Safety and performance of MR-conditional pacing systems with automated MRI mode at 1.5 and 3 Tesla.

OBJECTIVES: To evaluate at 1.5 and 3 T MRI the safety and performance of trademarked ENO®, TEO®, or OTO® pacing systems with automated MRI Mode and the image quality of non-enhanced MR examinations. METHODS: A total of 267 implanted patients underwent MRI examination (brain, cardiac, shoulder, cervical spine) at 1.5 (n = 126) or 3 T (n = 141). MRI-related device complications, lead electrical performances stability at 1-month post-MRI, proper functioning of the automated MRI mode and image quality were evaluated. RESULTS: Freedom from MRI-related complications at 1 month post-MRI was 100% in both 1.5 and 3 T arms (both p < 0.0001). The stability of pacing capture threshold was respectively at 1.5 and 3 T (atrial:: 98.9% (p = 0.001) and 100% (p < 0.0001); ventricular: both 100% (p < 0001)). The stability of sensing was respectively at 1.5 and 3 T (atrial: 100% (p = 0.0001) and 96.9% (p = 0.01); ventricular: 100% (p < 0.0001) and 99.1% (p = 0.0001)). All devices switched automatically to the programmed asynchronous mode in the MRI environment and to initially programmed mode after the MRI exam. While all MR examinations were assessed as interpretable, artifacts deteriorated a subset of examinations including mostly cardiac and shoulder ones. CONCLUSION: This study demonstrates the safety and electrical stability of ENO®, TEO®, or OTO® pacing systems at 1 month post-MRI at 1.5 and 3 T. Even if artifacts were noticed in a subset of examinations, overall interpretability was preserved. CLINICAL RELEVANCE STATEMENT: ENO®, TEO®, and OTO® pacing systems switch to MR-mode when detecting magnetic field and switch back on conventional mode after MRI. Their safety and electrical stability at 1 month post MRI were shown at 1.5 and 3 T. Overall interpretability was preserved. KEY POINTS: • Patients implanted with an MRI conditional cardiac pacemaker can be safely scanned under 1.5 or 3 Tesla MRI with preserved interpretability. • Electrical parameters of the MRI conditional pacing system remain stable after a 1.5 or 3 Tesla MRI scan. • The automated MRI mode enabled the automatic switch to asynchronous mode in the MRI environment and to initial settings after the MRI scan in all patients.

Creation of pacemaker remote monitoring networks between hospital and pharmacies during Covid-19 outbreak.

INTRODUCTION: Remote Monitoring (RM) of Cardiac Implantable Electronic Devices (CIEDs) is proven to be safe and efficient. It has been adopted in our center since years. At the time of the recent Covid-19 outbreak, we introduced and tested a collaborative organizational model, through a new RM device (Totem), creating a network with the surrounding territory and limiting CIED patients' presence in hospital. METHODS: We involved 4 neighbor pharmacies where Totem devices were installed; we called and informed 64 patients with Totem compatible pacemaker (PM) about the possibility to perform their PM follow-up (FU) in-pharmacy; 58 gave their consent and their data were inserted into our RM database. RESULTS: During an 18-month FU period, a total of 70 RM transmissions have been received: one alert of high atrial burden triggering a pharmacological optimization, one alert of high ventricular impedance leading to a new ventricular lead implantation and four alerts of elective replacement indicator. Fulfilled questionnaires revealed complete patient satisfaction. CONCLUSIONS: A collaborative network between our hospital and the surrounding territory to perform RM FUs of CIEDs during Covid-19 pandemic was feasible, leading to patient compliance and satisfaction and revealing important technical and clinical alerts.

Combining home monitoring temporal trends from implanted defibrillators and baseline patient risk profile to predict heart failure hospitalizations: results from the SELENE HF study.

AIMS: We developed and validated an algorithm for prediction of heart failure (HF) hospitalizations using remote monitoring (RM) data transmitted by implanted defibrillators. METHODS AND RESULTS: The SELENE HF study enrolled 918 patients (median age 69 years, 81% men, median ejection fraction 30%) with cardiac resynchronization therapy (44%), dual-chamber (38%), or single-chamber defibrillators with atrial diagnostics (18%). To develop a predictive algorithm, temporal trends of diurnal and nocturnal heart rates, ventricular extrasystoles, atrial tachyarrhythmia burden, heart rate variability, physical activity, and thoracic impedance obtained by daily automatic RM were combined with a baseline risk-stratifier (Seattle HF Model) into one index. The primary endpoint was the first post-implant adjudicated HF hospitalization. After a median follow-up of 22.5 months since enrolment, patients were randomly allocated to the algorithm derivation group (n = 457; 31 endpoints) or algorithm validation group (n = 461; 29 endpoints). In the derivation group, the index showed a C-statistics of 0.89 [95% confidence interval (CI): 0.83-0.95] with 2.73 odds ratio (CI 1.98-3.78) for first HF hospitalization per unitary increase of index value (P < 0.001). In the validation group, sensitivity of predicting primary endpoint was 65.5% (CI 45.7-82.1%), median alerting time 42 days (interquartile range 21-89), and false (or unexplained) alert rate 0.69 (CI 0.64-0.74) [or 0.63 (CI 0.58-0.68)] per patient-year. Without the baseline risk-stratifier, the sensitivity remained 65.5% and the false/unexplained alert rates increased by ≈10% to 0.76/0.71 per patient-year. CONCLUSION: With the developed algorithm, two-thirds of first post-implant HF hospitalizations could be predicted timely with only 0.7 false alerts per patient-year.

Access to magnetic resonance imaging of patients with magnetic resonance-conditional pacemaker and implantable cardioverter-defibrillator systems: results from the Really ProMRI study.

Aims: The Really ProMRI study evaluates magnetic resonance imaging (MRI) access for patients with cardiac implantable electronic devices (CIEDs) as well as the performance of magnetic resonance (MR)-conditional leads when undergoing MRI. Methods and results: Patients either with an MR-conditional pacemaker or implantable defibrillator (ICD) system or with at least a component (device or one or more leads) from an MR-conditional system, were asked to fill in a questionnaire when they were referred to a MR scan. The rate of prescription, denial, or execution of MR examinations was evaluated in a 1-year follow-up visit. In total, 555 patients [median age (interquartile range) 72.2 (62.2-78.6); 72% male] were enrolled, 49% (270) with a pacemaker, 51% (285) with an ICD system. Five-hundred and ten patients completed the follow-up period. A total of 37 MRI referrals were reported in 35 patients, with a consequent event rate of 7.0/100 patient-years (CI, 4.9-9.7). Fourteen were denied, while 23 [66%; (CI, 48-81%)] were performed. The number of patients with MR referrals was not statistically different between pacemaker and ICD groups (21 vs. 14; P = 0.178). The rate of scans performed was higher in the pacemaker subjects (19/23 vs. 4/14, P = 0.003), while it was similar between patients with or without a complete MR-conditional system (19/30 vs. 4/7, P = 0.606). Conclusion: In this study, we reported a 7.0/100 patient-year's event rate of MR prescriptions in CIED patients. Many examinations were denied, despite MR-conditional systems, especially in ICD patients. Regulatory and cultural changes are needed to allow wider access to MR imaging in CIED patients with MR-conditional systems.

Cardiac pacing in patients with neurally mediated syncope and documented asystole: effectiveness analysis from the Third International Study on Syncope of Uncertain Etiology (ISSUE-3) Registry.

AIMS: The randomized, double-blind Third International Study on Syncope of Uncertain Etiology (ISSUE-3) showed that dual-chamber permanent pacing was effective in reducing the recurrence of syncope in patients ≥ 40 years with severe asystolic, probably neurally mediated syncope (NMS), documented by implantable loop recorder (ILR). Analysis in ISSUE-3 was performed according to the intention-to-treat principle. In the present study, we performed an on-treatment analysis, which included additionally those non-randomized patients followed up in the ISSUE registry to evaluate in a better manner the effectiveness of cardiac pacing therapy. METHODS AND RESULTS: Initially, 504 patients received an ILR, 162 (32%) patients had a diagnosis consistent with NMS within a mean observation period of 15 ± 11 months: 99 (19%) patients had documentation of syncope with ≥ 3 s asystole or ≥ 6 s asystole without syncope. Sixty patients affected by asystolic NMS received cardiac pacing therapy and 86 (33 asystolic and 53 non-asystolic NMS) were untreated; 16 patients were lost to follow-up. Paced and unpaced groups had similar clinical characteristics. During subsequent follow-up, syncope recurred in 10 paced (17%) and in 40 non-paced (46%) patients. At 21 months, the estimated product-limit syncope recurrence rates were 27% [95% confidence interval (CI) 15-47] and 54% (95% CI 43-67), respectively (P = 0.01). With cardiac pacing, the risk of recurrence was reduced by 57% (hazard ratio = 0.43, 95% CI = 0.2-0.8). Complications of pacemaker therapy were haemothorax at implantation in one patient and lead dislodgement that required correction in two patients. CONCLUSION: Permanent cardiac pacing is effective in reducing recurrence of syncope in patients ≥ 40 years with severe asystolic possible NMS with a few complications. The study shows that 61% of patients with a diagnosis of NMS made by ILR received a pacemaker but 5.1 ILRs had to be implanted to find one patient who finally had a pacemaker implanted.

The OPTI-MIND study: a prospective, observational study of pacemaker patients according to pacing modality and primary indications.

AIMS: The OPTI-MIND study aims to collect 2-year clinical outcomes of pacemaker patients in real-world clinical practice, overall and according to patient characteristics and pacemaker settings. METHODS AND RESULTS: The present analysis of the OPTI-MIND study describes the programmed device settings after discharge from the pacemaker implant. The objective was to determine whether these settings fit recent guidelines for device-programmed physiological pacing based on the preservation of atrioventricular synchrony, avoiding unnecessary pacing, ensuring rate increase during exercise or preventing neurally mediated symptoms. A total of 1740 patients were enroled at 68 centres worldwide. Baseline patient characteristics and device programming settings are available in 1674 of 1740 patients (96%). Guidelines to ensure physiological pacing were followed in 41% of patients: in patients with sinus node disease (SND), and without atrioventricular block (AVB), device programming could have led to unnecessary right ventricular pacing in 38% of patients. In SND patients with chronotropic incompetence, assisted rate increase during exercise was not programmed in 42% of patients. In 11% of patients with AVB, atrioventricular (AV) synchrony was not pursued; the main drivers being advanced age and history of atrial fibrillation. Patients with both SND and AVB were generally programmed physiologically (87%). CONCLUSION: The present analysis showed that frequent deviations occurred when comparing the device settings at discharge from the pacemaker implant in clinical practice to the available guidelines on pacing mode selection. Analysis of 2-year outcomes in the OPTI-MIND study will provide an insight into whether specific physiological settings could improve the quality of pacing with a positive effect on patient outcome.

Impact of COVID-19 Pandemic on Remote Monitoring of Cardiac Implantable Electronic Devices in Italy: Results of a Survey Promoted by AIAC (Italian Association of Arrhythmology and Cardiac Pacing).

The COVID-19 pandemic has had a profound impact on the organisation of health care in Italy, with an acceleration in the development of telemedicine. To assess the impact of the COVID-19 pandemic on the spread of remote monitoring (RM) of cardiac implantable electronic devices (CIEDs) in Italy, a survey addressed to cardiologists operating in all Italian CIED-implanting centres was launched. A total of 127 cardiologists from 116 Italian arrhythmia centres took part in the survey, 41.0% of all 283 CIED-implanting centres operating in Italy in 2019. All participating centres declared to use RM of CIEDs. COVID-19 pandemic resulted in an increase in the use of RM in 83 (71.6%) participating centres. In a temporal perspective, an increase in the median number of patients per centre followed up by RM was found from 2012 to 2017, followed by an exponential increase from 2017 to 2020. In 36 participating centres (31.0%) a telehealth visits service was activated as a replacement for in-person outpatient visits (in patients with or without CIED) during the COVID-19 pandemic. COVID-19 pandemic has caused an acceleration in the use of RM of CIEDs and in the use of telemedicine in the clinical practice of cardiology.

Baseline heart rate variability predicts clinical events in heart failure patients implanted with cardiac resynchronization therapy: validation by means of related complexity index.

BACKGROUND: Studies on the physiology of the cardiovascular system suggest that generation of the heart rate (HR) signal is governed by nonlinear dynamics. Linear and nonlinear indices of HR variability (HRV) have been shown to predict outcome in heart failure (HF). Aim of the present study is to assess if a HR-related complexity predicts adverse clinical and cardiovascular events at 1 year in patients implanted with cardiac resynchronization therapy (CRT). METHODS: In sixty patients implanted with CRT (Renewal), 24-hour HR data were retrieved at patient discharge and 1-year follow-up. A set of linear indices of HRV were considered: mean HR, standard deviation of normal beat to normal beat (SDANN), and HR footprint. Two novel nonlinear indices were calculated by means of a specific algorithm (OntoSpace): HR-complexity (HR-Co) and HR-entropy (HR-En). Predictors of adverse clinical outcome (functional class deterioration or major hospitalizations for cardiovascular causes or all-cause mortality) and of HRV recovery were sought by means of multivariate analysis. RESULTS: HR-Co and HR-En were found to be highly correlated with the other traditional indices of HRV. Lower baseline values of COMPLEXITY WERE ASSOCIATED WITH ADVERSE CLINICAL OUTCOMES (HAZARD RATIO [HR] 0.71; 95% CONFIDENCE INTERVAL [CI] 0.54-0.95; P < 0.02). CONCLUSION: Complexity and entropy indices, calculated from 24-hour normal beat to normal beat (RR) intervals well represent patient's autonomic function. In this limited set of data, HF patients with lower baseline complexity-related indices, representing a more compromised autonomic function, present worse clinical outcome at 1-year follow-up.

Change in the use of remote monitoring of cardiac implantable electronic devices in Italian clinical practice over a 5-year period: results of two surveys promoted by the AIAC (Italian Association of Arrhythmology and Cardiac Pacing).

AIMS: The aim of this study was to evaluate the use of remote monitoring in Italian clinical practice and its trend over the last 5 years. METHODS: In 2012 and 2017, two surveys were conducted. Both were open to all Italian implanting centres and consisted of 25 questions on the characteristics of the centre, their actual use of remote monitoring, applied organizational models and administrative and legal aspects. RESULTS: The questionnaires were completed by 132 and 108 centres in 2012 and 2017, respectively (30.6 and 24.7% of all Italian implanting centres). In 2017, significantly fewer centres followed up fewer than 200 patients by remote monitoring than in 2012, while more followed up more than 500 patients (all P < 0.005). In most of the centres (77.6%) that responded to both surveys, the number of patients remotely monitored significantly increased from 2012 to 2017.In both surveys, remote monitoring was usually managed by physicians and nurses. Over the period, primary review of transmissions by physicians declined, while it was increasingly performed by nurses; the involvement of technicians rose, while that of manufacturers' technical personnel decreased. The percentage of centres in which transmissions were submitted to the physician only in critical cases rose (from 28.3 to 64.3%; P < 0.001). In 86.7% of centres, the lack of a reimbursement system was deemed the main barrier to implementing remote monitoring. CONCLUSION: In the last 5 years, the number of patients followed up by remote monitoring has increased markedly. In most Italian centres, remote monitoring has increasingly been managed through a primary nursing model. The lack of a specific reimbursement system is perceived as the main barrier to implementing remote monitoring .

Intrahospital organizational model of remote monitoring data sharing, for a global management of patients with cardiac implantable electronic devices: a document of the Italian Association of Arrhythmology and Cardiac Pacing.

: In recent years, the increasing number of patients with a cardiac implantable electronic device (CIED) has required different approaches in terms of the device's control and surveillance. It is increasingly difficult to keep the traditional in-office protocol device's control: we must think of a different organization dedicated to the activity of remote control and monitoring (RC/RM) of devices and patients.A CIED team structured with nurses, technicians and physicians should be organized inside the hospital, with the aim of CIED patients' managing and of creating a network between the various departments.Small hospitals may not be able to manage independently the CIEDs RC/RM and it is possible to hypothesize the creation of a collaborative network between neighbouring structures.This activity must combine the use of technology with the ability to take care of patients and to maintain adequate and meaningful relationships.

Overdrive versus conventional or closed-loop rate modulation pacing in the prevention of atrial tachyarrhythmias in Brady-Tachy syndrome: on behalf of the Burden II Study Group.

BACKGROUND: Optimizing dual-chamber pacing to prevent recurrences of atrial tachyarrhythmias (AT) in sinus node dysfunction is still debated. Despite the large number of studies, efficacy of sophisticated preventive algorithms has never been proven. It is not clear whether this is due to imperfect study designs or to a substantial inefficacy of pacing therapies. AIM: To intraindividually compare AT burden between an atrial overdrive and two heart rate modulation approaches: a conventional accelerometric-sensor-based DDDR mode and a contractility-driven rate responsive closed loop (CLS) algorithm. METHODS AND RESULTS: Four hundred fifty-one patients with Brady-Tachy syndrome (BTS), severe bradycardia, and a documented episode of atrial fibrillation were enrolled. One month after implant, each pacing therapy was activated for 3 months in random order. A simple log transformation was used to handle large and skew AT burden distributions. Estimates were adjusted for false-positive AT episodes and reported as geometric means (95% confidence interval). A significantly higher AT burden was observed during overdrive, 0.14% (0.09%, 0.23%) (adjusted, 0.12%[0.07%, 0.20%]). Both DDDR and CLS performed better: respectively, 0.11% (0.07%, 0.17%) (adjusted, 0.08%[0.05%, 0.14%]), 0.06% (0.03%, 0.09%) (adjusted, 0.04%[0.03%, 0.07%]). All the comparisons were statistically significant. During overdrive significantly more patients had AT episodes of duration between 1 minute and 1 hour. No significant differences were observed for longer episodes. CONCLUSIONS: Atrial overdrive showed the worst performance in terms of AT burden reduction and should not be preferred to heart rate modulation approaches that still have to be considered as a first-choice pacing mode in BTS.

Atrioventricular Interval Extension Is Highly Efficient in Preventing Unnecessary Right Ventricular Pacing in Sinus Node Disease: A Randomized Cross-Over Study Versus Dual- to Atrial Single-Chamber Mode Switch.

OBJECTIVES: This study sought to compare the Intrinsic Rhythm Support (IRSplus) and Ventricular Pace Suppress (VpS) in terms of right ventricular pacing percentage (VP %), mean atrioventricular interval (MAVI), atrial fibrillation, and cardiac volumes. BACKGROUND: Modern pacemakers are provided with algorithms for reducing unnecessary ventricular pacing. These may be classified as: periodic search for intrinsic atrioventricular (AV) conduction prolonging the AV delay accordingly; or DDD-ADI mode switch. The IRSplus and VpS algorithms belong to the former and latter classes, respectively. METHODS: Patients with sick sinus dysfunction without evidence of II/III degree AV block were 1:1 randomized to 6-month periods of either IRSplus or VpS, and then crossed over. Subsequent follow-ups were at the 12th month after randomization for device data retrieving, and at the 18th month with the same device programming for echocardiographic assessment. RESULTS: A total of 230 patients (62% males, median age 75 years [interquartile range: 69 to 79 years]) were enrolled. At a linear mixed-model analysis with order of treatment and investigational sites as nested random effects, differences in VP% and MAVI reached statistical significance: VP% was 1% (0% to 11%) during IRSplus and 3% (0% to 26%) during VpS (p = 0.029); MAVI was 225 ms (198 to 253 ms) during IRSplus and 214 ms (188 to 240 ms) during VpS (p = 0.014). No differences were observed in atrial fibrillation burden and incidence, ejection fraction, and cardiac volumes. CONCLUSIONS: Both IRSplus and VpS algorithms ensured VP% ≤3% in most patients with sinus node dysfunction and preserved AV conduction. The IRSplus was slightly more efficient in reducing VP% at the expense of a small MAVI increase, with statistical but clinically insignificant differences. (Ventricular Pace Suppression Versus Intrinsic Rhythm Support Study; NCT01528657).

Stroke incidence in patients with cardiac implantable electronic devices remotely controlled with automatic alerts of atrial fibrillation. A sub-analysis of the HomeGuide study.

BACKGROUND: Remote Monitoring (RM) of cardiac implantable electronic devices (CIEDs) is recommended in management of Atrial Fibrillation (AF), which is a recognized risk factor for thromboembolism. We tried to elucidate whether stroke incidence observed in a large, remotely monitored population was consistent with the CHA2DS2VASc risk profile. METHODS: Data from 1650 patients [76% male, age 72 (63-68), CHA2DS2VASc score 3.0 (2.0-4.0)] enrolled during the HomeGuide study and monitored with a daily-transmission RM system providing automatic alerts for AF, were analysed. Of those, 25% had a pacemaker and 75% an implantable cardioverter defibrillator with or without cardiac resynchronization. Estimations of the expected thromboembolic events were based on the population CHA2DS2VASc score profile used in a computer-simulated Markov model. RESULTS: Eight thromboembolic events were observed with a 4-year cumulative stroke rate of 0.8% (confidence interval, 0.4%-1.5%). Simulations returned from 18.7 to 17.1 expected events, depending on the AF duration assumed to trigger anticoagulation (one-sample log-rank p<0.03). During the study period, 681 (84%) AF episodes and 129 (16%) atrial tachycardias were detected in 291 patients (18%): 93% of episodes were detected remotely in 269 patients, 66% of whom had no history of AF. Medical interventions were necessary in 305 episodes, 85% of which were detected remotely. Reaction time was 1 (0-6) days for remotely-detected episodes and 33 (14-121) days for episodes detected in clinic (p<0.0001). CONCLUSIONS: In a large CIED population followed remotely for up to 4years, the incidence of thromboembolic events was less than half the estimations based on the CHA2DS2VASc risk profile.

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

BACKGROUND: 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. METHODS: 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. CONCLUSION: The ongoing Really ProMRI registry will assess the actual rate of and factors limiting the access to MRI for patients with MR-conditional CIEDs.

[Remote monitoring of implantable cardiac devices: health technology assessment ]. / Monitoraggio remoto dei dispositivi cardiaci impiantabili: health technology assessment.

Clinical follow-up of patients with cardiac implantable electronic devices is challenging because of the increasing technical complexity of devices and clinical complexity of patients. Remote monitoring (RM) offers the opportunity to optimize clinic workflow and to improve device monitoring and patient management by reducing in-hospital visits, physician and nurse time required for patient follow-up, and hospital and social costs. Continuous RM may lead to early detection of device malfunctions and clinical events, such as arrhythmias and heart failure. Early reaction may improve patient outcome. RM is easy to use and patients show a high level of acceptance and satisfaction. Implementing RM in daily practice may require changes in clinical workflow. Primary nursing-based models have demonstrated the best results. In spite of a favorable cost-benefit ratio, RM reimbursement still represents an issue in several European countries, including Italy, which limits widespread RM utilization. The fee-for-service payment approach, the global budget for device patient follow-up and/or integrated care packages for heart failure management represent the keys to introduce reimbursement and to improve patient care, while reducing healthcare costs.

Diagnosis of neurally mediated syncope at initial evaluation and with tilt table testing compared with that revealed by prolonged ECG monitoring. An analysis from the Third International Study on Syncope of Uncertain Etiology (ISSUE-3).

OBJECTIVE: According to the guidelines of the European Society of Cardiology, a presumed diagnosis of neurally mediated syncope (NMS) can be made when patients have a consistent history and competing diagnoses are excluded. In the present study, we compared the initial diagnosis of NMS by means of implantable loop recorder (ILR) documentation. METHODS: In this prospective multicentre observational study which involved 51 hospitals in nine countries in Europe and Canada, 504 NMS patients ≥40 years, who had suffered ≥3 syncopal episodes in the previous 2 years received an ILR and were followed up for a mean of 15±11 months. RESULTS: ILR recorded a spontaneous syncope in 187 cases, with an estimated diagnostic yield of 47% at 3 years. ILR findings were consistent with the initial diagnosis of presumed NMS in 162 (87%) patients whereas did not confirm NMS in another 25 (13%), who had an intrinsic cardiac arrhythmic cause (atrial tachyarrhythmias (#6), long pause on termination of tachyarrhythmia (#8), persistent bradycardia (#3), ventricular tachycardia (#4)) or a non-arrhythmic loss of consciousness (non-syncopal (#3), orthostatic hypotension (#1)). No clinical baseline feature was able to predict an intrinsic cardiac cause with the exception of more frequent non-syncopal atrial tachyarrhythmias on clinical history, which were present in 38% of cardiac versus 5% of NMS patients (p=0.001). Tilt table testing (TT) was positive in 76/136 (56%) presumed NMS and in 9/21 (43%) non-NMS patients (p=0.35); an asystolic response was present in 28/136 (21%) NMS and in 0/21 (0%) non-NMS patients (p=0.03). CONCLUSIONS: ILR findings showed results other than NMS in a small, although non-negligible, number of patients older than 40 years. TT was unable to discriminate between presumed NMS and non-NMS with the exception of an asystolic response which was highly specific.

Atrial tachyarrhythmia burden modelling by some electrophysiological parameters in pacemaker-recipient patients with Brady-Tachy syndrome.

AIMS: (1) To correlate atrial tachyarrhythmia (AT) burden of pacemaker-recipient Brady-Tachy syndrome (BTS) patients with a number of diagnostics-derived parameters after 1 month of DDD pacing; (2) to asses whether the activation of atrial overdrive or conventional rate-responsive pacing may affect relevant variables and their correlation. METHODS AND RESULTS: After 1 month of DDD pacing, rate-responsive function or persistent atrial overdrive was randomly activated for 3 months, in 92 BTS patients. Some pacemaker diagnostics parameters collected at 1- and 4-month follow-ups were included in multiple linear regression models, whose dependent variable was the Log transformation of AT burden and compared. With 1-month data, the only variables significantly correlating with Log AT burden were average (with a regression coefficient estimate of -0.07, P=0.02) and standard deviation (0.10, P=0.007) of atrial rate, mean premature atrial contraction (PAC) coupling interval (CI) (-0.005, P=0.001), frequency of PACs with CI<500 ms (1.30, P<10(-6)). Atrial pacing percentage (APP) and ventricular pacing percentage (VPP), PACs with CI>500 ms did not significantly correlate. Four-month data largely confirmed these results, except that in DDDR atrial rate average and standard deviation no longer correlated. Overdrive significantly increased APP and reduced PACs with CI>500 ms. CONCLUSION: AT burden showed significant dependence in DDD and during overdrive on atrial rate average and standard deviation. Highly premature PACs always significantly correlated with AT burden. Though increasing APP, which unexpectedly never correlated, overdrive could only reduce less premature PACs.