Primary Outcome Evaluation of a Next-Generation Left Atrial Appendage Closure Device: Results From the PINNACLE FLX Trial.

BACKGROUND: Left atrial appendage (LAA) occlusion provides an alternative to oral anticoagulation for thromboembolic risk reduction in patients with nonvalvular atrial fibrillation. Since regulatory approval in 2015, the WATCHMAN device has been the only LAA closure device available for clinical use in the United States. The PINNACLE FLX study (Protection Against Embolism for Nonvalvular AF Patients: Investigational Device Evaluation of the Watchman FLX LAA Closure Technology) evaluated the safety and effectiveness of the next-generation WATCHMAN FLX LAA closure device in patients with nonvalvular atrial fibrillation in whom oral anticoagulation is indicated, but who have an appropriate rationale to seek a nonpharmaceutical alternative. METHODS: This was a prospective, nonrandomized, multicenter US Food and Drug Administration study. The primary safety end point was the occurrence of one of the following events within 7 days after the procedure or by hospital discharge, whichever was later: death, ischemic stroke, systemic embolism, or device- or procedure-related events requiring cardiac surgery. The primary effectiveness end point was the incidence of effective LAA closure (peri-device flow ≤5 mm), as assessed by the echocardiography core laboratory at 12-month follow-up. RESULTS: A total of 400 patients were enrolled. The mean age was 73.8±8.6 years and the mean CHA2DS2-VASc score was 4.2±1.5. The incidence of the primary safety end point was 0.5% with a 1-sided 95% upper CI of 1.6%, meeting the performance goal of 4.2% (P<0.0001). The incidence of the primary effectiveness end point was 100%, with a 1-sided 95% lower CI of 99.1%, again meeting the performance goal of 97.0% (P<0.0001). Device-related thrombus was reported in 7 patients, no patients experienced pericardial effusion requiring open cardiac surgery, and there were no device embolizations. CONCLUSIONS: LAA closure with this next-generation LAA closure device was associated with a low incidence of adverse events and a high incidence of anatomic closure. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02702271.

Divergent effects of aging and sex on vasoconstriction to endothelin in coronary arterioles.

OBJECTIVE: The risk for cardiovascular disease increases with advancing age; however, the chronological development of heart disease differs in males and females. The purpose of this study was to determine whether age-induced alterations in responses of coronary arterioles to the endogenous vasoconstrictor, endothelin, are sex-specific. METHODS: Coronary arterioles were isolated from young and old male and female rats to assess vasoconstrictor responses to endothelin (ET), and ETa and ETb receptor inhibitors were used to assess receptor-specific signaling. RESULTS: In intact arterioles from males, ET-induced vasoconstriction was reduced with age, whereas age increased vasoconstrictor responses to ET in intact arterioles from female rats. In intact arterioles from both sexes, blockade of either ETa or ETb eliminated age-related differences in responses to ET; however, denudation of arterioles from both sexes revealed age-related differences in ETa-mediated vasoconstriction. In arterioles from male rats, ETa receptor protein decreased, whereas ETb receptor protein increased with age. In coronary arterioles from females, neither ETa nor ETb receptor protein changed with age, suggesting age-related changes in ET signaling occur downstream of ET receptors. CONCLUSIONS: Thus, aging-induced alterations in responsiveness of the coronary resistance vasculature to endothelin are sex-specific, possibly contributing to sexual dimorphism in the risk of cardiovascular disease with advancing age.

Age impairs Flk-1 signaling and NO-mediated vasodilation in coronary arterioles.

Impairment of flow-induced vasodilation in coronary resistance arterioles may contribute to the decline in coronary vasodilatory reserve that occurs with advancing age. This study investigated the effects of age on flow-induced signaling and activation of nitric oxide (NO)-mediated vasodilation in coronary resistance arterioles. Coronary arterioles were isolated from young (approximately 6 mo) and old (approximately 24 mo) male Fischer-344 rats to assess vasodilation to flow, vascular endothelial growth factor (VEGF), and ACh. Flow- and VEGF-induced vasodilation of coronary arterioles was impaired with age (P

Activation of JNK and xanthine oxidase by TNF-alpha impairs nitric oxide-mediated dilation of coronary arterioles.

Elevated levels of tumor necrosis factor-alpha (TNF), a proinflammatory cytokine, are associated with coronary artery disease. However, it is unclear whether vasodilator function of coronary resistance arterioles is susceptible to TNF. Herein, we examined whether TNF can affect endothelium-dependent nitric oxide (NO)-mediated dilation of coronary arterioles to adenosine and whether inflammatory signaling pathways such as mitogen-activated protein kinases, ceramide sphingolipids, and oxidative stress are involved in the TNF-mediated effect. To eliminate confounding influences associated with in vivo preparations, coronary arterioles from porcine heart were isolated and pressurized without flow for in vitro study. Intraluminal treatment with TNF (1 ng/ml, 90 min) significantly attenuated the NO release and vasodilation to adenosine. This inhibitory effect was not observed in denuded vessels or in the presence of NO synthase inhibitor l-NMMA. Histochemical data showed that superoxide production and JNK phosphorylation in arteriolar endothelial cells was enhanced by TNF. Administration of superoxide scavenger or inhibitors of ceramide-activated protein kinase (dimethylaminopurine), JNK (SP600125 and dicumarol), and xanthine oxidase (allopurinol) reduced superoxide production as well as restored NO release and vasodilation to adenosine. Conversely, the effects of TNF were insensitive to inhibitors of p38 (SB203580), ERK (PD98059), NAD(P)H oxidase (apocynin), or mitochondrial respiratory chain (rotenone). These data indicate that TNF inhibits endothelium-dependent NO-mediated dilation of coronary arterioles by ceramide-induced activation of JNK and subsequent production of superoxide via xanthine oxidase. Because myocardial ischemia augments adenosine production and elevates TNF level, inhibiting adenosine-stimulated endothelial release of NO by TNF could contribute to inadequate regulation of coronary blood flow during the development of ischemic heart disease.

Aging decreases vasoconstrictor responses of coronary resistance arterioles through endothelium-dependent mechanisms.

OBJECTIVE: Aging decreases coronary blood flow and maximal reserve capacity. Impaired blood flow capacity may be related to an increased vasoconstrictor capacity of coronary resistance vessels. This study tested the hypothesis that aging increases the vasoconstrictor responsiveness of coronary arterioles isolated from myocardium of young (4 months) and old (24 months) Fischer 344 rats. METHODS: Isolated coronary arterioles were cannulated and pressurized (60 cm H2O) via hydrostatic pressure reservoirs. RESULTS: Contrary to our hypothesis, aging decreased responsiveness of coronary arterioles to endothelin (ET, 1 x 10(-11)-3 x 10(-8) M), potassium chloride (KCl, 10-100 mM), and pressure-induced myogenic responses (0-140 cm H2O). Removal of the endothelium from coronary arterioles increased vasoconstriction to all agonists; however, age-related KCl vasoconstrictor response differences remained, suggesting that K+ channel activity and/or the relative contribution of specific K+ channels to maintenance of vascular smooth muscle membrane potential may change with age. Removal of the endothelium, in addition to increasing responsiveness, eliminated aging-induced differences in ET- and pressure-induced vasoconstriction. L-NAME (10(-5)) incubation resulted in a greater enhancement of spontaneous tone in arterioles from old rats compared to those of young rats. ETB (BQ-788, 3 x 10(-8)) receptor blockade eliminated the age-associated differences. CONCLUSION: Collectively, these data suggest an age-associated increase in endothelial modulation of coronary resistance vessel constriction. This enhanced endothelial attenuation of coronary arteriolar constriction appears to result from increased basal release of nitric oxide. These alterations of coronary vascular reactivity may contribute to age-induced redistribution of coronary blood flow and diminished cardiac function.

Time course of flow-induced vasodilation in skeletal muscle: contributions of dilator and constrictor mechanisms.

The purpose of this study was to determine the time course of flow-induced vasodilation in soleus and gastrocnemius muscle arterioles and the mechanisms that underlie vasodilatory responses to an increase in intraluminal flow. Vasodilation was assessed during 20 min of continuous exposure to intraluminal flow. Both soleus and gastrocnemius muscle arterioles dilated in response to flow, although the magnitude of vasodilation was greater in arterioles from the gastrocnemius muscle. Neither blockade of nitric oxide synthase with N(G)-nitro-L-arginine methyl ester (L-NAME) nor blockade of cyclooxygenase with indomethacin inhibited the initial vasodilation (0-2 min) in arterioles from either muscle. In contrast, vasodilation to sustained exposure to flow (2-20 min) was eliminated by treatment with L-NAME in arterioles from both muscles. Both depolarization with 40 mM KCl and blockade of Ca(2+)-activated K(+) channels inhibited the initial flow-induced dilation, and the inhibition was greater in gastrocnemius muscle arterioles than soleus muscle arterioles. In the presence of L-NAME, prolonged exposure to flow resulted in constriction in soleus and gastrocnemius muscle arterioles. This constriction was abolished by endothelin receptor blockade. These results indicate that the time course and magnitude of flow-induced vasodilation differs between arterioles from soleus and gastrocnemius muscles. The immediate response to increased flow is greater in gastrocnemius muscle arterioles and involves activation of K(+) channels. In arterioles from both soleus and gastrocnemius muscles, vasodilation to sustained flow exposure occurs primarily through production of nitric oxide. In the absence of nitric oxide, sustained exposure to flow results in pronounced constriction that is mediated by endothelin.