Reduction in shock burden with catheter ablation versus escalated antiarrhythmic drug therapy: Insights from the VANISH trial

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): 1. Canadian Institutes of Health Research (CIHR)

2. Additional financial support from St. Jude Medical and Biosense Webster

Background

Recurrent shocks for ventricular tachycardia (VT) are associated with an increased risk of heart failure and mortality and have a negative influence on quality of life. Catheter ablation has been shown to improve VT event-free survival in patients with antiarrhythmic drug (AAD)-refractory VT and prior myocardial infarction (MI); however, the effects of ablation on shock burden has yet to be investigated.

Purpose

Our primary objectives were to compare the shock-treated VT event burden and appropriate shock burden following randomization to treatment with either catheter ablation or escalated AAD therapy among VT patients with prior MI in the Ventricular tachycardia AblatioN versus escalated antiarrhythmic drug therapy in Ischemic Heart disease (VANISH) randomized trial.

Methods

Recurrent event analyses were performed using the intention-to-treat population of the VANISH trial. Shock-treated VT event burden was defined as the total number of VT events treated with ≥1 appropriate internal or external shocks. Appropriate shock burden was defined as the total number of appropriate internal and external shocks delivered, regardless of the number of VT events. All VT events and implantable cardioverter defibrillator (ICD) therapies were adjudicated by reviewers blinded to the treatment allocation. Three recurrent event models were used to compare the shock burden between treatment arms (Anderson-Gill (AG), Frailty, and Prentice, Williams, and Peterson Total Time (PWP-TT). Each model clustered by patient and accounted for competing risk of death with the Fine and Gray sub-distributions hazards model.

Results

Of the 259 patients enrolled in the VANISH trial [median age 69.8 (IQR 63.0-74.2) years, 7.0% women], 132 patients were randomized to ablation and 129 patients to escalated AAD therapy. Over a median follow-up of 23.4 (IQR 14.7-40.4) months, there were 138 shock-treated VT events [39.07 (95% CI 33.14-46.07) shock-treated VT events per 100 person-years] in the ablation arm and 218 shock-treated VT events [64.60 (95% CI 56.49–73.84) shock-treated VT events per 100 person-years] in the escalated AAD therapy arm (Figure 1). Ablation patients had a 40% lower shock-treated VT event burden (ie. number of shock-treated VT events) compared to patients randomized to escalated AAD therapy [Figure 1; AG HR 0.60 (95% 0.38-0.95)]. Further, there was also a statistically significant reduction in the appropriate shock burden (i.e. number of appropriate shocks) among ablation patients (169 appropriate shocks) compared to escalated AAD therapy patients (266 appropriate shocks) [Figure 1; AG HR 0.61 (95% CI 0.37-0.96)]. All results were consistent between the 3 recurrent event models.

Conclusion

Among patients with AAD-refractory VT and a prior MI, catheter ablation reduced shock-treated VT event burden and appropriate shock burden compared to escalated AAD therapy.

Comparative effectiveness of ventricular tachycardia ablation versus escalated antiarrhythmic drug therapy by location of myocardial infarction: A sub-study of the VANISH trial

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): Fonds de recherché du Québec-Santé (FRQS) [post doctoral award for Dr. Samuel)

BACKGROUND

Complexity of ventricular tachycardia (VT) substrate, efficiency of lesion formation, and the size and thickness of infarction area border zones differ based on location of myocardial infarctions (MI). These differences may translate into heterogeneity in risk of events and effectiveness of treatments for VT. Small observational studies suggest that VT from inferior infarctions have higher risk of early recurrence despite smaller infarct areas. However, differential effectiveness of VT treatments based on location of MI not been definitively established.

PURPOSE

The objective of this sub-study of the Ventricular tachycardia AblatioN versus escalated antiarrhythmic drug therapy in ISchemic Heart disease (VANISH) randomized trial was to compare the effectiveness of VT ablation by location of MI in reducing the composite endpoint of all-cause mortality, VT storm, or appropriate ICD therapy when compared to escalated pharmacological therapy in VT patients with a prior MI.

METHODS

VANISH participants were categorized into 3 subgroups based on MI location: 1. Inferior (may also have MI in other locations); 2. Non-inferior (no inferior MI, all patients not in group 1); and 3. Anterior (may also have MI in other locations). Inverse probability of treatment weighting was used to balance baseline characteristics (ie. age, sex, comorbidities, medications, and the location of additional infarctions) between patients randomized to ablation or escalated therapy within each subgroup. Weighted Cox proportional hazards models were calculated separately for each subgroup.

RESULTS

Of 259 patients enrolled in the VANISH trial [median age 69.8 (IQR 63.0-74.2) years, 7.0% women], 135 had an inferior MI, 124 a non-inferior MI, and 83 an anterior MI. Among patients with an inferior MI, no statistically significant difference in the primary outcome was detected between patients randomized to ablation or escalated therapy [aHR 0.78 (95% CI 0.51-1.20)]. In contrast, patients with non-inferior MIs had a statistically significant reduction in the incidence of the primary outcome with ablation [aHR 0.48 (95% CI 0.27-0.86)]; which was of greater magnitude than the reduction observed in the overall results of the VANISH trial [HR 0.72 (95% CI 0.53-0.98)]. In addition, a trend towards a reduction in the primary outcome with ablation was detected in patients with anterior MIs [aHR 0.50 (95% CI 0.23-1.09)].

CONCLUSION

The effectiveness of VT ablation versus escalated pharmacological therapy varies based on the location of the MI. Patients with MI scars located only in non-inferior regions of the ventricles derive greater benefit from VT ablation in reducing VT-related events. Further studies are required to explore reasons for this finding and to assess the impact of VT treatment strategies based on MI location in optimizing outcomes.

The effect of computer decision support on optimizing appropriate dosing of novel oral anticoagulant therapy in the IMPACT-AF study

Background

Guidelines favour use of the non-vitamin K oral anticoagulants (NOACs) over vitamin-K antagonists for stroke prevention in atrial fibrillation (AF). However, studies have shown these agents are being under-dosed relative to the doses recommended in the product labels.

Purpose

To assess the ability of a CDS tool, employed to support management of patients with AF in primary care, to optimize NOAC prescribing.

Methods

The Integrated Management Program Advancing Community Treatment of Atrial Fibrillation (IMPACT-AF) study was a cluster randomized controlled trial that assessed the ability of a CDS tool to optimize care of community-based AF patients. Between September 2014 and December 2016, 203 primary care providers (104 randomized to CDS use, 99 to usual care [UC]) and 1133 of their patients (n=597 CDS, n=548 UC) were enrolled. Among other functions, 9 CDS program rules provided recommendations on NOAC prescribing based upon a given patient's clinical profile, as per product labels. Appropriate NOAC prescribing within the IMPACT-AF study population was compared between patients managed with the CDS versus UC at baseline and 12-months.

Results

Of those patients prescribed a NOAC, a high proportion (approximately 70%) were managed as per NOAC prescribing recommendations at baseline (Fig. 1). At 12 months, this proportion did not appreciably change in the UC arm (Fig. 1). In the CDS arm, an 8.2% absolute/11.8% relative improvement in appropriate NOAC prescribing over baseline was seen at 12-months (Fig. 1).

A comparison of patients at baseline and 12-months within each arm revealed a non-significant decline in the level of appropriate NOAC prescribing in the UC group (p=0.53). In the CDS arm, a significant improvement was observed in appropriate NOAC prescribing over time (p<0.001).

Conclusion

Even prior to any quality improvement efforts, appropriate NOAC prescribing was higher than anticipated in this contemporary cohort of community-based AF patients. At 12-months, significant further improvements were seen in the CDS but not the UC arm. These findings suggest that physician decision support can help enhance appropriate NOAC prescribing in the primary care setting.

Figure 1. Appropriate NOAC prescribing

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Bayer Inc.

P6546Canadian Registry of Electronic Device Outcomes (CREDO): remote monitoring outcomes in the abbott battery performance alert, a multicentre cohort

Background

Cardiac implantable electronic devices have been known to have lead and device malfunctions leading to advisories. Increased use of remote monitoring of devices has been suggested to allow the identification of abnormal device performance and allow early intervention. We sought to describe the outcomes of patients with and without remote monitoring of in devices in the Abbott Premature Battery Depletion advisory with data from a Canadian registry

Methods

Patients with an Abbott device subject to the Battery Performance Alert Advisory from nine ICD implanting centres in Canada were included in the registry. The use of remote monitoring was identified from baseline and followup data in the registry. The primary outcome was detection of premature battery depletion and all cause mortality.

Results

2679 patents were identified with a device subject to the advisory. Devices were implanted between 2010 and 2017. 1716 patients (64%) had remote monitoring at baseline with this increasing to 83.7% at followup at 12 months. Premature battery depletion occurred in 43 patients (1.6%). Discovery of premature battery depletion was detected by remote monitoring in 70% of patients. There were 492 deaths during the follow up. Mortality was higher in those without a remote monitor compared to those with a remote monitor at follow-up and remote monitor at baseline and follow-up (11.3%, 2.6% versus 6.1% respectively; p=0.0186). There were no deaths attributed to premature battery depletion

Conclusion

The use of remote monitoring in patients with ICD and CRT under advisory reliably detected device failure and was associated with a reduction in all-cause mortality.

P1872Canadian electrophysiology labs registry report update 2011–2018

Background

Interventional cardiac electrophysiology (EP) is rapidly evolving; a nationwide registry was established and re-administered since 2011 to conduct a periodic review of resource allocation across Canada.

Methods

The registry collects annual data on EP lab infrastructure, imaging, tools, human resources, procedural volumes, and wait times. Leading physicians from each EP lab were contacted electronically.

Results

All Canadian EP centres were identified (n=30); 50% and 45% of active centres participated in the last 2 instalments of the registry. Since 2011, data has been consistently obtained from 11 university-affiliated centres. Table 1 reports trends in procedural volumes and operators. Figure 1 depicts the ablations done per operator. The mean wait time to see an electrophysiologist for an initial non-urgent consult is 23 weeks. The wait time between an EP consult and ablation date is 17.8 weeks for simple ablation, 15.9 weeks for VT ablation, and 30.1 weeks for AF ablation. On average centres have 2 (range: 1–4) rooms equipped for ablations; each centre uses the EP lab an average of 7 shifts per week. While diagnostic studies and radiofrequency ablations are performed in all centres, point-by-point cryoablation is available in 85% and cryoballoon in 77% of the centres; 38% of the respondents use circular ablation techniques.

Trends in procedural volumes + operators 2015–2016 2013–2014 2011–2012 Procedures per operator 117±70 120±68 113±42 Procedures per centre 498±299 477±245 446±237 Ratio of staff to trainees 2.0:1 1.6:1 1.5:1 Full time physicians per centre 4.1 (0–7) 4.1 (1–7) 3.5 (0–7) Nurses trained specifically for EP 4.6 (0–10) 4.4 (0–10) n/a Ablation procedures volume:   AV Reciprocal Tachycardia 12% 10% 11%   AV Nodal Re-entry Tachycardia 18% 19% 23%   Atrial Fibrillation/Atypical Flutter 33% 35% 30%   Typical Flutter 20% 14% 19%   Ventricular Tachycardia 8% 8% 10%   Total annual ablations in all respondent centres 5478 5243 4908 Mean ± standard deviation. Staff (full-time + part-time prorated to 0.5).

Annual ablation volumes per operator

Conclusion

This initiative provides contemporary data on invasive EP practices. The results show feasibility in data collection which will serve as a reference for decisions regarding resource planning.

Thermal developmental plasticity affects body size and water conservation of Drosophila nepalensis from the Western Himalayas

In the Western Himalayas, Drosophila nepalensis is more abundant during the colder and drier winter than the warmer rainy season but the mechanistic bases of such adaptations are largely unknown. We tested effects of developmental plasticity on desiccation-related traits (body size, body melanization and water balance traits) that may be consistent with changes in seasonal abundance of this species. D. nepalensis grown at 15°C has shown twofold higher body size, greater melanization (∼15-fold), higher desiccation resistance (∼55 h), hemolymph as well as carbohydrate content (twofold higher) as compared with corresponding values at 25°C. Water loss before succumbing to death was much higher (∼16%) at 15°C than 25°C. Developmental plastic effects on body size are associated with changes in water balance-related traits (bulk water, hemolymph and dehydration tolerance). The role of body melanization was evident from the analysis of assorted darker and lighter flies (from a mass culture of D. nepalensis reared at 21°C) which lacked differences in dry mass but showed differences in desiccation survival hours and rate of water loss. For adult acclimation, we found a slight increase in desiccation resistance of flies reared at lower growth temperature, whereas in flies reared at 25°C such a response was lacking. In D. nepalensis, greater developmental plasticity is consistent with its contrasting levels of seasonal abundance. Finally, in the context of global climate change in the Western Himalayas, D. nepalensis seems vulnerable in the warmer season due to lower adult as well as developmental acclimation potential at higher growth temperature (25°C).