Novel ventricular tachyarrhythmia detection enhancement detects undertreated life-threatening arrhythmias.

BACKGROUND: Ventricular tachyarrhythmias (VTA) with low and varying signal amplitudes and morphologies may not be successfully identified utilizing traditional implantable cardioverter-defibrillator algorithms. OBJECTIVE: Develop and validate a novel algorithm (VF Therapy Assurance, VFTA) to improve detection and timely delivery of high-voltage therapy (HVT) for these arrhythmias. METHODS: Arrhythmia detection was simulated on recorded VTA electrograms (EGMs) utilizing Abbott's Merlin.net database. EGMs where an HVT occurred only when VFTA was enabled, or where VFTA provided an HVT >30 seconds earlier than without VFTA, were readjudicated with physician review. As VFTA never prevents detection or therapy, EGMs where VFTA did not activate or alter HVT were not adjudicated. RESULTS: Among 564,353 recorded VTA EGMs from 20,000 devices, VFTA altered HVT in 105 EGMs from 67 devices. Physician adjudication determined that 81.9% (86/105) of these EGMs were true undertreated VTA episodes and would have received appropriate HVT with VFTA enabled. Furthermore, 65% of the episodes (56/86) were ventricular fibrillation, were polymorphic, did not self-terminate during the recording window, or were not amenable antitachycardia pacing. Of those, 87.5% (49/56) would not have elicited HVT without VFTA. Overall, VFTA provided new or earlier appropriate HVT in 0.27% (53/20,000) of devices with an increase in inappropriate HVT in 0.07% (14/20,000) devices. CONCLUSION: The VFTA algorithm successfully identifies VTA missed by traditional detection algorithms, owing to undersensed ventricular signals resulting in the rate falling below the programmed detection rate. The use of VFTA increases the likelihood of delivering life-saving HVT.

Comparative study of acute and mid-term complications with leadless and transvenous cardiac pacemakers.

BACKGROUND: Leadless cardiac pacemakers (LCPs) aim to mitigate lead- and pocket-related complications seen with transvenous pacemakers (TVPs). OBJECTIVE: The purpose of this study was to compare complications between the LCP cohort from the LEADLESS Pacemaker IDE Study (Leadless II) trial and a propensity score-matched real-world TVP cohort. METHODS: The multicenter LEADLESS II trial evaluated the safety and efficacy of the Nanostim LCP (Abbott, Abbott Park, IL) using structured follow-up, with serious adverse device effects independently adjudicated. TVP data were obtained from Truven Health MarketScan claims databases for patients implanted with single-chamber TVPs between April 1, 2010 and March 31, 2014 and more than 1 year of preimplant enrollment data. Comorbidities and complications were identified via International Classification of Diseases, Ninth Revision and Current Procedural Terminology codes. Short-term (≤1 months) and mid-term (>1-18 months) complications were compared between the LCP cohort and a propensity score-matched subset of the TVP cohort. RESULTS: Among 718 patients with LCPs (mean age 75.6 ± 11.9 years; 62% men) and 1436 patients with TVPs (mean age 76.1 ± 12.3 years; 63% men), patients with LCPs experienced fewer complications (hazard ratio 0.44; 95% confidence interval 0.32-0.60; P < .001), including short-term (5.8% vs 9.4%; P = .01) and mid-term (0.56% vs 4.9%; P < .001) events. In the short-term time frame, patients with LCPs had more pericardial effusions (1.53% vs 0.35%; P = .005); similar rates of vascular events (1.11% vs 0.42%; P = .085), dislodgments (0.97% vs 1.39%; P = .54), and generator complications (0.70% vs 0.28%; P = .17); and no thoracic trauma compared to patients with TVPs (rate of thoracic trauma 3.27%). In short- and mid-term time frames, TVP events absent from the LCP group included lead-related, pocket-related, and infectious complications. CONCLUSION: Patients with LCPs experienced fewer overall short- and mid-term complications, including infectious and lead- and pocket-related events, but more pericardial effusions, which were uncommon but serious.

Effects of deliberate practice on crisis decision performance.

This study examined the impact of deliberate practice on pilot decision making in once-in-a-career crisis decision scenarios. First we explored the impact of deliberate practice on pilot decision-making performance for crisis flying scenarios that had been practiced in their entirety. Then we looked at the impact of deliberate practice in which one aspect of the crisis scenario--the particular malfunction--was unpracticed. We analyzed pilot decision-making performance in response to 160 airborne mechanical malfunctions. We initially found that deliberate practice significantly improves decision-making performance for wholly practiced crises but does not improve decision-making performance when the specific malfunction has not been practiced. We then split decision making for each crisis into two phases: assessment and action selection. For wholly practiced crisis scenarios, additional deliberate practice positively impacts each decision-making phase. However, for part-practiced scenarios, deliberate practice appears to differentially affect phase of error. Specifically, pilots with more deliberate practice erred in action selection, whereas less-practiced pilots erred in assessment. Actual or potential applications of this research include training proscriptions for crisis decision making.