides for the detailed evaluation of atrial and ventricular volumes and function, MRI can be used in combination with body surface potential mapping (BSPM) in a non-invasive inverse potential mapping (IPM) strategy. In non-invasive IPM, epicardial potentials are reconstructed from recorded body surface potentials (BSP). In order to investigate whether an IPM method with a limited number of electrodes could be used for the purpose of non-invasive focus localization, it was applied in patients with implanted pacing devices. Ventricular paced beats were used to simulate ventricular ectopic foci.MethodsTen patients with an MRI-conditional pacemaker system and a structurally normal heart were studied. Patient-specific 3D thorax volume models were reconstructed from the MRI images. BSP were recorded during ventricular pacing. Epicardial potentials were inversely calculated from the BSP. The site of epicardial breakthrough was compared to the position of the ventricular lead tip on MRI and the distance between these points was determined.ResultsFor all patients, the site of earliest epicardial depolarization could be identified. When the tip of the pacing lead was implanted in vicinity to the epicardium, i.e. right ventricular (RV) apex or RV outflow tract, the distance between lead tip position and epicardial breakthrough was 6.0 ± 1.9 mm.ConclusionsIn conclusion, the combined MRI and IPM method is clinically applicable and can identify sites of earliest depolarization with a clinically useful accuracy.Electronic supplementary materialThe online version of this article (doi:10.1007/s10840-015-0054-9) contains supplementary material, which is available to authorized users.

Research Toolkit: Supporting SPN Member Inquiries

Background:Although guidelines for routine follow-up of pacemakers and implantable cardioverter defibrillators (ICDs) are available for adults,minimal data support their appropriateness in pediatrics and congenital heart disease. Objective: To define current practices of cardiac rhythm device (CRD) follow-up among pediatric electrophysiologists. Methods: Pediatric and Congenital EP Society (PACES) members were surveyed regarding frequency of CRD in-person follow-up as well as transtelephonicmonitoring (TTM) and remotemonitoring (RM) practices. If homemonitoringwas used, the effect on in-person follow-upwas evaluated. Results: A total of 106 PACES members responded to the survey. Uncomplicated pacemaker and ICD patients were both followed in- person at a median interval of 6 months (range 1–12 months). TTM was utilized by 67% of responders (median interval 3 months; range 1–6 months), while RM was used by 87% for pacemakers (median interval 3 months; range 1–6months) and 92% for ICDs (median interval 3months; range 2 weeks–6 months). When TTM was used, 21% of responders reduced their frequency of pacemaker clinic visits. In comparison, RM reduced the frequency of clinic visits for pacemakers and ICDs in 32% and 31% of responders, respectively. Patient age was an independent factor in determining CRD follow-up for 49% of responders. Conclusion: While CRD follow-up by pediatric electrophysiologists in general follows adult guidelines, individual practices widely vary. In contrast to published recommendations in adults, TTM and RM utilization does not reduce the frequency of in-person visits for the majority of pediatric electrophysiologists. View a PDF of this poster presentation at http://www.pedsnurses.org/ d/do/804. Selected Abstracts from the 2015 SPN Conference http://dx.doi.org/10.1016/j.pedn.2015.06.016 Education: Beyond Borders: Partnerships in Healthcare Delivery DebreaM.GriffithMBA, RN,NE-BC a , Sylvia A. RineairMSHA, BSN, RN, VA-BC b , Diedre Bricker MSN, RN, CRRN c a Lurie Children's Hospital b Cincinnati Children's Hospital Medical Center c Children's Hospital Colorado Abstract Education Problem and Purpose: Potential complications from a peripheral intravenous (PIV) extravasation can lead to serious patient harm. Preventing these injuries is a safety priority for all institutions. The Infusion Nurses Society (INS) Scale, currently used in many medical institutions combines the concepts of extravasated fluid volume and local medication toxicity into a single grading system. This method of monitoring extravasations presents significant challenges related to documentation and analysis of the types, causation, and severity of extravasations for pediatric patients. Recognizing the Education Problem and Purpose: Potential complications from a peripheral intravenous (PIV) extravasation can lead to serious patient harm. Preventing these injuries is a safety priority for all institutions. The Infusion Nurses Society (INS) Scale, currently used in many medical institutions combines the concepts of extravasated fluid volume and local medication toxicity into a single grading system. This method of monitoring extravasations presents significant challenges related to documentation and analysis of the types, causation, and severity of extravasations for pediatric patients. Recognizing the challenges associated with the current INS scale, a medical institution sought out to develop and implement a new Intravenous Extravasation Assessment and Documentation Tool (IEADT). Objectives and Content: 1) Evaluate tools needed to improve PIV safety for patients. 2) Identify collaboration strategies for implemen- tation of improvement initiative among other hospitals. 3) Describe positive outcomes related to sharing of information to improve patient safety. Education content was similar at all three organizations focusing on establishing partnerships, integration and utilization of technology, and utilization of the tool. Teaching Strategies: The lead hospital utilized a variety of strategies to educate their clinical staff and implement a hospital wide change initiative. To spread the implementation of the new tool beyond their hospital, staff representatives from the lead hospital collaborated with two other pediatric institutions. Partnerships were created between

Minimizing right ventricular pacing in pacemaker patients with intact and compromised atrioventricular conduction : Results from the EVITA Trial.

Unnecessary ventricular pacing is associated with increased morbidity and mortality. Over the years different algorithms have been developed to reduce right ventricular pacing. Goal of the present study was to test the efficacy of the ventricular intrinsic preference (VIP) algorithm in patients with atrioventricular intact (AVi) and atrioventricular compromised (AVc) AV-conduction. Evaluation of VIP feature in pacemaker patients (EVITA) was a multicenter, prospective, randomized trial (Trials.gov Identifier: NCT00366158). In total, 389 patients were randomized to AVc group: n = 140/132 VIP OFF/VIP On, AVi group: n = 54/63 VIP OFF/VIP ON). One-month post-implantation AV conduction testing (AVc: PR/AR interval > 210 ms) was performed. Follow-up visits occurred 6 and 12 months after DDD-pacemaker implantation. In AVi and AVc-patients initiation of the VIP feature significantly reduced incidence of ventricular pacing (AVi: 53 ± 38 vs. 9 ± 21%, p = 0.0001; AVc: 79 ± 31 vs. 28 ± 35%, p = 0.0001). DDD-pacemaker implantation per se significantly reduced incidence of AF in VIP ON (AVi 27 vs. 0%, p < 0.0001; AVc 29 vs. 3%, p < 0.0001) and VIP OFF patients (AVi 43 vs. 4%, p < 0.0001; AVc 33 vs. 3, p < 0.0001), without significant differences between VIP ON and OFF groups (p > 0.05). In the AVc group activation of VIP significantly reduced incidence of adverse events (AE). All-cause mortality was not significantly different in VIP ON (n = 5) and VIP OFF (n = 4, p > 0.05) patients. AV search hysteresis (VIP) markedly reduces ventricular pacing both in patients with normal AV conduction and in patients with prolonged PR interval or intermittent AV block.

German Roentgen Society Statement on MR Imaging of Patients with Cardiac Pacemakers.

The aim of this paper is to inform physicians, especially radiologists and cardiologists, about the technical and electrophysiological background of MR imaging of patients with implanted cardiac pacemakers (PM) and to provide dedicated clinical practice guidelines how to perform MR exams in this patient group. The presence of a conventional PM system is not any more considered an absolute contraindication for MR imaging. The prerequisites for MR imaging on pacemaker patients include the assessment of the individual risk/benefit ratio as well as to obtain full informed consent about the off label character of the procedure and all associated risks. Furthermore the use of special PM-related (e.g. re-programming of the PM) and MRI-related (e.g. limitation of whole body SAR to 2 W/kg) precautions is required and needs to be combined with adequate monitoring during MR imaging using continuous pulsoximetry. MR conditional PM devices are tested and approved for the use in the MR environment under certain conditions, including the field strength and gradient slew rate of the MR system, the maximum whole body SAR value and the presence of MR imaging exclusion zones. Safe MR imaging of patients with MR conditional PM requires the knowledge of the specific conditions of each PM system. If MR imaging within these specific conditions cannot be guaranteed in a given patient, the procedure guidelines for conventional PM should be used. The complexity of MR imaging of PM patients requires close cooperation of radiologists and cardiologists. Conventional pacemaker systems are no longer an absolute but rather a relative contraindication for performing an MR examination. The procedural management of conventional pacemaker includes the assessment of the individual risk/benefit ratio, comprehensive patient informed consent about specific related risks and "off label" use, extensive PM- and MRI-related safety precautions as well as adequate monitoring techniques during the MR exam. Decisive for patient safety are precise understanding of, and compliance with, the terms of use for the specific MR-conditional pacemaker system. If the electrophysiological and MRI-specific conditions for use of MR-conditional pacemakers are not met or compliance with these conditions for use cannot be guaranteed, the device must be treated like a conventional pacemaker.

Eligibility for the Subcutaneous Implantable Cardioverter-Defibrillator in Patients With Hypertrophic Cardiomyopathy.

High-risk hypertrophic cardiomyopathy (HCM) patients benefit from the implantable cardioverter defibrillator (ICD). The subcutaneous ICD (S-ICD) may provide comparable protection while avoiding the shortcomings of transvenous (TV) leads. We assessed S-ICD eligibility according to surface ECG screening test in a cohort of high-risk HCM patients. 47 HCM patients (3 S-ICD candidates; 41 TV-ICD patients without pacing indication; and 3 pacemaker-dependent TV-ICD patients) underwent 4 screening protocols: standard (n = 44); exercise (n = 33); continuous pacing (n = 44); alternating paced/spontaneous QRS (n = 41). Of the 44 patients in the standard screening group, 41 (93%) were eligible. Max LV thickness was inversely related to the number of qualifying leads (3 leads: 21 ± 4 mm; 2 leads: 22 ± 6 mm; 1 lead: 25 ± 6 mm; no leads: 28 ± 11 mm; P = 0.07). Of the 33 patients in the exercise group, 5 were ineligible (3 after exercise). Of these, 2 became eligible after moving sternal electrodes from the left to the right parasternal line (eligibility rate: 30/33; 91%). Of the 44 patients in the continuous pacing group, 28 (64%) were eligible, 8 of which with right parasternal electrodes. In the paced/spontaneous QRS group (n = 41), 21 patients (51%) had at least 1 eligible lead during pacing and retained compatibility on the same lead during spontaneous rhythm, 5 of which with right parasternal electrodes. S-ICD screening failure is low in HCM, provided that patients with severe hypertrophy are carefully evaluated. Exercise test should be performed and right parasternal leads tested. Pacemaker patients display lower eligibility rate.

Tilt-table testing of patients with pacemaker and recurrent syncope

The diagnosis of recurrent syncope in patients with pacemakers (PM) is quite challenging and the etiology of syncope is often multifactorial. To portray the mechanism of syncope in PM patients, we report the results of head-up tilt table testing (HUT) in a series of patients with PM, originally implanted for reasons other than neurally mediated syncope, referred due to syncope or pre-syncope (aborted syncope, vertigo, suspected orthostatic hypotension).Forty-one patients with PM undergoing a HUT in our syncope unit between January 1st, 2007 and December 31st 2011 were included. A standard HUT protocol with nitroglycerine provocation was used and the test results were classified according to current guidelines. Baseline data were retrieved from the medical records.Overall, 54% of patients had a positive response to HUT. Vasodepressor or orthostatic hypotensive response were the most prevalent responses accounting for 72% of patients with a positive test. There were no differences between groups with positive or negative test result regarding age, gender, resting blood pressure and heart rate, daily fluid intake, pacing mode, pacing indication or pacing rhythm at rest.HUT in patients with pacemakers has a high diagnostic yield. Although, the majority of patients had a vasodepressor or orthostatic hypotensive response, cardioinhibitory response leading to syncope was also seen.

Association between ventricular pacing and persistent atrial fibrillation in patients indicated to elective pacemaker replacement: Results of the Prefer for Elective Replacement MVP (PreFER MVP) randomized study

Pacing in the right ventricle can cause a variety of detrimental effects, including atrial tachyarrhythmias (atrial tachycardia [AT]/atrial fibrillation [AF]). The purpose of this study was to evaluate the incidence and predictors of persistent AT/AF in patients with long-term exposure to ventricular pacing. In a multicenter international trial, 605 patients (age 75 ± 11 years, 240 women) referred for replacement of an implanted pacemaker or implantable cardioverter-defibrillator (ICD), with a history of high-percentage (>40%) ventricular pacing, were randomly allocated to standard dual-chamber pacing or managed ventricular pacing (MVP), a pacing modality that minimizes ventricular pacing. The main end-point of this secondary analysis of the PreFER MVP randomized study was persistent AT/AF, defined as ≥7 consecutive days with AT/AF or AT/AF interrupted by atrial cardioversion or AT/AF present during 2 consecutive follow-up visits. Persistent AT/AF was observed in 71 patients (11.7%) after 2 years of follow-up. At multivariable Cox regression analysis, prior AT/AF (hazard ratio [HR] 2.85, 95% confidence interval [CI] 1.20-6.22, P = .017) and ventricular pacing percentage, estimated in the first 3 months, ≥10% (HR 3.24, 95% 95% CI 1.13-9.31, P = .029) were independent predictors for persistent AT/AF. MVP was associated with persistent AT/AF risk (HR 3.41, 95% 95% CI 1.10-10.6, P = .024) in the subgroup of patients with baseline long PR interval (PR >230 ms) but not in the whole population. In pacemaker and ICD replacement patients, a high percentage of ventricular pacing is associated with higher risk of persistent AT/AF. Use of algorithms that minimize right ventricular pacing may benefit patients with normal spontaneous AV conduction but should be evaluated with caution in patients with long PR interval.

The Relationship Between Level of Adherence to Automatic Wireless Remote Monitoring and Survival in Pacemaker and Defibrillator Patients

BackgroundRemote monitoring (RM) technology embedded within cardiac rhythm devices permits continuous monitoring, which may result in improved patient outcomes. ObjectivesThis study used “big data” to assess whether RM is associated with improved survival and whether this is influenced by the type of cardiac device and/or its degree of use. MethodsWe studied 269,471 consecutive U.S. patients implanted between 2008 and 2011 with pacemakers (PMs), implantable cardioverter-defibrillators (ICDs), or cardiac resynchronization therapy (CRT) with pacing capability (CRT-P)/defibrillation capability (CRT-D) with wireless RM. We analyzed weekly use and all-cause survival for each device type by the percentage of time in RM (%TRM) stratified by age. Socioeconomic influences on %TRM were assessed using 8 census variables from 2012. ResultsThe group had implanted PMs (n = 115,076; 43%), ICDs (n = 85,014; 32%), CRT-D (n = 61,475; 23%), and CRT-P (n = 7,906; 3%). When considered together, 127,706 patients (47%) used RM, of whom 67,920 (53%) had ≥75%TRM (high %TRM) and 59,786 (47%) <75%TRM (low %TRM); 141,765 (53%) never used RM (RM None). RM use was not affected by age or sex, but demonstrated wide geographic and socioeconomic variability. Survival was better in high %TRM versus RM None (hazard ratio [HR]: 2.10; p < 0.001), in high %TRM versus low %TRM (HR: 1.32; p < 0.001), and also in low %TRM versus RM None (HR: 1.58; p < 0.001). The same relationship was observed when assessed by individual device type. ConclusionsRM is associated with improved survival, irrespective of device type (including PMs), but demonstrates a graded relationship with the level of adherence. The results support the increased application of RM to improve patient outcomes.

The influence of cholinesterase inhibitor therapy for dementia on risk of cardiac pacemaker insertion: a retrospective, population-based, health administrative databases study in Ontario, Canada.

BackgroundCholinesterase inhibitors are used to treat the symptoms of dementia and can theoretically cause bradycardia. Previous studies suggest that patients taking these medications have an increased risk of undergoing pacemaker insertion. Since these drugs have a marginal impact on patient outcomes, it might be preferable to change drug treatment rather than implant a pacemaker. This population-based study determined the association of people with dementia exposed to cholinesterase inhibitor medication and pacemaker insertion.MethodsWe used data from the Ontario health administrative databases from January 1, 1993 to June 30, 2012. We included all community-dwelling seniors who had a code for dementia and were exposed to cholinesterase inhibitors (donezepil, galantamine, and rivastigmine) and/or drugs used to treat co-morbidities of hypertension, diabetes, depression and hypothyroidism. We controlled for exposure to anti-arrhythmic drugs. Observation started at first exposure to any medication and continued until the earliest of pacemaker insertion, death, or end of study.Results2,353,909 people were included with 96,000 (4.1%) undergoing pacemaker insertion during the observation period. Case–control analysis showed that pacemaker patients were less likely to be coded with dementia (unadjusted OR 0.42 [95%CI 0.41-0.42]) or exposed to cholinesterase inhibitors (unadjusted OR 0.39 [95%CI 0.37-0.41]). That Cohort analysis showed patients with dementia taking cholinesterase inhibitors had a decreased risk of pacemaker insertion (unadj-HR 0.58 [0.55-0.61]). Adjustment for patient age, sex, and other medications did not notably change results, as did restricting the analysis to incident users.ConclusionsPatients taking cholinesterase inhibitors rarely undergo, and have a significantly reduced risk of, cardiac pacemaker insertion.

Clinical Significance of Nonsustained Ventricular Tachycardia on Routine Monitoring of Pacemaker Patients.

Permanent pacemakers (PPMs) are capable of recording tachyarrhythmic events including nonsustained ventricular tachycardia (NSVT), though the clinical significance of NSVT on routine PPM evaluation is unknown. Our goals: assess the prevalence of NSVT on routine PPM follow-up and survival of PPM patients with NSVT, without NSVT, and with ventricular high rate (VHR) episodes of undefined origin. A single-center retrospective, cohort study was performed on patients implanted with PPMs capable of recording NSVT, defined as ≥5 consecutive ventricular beats at ≥170/minutes lasting <30 seconds. Patients were categorized: (1) no NSVT; (2) NSVT; or (3) VHR episodes of uncertain etiology. The primary endpoint was all-cause mortality within 6 months of last follow-up. Note that in 1,125 enrollees (51.8% male, age 74.2 ± 15.5 years, ejection fraction 57.0 ± 9.0%), 742 (66%) had no NSVT, 223 had NSVT (20%), and 160 (14%) had VHR. There were no differences in ejection fraction, diabetes, hypertension, coronary disease, prior myocardial infarction, baseline creatinine, QRS duration, prevalence of left bundle branch block, or β-blocker use among groups. "No NSVT" patients were older (P = 0.013), NSVT patients had more males (P = 0.012); atrial fibrillation and digoxin use were more prevalent in VHR patients (P < 0.01). During median follow-up of 2.8 years there were 93 deaths within 6 months of last follow-up with no differences in survival among groups (log rank P = 0.47). Age, ejection fraction at time of implant, and β-blocker use were independent predictors of survival. NSVT detected on routine PPM follow-up in this patient population with a preserved ejection fraction is not associated with long-term mortality.

Magnetic resonance imaging safety in pacemaker and implantable cardioverter defibrillator patients: how far have we come?

Magnetic resonance imaging (MRI) has long been regarded a general contraindication in patients with cardiovascular implanted electronic devices such as cardiac pacemakers or cardioverter defibrillators (ICDs) due to the risk of severe complications and even deaths caused by interactions of the magnetic resonance (MR) surrounding and the electric devices. Over the last decade, a better understanding of the underlying mechanisms responsible for such potentially life-threatening complications as well as technical advances have allowed an increasing number of pacemaker and ICD patients to safely undergo MRI. This review lists the key findings from basic research and clinical trials over the last 20 years, and discusses the impact on current day clinical practice. With ‘MR-conditional’ devices being the new standard of care, MRI in pacemaker and ICD patients has been adopted to clinical routine today. However, specific precautions and specifications of these devices should be carefully followed if possible, to avoid patient risks which might appear with new MR technology and further increasing indications and patient numbers.

Identification of bacteriology and risk factor analysis of asymptomatic bacterial colonization in pacemaker replacement patients.

BackgroundRecent researches revealed that asymptomatic bacterial colonization on PMs might be ubiquitous and increase the risk of clinical PM infection. Early diagnosis of patients with asymptomatic bacterial colonization could provide opportunity for targeted preventive measures.ObjectiveThe present study explores the incidence of bacterial colonization of generator pockets in pacemaker replacement patients without signs of infection, and to analyze risk factors for asymptomatic bacterial colonization.MethodsFrom June 2011 to December 2013, 118 patients underwent pacemaker replacement or upgrade. Identification of bacteria was carried out by bacterial culture and 16S rRNA sequencing. Clinical risk characteristics were analyzed.ResultsThe total bacterial positive rate was 37.3% (44 cases), and the coagulase-negative Staphylococcus aureus detection rate was the highest. Twenty two (18.6%) patients had positive bacterial culture results, of which 50% had coagulase-negative staphylococcus. The bacterial DNA detection rate was 36.4 % (43 cases). Positive bacterial DNA results from pocket tissues and the surface of the devices were 22.0% and 29.7%, respectively. During follow-up (median, 27.0 months), three patients (6.8%, 3/44) became symptomatic with the same genus of microorganism, S. aureus (n=2) and S. epidermidis (n=1). Multivariable logistic regression analysis showed that history of bacterial infection, use of antibiotics, application of antiplatelet drugs, replacement frequency were independent risk factors for asymptomatic bacterial colonization.ConclusionThere was a high incidence of asymptomatic bacterial colonization in pacemaker patients with independent risk factors. Bacterial culture combined genetic testing could improve the detection rate.

Corrected QT in Ventricular Paced Rhythms: What Is the Validation for Commonly Practiced Assumptions?

Introduction: Ventricular pacing (VP) may impact the accuracy of QT interval measurement, as it increases the QT by increasing the QRS duration amongst other mechanisms. We aimed to investigate the accuracy of the commonly used clinical practice of subtracting 50 ms from the corrected QT (QTc) in ventricular paced rhythms. Methods: We conducted a prospective observational study on 23 consecutive pacemaker patients. Four ECGs were recorded for each subject, 2 in their native rate and 2 following an atrial paced, atrial sensed and inhibited response to sensing and then a dual pacing, dual sensing and dual response pacing of 100 bpm to allow for an intrinsic and a ventricular paced QRS, respectively. The averaged QTc in the ventricular paced rhythm was then compared with the non-ventricular-paced QTc for individual subjects. Results: At a mean spontaneous heart rate of 66 bpm (SD ±8), the mean difference in QTc between the ventricular paced and nonpaced QRS was 48.27 ms (95% CI = 32-64.6 ms, p < 0.001). At faster paced rates, the mean QTc difference was 81.3 ms (95% CI = 35.8-126.8 ms, p = 0.002). Conclusions: The QTc measurement during VP confirms the current 50-ms subtraction assumption rule within a range of ±16 ms at an average heart rate of 66 bpm. However, at faster heart rates, the 50-ms adjustment may underestimate the QTc discrepancy between a wide and normal QRS.

Cardiac MRI in patients with cardiac pacemakers: practical methods for reducing susceptibility artifacts and optimizing image quality.

Magnetic resonance imaging (MRI) of pacemaker patients has become available despite of previous contraindications. However, pacing systems containing ferromagnetic material may hamper the diagnostic quality of cardiac MR (CMR) images. To study methods for reducing susceptibility-based artifacts in CMR examinations of pacemaker patients. Altogether 16 patients were scanned with 1.5T MRI scanner using cine balanced steady-state free-precession (bSSFP) and spoiled gradient echo (SPGR) sequences. The use of frequency-scout was also evaluated. For myocardial late gadolinium-enhanced (LGE) imaging, SPGR or bSSFP readout inversion-recovery prepared gradient echo sequences were used with and without phase-sensitive inversion-recovery (PSIR). Two radiologists subjectively compared the image quality (IQ) and the ranges of susceptibility artifacts were evaluated objectively. The IQ proved adequate for diagnosing each patient, although in a few patients with a left-side implanted generator, artifacts hampered IQ in the anterior and anteroseptal segments of the myocardium in bSSFP cine and LGE sequences. In bSSFP cine, the use of frequency-scout could often transfer the banding artifacts away from the left ventricular myocardium. In LGE imaging, the artifacts were more pronounced in IR-bSSFP and PSIR than in IR-SPGR sequences. The ranges of generator-based artifacts were greater in bSSFP (10-12 cm) than in SPGR (6 cm) sequences due to banding artifacts. The artifacts caused by pacemakers typically did not compromise the diagnostic IQ. The use of frequency-scout prior to bSSFP cine or the use of SPGR-based sequences could also improve IQ.

UNDERTREATMENT IN PATIENTS WITH DUAL CHAMBER PACEMAKERS AND ATRIAL FIBRILLATION DETECTED

Atrial fibrillation (AF) is the most common arrhythmia, highly present in our clinical practice. In pacemaker patients, AF is often underdiagnosed and undertreated. In this study we evaluate if our patients with dual chamber pacemakers are adequately treated by oral anticoagulation(OAC) when AF is