Background: The Subcutaneous ICD (S-ICD) is safe and effective for sudden cardiac death prevention. However, patients in previous S-ICD studies had fewer comorbidities, less left ventricular dysfunction and received more inappropriate shocks (IAS) than in typical transvenous (TV)-ICD trials. The UNTOUCHED trial was designed to evaluate the IAS rate in a more typical, contemporary ICD patient population implanted with the S-ICD using standardized programming and enhanced discrimination algorithms. Methods: Primary prevention patients with left ventricular ejection fraction (LVEF) ≤ 35% and no pacing indications were included. Generation 2 or 3 S-ICD devices were implanted and programmed with rate-based therapy delivery for rates ≥ 250 beats per minute (bpm) and morphology discrimination for rates ≥200 and < 250 bpm. Patients were followed for 18 months. The primary endpoint was the IAS free rate compared to a 91.6% performance goal, derived from the results for the ICD-only patients in the MADIT-RIT study. Kaplan-Meier analyses were performed to evaluate event-free rates for IAS, all cause shock, and complications. Multivariable proportional hazard analysis was performed to determine predictors of endpoints. Results: S-ICD implant was attempted in 1116 patients and 1111 patients were included in post-implant follow-up analysis. The cohort had a mean age of 55.8±12.4 years, 25.6% women, 23.4% black race, 53.5% with ischemic heart disease, 87.7% with symptomatic heart failure and a mean LVEF of 26.4±5.8%. Eighteen-month freedom from IAS was 95.9% (Lower confidence limit LCL 94.8%). Predictors of reduced incidence of IAS were implanting the most recent generation of device, using the three-incision technique, no history of atrial fibrillation, and ischemic etiology. The 18-month all cause shock free rate was 90.6% (LCL 89.0%), meeting the prespecified performance goal of 85.8%. Conversion success rate for appropriate, discrete episodes was 98.4%. Complication free rate at 18 months was 92.7%. Conclusions: This study demonstrates high efficacy and safety with contemporary S-ICD devices and programming despite the relatively high incidence of co-morbidities in comparison to earlier S-ICD trials. The inappropriate shock rate (3.1% at one year) is the lowest reported for the S-ICD and lower than many TV ICD studies using contemporary programming to reduce IAS. Clinical Trial Registration: URL https://clinicaltrials.gov Unique Identifier NCT02433379

Background-Long-term inhibition of nitric oxide synthase (NOS) is known to induce hypertension and perivascular fibrosis. Recent evidence also suggests that long-term NOS inhibition induces expression of plasminogen activator inhibitor-1 (PAI-1) in vascular tissues and that PAI-1 may contribute to the development of fibrosis after chemical or ionizing injury. On the basis of these observations, we hypothesized that PAI-1 may influence the vascular response to long-term NOS inhibition by N -nitro-L-arginine methyl ester (L-NAME). Methods and Results-We compared the temporal changes in systolic blood pressure and coronary perivascular fibrosis in PAI-1-deficient (PAI-1 Ϫ/Ϫ ) and wild-type (WT) male mice (Nϭ6 per group). At baseline, there were no significant differences in blood pressure between groups. After initiation of L-NAME, systolic blood pressure increased in both groups at 2 weeks. Over an 8-week study period, systolic blood pressure increased to 141Ϯ3 mm Hg in WT animals versus 112Ϯ4 mm Hg in PAI-1 Ϫ/Ϫ mice (PϽ0.0001). The extent of coronary perivascular fibrosis increased significantly in L-NAME-treated WT mice (PϽ0.01 versus PAI-1 Ϫ/Ϫ mice). Cardiac type I collagen mRNA expression was greater in control (PϽ0.01) and L-NAME-treated PAI-1 Ϫ/Ϫ (PϽ0.05) groups than in control WT mice, indicating that PAI-1 deficiency prevents the increase of collagen deposition by promoting matrix degradation. Conclusions-These findings suggest that PAI-1 deficiency alone is sufficient to protect against the structural vascular changes that accompany hypertension in the setting of long-term NOS inhibition. Direct inhibition of vascular PAI-1 activity may provide a new therapeutic strategy for the prevention of arteriosclerotic cardiovascular disease.

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Plasminogen activator inhibitor-1 (PAI-1) is the major inhibitor of plasminogen activation and likely plays important roles in coronary thrombosis and arteriosclerosis. Tumor necrosis factor-␣ (TNF␣) is one of many recognized physiological regulators of PAI-1 expression and may contribute to elevated plasma PAI-1 levels in sepsis and obesity. Although TNF␣ is a potent inducer of PAI-1 expression in vitro and in vivo, the precise location of the TNF␣ response site in the PAI-1 promoter has yet to be determined. Transient transfection studies using luciferase reporter constructs containing PAI-1 promoter sequence up to 6.4 kb failed to detect a response to TNF␣. Moreover, TNF␣ failed to induce expression of enhanced green fluorescent protein under the control of a 2.9-kb human PAI-1 promoter in transgenic mice, although endogenous murine PAI-1 was strongly induced. These data suggested that the TNF␣ response element in the PAI-1 gene is remote from the proximal promoter region. In this study, seven candidate regulatory regions were identified using cross-species sequence homology analysis as well as DNase I-hypersensitive site analysis. We identified a 5 distal TNF␣-responsive enhancer of the PAI-1 gene located 15 kb upstream of the transcription start site containing a conserved NFBbinding site that mediates the response to TNF␣. This newly recognized site is fully capable of binding NFB subunits p50 and p65, whereas overexpression of the NFB inhibitor IB prevents TNF␣-induced activation of this enhancer element.Plasminogen activator inhibitor 1 (PAI-1), 1 a member of the serine protease inhibitor (serpin) family, was isolated 20 years ago and was identified as the primary inhibitor of fibrinolysis by rapidly binding and inactivating both tissue-type plasminogen activator (PA) and urokinase-type PA (1, 2). Subsequently, it has been shown that PAI-1 is involved in many other physiological functions, including ovulation, embryogenesis, angiogenesis, metastasis, and arteriosclerosis through its interactions with PAs, the urokinase-type PA receptor, and vitronectin (3-8).Under normal conditions, PAI-1 is present in plasma at low concentrations. High levels of PAI-1 are observed in a variety of clinical settings, including type 2 diabetes mellitus (9), obesity (3, 10), cancer (4, 11), and infection (12)(13)(14). In addition, increased PAI-1 levels are associated with an increased risk of type 2 diabetes (15), myocardial infarction (16), and stroke (17). In severe sepsis, increased plasma PAI-1 levels are associated with poor prognosis (18) and appear to predict the development of septic shock in meningococcemia (19).Active PAI-1 is conformationally unstable and has a short half-life in circulation (20). Furthermore, except in platelets, which contain large quantity of predominately latent PAI-1, there is no storage pool of PAI-1 in cells (21). As a result, transcriptional control of PAI-1 is a pivotal mechanism in determining tissue and plasma PAI-1 content. Accordingly, the molecular regulation of PAI-1 expression ha...

SUMMARYAtrial fibrillation (AF) is the most common cardiac arrhythmia and carries a significant risk of stroke and heart failure. The molecular etiologies of AF are poorly understood, leaving patients with limited therapeutic options. AF has been recognized as an inherited disease in almost 30% of patient cases. However, few genetic loci have been identified and the mechanisms linking genetic variants to AF susceptibility remain unclear. By sequencing 193 probands with lone AF, we identified a Q76E variant within the coding sequence of the bone morphogenetic protein (BMP) antagonist gremlin-2 (GREM2) that increases its inhibitory activity. Functional modeling in zebrafish revealed that, through regulation of BMP signaling, GREM2 is required for cardiac laterality and atrial differentiation during embryonic development. GREM2 overactivity results in slower cardiac contraction rates in zebrafish, and induction of previously identified AF candidate genes encoding connexin-40, sarcolipin and atrial natriuretic peptide in differentiated mouse embryonic stem cells. By live heart imaging in zebrafish overexpressing wild-type or variant GREM2, we found abnormal contraction velocity specifically in atrial cardiomyocytes. These results implicate, for the first time, regulators of BMP signaling in human AF, providing mechanistic insights into the pathogenesis of the disease and identifying potential new therapeutic targets.