Cost-effectiveness of ablation of ventricular tachycardia in ischaemic cardiomyopathy: Limitations in the trial evidence base

Objective: Catheter ablation is an important treatment for ventricular tachycardia (VT) that reduces the frequency of episodes of VT. We sought to evaluate the cost-effectiveness of catheter ablation versus antiarrhythmic drug (AAD) therapy. / Methods: A decision-analytic Markov model was used to calculate the costs and health outcomes of catheter ablation or AAD treatment of VT for a hypothetical cohort of patients with ischaemic cardiomyopathy and an implantable cardioverter-defibrillator. The health states and input parameters of the model were informed by patient-reported health-related quality of life (HRQL) data using randomised clinical trial (RCT)-level evidence wherever possible. Costs were calculated from a 2018 UK perspective. / Results: Catheter ablation versus AAD therapy had an incremental cost-effectiveness ratio (ICER) of £144 150 (€161 448) per quality-adjusted life-year gained, over a 5-year time horizon. This ICER was driven by small differences in patient-reported HRQL between AAD therapy and catheter ablation. However, only three of six RCTs had measured patient-reported HRQL, and when this was done, it was assessed infrequently. Using probabilistic sensitivity analyses, the likelihood of catheter ablation being cost-effective was only 11%, assuming a willingness-to-pay threshold of £30 000 used by the UK’s National Institute for Health and Care Excellence. / Conclusion: Catheter ablation of VT is unlikely to be cost-effective compared with AAD therapy based on the current randomised trial evidence. However, better designed studies incorporating detailed and more frequent quality of life assessments are needed to provide more robust and informed cost-effectiveness analyses

Therapeutic benefits of distal ventricular pacing in mid-cavity obstructive hypertrophic cardiomyopathy.

INTRODUCTION: Hypertrophic cardiomyopathy (HCM) patients with left ventricular (LV) mid-cavity obstruction (LVMCO) often experience severe drug-refractory symptoms thought to be related to intraventricular obstruction. We tested whether ventricular pacing, guided by invasive haemodynamic assessment, reduced LVMCO and improved refractory symptoms. METHODS: Between December 2008 and December 2017, 16 HCM patients with severe refractory symptoms and LVMCO underwent device implantation with haemodynamic pacing study to assess the effect on invasively defined LVMCO gradients. The effect on the gradient of atrioventricular (AV) synchronous pacing from sites including right ventricular (RV) apex and middle cardiac vein (MCV) was retrospectively assessed. RESULTS: Invasive haemodynamic data were available in 14 of 16 patients. Mean pre-treatment intracavitary gradient was 77 ± 22 mmHg (in sinus rhythm) versus 21 ± 21 mmHg during pacing from optimal ventricular site (95% CI: -70.86 to -40.57, p < 0.0001). Optimal pacing site was distal MCV in 12/16 (86%), RV apex in 1/16 and via epicardial LV lead in 1/16. Pre-pacing Doppler-derived gradients were significantly higher than at follow-up (47 ± 15 versus 24 ± 16 mmHg, 95% CI: -37.19 to -13.73, p < 0.001). Median baseline NYHA class was 3, which had improved by ⩾1 NYHA class in 13 of 16 patients at 1-year post-procedure (p < 0.001). The mean follow-up duration was 4.6 ± 2.7 years with the following outcomes: 8/16 (50%) had continued symptomatic improvement, 4/16 had symptomatic decline and 4/16 died. Contributors to symptomatic decline included chronic atrial fibrillation (AF) (n = 5), phrenic nerve stimulation (n = 3) and ventricular ectopy (n = 1). CONCLUSION: In drug-refractory symptomatic LVMCO, distal ventricular pacing can reduce intracavitary obstruction and may provide long-term symptomatic relief in patients with limited treatment options. A haemodynamic pacing study is an effective strategy for identifying optimal pacing site and configuration

Finding the right pathway is the key to success

Introduction We present a case involving an initially unsuccessful ablation attempt of a right ventricular outflow tract (RVOT) ventricular tachycardia (VT) and the subsequent management that provided a definitive diagnosis and effective treatment. VT with left bundle branch block morphology and an inferior axis is often caused by focal tachycardia arising from the RVOT. The differential for this arrhythmia includes a macroreentrant VT. This can be due to arrhythmogenic right ventricular cardiomyopathy (ARVC),1 which is diagnosed using a combination of clinical cues and electrical and noninvasive imaging to meet the Task Force Criteria.2 This case demonstrates the difficulties with diagnosis in the early subclinical phase of ARVC and illustrates the pathophysiology of reentrant VT

Epicardial catheter ablation for ventricular tachycardia on uninterrupted warfarin: A safe approach for those with a strong indication for peri-procedural anticoagulation?

BACKGROUND: Current guidelines for epicardial catheter ablation for ventricular tachycardia (VT) advocate that epicardial access is avoided in anticoagulated patients and should be performed prior to heparinisation. Recent studies have shown that epicardial access may be safe in heparinised patients. However, no data exist for patients on oral anticoagulants. We investigated the safety of obtaining epicardial access on uninterrupted warfarin. METHODS: A prospective registry of patients undergoing epicardial VT ablation over two years was analysed. Consecutive patients in whom epicardial access was attempted were included. All patients were heparinised prior to epicardial access with a target activated clotting time (ACT) of 300-350s. Patients who had procedures performed on uninterrupted warfarin (in addition to heparin) were compared to those not taking an oral anticoagulant. RESULTS: 46 patients were included of which 13 were taking warfarin. There was no significant difference in clinical and procedural characteristics (except INR and AF) between the two groups. Epicardial access was achieved in all patients. There were no deaths and no patients required surgery. A higher proportion of patients in the warfarin group had a drop in haemoglobin of >2g/dL compared to the no-warfarin group (38.5% versus 27.3%, p=0.74) and delayed pericardial drain removal (7.8% versus 3.03%, p=0.47). There was no difference in overall procedural complication rate. No patients required warfarin reversal or blood transfusion. CONCLUSION: Epicardial access can be achieved safely and effectively in patients' anticoagulated with warfarin and heparinised with therapeutic ACT. This may be an attractive option for patients with a high stroke risk

Impact of attributed audit on procedural performance in cardiac electrophysiology catheter laboratory

PURPOSE: Audit has played a key role in monitoring and improving clinical practice. However, audit often fails to drive change as summative institutional data alone may be insufficient to do so. We hypothesised that the practice of attributed audit, wherein each individual's procedural performance is presented will have a greater impact on clinical practice. This hypothesis was tested in an observational study evaluating improvement in fluoroscopy times for AF ablation. METHODS: Retrospective analyses of fluoroscopy times in AF ablations at the Barts Heart Centre (BHC) from 2012-2017. Fluoroscopy times were compared pre- and post- the introduction of attributed audit in 2012 at St Bartholomew's Hospital (SBH). In order to test the hypothesis, this concept was introduced to a second group of experienced operators from the Heart Hospital (HH) as part of a merger of the two institutions in 2015 and change in fluoroscopy times recorded. RESULTS: A significant drop in fluoroscopy times (33.3 ± 9.14 to 8.95 ± 2.50, p < 0.0001) from 2012-2014 was noted after the introduction of attributed audit. At the time of merger, a significant difference in fluoroscopy times between operators from the two centres was seen in 2015. Each operator's procedural performance was shared openly at the audit meeting. Subsequent audits showed a steady decrease in fluoroscopy times for each operator with the fluoroscopy time (min, mean±SD) decreasing from 13.29 ± 7.3 in 2015 to 8.84 ± 4.8 (p < 0.0001) in 2017 across the entire group. CONCLUSIONS: Systematic improvement in fluoroscopy times for AF ablation procedures was noted byevaluating individual operators' performance. Attributing data to physicians in attributed audit can promptsignificant improvement and hence should be adopted in clinical practice

Early Results on the Utilisation of ECG-Imaging during Catheter Ablation Procedures for Prediction of Sites of Earliest Activation during Re-entrant Ventricular Tachycardia

Success rate of ventricular tachycardia (VT) ablation remains sub-optimal. Current technology does not allow fast and accurate delineation of the ablation target. Noninvasive panoramic ECG-imaging (ECGI) offers the possibility of studying the interaction between arrhythmogenic substrate and earliest sites of activation during VT to improve ablation strategies. ECGI mapping (CardioInsight, Medtronic) was performed in 5 patients undergoing VT ablation. Ventricular pacing was delivered from the RV and three indices were measured at each ventricular site to map susceptibility to arrhythmia initiation: Re-entry vulnerability index (RVI), local dispersion of AT (∆AT) and local dispersion of repolarization (∆ARI). Regions of high susceptibility were defined as those corresponding to the bottom 5% of RV I and the upper 5% of ∆AT and ∆ARI. Morphologically distinct VTs were analyzed to measure the AT sequence and localize the region of earliest epicardial activation (AT < 5 ms). In total, 20 VTs were analyzed (4.0 ± 1.2 per patient). The minimum distance between the region of high vulnerability and the region of earliest AT during VT was 5.6 ± 8.6 mm for RV I, 6.1 ± 10.8 mm for ∆AT and 12.8 ± 22.4 mm for ∆ARI (P > 0.13 for all pair-wise comparison). The vulnerable region presented at least partial overlap with the region of earliest activation during VT in 50%, 55% and 50% of all VTs for RV I, ∆AT and ∆ARI, respectively. These early data confirm the mechanistic link between markers of arrhythmogenic risk and VT initiation and suggest that ECGI could be potentially used for targeting ablation in non-inducible or hemodynamically non-tolerated VTs

The Safety and Feasibility of Transitioning From Transfemoral to Transradial Access Left Ventricular Endomyocardial Biopsy

BACKGROUND: Left ventricular endomyocardial biopsy (LVEMB) is commonly performed via the transfemoral route. Radial access may help reduce vascular access complications, but there are few data on the safety and feasibility of transradial LVEMB. OBJECTIVE: Describe the safety and feasibility of transitioning from transfemoral to transradial access LVEMB. METHODS: This is a single-center, prospective, observational cohort study. Fifty procedures in 49 patients were included, 25 (50%) via the femoral route and 25 (50%) via the radial route. RESULTS: The cohort had a mean age of 47 ± 13 years and the most common indication for LVEMB was myocarditis. From June 2015 until September 2016, all procedures (n = 21) were performed via the femoral approach; thenceforth, there was a gradual transition to the radial approach. More tissue samples were obtained when the procedure was performed via the femoral approach (P<.01). The minimum sampling target of 3 specimens was not met in 4 patients (16%) via the radial approach and in 1 patient (4%) via the femoral approach. Complications occurred in 3/25 transradial procedures (12%; 2 cardiac perforations and 1 forearm hematoma) and 3/25 transfemoral procedures (12%; 1 cardiac perforation, 1 femoral artery pseudoaneurysm, and 1 ventricular fibrillation). Cardiac perforations via the transradial approach occurred during the early transition period. There were no deaths. CONCLUSIONS: Transradial LVEMB is feasible, with a similar complication profile to femoral procedures, but associated with a smaller number of specimens. Transitioning from transfemoral to transradial procedures may initially be associated with a higher risk of complications and potentially a lower diagnostic yield

Initial experience of the High-Density Grid catheter in patients undergoing catheter ablation for atrial fibrillation

Purpose: A significant proportion of patients undergoing catheter ablation for atrial fibrillation (AF) experience arrhythmia recurrence. This is mostly due to pulmonary vein reconnection (PVR). Whether mapping using High-Density Wave (HDW) technology is superior to standard bipolar (SB) configuration at detecting PVR is unknown. We aimed to evaluate the efficacy of HDW technology compared to SB mapping in identifying PVR. / Methods: High-Density (HD) multipolar Grid catheters were used to create left atrial geometries and voltage maps in 36 patients undergoing catheter ablation for AF (either due to recurrence of an atrial arrhythmia from previous AF ablation or de novo AF ablation). Nineteen SB maps were also created and compared. Ablation was performed until pulmonary vein isolation was achieved. / Results: Median time of mapping with HDW was 22.3 [IQR: 8.2] min. The number of points collected with HDW (13299.6±1362.8 vs 6952.8±841.9, p<0.001) and used (2337.3±158.0 vs 1727.5±163.8, p<0.001) was significantly higher compared to SB. Moreover, HDW was able to identify more sleeves (16 for right and 8 for left veins), where these were confirmed electrically silent by SB, with significantly increased PVR sleeve size as identified by HDW (p<0.001 for both right and left veins). Importantly, with the use of HDW, the ablation strategy changed in 23 patients (64% of targeted veins) with a significantly increased number of lesions required as compared to SB for right (p=0.005) and left veins (p=0.003). / Conclusion: HDW technology is superior to SB in detecting pulmonary vein reconnections. This could potentially result into a significant change in ablation strategy and possibly to increased success rate following pulmonary vein isolation

Evaluation of the Re-entry Vulnerability Index to Predict Ventricular Tachycardia Circuits Using High Density Contact Mapping

BACKGROUND: Identifying arrhythmogenic sites to improve ventricular tachycardia (VT) ablation outcomes remains unresolved. The re-entry vulnerability index (RVI) combines activation and repolarization timings to identify sites critical for re-entrant arrhythmia initiation without inducing VT. OBJECTIVE: To provide the first assessment of RVI's capability to identify VT sites of origin using high-density contact mapping and comparison with other activation-repolarization markers of functional substrate. METHODS: 18 VT ablation patients (16M, 72% ischemic) were studied. Unipolar electrograms were recorded during ventricular pacing and analysed off-line. Activation time (AT), activation-recovery interval (ARI), repolarization time (RT) were measured. Vulnerability to re-entry was mapped based on RVI and spatial distribution of AT, ARI and RT. The distance from sites identified as vulnerable to re-entry to the VT site of origin was measured, with distances 20 mm indicating accurate and inaccurate localization, respectively. RESULTS: The origin of 18 VTs was identified (n=6 entrainment, n=12 pace-mapping). RVI maps included 1012, 408-2098 (median, 1st-3rd quartiles) points/patient. RVI accurately localized 72.2% VT sites of origin, with median distance equal to 5.1, 3.2-10.1 mm. Inaccurate localization was significantly less frequent for RVI than AT (5.6% vs 33.3%, OR=0.12, P=0.035). Compared to RVI, distance to VT sites of origin was significantly larger for sites showing prolonged RT and ARI, and non-significantly larger for sites showing highest AT and ARI gradients. CONCLUSION: RVI identifies vulnerable regions closest to VT sites of origin. Activation-repolarization metrics may improve VT substrate delineation and inform novel ablation strategies