BACKGROUND Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation to treat patients with symptomatic drugrefractory atrial fibrillation (AF).OBJECTIVE The purpose of this study was to assess the safety and efficacy of PVI using the cryoballoon catheter to treat patients with persistent AF.METHODS STOP Persistent AF (ClinicalTrials.gov Identifier: NCT03 012841) was a prospective, multicenter, single-arm, Food and Drug Administration-regulated trial designed to evaluate the safety and efficacy of PVI-only cryoballoon ablation for drug-refractory persistent AF (continuous episodes ,6 months). The primary efficacy endpoint was 12-month freedom from 30 seconds of AF, atrial flutter (AFL), or atrial tachycardia (AT) after a 90-day blanking period. The prespecified performance goals were set at .40% and ,13% for the primary efficacy and safety endpoints, respectively. Secondary endpoints assessed quality of life using the AFEQT (Atrial Fibrillation Effect on Quality of Life) and SF (Short Form)-12 questionnaires. RESULTSOf 186 total enrollments, 165 subjects (70% male; age 65 6 9 years; left atrial diameter 4.2 6 0.6 cm; body mass index 31 6 6) were treated at 25 sites in the United States, Canada, and Japan. Total procedural, left atrial dwell, and fluoroscopy times were 121 6 46 minutes, 102 6 41 minutes, and 19 6 16 minutes, respectively. At 12 months, the primary efficacy endpoint was 54.8% (95% confidence [CI] 46.7%-62.1%) freedom from AF, AFL, or AT. There was 1 primary safety event, translating to a rate of 0.6% (95% CI 0.1%-4.4%). AFEQT and SF-12 assessments demonstrated significant improvements from baseline to 12 months postablation (P ,.001). CONCLUSIONThe STOP Persistent AF trial demonstrated cryoballoon ablation to be safe and effective in treating patients with drug-refractory persistent AF characterized by continuous AF episodes ,6 months.

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01490814.

Background: The FIRE AND ICE trial assessed efficacy and safety of pulmonary vein (PV) isolation using cryoballoon versus radiofrequency current (RFC) ablation in patients with drug refractory, symptomatic, paroxysmal atrial fibrillation (AF). The purpose of the current study was to assess index lesion durability as well as reablation strategy and outcomes in trial patients undergoing a reablation procedure. Methods: Patients with reablation procedures during FIRE AND ICE were retrospectively consented and enrolled at 13 trial centers. The first reablation for each patient was included in the analysis. Documented arrhythmias before reablation, number and location of reconnected PVs, lesions created during reablations, procedural characteristics, and acute as well as long-term outcomes were assessed. Results: Eighty-nine (36 cryoballoon and 53 RFC) patients were included in this study. Paroxysmal atrial fibrillation was the predominant recurrent arrhythmia (69%) before reablation. Reablations occurred at a median of 173 and 182 days ( P =0.54) in the cryoballoon and RFC cohorts, respectively. The number of reconnected PVs was significantly higher in the RFC than the cryoballoon group (2.1±1.4 versus 1.4±1.1; P =0.010), which was driven by significantly more reconnected left superior PVs and markedly more reconnected right superior PVs. The number of (predominantly RFC) lesions applied during reablation was significantly greater in patients originally treated with RFC (3.3±1.3 versus 2.5±1.5; P =0.015) with no difference in overall acute success ( P =0.70). After reablation, no differences in procedure-related rehospitalization or antiarrhythmic drug utilization were observed between cohorts. Conclusions: At reablation, patients originally treated with the cryoballoon had significantly fewer reconnected PVs, which may reflect RFC catheter instability in certain left atrial regions, and thus required fewer lesions for reablation success. Repeat ablations were predominantly performed with RFC and resulted in similar acute success, duration of hospitalization, and antiarrhythmic drug prescription between the study cohorts. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT03314753.

Background It is common practice to observe patients during an overnight stay (ONS) following a catheter ablation procedure for the treatment of atrial fibrillation (AF). Objectives To investigate the safety and economic impact of a same‐day discharge (SDD) protocol after cryoballoon ablation for treatment of AF in high‐volume, geographically diverse US hospitals. Methods We retrospectively reviewed 2374 consecutive patients (1119 SDD and 1180 ONS) who underwent cryoballoon ablation for AF at three US centers. Baseline characteristics, acute procedure‐related complications, and longer‐term evaluations of safety were recorded during routine clinical follow‐up. The mean cost of an ONS was used in a one‐way sensitivity analysis to evaluate yearly cost savings as a function of the percentage of SDD cases per year. Results The SDD and ONS cohorts were predominately male (69% vs. 67%; p = .3), but SDD patients were younger (64 ± 11 vs. 66 ± 10; p < .0001) with lower body mass index (30 ± 6 vs. 31 ± 61; p < .0001) and CHA2DS2‐VASc scores (1.4 ± 1.0 vs. 2.2 ± 1.4; p < .0002). There was no difference between SDD and ONS in the 30‐day total complication rate (n = 15 [1.26%] versus n = 24 [2.03%]; p = .136, respectively). The most common complication was hematoma in both the SDD (n = 8; 0.67%) and ONS (n = 11; 0.93%) cohorts. Sensitivity analysis demonstrated that when 50% of every 100 patients treated were discharged the same day, hospital cost savings ranged from $45 825 to $83 813 per year across US hospitals. Conclusions SDD following cryoballoon ablation for AF appears to be safe and is associated with cost savings across different US hospitals.

Background Cryoballoon ablation is a commonly used approach to treat patients with atrial fibrillation (AF). Objectives Report on the safety and efficacy of cryoballoon ablation for the treatment of AF in the largest global cohort of cryoablated patients prospectively studied within a single registry. Methods The Cryo AF Global Registry is a prospective, multi‐center registry. Patients with paroxysmal AF (PAF) or persistent AF (PsAF) were treated with the cryoballoon catheter according to routine practices at 93 sites across 36 countries. Primary efficacy endpoints included freedom from AF and freedom from AF/atrial flutter (AFL)/atrial tachycardia (AT) ≥30 seconds. The primary safety endpoint was serious device‐ or procedure‐related adverse events over 12 month follow‐up. Results During this evaluation window, 2922 subjects completed an index cryoballoon procedure, and 1440 completed 12 month follow‐up. The cohort was 61 ± 12 years of age, 36.3% female, and 78.7% PAF. Serious device‐ and procedure‐related adverse event rates were 1.5% and 3.4%, respectively. Freedom from AF/AFL/AT after the 90 day blanking period was 86.4% (95% CI: 84.3%‐88.3%) in patients with PAF and 70.9% (95% CI: 64.6%‐76.4%) in patients with PsAF. Freedom from AF/AFL/AT in first‐line PAF and PsAF was 90.0% (95% CI: 86.4%‐92.7%) and 72.9% (95% CI: 58.6%‐83.0%) at 12 months, respectively. Conclusions The Cryo Global AF Registry is the largest evaluation to demonstrate cryoablation is an efficient, safe, and effective treatment for patients with AF worldwide. Cryoablation was commonly used to treat patients prior to an AAD failure and may facilitate earlier therapy for patients on the AF disease continuum.

For most individuals, the respiratory control system produces a remarkably stable and coordinated motor output—recognizable as a breath—from birth until death. Very little is understood regarding the processes by which the respiratory control system maintains network stability in the presence of changing physiological demands and network properties that occur throughout life. An emerging principle of neuroscience is that neural activity is sensed and adjusted locally to assure that neurons continue to operate in an optimal range, yet to date, it is unknown whether such homeostatic plasticity is a feature of the neurons controlling breathing. Here, we review the evidence that local mechanisms sense and respond to perturbations in respiratory neural activity, with a focus on plasticity in respiratory motor neurons. We discuss whether these forms of plasticity represent homeostatic plasticity in respiratory control. We present new analyses demonstrating that reductions in synaptic inputs to phrenic motor neurons elicit a compensatory enhancement of phrenic inspiratory motor output, a form of plasticity termed inactivity-induced phrenic motor facilitation (iPMF), that is proportional to the magnitude of activity deprivation. Although the physiological role of iPMF is not understood, we hypothesize that it may have an important role in protecting the drive to breathe during conditions of prolonged or intermittent reductions in respiratory neural activity, such as following spinal cord injury or during central sleep apnea.

Background Heart failure (HF) and atrial fibrillation (AF) often coexist; yet, outcomes of ablation in patients with AF and concomitant HF are limited. This analysis assessed outcomes of cryoablation in patients with AF and HF. Methods and Results The Cryo AF Global Registry is a prospective, multicenter registry of patients with AF who were treated with cryoballoon ablation according to routine practice at 56 sites in 26 countries. Patients with baseline New York Heart Association class I to III (HF cohort) were compared with patients without HF. Freedom from atrial arrhythmia recurrence ≥30 seconds, safety, and health care utilization over 12‐month follow‐up were analyzed. A total of 1303 patients (318 HF) were included. Patients with HF commonly had preserved left ventricular ejection fraction (81.6%), were more often women (45.6% versus 33.6%) with persistent AF (25.8% versus 14.3%), and had a larger left atrial diameter (4.4±0.9 versus 4.0±0.7 cm). Serious procedure‐related complications occurred in 4.1% of patients with HF and 2.6% of patients without HF ( P =0.188). Freedom from atrial arrhythmia recurrence was not different between cohorts with either paroxysmal AF (84.2% [95% CI, 78.6–88.4] versus 86.8% [95% CI, 84.2–89.0]) or persistent AF (69.6% [95% CI, 58.1–78.5] versus 71.8% [95% CI, 63.2–78.7]) ( P =0.319). After ablation, a reduction in AF‐related symptoms and antiarrhythmic drug use was observed in both cohorts (HF and no‐HF), and freedom from repeat ablation was not different between cohorts. Persistent AF and HF predicted a post‐ablation cardiovascular rehospitalization ( P =0.032 and P =0.001, respectively). Conclusions Cryoablation to treat patients with AF is similarly effective at 12 months in patients with and without HF. Registration URL: https://www.clinicaltrials.gov ; Unique Identifier: NCT02752737.

Key pointsr Intermittent reductions in respiratory neural activity, a characteristic of many ventilatory disorders, leads to inadequate ventilation and arterial hypoxia. Both intermittent reductions in respiratory neural activity and intermittent hypoxia trigger compensatory enhancements in inspiratory output when experienced separately, forms of plasticity called inactivity-induced inspiratory motor facilitation (iMF) and long-term facilitation (LTF), respectively.r Reductions in respiratory neural activity that lead to moderate, but not mild, arterial hypoxia occludes plasticity expression, indicating that concurrent induction of iMF and LTF impairs plasticity through cross-talk inhibition of their respective signalling pathways.r Moderate hypoxia undermines iMF by enhancing NR2B-containing NMDA receptor signalling, which can be rescued by exogenous retinoic acid, a molecule necessary for iMF.r These data suggest that in ventilatory disorders characterized by reduced inspiratory motor output, such as sleep apnoea, endogenous mechanisms of compensatory plasticity may be impaired, and that exogenously activating respiratory plasticity may be a novel strategy to improve breathing.Abstract Many forms of sleep apnoea are characterized by recurrent reductions in respiratory neural activity, which leads to inadequate ventilation and arterial hypoxia. Both recurrent reductions in respiratory neural activity and hypoxia activate mechanisms of compensatory plasticity that augment inspiratory output and lower the threshold for apnoea, inactivity-induced inspiratory motor facilitation (iMF) and long-term facilitation (LTF), respectively. However, despite frequent concurrence of reduced respiratory neural activity and hypoxia, mechanisms that induce and regulate iMF and LTF have only been studied separately. Here, we demonstrate that recurrent reductions in respiratory neural activity ('neural apnoea') accompanied by cessations in ventilation that result in moderate (but not mild) hypoxaemia do not elicit increased inspiratory output, suggesting that concurrent induction of iMF and LTF occludes plasticity. A key role for NMDA receptor activation in impairing plasticity following concurrent neural apnoea and hypoxia is indicated since recurrent hypoxic neural apnoeas triggered increased phrenic inspiratory Daryl Fields is currently a neurosurgery resident at the University of Pittsburgh. He completed his medical degree and research doctorate at the University of Wisconsin Madison under the mentorship of Dr Tracy Baker, PhD. Daryl's research is focused on creating readily translatable therapies for movement control disorders: (1) development of animal models to better understand deficits in movement control and (2) development of pharmacological therapies for improved motor rehabilitation. He has contributed to the development of several novel research directions that continue to progress the field of motor control/rehabilitation. 3952 D. P. Fields and others J Physiol 597.15 output in rats in which spinal NR2B-containing ...