Subcutaneous Implantable Defibrillator programming: an analysis of Italian clinical practice and its evolution

Background

The UNTOUCHED study (designed in 2017 and published in 2021) demonstrated high success rate for termination of ventricular arrhythmias, and very low inappropriate shock rate in subcutaneous implantable cardioverter-defibrillator (S-ICD) recipients. The prescribed device programming included a conditional zone between 200 and 250 beats per minute (bpm) with discrimination algorithms employed to avoid delivering inappropriate shocks in this range, and a shock zone based on the rate alone for arrhythmias >250 bpm. Whether these results influenced clinical practice is unknown.

Methods

We assessed the programming at implantation and changes in programmed parameters at follow-up (≥1 year) in a cohort of S-ICD recipients enrolled in the Rhythm Detect registry at 56 centers.

Results

From 2013 to 2021, 1521 consecutive patients (aged 49±15 years; 79% male, 52% dilated cardiomyopathy, 31% arrhythmic syndromes, 16% hypertrophic cardiomyopathy) were analyzed. At implantation, the programmed sensing vector was the Primary in 59% of patients, the Secondary in 35%, the Alternate in 6%. At follow-up, the sensed vector was changed in 13% of patients. The programmed conditional zone cutoff was set to 200 [200–220] bpm (median [25–75 percentile]), and the shock zone cutoff to 230 [210–250] bpm. At follow-up, the conditional zone cutoff was reprogrammed in 13% of patients, but the median value in the overall population did not change (200 [200–220] bpm; p>0.05). The shock zone cutoff was reprogrammed in 43% of cases, and the overall median value was 250 [230–250] bpm (p<0.001 versus implantation). Sorting patients by implantation date, we observed that in the first 764 patients (implanted ≤2017) the shock zone cutoff was set to 210 [210–230] bpm at implantation and to 240 [230–250] bpm at follow-up (reprogrammed in 66% of cases). While in patients implanted >2017, it was already set to 250 [230–250] bpm at implantation and to 250 [240–250] bpm at follow-up (reprogrammed in 20% of cases, p<0.001 versus ≤2017).

Conclusions

S-ICD programming parameters are rarely changed during follow-up (approximately 13% of patients). The only exception in clinical practice was the shock zone cutoff. Centers have begun to program high cutoffs in recent years. This happened at the time of implantation for new S-ICD recipients and at follow-up for pre-existing implants. This behavior is consistent with a substantial adoption of published trial findings and could contribute to reduce the incidence of inappropriate shocks in clinical practice.

Funding Acknowledgement

Type of funding sources: None.

Intermuscular technique for implantation of the subcutaneous implantable defibrillator: a propensity-matched case-control study

Background

A previous randomized study (PRAETORIAN) demonstrated that the subcutaneous implantable cardioverter–defibrillator (S-ICD) was noninferior to transvenous ICD with respect to device-related complications and inappropriate shocks. However, that was performed prior to the widespread adoption of pulse generator implantation in the intermuscular (IM) space instead of the traditional subcutaneous (SC) pocket.

Purpose

To compare survival from device-related complications and inappropriate shocks between patients who underwent S-ICD implantation with the generator positioned in an IM position in comparison with a SC pocket.

Methods

We analyzed 1577 consecutive patients who had undergone S-ICD implantation from 2013 to 2021 and were followed up until December 2021. SC patients were propensity-matched with patients of the IM group, and their outcomes were compared.

Results

SC implantations were performed in 367 (23%) patients. These patients were propensity-matched with 367 IM patients. Intra-procedural complications were reported in 9 (2.5%) patients in the SC Group and 7 (1.9%) in the IM Group. During a median follow-up of 29 months, device-related complications were reported in 55 (7.5%) patients and inappropriate shocks were reported in 54 (7.4%) patients. The risk of the composite primary endpoint was lower in the matched IM Group than in the SC Group (unadjusted hazard ratio 0.67, 95% CI 0.45–0.99, p=0.042), while the risk of appropriate shocks was similar between groups (unadjusted hazard ratio 0.99, 95% CI 0.60–1.64, p=0.976). There was no significant interaction between generator positioning and variables such as gender, age, body mass index, ejection fraction and generation of the device.

Conclusions

In this experience, IM S-ICD generator positioning was superior to SC positioning in reducing device-related complications and inappropriate shocks.

Funding Acknowledgement

Type of funding sources: None.

Real-world survival of model-3501 subcutaneous implantable defibrillator lead

Funding Acknowledgements

Type of funding sources: None.

Background

In December 2020, the subcutaneous implantable cardioverter-defibrillator (S-ICD) lead model-3501 was subject to a safety notification because of increased risk of fracture at a location just distal to the proximal sense ring. The manufacturer’s product performance report currently reports a lead survival probability of 98.8% at 45 months. However, no multicenter long-term performance information exists for this lead.

Purpose

Our aim was to assess the longevity of model-3501 leads and to compare it with that of the previous model-3401.

Methods

This analysis included consecutive patients who received an S-ICD with a model-3501 or a model-3401 lead at 66 Italian participating centers of the Rhythm Detect registry. A lead failed if it required extraction/replacement because of abnormalities suggestive of a structural defect, e.g. out-of-range impedance, nonphysiological electrical noise or ineffective therapy.

Results

From January 2013 to July 2021, 2403 patients were implanted and followed up (78% male, age 49±15years, ejection fraction 45±16%, body mass index 26±4Kg/m2). A 3501-model lead was used in 1697 patients and a 3401-model in 706 patients. During a median follow-up of 38 months [25th–75th percentile: 24-55], we detected 4 malfunctioning model-3501 leads and 2 model-3401 leads. After analysis of the returned leads by the manufacturer’s technical services, a single model-3501 lead failure was a fracture distal to the proximal ring electrode, as described in the manufacturer’s advisory letter. No deaths or permanent injuries occurred as a result of lead failures. The survival of 3501-model leads at 4 years was 99.5% (95% confidence interval, 99.0 to 99.9) compared with 99.9% (95% confidence interval, 99.6 to 100.0) of 3401-model leads (p=0.110). The cumulative occurrence rate of the 3501-model safety notification fracture was 0.1% (95% confidence interval, 0.0 to 0.3).

Conclusions

In this large multicenter analysis, the survival probability of model-3501 S-ICD leads was in line with that reported by the manufacturer, was not significantly lower than that of 3401-model leads (not affected by a safety notification), and still higher than that reported with transvenous leads. Although an enhanced electrode is now available, which addresses the potential for electrode body fracture, the present findings are reassuring and may have significant implications for the management of patients who have affected leads.

The subcutaneous ICD replacement in the clinical practice: preliminary observations from the multicentre RHYTHM DETECT

Funding Acknowledgements

Type of funding sources: None.

Background

Experience with the subcutaneous implantable cardioverter-defibrillator (S-ICD) is expanding rapidly. However, few data on generator replacement exist.

Purpose

The aim of this analysis was to describe the procedural characteristics of the pulse generator replacement in the current Italian practice and to provide a preliminary insight in the possible acute complications associated with first elective S-ICD generator replacements.

Methods

We analyzed 106 consecutive patients enrolled in the Rhythm Detect registry who underwent elective replacement of the S-ICD generator from September 2019 to July 2021. Procedures were accomplished according to the local clinical practice. A chest X-ray was performed, and the PRAETORIAN score was assessed and compared with the one measured after the first implantation.

Results

All replacements were performed in electrophysiology laboratories, 50% in day-hospital regimen, by 1 or 2 expert operators. Procedures were performed using local (87%) or general anaesthesia (13%). The median procedure duration was 40 (30-45) min. The previous S-ICD generator was in a subcutaneous pocket in 58 (55%) patients, and in an intermuscular pocket in the remaining patients. The PRAETORIAN score of the previous system was low (<90) in 93% of patients and intermediate in 7% of patients. In all patients with the device in an intermuscular pocket, the PRAETORIAN score was <90. During the replacement procedure, 22 S-ICD (3 with PRAETORIAN ≥90 before replacement) were removed from the initial subcutaneous position and placed in an intermuscular pocket. After replacement all patients with intermuscular devices had a score <90, and the overall proportion of patients with low-risk PRAETORIAN score raised to 97%. Defibrillation testing was performed only in 10% of patients, while testing was performed in 77% of patients at the first implantation procedure. No procedure-related complications occurred.

Conclusions

S-ICD replacements seem easy to perform with no peri-procedural complications. The adoption of an intermuscular pocket is associated with optimal positioning according to the PREATORIAN score, and seems preferred also in many cases of generators previously placed subcutaneously. In the Italian clinical practice conversion testing is rarely performed at device replacement.

Defibrillation testing of subcutaneous versus transvenous defibrillators in the clinical practice: a nationwide survey in Italy

Aims

According to current guidelines, defibrillation testing (DT) for efficacy can be omitted in patients undergoing transvenous implantable cardioverter–defibrillator (T-ICD) implantation. DT is still recommended for patients at risk for a high defibrillation threshold (e.g. hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, right-sided implantations) and for ICD generator changes. Moreover, a class I recommendation remains to perform DT during the implantation of subcutaneous ICD (S-ICD). The aim of the present survey was to analyze the current practice of DT during T-ICD and S-ICD implantations in Italy.

Methods

In March 2021, an ad hoc questionnaire on the current performance of DT and the standard practice adopted during testing was completed by 72 operators at Italian centers implanting S-ICD and T-ICD.

Results

48 (67%) operators reported never performing DT during de-novo T-ICD implantations, while no operators perform it systematically. The remaining respondents perform it in specific cases: right sided implantations (54%), poor signal sensing (46%), secondary prevention patients (42%), arrhythmic syndromes (13%), hypertrophic cardiomyopathy (8%). DT is never performed at T-ICD generator change. At the time of de-novo S-ICD implantation, DT is never performed by 9 (13%) operators and performed systematically by 48 (66%). The remaining operators perform DT in cases of: secondary prevention patients (73%), sub-optimal S-ICD placement (33%), non-compromised ejection fraction (33%) or obese patients (7%). DT is not performed at S-ICD generator change by 92% of operators. DT is conducted by delivering a first shock energy of 65J by 60% of operators, while the remaining 40% test lower energy values. The most frequently reported conditions for revising the system at the end of de- novo implantation procedure is high shock impedance (54%) and sub-optimal S-ICD placement or high PRAETORIAN score (50%). With adequately low shock impedance and optimal system placement, 37% of operators would accept a defibrillation margin <15J.

Conclusion

In current clinical practice, the vast majority of operators omit DT at T-ICD implantation, even when still recommended in the guidelines. DT is also frequently omitted at S-ICD implantation. We also report a wide variability among operators in the procedures followed during DT and in the criteria applied for defining the procedural success.

Funding Acknowledgement

Type of funding sources: None.

Performance of transcatheter pacing system use in Relation to Patient Age

Background

Real-world safety data on the use of transcatheter pacing systems in particularly young and elderly patients is still limited.

Purpose

The aim of this analysis was to investigate the effect of age on the safety and efficacy of leadless pacemaker implant.

Methods

From May 2016 through July 2019, 577 patients were implanted with a leadless single chamber pacemaker according to current pacing indication in 15 Italian cardiologic centers. The population was divided into age quartiles for evaluation, including: 1) <70 years, 2) 70–77 years, 3) 78–83 years, and 4) ≥83 years. Procedural data, complications, electrical parameters were collected at baseline and during the follow up.

Results

Procedural-related complication occurrence was very low (<1.0%) and similar in the four subgroups according to age. No cardiac tamponade was reported. Among the groups, no difference was observed in procedural time, fluoroscopy time duration and electrical parameters (mean pacing impedance: 750±192 and 599±156, mean pacing threshold: 0.7±0.5 and 0.7±0.6, and mean right ventricular sensing 10.7±6.1 and 11.5±4.8 at implant and last follow up, respectively). Figure 1 showed the distribution of age in the patient population.

Conclusion

The reported data demonstrated a high degree of safety during leadless implant across all patient ages. Procedural complications and device electrical measurements were similar among the different ages.

Funding Acknowledgement

Type of funding sources: None.

Ventricular arrhythmias among patients with implantable cardioverter-defibrillator during the COVID-19 pandemic

Background

Coronavirus Disease-2019 (COVID-19) has been associated with myocardial injury and higher risk of arrhythmic complications. However, no reports are available about the effect of the ongoing pandemic on arrhythmias in patients at risk.

Objective

To describe the effect of COVID-19 pandemic on arrhythmic burden among high-risk patients.

Methods

This is a cross-sectional study on the incidence of ventricular arrhythmia (VA) during the pandemic outbreak (study period), compared to the same timeframe in 2019 (reference period). Inclusion criteria were age (>18 years) and having an implantable cardiac defibrillator (ICD).

Results

Among 455 patients enrolled (mean age 64.9 ± 15.7 years; 25.1% females and 39.6% with CRTD), in the study period, 45 (9.9%) patients experienced a total of 86 VA; 8 patients (1.7%) required antitachycardia-pacing (ATP) and 6 (1.3%) at least one shock. In the reference period, a total of 69 events occurred in 36 patients (7.9%). Six patients (1.3%) required ATP and three (0.7%) at least one shock. The number of patients that suffered from any arrhythmic events in the study period (9.9% vs 7.9%) did not significantly differ from the reference period (χ2 = 1.09, P = .29). The main predictor of VA during the COVID-19 pandemic was the previous history of any ICD therapy (OR = 3.84, P < .001).

Conclusions

No evidence of an increase of arrhythmic burden was found during the COVID-19 pandemic among patients with an ICD.

Cardiac arrhythmias and In-hospital mortality amongst patients with takotsubo cardiomyopathy: A retrospective study in an Italian population

•

Takotsubo cardiomyopathy was more common in women and the mortality rate was 2.2%.

•

Ventricular arrhythmias were the strongest predictor of mortality.

•

Age was associated with increased mortality in women with takotsubo cardiomyopathy.

Background

Methods

Results

Conclusion

Transient ICD malfunctions during oncologic radiotherapy: a multi-centre, randomized, in-vitro study

Background

Direct exposure of implantable cardioverter-defibrillators (ICDs) during radiotherapy is still considered potentially harmful, or even unsafe, by manufacturers and current recommendations. The effects of photon beams on ICDs are unpredictable, depending on multiple factors, and malfunctions may present during exposure.

Purpose

To evaluate transient ICD malfunctions by direct exposure to doses up to 10 Gy during low-energy RT, forty-three contemporary wireless-enabled ICDs, with at least 4 months to elective replacement indicator (ERI) were evaluated in a real-time in-vitro session in three different centres.

Methods

All ICDs had baseline interrogation. Single chamber devices were programmed to the VVI/40 mode and dual or triple chamber devices were programmed to the DDD/40 mode. Rate response function and antitachycardia therapies were disabled, with the ventricular tachycardia (VT)/ventricular fibrillation (VF) detection windows still active. A centring computed tomography was performed to build the corresponding treatment plan and the ICDs were blinded randomized to receive either 2-, 5- or 10-Gy exposure by a low photon-energy linear accelerator (6MV) in a homemade water phantom (600 MU/min). The effective dose received by the ICDs was randomly assessed by an in-vivo dosimetry. During radiotherapy, the ICDs were observed in a real-time session using manufacturer specific programmer, and device function (pacing, sensing, programmed parameters, arrhythmia detections) was recorder by the video camera in the bunker throughout the entire photon exposure. All ICDs had an interrogation session immediately after exposure.

Results

During radiotherapy course, almost all ICDs (93%) recorded major or minor transient electromagnetic interferences. On detail, sixteen ICDs (37.2%) reported atrial and/or ventricular oversensing, with base-rate-pacing inhibition and VT/VF detection. Twenty-four ICDs (55.8%) recorded non clinically relevant noise, and no detections were observed. Only three ICDs (7%) reported neither transient malfunction nor minor noise, withstanding direct radiation exposure. At immediate post-exposure interrogation, the ICDs that recorded major real-time malfunctions had VT/VF detections stored in the device memory. In none of the ICDs spontaneous changes in parameter settings were reported. Malfunctions occurred regardless of either 2-, 5- or 10-Gy photon beam exposure.

Conclusions

Transient electromagnetic interferences were observed in most of the contemporary ICDs during radiotherapy course, regardless of photon dose. To avoid potentially life-threatening ICD malfunctions such as pacing inhibition or inappropriate shock delivery, magnet application on the pocket site or ICD reprogramming to the asynchronous mode are still suggested in ICD patients ongoing even low energy radiotherapy exposure.

Funding Acknowledgement

Type of funding source: None

Permanent CIED malfunctions after oncologic radiotherapy: a multi-centre, randomized, in vitro evaluation

Background

Direct photon exposure of pacemakers (PMs) or implantable cardioverter-defibrillators (ICDs) during oncologic radiotherapy may transiently or permanently affect normal device function. To evaluate potential malfunctions by direct exposure to doses up to 10 Gy in 6-MV oncologic radiotherapy, commonly considered unsafe or even not recommended, 145 PMs and 65 ICDs were observed in three different centres.

Methods

All devices had a baseline interrogation and reprogramming to VVI/40 or to DDD/40 mode, depending on type and model. Rate-adaptive function was disabled in all the devices, whereas in ICDs, even antitachycardia therapies were disabled with the ventricular tachycardia/fibrillation (VT/VF) windows left enabled. To build the corresponding treatment plan, a centring computed tomography was performed with different Treatment Plan Systems among the centres. The devices were blinded randomized to receive either 2-, 5- or 10-Gy direct exposure by a 6-MV linear accelerator (different among the three centres) in a water phantom (600 MU/min). The effective dose received was assessed by a random in-vivo dosimetry. All devices had a telemetry interrogation immediately after exposure and once monthly during a six-month follow-up.

Results

Immediately after photon exposure, no changes in device parameters or software errors were observed in 209 devices (99.5%). A non-reprogrammable reset to emergency back-up mode (VVI/65) occurred in a PM (0.5% overall; 0.7% among PMs). Seven PMs reached the Elective Replacement Indicator immediately after exposure (3.3% overall; 4.8% among PMs). Sixteen ICDs (7.6% overall; 24.6% among ICDs) had multiple VT/VF detections stored in the device memory. Two PMs (1% overall; 1.4% among PMs) reported atrial fibrillation detections.

During a six-month follow-up, a non-reprogrammable software reset (back-up to VVI/65 mode) was reported in one PM three months after a single exposure of 2 Gy (0.5% overall; 0.7% among PMs). Abnormal battery drain was observed in thirteen PMs (6.2% overall; 9% among PMs), and in one ICD (0.5% overall; 1.5% among ICDs). All events presented regardless of exposure dose of either 2, 5, or 10 Gy.

Conclusions

Last-generation devices, both PMs and ICDs, withstood direct 6-MV photon exposure up to 10 Gy, commonly considered not recommended or even unsafe by manufacturer statements and clinical guidelines. The most common failures were referred to battery issues. Malfunctions occurred solely in less recent devices, regardless of photon dose.

Funding Acknowledgement

Type of funding source: None

P1443Accuracy of three algorithms in predicting accessory pathway localization in a pediatric population with ventricular pre-excitation

BACKGROUND

Prediction of accessory pathway location is extremely important before scheduling ablation, even more in paediatric patients. Given the absence in the literature of conclusive and recent studies that established the best algorithm to predict location in these patients, especially after the introduction of 3D mapping systems, we designed a study to compare three previously published algorithms.

AIM

The aim of this study is to assess and compare the accuracy in predicting accessory pathway location of the algorithm by Arruda, Boersma and Chiang.

METHODS

This is a multicenter, observational, retrospective clinical study based on the analysis of the resting 12-leads ECGs of children (aged 0-18 years) with ventricular pre-excitation pattern. The study lasts from January 2013 to June 2019. We analyzed the accuracy (defined as percentage of true positive values) of predicted location by each algorithm, which could include one or more than one of 13 regions around mitral and tricuspid annuli.

RESULTS

Study population was composed by 120 patients, mean age was 12.7 +/- 3.6 years (height 155.6 +/-19.3 cm and weight 48.3 +/- 17.1 kg). The algorithm by Boersma has the highest percentage of predicted pathway locations that are found to be concordant with the site of successful AP ablation (see table). When we corrected for pre-test probability, the algorithm by Arruda makes the possibility of one specific location 8 times higher, the one by Boersma 6.4 times higher and the one by Chiang 6.9 times higher than by chance. 

CONCLUSIONS

The algorithm by Boersma showed the highest accuracy in accessory pathway location, on the other hand the one by Arruda seems to have the highest corrected accuracy in accessory pathway among children.

table 1 Arruda Boersma Chiang Number of locations 13 9 13 Total accuracy 0,617 0,717 0,533 Corrected accuracy per locations 8,0158 6,4494 6,929

Abstract Figure. picture 1

P1134Cardiac pacemakers and transient electromagnetic interferences during radiotherapy courses: a multicentre, real-time, in-vitro evaluation

Funding Acknowledgements

None

Background

The effects of high dose oncologic radiotherapy (RT) on cardiac pacemakers (PMs), at even less than 6 MV power, are unpredictable, depending on multiple factors. Normal PM function may be impaired during direct exposure, due to electromagnetic interferences (EMIs). Potentially life-threatening malfunctions may occur, expecially in PM-dependent patients, and both manufacturers and guidelines discourage direct exposure.

Purpose

To evaluate transient EMI-related PM malfunctions during direct exposure to doses up to 10 Gy during radiotherapy course, 17 wireless-telemetry-enabled PMs with sufficient residual battery charge for the purpose of the study (at least 4 months to elective replacement indicator, E.R.I.) were evaluated in three different centres.

Methods

All PMs underwent baseline interrogation. Single chamber devices were programmed in the VVI/40 mode while dual or triple chamber devices were programmed in the DDD/40 mode. To avoid the "run-away" phenomenon during exposure rate-adaptive function was disabled. A centering computed tomography was performed to build the corresponding treatment plan and the PMs were blinded randomized to receive either 2, 5 or 10 Gy exposure by a 6 MV linear accelerator in a homemade water phantom (600 Um/min). The effective dose received by the PMs was randomly assessed by an in-vivo dosimetry. During RT course, the devices were observed in a real-time session using manufacturer specific equipment, and PM function (pacing and sensing, programmed parameters) was recorder by a video camera in the bunker throughout the entire radiation exposure.

Results

During RT course, 13 PMs (76.5%) recorded not clinically relevant minor transient  EMIs, and no atrial and/or ventricular oversensing nor base-rate-pacing inhibition were observed. Only 4 PMs (23.5%) reported neither transient malfunction nor minor EMIs, withstanding direct radiation exposure. Transient EMI-related malfunctions were observed regardless of either 2, 5 or 10 Gy exposure.

Conclusions

Minor, not clinically relevant EMI-related interferences were observed in most of the PMs during direct exposure. Nevertheless, to avoid potentially life-threatening PM malfunctions, magnet application on the PM pocket site or reprogramming are still suggested in PM-dependent (high risk) patients ongoing even low energy RT exposure.

910Noise-related malfunctions in modern ICDs during oncologic radiotherapy: a multicentre, real-time, in-vitro observation

Funding Acknowledgements

None

Background

Direct photon exposure of implantable cardioverter-defibrillators (ICDs) during radiotherapy is still considered not recommended, or even unsafe, by manufacturers and guidelines. The effects of photon beams on ICDs are unpredictable, depending on multiple factors, and electromagnetic interferences (EMIs) may present during exposure.

Purpose

To evaluate transient ICD malfunctions by direct exposure to doses up to 10 Gy during low-energy radiotherapy, 36 contemporary wireless-enabled ICDs, with at least 4 months to elective replacement indicator (E.R.I.) were evaluated in a realtime in-vitro session.

Methods

All ICDs had baseline interrogation. Single chamber devices were programmed in the VVI/40 mode and dual or triple chamber devices were programmed in the DDD/40 mode. Rate response function and antitachycardia therapies were disabled, with the ventricular tachycardia (VT)/ventricular fibrillation (VF) detection windows still working. A centering computed tomography was performed to build the corresponding treatment plan and the ICDs were blinded randomized to receive either 2, 5 or 10 Gy exposure by a low photon-energy linear accelerator (6MV) in a homemade water phantom (600 MU/min). The effective dose received by the ICDs was randomly assessed by an in-vivo dosimetry. During radiotherapy course, the devices were observed in a real-time session using manufacturer specific programmer, and ICD function (pacing, sensing, programmed parameters, detection) was recorder by the video camera in the bunker throughout the entire photon exposure. All ICDs had an interrogation session immediately after exposure.

Results

During radiotherapy course, almost all ICDs (90.9%) recorded major or minor transient EMIs. On detail, 16 ICDs (44.4%) reported EMI-related atrial and/or ventricular oversensing, with base-rate-pacing inhibition and VT/VF detection. 16 ICDs (44.4%) recorded not clinically relevant minor EMIs, and no detections were observed. Only 4 ICDs (11.2%) reported neither transient malfunction nor minor EMIs, withstanding direct radiation exposure. At immediate post-exposure interrogation, the ICDs that recorded major real-time malfunctions had VT/VF detections stored in the device memory. In none of the ICDs spontaneous changes in parameter settings were reported. EMI-related malfunctions occurred regardless of either 2, 5 or 10 Gy photon beam exposure.

Conclusions

Transient EMIs were observed in most of the contemporary ICDs. To avoid potentially life-threatening ICD malfunctions such as pacing inhibition or inappropriate shock delivery, magnet application on the pocket site or reprogramming in the asynchronous mode are still suggested in ICD patients ongoing even low energy radiotherapy exposure.

P551Permanent cardiac implantable device damage during direct photon exposure for oncologic radiotherapy: a multicentre, in-vitro observation

Funding Acknowledgements

None

Backgroung. Direct photon exposure of cardiac implantable devices (CIEDs), both pacemakers (PMs) or implantable cardioverter defibrillators (ICDs), during oncologic radiotherapy (RT) courses may transiently or permanently affect normal device function.

Purpose

To evaluate CIED damage by direct exposure to doses up to 10 Gy in oncologic RT, commonly considered unsafe or even potentially harmful, 206 CIEDs (143 PMs and 63 ICDs) from three different centres, with at least 4 months to Elective Replacement Indicator (E.R.I.) were observed.

Methods. All CIEDs had a baseline telemetry interrogation. Single chamber devices were programmed in the VVI/40 mode and dual or triple chamber ones were programmed in the DDD/40 mode. Rate adaptive function was disabled. In ICDs, antitachycardia therapies were disabled with the ventricular tachycardia/fibrillation window left enabled. A centering Computed Tomography was performed to build the corresponding treatment plan and CIEDs were blinded randomized to receive either 2, 5 or 10 Gy (direct exposure) by a 6 MV linear accelerator in a home-made water phantom. An in-vivo dosimetry randomly assessed the effective dose received by the CIEDs. All CIEDs were interrogated immediately after exposure and monthly during a three-month follow-up.

Results. Immediately after photon exposure, no changes in device setting or software errors were observed in 205 CIEDs (99·5%). Reset to emergency back-up mode was observed in a PM (0·49% overall; 0·7% among PMs). Seven PMs reached the E.R.I immediately after exposure (3·4% overall; 4·9% among PMs). Sixteen ICDs (7·8% overall; 25·4% among ICDs) reported multiple ventricular  tachycardia/fibrillation detections stored in the device memory. During follow-up, a non-reprogrammable software reset (emergency backup VVI/65 mode) was observed in one PM after a single dose of 2 Gy (0·49% overall; 0.7% among PMs), whereas an abnormal battery drain was observed in 6 PMs (2.9% overall; 4.2% among PMs). No battery issues were observed in ICDs. All reported events occurred regardless of either 2, 5, or 10 Gy direct exposure. Malfunctions were observed in only older CIEDs.

Conclusions. Recent CIEDs have shown to be safe during oncologic RT, withstanding direct exposure up to 10 Gy, commonly considered not recommended or even unsafe by manufacturers statements and clinical guidelines. Malfunctions occurred solely in older devices.

P2871Attenuated clinical benefit after ICD replacement over long term follow-up in a contemporary large world population: insight to the DECODE registry

Background

Cardiac Implantable Electronic Device (CIED) surgery is threatened by serious complications both during the procedure and during follow-up. The factors associated to attenuated clinical benefit over long term follow-up are poorly understood.

Purpose

To evaluate type and extent of Adverse Events (AEs) and potential predictors of major AEs over 12 months after ICD/CRT-D replacement/upgrade in a contemporary Italian population.

Methods

Detect long-term complications after ICD replacement (DECODE) was a prospective, single-arm, multicenter cohort study aimed at estimating medium- to long-term complications in a large population of patients (pts) who underwent ICD/CRT-D replacement/upgrade from 2013 to 2015. The endpoint for this analysis is death from any cause, procedure-related infection, and surgical actions/hospitalizations necessary to treat the AEs.

Results

We included 983 consecutive pts (median age 71 years, 76% male, 55% ischemic, 47% CRT-D). During a mean follow-up duration of 353±49 days, 7% of the pts died. A total of 104 AEs occurred in 70 (7.1%) pts. 43 (4.4%) pts needed at least one surgical action to treat the AEs. A total of 23 (2.3%) pts had infective AEs (CIED related in 12 pts, due to other causes in 11). Mortality was unrelated to the occurrence of overall AEs, or of CIED-related AEs, or of surgical actions/hospitalizations needed to correct AEs. The endpoint was reached by 109 (11%) pts over 12-month follow-up (97 pts had a single event, and 12 pts had two events). The median time to the endpoint was 137 [50 - 254] days. On multivariate Cox regression analysis adjusted for baseline confounders, ischemic cardiomyopathy (HR = 1.86, 95% CI: 1.18 to 2.91; p=0.0076), hospitalization prior to the procedure (2.34, 1.35 to 4.05; 0.0025) and anticoagulation (1.91, 1.25 to 2.92; 0.0032) were associated with the endpoint during follow-up.

Conclusion

Evaluation of the patient's profile may assist in predicting vulnerability and should prompt reconsideration of the procedure by deferring at a more stable clinical status, and carefully individualized in the setting of upgrades and anticoagulation management

Acknowledgement/Funding

None

Validation of Criteria for Selective His Bundle and Para-Hisian Permanent Pacing

BACKGROUND

His Bundle (HB) pacing is a valid alternative to right ventricular pacing for patients with preserved His-ventricle conduction who are candidates for permanent stimulation. Permanent pacing in the HB area enables Selective HB pacing (SHBP) or para-Hisian pacing (PHP) to be achieved. The aim of our study was to draw up a set of easy criteria to differentiate and validate the two kinds of stimulations according to the pacing output and the ECG/EKG signals.

METHODS AND RESULTS

From February to July 2005, 17 patients eligible for a pacemaker (PM) procedure underwent implantation with the Medtronic SelectSecure lead (Medtronic, Minneapolis, MN, USA) screwed into the HB area.SHBP was defined when the intrinsic QRS was equal, in both duration and morphology, to the paced QRS, the His-Ventricular (H-V) interval was equal to Pace-Ventricular interval (Vp-V) and, at low output, only the HB was captured, while increasing the output resulted in both the HB and right ventricular (RV) being captured (widening of QRS at high output). Conversely, PHP was defined when the intrinsic QRS differed from the paced one, either in morphology or in duration and, at high output, both the RV and HB were captured (non-SHBP), while decreasing the output resulted in losing HB capture (widening of QRS at low output). According to these criteria, SHBP was achieved in 11 patients, while in the remaining 6, PHP was obtained. No adverse events were reported.

CONCLUSIONS

The above criteria enabled SHBP and PHP to be validated easily and clearly. A longer follow-up will be needed in order to ascertain whether the clinical outcome of these two approaches differs.

Esophageal motor abnormalities in children with gastroesophageal reflux and peptic esophagitis

Esophageal motility was studied in 26 children with gastroesophageal reflux. In 11 patients (group A), esophagitis was severe; in the remaining 15 (group B), either mild or no microscopic changes were found. Lower esophageal sphincter pressure and amplitude, as well as velocity and duration of esophageal pressure waves, were manometrically measured. All patients underwent a 12-week intensive antacid course. Manometric tracings, blindly read, were compared with those of 16 age-matched children with emesis without proven reflux (group C). Among the variables analyzed, amplitude of the motor waves was significantly lower in patients with severe esophagitis than in group B and C patients (P less than 0.01). Nonspecific motor defects (simultaneous, broad-based, double-peaked waves) were more commonly present in group A. At the end of therapy, symptoms had either disappeared or significantly improved. Endoscopic and histologic studies showed disappearance of the severe inflammatory changes. Manometry, repeated in patients with cured severe esophagitis, showed normalization of the amplitude and significant decrease of the nonspecific motility abnormalities. We conclude that severe gastroesophageal reflux disease in children causes esophageal motor dysfunction, resulting from esophageal inflammation. The occurrence of esophageal motility disorders only in patients with severe esophagitis and its disappearance after therapy may account for the favorable course of reflux disease in infancy.