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. 2016 Feb 22;17(Suppl 5):v14–v15. doi: 10.1093/europace/euv327

Moderated Posters 1

PMCID: PMC4892102
Europace. 2016 Feb 22;17(Suppl 5):v14–v15.

43: Pragmatic versus electrocardiogrpahic-guided loop reocrder position, an outcomes study

D Abdul-Rahman 1, MF Paton 1, J Gierula 1, P Bramley 1, HA Jamil 1, KK Witte 1

Abstract

Background: The implantable loop recorder (ILR) is an electronic cardiac device indicated to aid diagnosis in patients with recurrent unexplained episodes of syncope or palpitations. At Leeds General Infirmary there are two surgical approaches for ILR implantation. The first utilises electrocardiographic mapping to obtain a position of optimal QRS signal characteristics; this is usually at the left sternal edge (LSE). The second approach focuses on cosmetic outcome, placing the ILR where pacemakers are typically fitted, at the left infra-clavicular (LIC) site. Patients referred for an ILR implant are assigned consecutively and randomly to the lists of operators applying either of the surgical approaches.

Diagnostic utility, forming a symptom-rhythm correlation leading to a diagnosis, is a clinically relevant way of evaluating these approaches. The aim of this project was to investigate whether the use of electrocardiographic mapping to determine an ILR implant position can influence diagnostic utility.

Methods: The current report concerns two studies. Initially, a retrospective study was carried out, involving 77 patients (46% male) implanted with an ILR during 2010. Data regarding ILR position at implantation and diagnostic outcomes of the patients were collected. Subsequently, we collected electrical and demographic data prospectively from 95 patients (46% male) with standard indications for ILR implantation: recurrent unexplained syncope, pre-syncope or palpitations, at implant and at the 6-week follow-up check. Statistical analysis was undertaken using SPSS statistical software. A p value < 0.05 was considered statistically significant.

Results: Groups in both studies were well matched for basic demographics and indications. Diagnostic utility did not differ according to implant site; the rate of diagnosis was 82% at LSE and 83% at LIC. The prospective study showed that although at implant, the QRS signal was significantly weaker at LIC (p <0.001); at the 6-week check the QRS signal became analogous between the groups (p=0.21) (Figure 1).

Conclusion: Electrocardiographic mapping does not improve QRS signals at follow-up and therefore does not affect diagnostic utility of loop recorders implanted for standard indications. Hence a pragmatic approach that considers cosmetic factors and the potential requirement for future device therapy is a reasonable way to determine position at the time of the initial implantation.

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Europace. 2016 Feb 22;17(Suppl 5):v14–v15.

44: Initial experience of reveal linq implantation without antibiotics in a non-theatre setting

P Le Page 1, J He 1, H Cusden 1, A Taylor 1, M Ghandi 1, J Dean 1, P Spurrell 1, MJ Lovell 1

Abstract

Introduction: Early generation implantable loop recorders (ILR's) require implantation in a theatre environment typically with antibiotic cover to minimise the risk of infection. We set out to establish whether the new Medtronic Reveal LINQ TM (RL) device could be safely implanted in a non-theatre setting without the use of antibiotics.

Methods: We enrolled consecutive patients attending our centre for implantation of an RL device from June 2014 to May 2015. All procedures were performed in a non-theatre environment. Anticoagulation or antiplatelet medications were continued for all procedures. Patients were placed on a reclining couch at 40 degrees with the chest exposed. Operators wore a surgical gown and gloves. Chlorhexidine with 70% alcohol was used for skin preparation. The RL device was then implanted using the standard technique. The wound was closed with staples and covered with a clear dressing. No antibiotics were administered. Patients then recovered in an adjacent room for device set-up and home monitoring information prior to discharge one hour later.

Patients were followed-up using the Reveal LINQ MyCareLink TM System and through telephone clinics.

Results: In total 106 patients had an RL implant during the study. Six patients were lost to follow-up; two relocated and four died, all of which were non-arrhythmic and unrelated to device implantation. The remaining 100 patients were followed-up for a mean of 185 days, range 15–358 days. Demographics and arrhythmia detection are shown in Table 1.

Mean procedure time from patient entry to exit from procedure room was 18 minutes.

During follow-up there were no infective complications. No complications related to anticoagulation or antiplatelet medication were noted. Two patients had RLs explanted for erosion. A further two patients requested removal of the device due to discomfort

Mean age 78 (range 19–95)
Male 60 (56%)
Female 46 (44%)
Antiplatelet use 23%
Anticoagulation use 12%
Mean time to significant arrhythmia 111 (17-452) days
Mean time to significant symptom 86 (1–369) days
Arrhythmia detection 33%
Subsequent pacemaker implant 16%
Typical symptoms and demonstration of sinus rhythm 26%
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Conclusion: During a mean of 185 days of follow-up a diagnosis was obtained in 59% of patients implanted with a Reveal LINQ TMdevice.

Unexpectedly, four devices were explanted during follow up for erosion or discomfort. We believe this is related to the learning curve of the new procedure. In particular implanters must endeavour to implant RL devices parallel to the subcutaneous tissue and ensure they are fully deployed to minimise these risks.

Our data shows that implantation of these devices in a non-theatre setting without the use of antibiotics is quick, safe and carries a low risk of infection. This has important implications with respect to the best use of expensive resources such as theatre time.

Europace. 2016 Feb 22;17(Suppl 5):v14–v15.

45: The importance of lead selection on the interpretation of T wave alternans

C Hayward 1, H Patel 1, A Morley-Smith 1, K Patel 2, R Shaikh 3, J Simonotto 4, A Lyon 1

Abstract

Introduction: T wave alternans (TWA) showed promise as a measure of arrhythmia risk but the evidence for its use to guide patient selection for defibrillator implantation has not been compelling. REFINE-ICD is currently investigating this using the modified moving average (MMA) method to derive TWA values from Holter monitors. There is no consensus as to which lead of the ECG should be interrogated to establish the most valid TWA value. Our objective was to investigate whether lead selection significantly affects the interpretation of TWA using the MMA method.

Methods: Part 1(simulation studies): Cardiac alternans can be a global or regional phenomenon. ECGSIM was used to create action potential duration alternans (APDA) of 4ms in different locations within the left ventricle (anterior, apical, posterior and lateral), in the right ventricle (RV) and globally. APDA in the myocardium generates TWA on the surface ECG. TWA magnitude in all 12 leads of the simulated ECG was determined using a method analogous to the MMA method. Part 2 (clinical studies): 20 patients with heart failure were monitored using 24 hour 12-lead Holter monitors and TWA determined using the MMA method. The peak TWA was recorded for each of the 12 leads over the 24 hour period.

Results: For all simulation studies the chest leads displayed the highest levels of TWA (Figure 1). The maximum magnitude of TWA was found in different leads depending on the underlying source of APDA: V3 for anterior and global APDA, V4 for apical APDA, V6 for lateral APDA, and V2 for posterior and RV APDA. Despite the same magnitude of APDA being simulated in each region, there was a large variation in the maximum TWA recorded from 16.5 µV (during lateral APDA) to 44.1 µV (during anterior APDA). In addition, TWA magnitude dropped off rapidly in the leads adjacent to the maximally recorded TWA.

For the clinical study, the lead displaying the peak overall TWA was different between subjects: in 65% peak TWA was seen in V5, in 15% it was seen in V4, in 15% V3 and in 5% lead II. There was significant variability across the 12 leads in terms of the maximum TWA recorded with some individuals varying by as much as 40 µV (mean 28 µV) depending on which lead was used.

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Conclusions: Lead choice is important when analysing TWA. In the simulation study, the maximum TWA was recorded in leads V2, V3, V4 or V6 depending on the location of the underling APDA. Similarly, in the clinical study, maximum TWA was recorded in different leads for different subjects. These data would suggest that analysis of TWA should involve analysis of as many leads as is feasible, focusing on the chest leads. Another important finding is that depending on where the APDA was simulated the maximum TWA varied significantly from 16.5 µV to 44.1 µV. This variability in location of alternans in the myocardium is likely to exist in patients and as a result some patients with significant APDA may not be identified when using the surface ECG.

Europace. 2016 Feb 22;17(Suppl 5):v14–v15.

46: T wave alternans during tilt table testing

C Hayward 1, H Patel 1, J Simonotto 2, A Morley-Smith 1, K Patel 3, R Shaikh 4, C DiMario 1, S Rosen 2, R Sutton 2, T Salukhe 5, A Lyon 1

Abstract

Introduction: T wave alternans (TWA) determined by the modified moving average (MMA) method is currently being assessed as a marker to guide patient selection for defibrillator implantation in the REFINE-ICD study. There is little data on the effect of sympathetic nervous system (SNS) activation on TWA. We examined the effect of tilting, a manoeuvre known to activate the SNS, on TWA and investigated the effect of age and gender on TWA.

Methods: We conducted a retrospective study examining clinically indicated tilt table tests (TTTs) performed between 2012-2015. Patients with cardiovascular disease (including coronary artery disease, atrial fibrillation and heart failure) and those taking relevant cardiac medications were excluded as these factors are known to affect TWA. TWA was measured using the MMA method. Mean TWA values were derived for the 5 minutes before (pre-tilt) and 5 minutes after tilting. Heart rate variability (HRV) and haemodynamic parameters were also derived at these times. Subgroup analyses were performed to investigate the effect of gender and age on TWA.

Results: 343 suitable patients were identified of whom 39% were male, age range 7-91 years (mean age 29.2 years [SD 16.4]). Tilting resulted in a significant increase in TWA from 28.8 µV to 33.5 µV (P < 0.001). Co-incident with this there was an increase in heart rate and blood pressure along with an elevation in the low frequency:high frequency (LF:HF) ratio of HRV. There was no correlation between change in heart rate and change in TWA on tilting. Subgroup analyses revealed that men had a significantly greater pre-tilt TWA (32.0 µV vs 26.8 µV P < 0.001), a higher pre-tilt LF:HF ratio (1.42 vs 1.15 P = 0.023) and lower pre-tilt heart rate (69bpm vs 75bpm P < 0.001). While these baseline parameters were different between genders, the response to tilting was not different between genders. When the cohort was divided in to tertiles of age there was no effect of age on TWA. None of the measured parameters predicted which patients would experience syncope, which occurred in 52% of the study population.

Conclusions: Tilting results in a significant increase in TWA. This appears to be independent of the typical heart rate changes seen with tilting. Age does not appear to affect TWA but our findings are limited by a skewed age range as a result of excluding those with cardiovascular disease or taking cardiac medications. The gender differences we found at baseline in TWA merits further study using ambulatory monitoring, especially as different thresholds have not been used for men and women in on-going studies such as REFINE-ICD.

Europace. 2016 Feb 22;17(Suppl 5):v14–v15.

47: For how long should patients refrain from driving after receiving an implantable cardioverter defibrillator for secondary prevention?

RT Ford 1, MH Anderson 2

Abstract

The freedom of driving is an important part of the lives of many people. Any restrictions on driving need to balance the impact on the individual against the risk to society of allowing that person to drive. Currently, secondary prevention ICD patients in the UK are not allowed to drive for six months following implantation. Recent studies have suggested this may be excessive and the European Heart Rhythm Association currently recommends a three month ban. We examined the incidence of DVLA disqualifying ventricular arrhythmias in our centre's population after implantation of a secondary prevention ICD. The current DVLA standard requires an annual incidence of incapacitation below 20% to allow Class I (private motor vehicle) licensing. We expected that the incidence of events would be low enough to suggest the current six-month ban is too strict and could be reduced to three months.

Methods: 246 patient records from a single implanting centre with a catchment population of 970,000 were analysed for the six month period following implantation to assess for disqualifying events as defined by the DVLA (Ventricular arrhythmia associated with incapacitation, delivery of a shock therapy or symptoms if treated by antitachycardia pacing). Any events that occurred were grouped into 0-3 or 4-6 months periods. Patients were stratified into those who had an event(s) at 0-3 months and those who did not. Those who had no events at 0-3 months were then further sub-divided into those who had an event(s) at 4-6 months and those who did not. For events where the timing was unclear, ICD printouts were scrutinised to confirm the date. Annualised incidence rates for events were then calculated for the 0-3 and 4-6 month periods.

Results: Of the 246 patients, 29 had a disqualifying event in the first 3 months, giving an annualised event rate of 47% at 0-3 months. Of the 217 patients who did not have an event in the first 3 months, 11 had one in the 4-6 month period. This gave an annualised event rate of 20.2% at 4-6 months, just above the DVLA acceptable rate of 20% (see figure 1).

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Figure 1. Annualised disqualifying event rates after secondary prevention ICD implantation

Conclusion: Using the current DVLA methodology the data from our secondary prevention ICD patients does not support a further reduction in the post implant driving ban below 6 months. The literature suggests that actual accident rates in ICD patients are significantly lower than predicted by this strict methodology. There is a case for the DVLA to review its methodology to ensure an appropriate balance between individual freedom and societal risk.

Europace. 2016 Feb 22;17(Suppl 5):v14–v15.

48: Eligibility of hypertrophic cardiomyopathy patients for subcutaneous ICD: results of postural & exercise ECG screening

NT Srinivasan 1, KH Patel 1, PD Lambiase 1

Abstract

Introduction: Subcutaneous cardioverter defibrillator (S-ICD) implantation requires pre-procedure ECG screening to minimise therapy. Initial studies have shown that up to 7.4% patients (pts) are ineligible for S-ICD. We investigated the proportion of pts with HCM meeting the ECG criteria for S-ICD & reasons for failure.

Methods: 44 pts (70% male, age 51 +/-15 years ) with HCM & ≥1 risk factors for sudden cardiac death were screened. Exclusion critera: inability to exercise, age <20 or >70 years or pacing indication. Eligibility for S-ICD required at least ≥1 sensing vector passing criteria in all 3 screening positions.

Results: 18% of patients failed screening for S-ICD. Genders were equivalent, (16%F, 20%M p = 0.75). 87% failed at rest & 13% on exercise. Mean EF was 65 ±10%, Max. wall thickness 16 ± 0.3 mm, 2% had >30mmHg LVOT gradient, 57% had NSVT. 48% of patients had a transvenous ICD, of which 86% passed S-ICD screening. Univariate predictors for screening failure were a prolonged QRS duration (OR 1.03), increased T-wave amplitude (OR 1.4), low R-wave amplitude in lead aVF(OR 0.79) & a reduced R:T ratio in lead aVF(OR 0.63).

Conclusion: A greater proportion of HCM pts do not meet criteria for S-ICD than previously reported. Prolonged QRS, increased maximal T wave amplitude, low R-wave amplitude in aVF & a reduced R:T ratio in aVF are associated with screening failure. Next generation device algorithms are needed to enable greater device implantation in HCM.

Table 1.

Factors determining screening failure for S-ICD in HCM Patients.

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Europace. 2016 Feb 22;17(Suppl 5):v14–v15.

49: Assessing response to biventricular pacing: non-invasive cardiac monitoring is not sufficiently reproducible to reliably detect response

JHP Gamble 1, M Jones 1, N Herring 1, PWX Foley 1, R Khiani 2, K Rajappan 1, Y Bashir 1, TR Betts 1

Abstract

Introduction: Invasive monitoring of cardiac haemodynamics, such as dP/dt max, has been used to assess acute haemodynamic response (AHR) to biventricular pacing (BiVP). Non-invasive cardiac output monitoring (NICM) would be more straightforward, but has not been validated for this application.

Methods: A pressure wire measured LV systolic pressure (LVSP) and LV dP/dt max in patients undergoing endocardial and epicardial pacing procedures. Patients were anaesthetized or sedated and in a steady state. A thoracic bioreactance NICM device simultaneously assessed stroke volume, derived parameters and the maximum rate of change of the bioreactance signal (dX/dt). At several LV pacing sites per patient we assessed the AHR to BiVP as the change in haemodynamics from a baseline of RV pacing, over 30 seconds, repeated in a random order.

Correlation between the techniques and parameters was assessed with random effects multilevel analysis. Signal-noise ratio was defined as mean effect/standard deviation of repeated measurements at the same settings in the same patient, and used to calculate the number of repeated measurements required to detect the mean AHR.

Results: 33 patients were included, age 67 ± 14, 24 male (73%), 21 (64%) ischaemic, QRSD 151 ± 24, EF 28 ± 7%. AHR was assessed 340 times, at a mean of 11 BiVP configurations per patient.

There were statistically significant correlations between the values of dP/dt max and the values of LVSP and NI-CI, NI-SV, and NI-dX/dt (p < 0.01). There were also significant correlations between AHR by dP/dt max and AHR by LVSP and all the NICM parameters (p < 0.01, except NI-SV and NI-SVI, p = 0.03, 0.049).

Standard deviation of repeated measures of parameter values at the same pacing configurations for dP/dt max was 5.1% of the mean value of dP/dt max, 4.6% for LVSP, and 9.8-12.2% for the NICM parameters.

Signal-noise ratio for AHR was 2.5 for dP/dt max, 1.03 for LVSP, and 0.2 for the NICM parameters, resulting in 1 repetition required for dP/dt max, 2 for LVSP, and 35-45 for the NICM parameters to detect the mean AHR value.

Conclusions: Thoracic bioreactance NICM appears not to be a viable way to assess AHR to BiV pacing, due to poor reproducibility.

The results support the use of blood pressure and dp/dt max to detect AHR, with a suitable number of repetitions. As an illustration we used the mean AHR, but greater number of repeated measures would be needed to detect smaller differences in AHR such as during LV lead site choice or CRT optimisation.

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Figure Modified boxplot to illustrate AHR and measurement error. The boxes represent interquartile range and median of AHR for each parameter. The error bars are the standard deviation of repeated measures of AHR at the same settings.

Europace. 2016 Feb 22;17(Suppl 5):v14–v15.

50: Transvenous extraction of infected cardiac implantable electronic devices - a single centre experience

CEP Brough 1, C McGee 2, A Rao 2, DJ Wright 2

Abstract

Introduction: The incidence of cardiac implantable electronic device (CIED) extractions continues to increase, dominated by extraction secondary to infection. Knowledge of real world CIED transvenous extraction practice is limited, by the absence of national and European registries. Through describing the patient population requiring infected CIED extraction operations, individuals at high risk for device removal will be characterized and the procedural outcomes (tools required, success, complications, re-admission, mortality), will inform health service planners for the future.

Methods: At a single, UK tertiary cardiac centre between April 2006–March 2014, consecutive transvenous CIED extractions were observed for; (1) extraction tools required, (2) complications, (3) 30-day hospital re-admission and (4) death within 1-year. Procedures were contemporarily documented in clinical health records and retrospectively analysed.

Results: Among 335 patients (261 male, 74 female), 336 transvenous extraction procedures were performed; local infection 60%, systemic infection 27% or endocarditis 13%. The median age was 73 years (15–95) and co-morbidities are presented in the table below.

Infection Related Extractions n = 336
Co-morbidities
 Prior cardiac surgery 69 (21%)
 Congenital/corrected congenital heart disease 7 (2%)
 Diabetes mellitus 63 (19%)
 Immuno-compromised 17 (5%)
 Renal impairment 48 (14%)
Anti-Platelet/Anti-Coagulant Prescribed 204 (61%)
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The median implant duration was 7 years (0–33 years), with 175 (52%) of procedures preceeded by at least 1 device related operation within 12 months (50 generator replacements, 43 system reburial, 26 lead only revision, 18 generator and lead revision, 11 primary implant, 10 system upgrade, 11 extraction attempt, 4 site aspiration, 2 haematoma). 97% of leads were successfully extracted (748/771); 39% (295) no specialist equipment, 45% (336) laser, 11% (81) polypropylene sheath, 3.2% (24) combined laser and polypropylene sheat and 1.6% (12) by multiple methods including conversion of vascular access route.

Microbial sampling was performed in 90% of procedures, 51% had a positive growth.

The median length of hospital admission was 7 days (day case–78 days), with 247 patients admitted to level 2 care and 17 to level 3.

A 2% per procedure major complication rate and 9% 30-day hospital re-admission rate was observed. The 1-year all cause mortality was 4%.

Conclusion: Local infection is the dominant indication for infected CIED extraction. The incidence is greater in the male population and within 1 year of device site intervention. 97% of leads can be successfully removed, however >60% will require specialist extraction equipment. The procedure is associated with a 2% major complication rate, 9% 30-day hospital readmission and 4% 1-year all cause mortality.

Articles from Europace are provided here courtesy of Oxford University Press

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