Role of routine chest xrays and device checks in detecting peri-procedural complications associated with cardiac device implantation: a UK tertiary centre experience

Introduction

Complications associated with Cardiac implantable electronic devices (CIEDs) are not uncommon, most of which occur in the perioperative phase. Until recently, guidance on implemented measures for early detection of peri-operative complications were lacking. The ESC guidelines on pacing recommend routine follow up of all newly implanted devices within 72 hours of implant. While the recently published EHRA expert consensus and practical guide on CIEDs recommend that a chest x-ray should be performed within 24 hours in all patients to rule out pneumothorax and document lead positions.

Purpose

At our tertiary centre for CIEDs, it is routine practice to perform CIEDs implantations on a day-case basis, targeting same day discharge for uncomplicated procedures. CXRs are performed 4 hours after the implant, and CIEDs are fully checked twice, once “on table” at the end of the procedure, and again after mobilisation and prior to discharge. In our analysis, we aimed to identify the yield of complications that could be detected early-on using these routine measures in all our implant procedures.

Methods

We performed a retrospective analysis of consecutive CIED implants performed between January and December 2019. The following information were collected; types and indications for device therapy, device checks reports, CXR reports, and clinical notes for documented symptoms or signs suggestive of peri-procedural complications.

Results

A total of 578 patients (Age 74±16 years, 68% male) were included in our analysis, for demographics see table. All patients had routine CXRs and 2 device checks. There were 16 (2.8%) peri-procedural complications associated with our device implants, 7 (1.2%) pneumothoraxes, 6 (1%) pericardial effusions, and 3 (0.5%) lead displacements.

In 4 out of the 7 peri-procedural pneumothoraxes, the operator reported difficulty gaining access. 2 patients with pneumothorax reported chest pain, 1 patient reported shortness of breath and 1 had low O2 saturations. There were 2 asymptomatic cases of pneumothorax after reportedly straightforward procedures and were only detected on the routine CXRs, one of them required chest drain insertion and the other treated conservatively.

2 out of the 3 lead displacements were detected on both CXRs and pre-discharge pacing checks and didn't require intervention, while 1 case of lead displacement occurred after the pacing checks and CXRs were reported to be satisfactory, further pacing checks triggered by patient's symptoms and bradycardia on the monitor revealed lead displacement requiring intervention prior to discharge.

Conclusion

Routine post CIED implantation CXRs can detect early – otherwise clinically silent-periprocedural complications and appropriately remains a requirement for all CIED implants. While repeat post mobilisation device checks has low yield of detection of complications and can be reasonably abandoned provided that initial “on-table” checks are satisfactory.

Funding Acknowledgement

Type of funding sources: None.

Accuracy of AF burden detection with the new Confirm Rx with Sharp-sense technology

Funding Acknowledgements

Type of funding sources: None.

Introduction

Implantable cardiac monitors (ICMs) are increasingly used to monitor atrial fibrillation (AF) burden following catheter ablation. AF burden recorded by the Confirm Rx™ ICM cannot be modified even after adjudication of false-positive (FP) episodes. We sought to investigate accuracy of the AF burden detection in a UK cohort.

Methods

This multicentre retrospective study included patients with Confirm Rx™ and at least one episode >6 minutes across 9 UK hospitals. Each episode had a corresponding 120-second EGM (electrogram) and heart rate scatterplot which was considered representative of the whole episode. One cardiologist adjudicated all EGMs as ‘True AF’ or ‘False positive’ and a random sample of 10% was reviewed to account for intra and interobserver variability. AF burden was computed as the duration of all episodes classified as AF by the Confirm-Rx divided by the total duration of follow-up. ‘True-AF’ burden was calculated by dividing the duration of episodes adjudicated as ‘True-AF’ by the total duration of follow-up. We also investigated the accuracy of AF burden according to implantation indication and episode duration.

Results

A total of 16,230 individual AF episodes were included from 232 consecutive patients. Overall, 26,137 hours of AF were recorded and a total follow-up 315 patient-years which equates to an AF burden of 0.95%. However, only 24,404.7 (93.3%) hours represented time in ‘True-AF’ and a ‘True-AF’ burden for the whole cohort of 0.89% (Table 1). Patients with a Confirm-Rx™ for palpitations and suspected AF had the lowest proportion of ‘True-AF’ burden and had a modest contribution to the overall AF burden (Figure 1). Conversely, patients with known AF had the highest proportion of ‘True-AF’ burden recorded. Most AF (84.5%) episodes lasted less than 1 hour with approximately a quarter adjudicated as false-positive detections, but their contribution towards overall AF burden was very small (Figure 2A-2B). In contrast, AF >3 hours accounted for 76.4% of time in AF and the proportion of ‘True-AF’ burden was 98.5%.

Conclusion

The accuracy of the estimated AF burden for the whole cohort was excellent (93.3%), driven by the high proportion of ‘True-AF’ burden in AF>3 hours.

Establishing safe, effective ablation in the diseased human ventricle: an analysis of generator impedance and electrogram attenuation

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Biosense Webster Inc

Background

Predictors of effective and safe lesion delivery in the human left ventricle have not been established. Generator impedance (GI) drop and electrogram (EGM) attenuation are indices which can be used as surrogates for ablation lesion parameters. Tissue pops are a complication of myocardial overheating preceded by a rise in GI and can have adverse consequences.

Purpose

To establish the relationships between Ablation Index (AI), Force Time Integral (FTI) and contact force with GI and EGM attenuation. To establish factors early in ablation that are predictive of a GI rise.

Methods

Patients undergoing ventricular tachycardia ablation were recruited. All ablations were performed with contact force sensing surround flow catheters. Electrograms were collected pre and post ablation, with GI, AI, FTI measured during. Ablations were divided into low (LVM, < 0.50mV), intermediate (IVM, 0.51 – 1.50mV) and normal voltage (NVM, > 1.50mV) based upon pre-ablation bipolar EGM amplitude. Ablations with a 5% rise in GI from maximal drop were noted and predictors of this explored.

Results

In 15 patients, 402 ablations were analysed. Filtered percentage GI drop correlated with AI and FTI, (p < 0.0005, Spearman’s ρ = 0.522 and 0.524) and reached a plateau at 763AI and 713gs, a filtered GI drop of 7.5% (Figure 1). Shallower curves occurred progressively from NVM to IVM to LVM, (p < 0.0005), (Figure 2)

The bipolar EGM significantly attenuated with ablation, (median attenuation 0.14mV, [29.3%], p <0.0005), but percentage attenuation did not correlate with AI or FTI.

Parameters associated with a GI rise during ablation were greater mean CF to maximum GI drop, (p = 0.002), greater initial percentage GI drop at 5 seconds, (p < 0.0005), power of 50W (p = 0.005), and perpendicular orientation, (p = 0.006). Percentage GI drop at 5 seconds was the best predictor of ablations with a GI rise, (AUCROC 0.773; 95% CI 0.708 – 0.838; optimal cut-off 2.44%). Mean contact force to maximum GI drop was a poor predictor of a GI rise (AUCROC 0.647; 95% CI 0.577 – 0.718, optimal cut-off 14.7g).

Conclusion

During left ventricular ablation, AI of 763 and FTI of 713gs should be targeted, with a lower impedance drop observed for more scarred myocardium. A GI drop of <2.5% at 5 seconds and contact force < 15g should be used to optimise ablation safety.

Diagnostic accuracy of the Confirm-Rx atrial fibrillation detection algorithm in real-world patients

Funding Acknowledgements

Type of funding sources: None.

Introduction

Continuous rhythm monitoring with implantable cardiac monitors (ICMs) is commonly used to detect and characterise atrial fibrillation (AF) episodes. The Confirm Rx™ with SharpSense™ technology offers four new discriminators and second pass analysis aimed at enhancing detection and improving accuracy for cardiac arrhythmias. This study sought to investigate the diagnostic accuracy of the Confirm Rx™ AF detection algorithm in a UK cohort of ‘real-world’ patients.

Methods

This multicentre retrospective study included patients with Confirm Rx™ and at least one episode of AF>6 minutes from August 2018 to August 2021 across 9 UK hospitals. Each episode had a corresponding 120-second electrogram (EGM) and heart rate scatterplot. One cardiologist manually adjudicated all EGMs as ‘True-AF’ or ‘False-positive. To assess for intra and inter-observer variability, 10% of the EGMs were reviewed. Diagnostic accuracy was determined by calculating the raw and patient-averaged positive predictive value (PPV) for AF episode of different durations and implant indications.

Results

During the study 232 patients met inclusion criteria with a total of 315 patient-years of follow-up. 16,320 individual AF episodes were adjudicated; intra- and interobserver variability was excellent (Cohen’s kappa 0.85 and 0.86, respectively). The rate of ‘True-AF’ detection was 3.19 episodes per month corresponding to a raw PPV of 74.5% for the whole cohort. The highest number of episodes per months was observed in patients with a Confirm-Rx for palpitations (5.1) and suspected AF (5.8) but only approximately half of these represented ‘True-AF’ episodes (Figure 1). Patients with known AF had the lowest rate of AF episodes (1.6 episodes per month) but the highest proportion of ‘True-AF’ episodes (PPV of 95.5%). A clear trend of improving diagnostic accuracy was seen with longer AF episodes (Table1). AF>3 hours had a PPV above 94% and all episodes lasting longer than 24 hours were ‘True-AF’. For AF episode of short duration, the PPV varied with the population being monitored; however, for longer AF episodes the PPV increased significantly and irrespective of implant indication (Figure 2).

Conclusion

Overall, the Confirm Rx™ ICM diagnostic accuracy was modest for all AF episodes lasting longer than 6 minutes (74.5%) but improved considerably for longer AF episodes irrespective of implant indication.

Application of recurrence plot analysis to characterise whole chamber propagation of atrial fibrillation

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): Oxford Biomedical Research Centre

Introduction

Non-contact charge density mapping allows visualisation of whole chamber propagation during atrial fibrillation (AF). The identification of regions with repetitive or, conversely, more complex patterns of wavefront propagation may provide clues to mechanisms responsible for AF maintenance and lead to improved outcomes from catheter ablation. Our novel mapping approach based on signal recurrence plots has never been applied to whole chamber, bi-atrial recording of atrial fibrillation.

Purpose

To apply recurrence analysis to characterise whole chamber bi-atrial AF propagation.

Methods

Non-contact dipole signals from left and right atrial maps were obtained during simultaneous bi-atrial charge density mapping of AF. Signals were converted to phase and mean phase coherence calculated for the generation of recurrence distance matrices for the whole chamber and each anatomical region (6x LA and 4x RA) over the 30-second recording duration, where a value of 1 (purple, see figure panel A) represents uniform repetitive conduction, and 0 (red), irregular, non-repetitive activity. Whole chamber and regional mean recurrence values were calculated and correlated with the frequency of wavefronts of localised irregular activation patterns.

Results

Maps were obtained prior to ablation in 21 patients (5 paroxysmal (pAF), 16 persistent AF (persAF)) undergoing de-novo catheter ablation procedures. Whole chamber recurrence was higher in patients with pAF (0.40 ± 0.08) than persAF (0.34 ± 0.05), p < 0.0005. There was an inverse correlation between regional recurrence values and the number of localised irregular activations detected (-0.7021, p < 0.0005, figure panel B) with the lateral LA and anterior RA demonstrating the highest recurrence values in each chamber (figure panel C).

Conclusion

Use of recurrence distance matrices characterises global AF propagation phenotypes. Regional values are inversely correlated with the frequency of localised irregular activation patterns identified demonstrating an anatomic dependence in the level of AF propagation complexity, greatest in the anterior LA and septal RA. Comparison of strategies targeting regions with maximal vs. minimal values during catheter ablation may define an optimal approach to treatment of persistent AF. Abstract Figure. Recurrence abstract figure

P1389Periodicity and Spatial Stability of Complex Propagation Patterns in Atrial Fibrillation

Introduction

Non-contact charge density mapping identifies complex wavefront propagation including localised rotational activation (LRA), localised irregular activation (LIA) and focal firing (FF). However, the duration of mapping required to reveal underlying patterns and their temporal stability is unknown.

Purpose

We sought to evaluate the variability in propagation patterns over increasing durations of recordings up to 30 seconds and examine the stability of these patterns between 2 separate maps with the aim of identifying the minimum duration required to reveal underlying patterns and how they represent the stable arrhythmia substrate.

Methods

Patients undergoing first time AcQMap guided catheter ablation were studied. 30s recordings of left atrial propagation were analysed. LIA, LRA, and FF were quantified for frequency, percentage time present and percentage surface area affected (for FF only frequency was assessed) at increasing durations up to 30s in 1s increments. At each incremental recording duration the percentage change in each variable was calculated. For occurrence frequency the results for every possible combination of maps of increasing duration within the 30s recording were compared whilst for occurrence time and surface area a 5s moving average at 1s increments was calculated. The point at which variability was seen to plateau represents the minimum optimal mapping duration. Spatial stability was assessed by correlating the frequency of patterns at each vertex of the anatomy over 2 separate 30s recordings. Stability of regions with the most repetitive patterns were compared using Cohen’s kappa statistic.

Results

15 patients were analysed (age 63 ± 9, 10 male, BMI 30 ± 5, CHA2DS2Vasc 1 ± 1.3, ejection fraction 54 ± 12%, left atrial diameter 46 ± 7mm, paroxysmal 1, persistent 14) with 11 included in the spatial stability analysis due to availability of recordings of sufficient duration. LRA demonstrated most variability followed by LIA and FF. Variability in LIA, LRA and FF decrease at increasing durations. LIA and FF variability plateau by 13 and 17s respectively. LRA plateaus at 23s. Variability of <10% is reached in all parameters at 18s.

LIA demonstrated the greatest stability with average R2 of 0.76 ± 0.14 (figure). Average R2 for LRA and FF were 0.45 ± 0.16 and 0.47 ± 0.12.  Low frequency focal firings were widely distributed across the atrial surface. For FF occurring at a frequency ≥10 over the 30s, average R2 value was 0.65 ± 0.14. Cohen kappa statistic was 0.70 for LIA and 0.45 for LRA.

Conclusion

Mapping durations of ≥23s are required to identify all temporally variable propagation patterns although shorter durations will identify less variable LIA and FF. 

LIA demonstrates high spatiotemporal stability and may best reflect disrupted conduction caused by the underlying atrial substrate and tissue architecture. Regions of high frequency FF are temporally stable and may represent important targets for ablation.

Abstract Figure 1

Safety and efficacy of multipolar pulmonary vein ablation catheter vs. irrigated radiofrequency ablation for paroxysmal atrial fibrillation: a randomized multicentre trial

Aims

The current challenge in atrial fibrillation (AF) treatment is to develop effective, efficient, and safe ablation strategies. This randomized controlled trial assesses the medium-term efficacy of duty-cycled radiofrequency ablation via the circular pulmonary vein ablation catheter (PVAC) vs. conventional electro-anatomically guided wide-area circumferential ablation (WACA).

Methods and results

One hundred and eighty-eight patients (mean age 62 ± 12 years, 116 M : 72 F) with paroxysmal AF were prospectively randomized to PVAC or WACA strategies and sequentially followed for 12 months. The primary endpoint was freedom from symptomatic or documented >30 s AF off medications for 7 days at 12 months post-procedure. One hundred and eighty-three patients completed 12 m follow-up. Ninety-four patients underwent PVAC PV isolation with 372 of 376 pulmonary veins (PVs) successfully isolated and all PVs isolated in 92 WACA patients. Three WACA and no PVAC patients developed tamponade. Fifty-six percent of WACA and 60% of PVAC patients were free of AF at 12 months post-procedure (P = ns) with a significant attrition rate from 77 to 78%, respectively, at 6 months. The mean procedure (140 ± 43 vs. 167 ± 42 min, P<0.0001), fluoroscopy (35 ± 16 vs. 42 ± 20 min, P<0.05) times were significantly shorter for PVAC than for WACA. Two patients developed strokes within 72 h of the procedure in the PVAC group, one possibly related directly to PVAC ablation in a high-risk patient and none in the WACA group (P = ns). Two of the 47 patients in the PVAC group who underwent repeat ablation had sub-clinical mild PV stenoses of 25–50% and 1 WACA patient developed delayed severe PV stenosis requiring venoplasty.

Conclusion

The pulmonary vein ablation catheter is equivalent in efficacy to WACA with reduced procedural and fluoroscopy times. However, there is a risk of thrombo-embolic and pulmonary stenosis complications which needs to be addressed and prospectively monitored.

ClinicalTrials.gov Identifier

NCT00678340.

What is the role for revascularisation in patients being considered for ICD therapy?

Patients being considered for ICD therapy are a heterogeneous group.For the vast majority, who have significant left ventricular impairment, it has become common practice to assess their coronary artery anatomy as a surrogate for ischaemia and/or viability. Such patients are therefore frequently under the care of both electrophysiologists and interventionists. The coronary anatomy often raises the dilemma about whether such patients should undergo revascularisation. If the patients present with angina or in the context of an acute myocardial infarct then this decision is clear cut. By contrast, however, a significant proportion of them have no history to suggest ongoing ischaemia or of recent MI. In conventional practice, therefore, there would be no decisive mandate to offer them revascularisation, especially PCI, in the absence of further objective evidence of ischaemia or viability. A review of the literature in our paper does not resolve this dilemma.Further observational data are required to help guide cardiologists as to which of these patients will benefit from revascularisation, since in many cases the coronary anatomy is no surrogate for the presence of ischaemia or viability.

Radiation peak skin dose to risk stratify electrophysiological procedures for deterministic skin damage

Ionising radiation is has the potential to cause harm both by increasing the probability future malignancy (stochastic mechanisms) and by direct physical injury (deterministic mechanisms). Several measures have been developed to quantify radiation exposure during a procedure and cardiologists usually refer to fluoroscopic screening time (FST). FST, however, has limitations for predicting deterministic injury which is directly dependant on peak skin dose (PSD). We compared FST to PSD for a range of interventional cardiac electrophysiology procedures.

METHODS

All patients undergoing electrophysiology procedures during a 2-month period in our institution were studied. Demographic details, nature of procedure, FST and PSD were measured. The FST to PSD ratio was calculated and compared between patient and procedural factors.

RESULTS

67 procedures on patients (23 female) with body mass index (BMI) of 28 (SD 5) Kg/m2 were studied. Screening times ranged from 0.2 to 96.6 min (median 11.2). PSD ranged from <0.1 to 1108 mGy (median 141). There was a positive correlation between PSD to FST ratio and BMI (r = 0.59, p < 0.001). The PSD to FST ratio was higher in cardiac resynchronization therapy (CRT) devices than single or dual chamber ICDs (p = 0.002).

CONCLUSION

FST is not a reliable predictor of deterministic skin injury and in high-risk procedures such as CRT devices and those on individuals of high BMI PSD should be measured.

Evaluation of body weight as a predictive factor for transvenous ventricular defibrillation characteristics

AIMS

To investigate the correlation between body weight and defibrillation threshold (DFT) for transvenous lead systems using a porcine model.

METHODS AND RESULTS

Twenty-eight pigs were anaesthetised and DFTs assessed in single and dual coil configurations using a four-reversal binary search method. DFT was correlated with body weight in the RV --> Can and RV --> SVC + Can configurations. A Pearson correlation coefficient and a two-sided p-value were calculated. A positive correlation exists between body weight and DFT in RV --> Can (r=0.66, p<0.000) and RV --> SVC + Can (r=0.44, p=0.018).

CONCLUSION

There is a significant correlation between body weight and DFT in swine. This tends to be greater in the two-electrode than in the three-electrode configuration. With these and previous human observations, one may predict a higher DFT in heavy individuals and make appropriate procedural adjustments.

Comparison of coronary venous defibrillation with conventional transvenous internal defibrillation in man

OBJECTIVE

Animal studies have shown that defibrillation in coronary veins is more effective than in the right ventricle. We aimed to assess the feasibility of placing defibrillation electrodes in the middle cardiac vein (MCV) in man and its impact on defibrillation requirements.

METHODS

A prospective randomised study conducted in a tertiary referral centre. 10 patients (9 male) undergoing ICD implantation (65 (12) yrs) for NASPE/BPEG indications were studied. Defibrillation thresholds (DFT) were measured, using a binary search and an external defibrillator after 10 seconds of ventricular fibrillation, for the following configurations in each patient (order of testing randomised): RV + MCV --> Can and RV --> SVC + Can.

INTERVENTIONS

A dual coil defibrillation electrode was placed transvenously in the right ventricle (RV) in the conventional manner. Using a guiding catheter a 3.2 Fr (67.5 mm length) electrode was placed transvenously in MCV. A test-can was placed subcutaneously in the left pectoral region.

RESULTS

Lead placement was possible in 8/10 pts. Time to perform a middle cardiac venogram and place the electrode was 21 (23) mins. No adverse events were observed. Defibrillation current was less (6.7 (2.7) A) with RV + MCV --> Can compared to the conventional RV --> SVC + Can configuration (8.9 (3.4) A, p = 0.03). There was no significant difference in defibrillation voltage or energy. However, shock impedance was higher in the former configuration (57 (10) v. 43 (6) Omega, p = 0.001).

CONCLUSIONS

In the majority of cases placement of a defibrillation lead in MCV is feasible. Defibrillation current requirements are 25% less when the shock is delivered using a MCV electrode.