Novel subgroups in acute respiratory failure based on the trajectories of three endotheliopathy biomarkers: A cohort study.

Baseline levels of endotheliopathy are associated with worse respiratory outcomes and mortality in undifferentiated acute respiratory failure (ARF), but knowledge is lacking on the development of endotheliopathy over time in ARF. We, therefore, aimed to evaluate the prognostic significance of trajectories of endotheliopathy during the first days of ARF. We performed a secondary, exploratory analysis of a single-center prospective cohort including 459 patients requiring mechanical ventilation. Based on Days 1-3 Syndecan-1, soluble Thrombomodulin (sTM), and Platelet Endothelial Cell Adhesion Molecule-1 (PECAM-1), we divided patients into subgroups using latent class mixed modeling and correlated subgroups with clinical outcomes using Cox regression. Based on Syndecan-1 and sTM, respectively, we identified two subgroups. Based on PECAM-1, we identified three subgroups. Subgroups based on Syndecan-1 and sTM were identifiable from the baseline levels, but subgroups based on PECAM-1 were not. Patients with persistently high levels of both sTM and PECAM-1 were liberated from mechanical ventilation more slowly (Group high vs. Group low, sTM: hazard ratio [HR]: 0.66, 95% confidence interval [CI]: 0.50-0.88, p = .01, PECAM-1: HR: 0.59, 95% CI: 0.37-0.93, p = .02) and had higher 30-day mortality (sTM: HR: 1.90, 95% CI: 1.20-3.01, p = .01, PECAM-1: HR: 4.25, 95% CI: 1.99-9.07, p < .01). In ARF requiring mechanical ventilation, patients in subgroups with persistently high levels of sTM and PECAM-1 had lower rates of liberation from mechanical ventilation and higher 30-day mortality. However, patients with persistently high levels of sTM were identifiable based on the baseline level, and only the trajectory of PECAM-1 added information to that of the baseline level.

Endotheliopathy is associated with slower liberation from mechanical ventilation: a cohort study.

BACKGROUND: Endotheliopathy is suggested as pivotal pathophysiology of sepsis and trauma-associated organ failure, but its role in acute respiratory failure is not yet determined. We investigated if endotheliopathy biomarkers at ICU admission are associated with illness severity and clinical outcomes in patients with acute respiratory failure requiring mechanical ventilation. METHODS: We conducted a prospective single-center cohort study including 459 mechanically ventilated adults at ICU admission. Plasma levels of three endotheliopathy biomarkers were measured at ICU admission: Syndecan-1, soluble Thrombomodulin (sTM), and Platelet Endothelial Cell Adhesion Molecule-1 (PECAM-1). The primary outcome was the rate of liberation from mechanical ventilation, which is presented together with the rate of the competing risk of death while still on mechanical ventilation. Secondary outcomes were PaO2/FiO2-ratios on admission and on last measurement in patients dying within five days, and 30-day all-cause mortality. The primary outcome and 30-day all-cause mortality were analyzed using Cox regression, controlled for gender, age, chronic obstructive pulmonary disease, septic shock, heart failure, PaO2/FiO2-ratio at admission, respiratory infection, acute kidney injury, and bilirubin. PaO2/FiO2-ratios were analyzed using linear regression, controlled for age, chronic obstructive pulmonary disease, respiratory infection, and shock. RESULTS: Patients with high sTM were liberated from mechanical ventilation at a lower rate (adjusted hazard ratio (HR) 0.71, for an increase from the 25th to the 75th percentile, 95% confidence interval (CI) 0.54-0.93, p = 0.01). Patients with high PECAM-1 were liberated from mechanical ventilation at a lower rate, but only during the first 5 days (adjusted HR 0.72, for an increase from the 25th to the 75th percentile, 95% CI 0.58-0.9, p < 0.01). High levels of Syndecan-1 and PECAM-1 were associated with a higher rate of death while still on mechanical ventilation. sTM and PECAM-1 were negatively associated with PaO2/FiO2-ratio at ICU admission and no biomarker was associated with last measured PaO2/FiO2-ratio. High levels of all biomarkers were associated with higher 30-day all-cause mortality. CONCLUSION: In acute respiratory failure, endotheliopathy biomarkers are associated with lower rates of liberation from mechanical ventilation, hypoxemia at ICU admission, and 30-day all-cause mortality.

Polyunsaturated fatty acid analogs act antiarrhythmically on the cardiac IKs channel.

Polyunsaturated fatty acids (PUFAs) affect cardiac excitability. Kv7.1 and the ß-subunit KCNE1 form the cardiac IKs channel that is central for cardiac repolarization. In this study, we explore the prospects of PUFAs as IKs channel modulators. We report that PUFAs open Kv7.1 via an electrostatic mechanism. Both the polyunsaturated acyl tail and the negatively charged carboxyl head group are required for PUFAs to open Kv7.1. We further show that KCNE1 coexpression abolishes the PUFA effect on Kv7.1 by promoting PUFA protonation. PUFA analogs with a decreased pKa value, to preserve their negative charge at neutral pH, restore the sensitivity to open IKs channels. PUFA analogs with a positively charged head group inhibit IKs channels. These different PUFA analogs could be developed into drugs to treat cardiac arrhythmias. In support of this possibility, we show that PUFA analogs act antiarrhythmically in embryonic rat cardiomyocytes and in isolated perfused hearts from guinea pig.

Socio-economic position, multimorbidity, and health care utilization among Danish left ventricular assist device patients.

AIMS: Increasing numbers of patients with advanced heart failure and significant comorbidity and social barriers are considered for left ventricular assist devices (LVADs). We sought to examine health care utilization post-LVAD implantation, including the influence of individual-level socio-economic position and multimorbidity. METHODS AND RESULTS: We conducted a Danish nationwide cohort study linking individual-level data from clinical LVAD databases, the Scandiatransplant Database, and Danish national medical and administrative registries. Socio-economic position included cohabitation status, educational level, and employment status. Multimorbidity was defined as two or more chronic conditions from at least two chronic disease groups. Health care utilization (hospital activity, general practice activity, and redeemed medical prescriptions) within 2 years post-discharge after LVAD implantation was evaluated using descriptive statistics at 0.5 year intervals. We identified 119 patients discharged alive with first-time LVAD implanted between 2006 and 2018. The median age of the patients was 56.1 years, and 88.2% were male. Patients were followed until heart transplantation, LVAD explantation, death, 31 December 2018, or for 2 years. The median follow-up was 0.8 years. The highest median use of health care services was observed 0-0.5 years post-LVAD discharge compared with the subsequent follow-up intervals: 0.5-1, 1-1.5, and 1.5-2 years, respectively. The median (interquartile range) number of hospitalizations was 10 (7-14), bed days 14 (9-28), outpatient visits 8 (5-12), telephone contacts with a general practitioner 4 (2-8), and total redeemed medical prescriptions 26 (19-37) within 0-0.5 years post-LVAD discharge compared with the median utilization within the consecutive follow-up periods [e.g. within 0.5-1 year: hospitalizations 5 (3-8), bed days 8 (4-14), outpatient visits 5 (3-8), telephone contacts 2 (0-5), and redeemed medical prescriptions 24 (18-30)]. The median use of health care services was stable from 0.5 years onwards. The median number of hospitalizations and bed days was slightly higher in patients living alone with a low educational level or low employment status within 0-0.5 years post-LVAD implantation. Finally, the median number of in-hospital days and redeemed prescriptions was higher among patients with pre-existing multimorbidity. CONCLUSIONS: Among patients who underwent LVAD implantation, health care utilization was high in the early post-LVAD discharge phase and was influenced by socio-economic position. Multimorbidity influenced the number of in-hospital days and redeemed prescriptions during the 2 year follow-up.

Influence of socioeconomic status on rates of advanced heart failure therapies.

BACKGROUND: Socioeconomic deprivation is associated with a lower likelihood of referral for advanced heart failure (HF) evaluation, but it is not known whether it influences rates of advanced HF therapies independently of key hemodynamic measures and comorbidity following advanced HF evaluation in a universal healthcare system. METHODS: We linked data from a single-center Danish clinical registry of consecutive patients evaluated for advanced HF with patient-level information on socioeconomic status. Patients were divided into groups based on the level of education (low, medium, and high), combined degree of socioeconomic deprivation (low, medium, and high), and household income quartiles. Rates of the combined outcome of left ventricular assist device implantation or heart transplantation (advanced HF therapy) with death as a competing risk were estimated with cumulative incidence functions, and Cox proportional hazards models adjusted for age, sex, central venous pressure, cardiac index, and comorbidities. RESULTS: We included 629 patients, median age 53 years, of whom 77% were men. During a median follow-up of 5 years, 179 (28%) underwent advanced HF therapy. The highest level of education was associated with higher rates (high vs low, adjusted HR 1.81 95% CI 1.14-2.89, p = 0.01), whereas household income quartile groups (Q4 vs Q1, adjusted HR 1.37 95% CI 0.76-2.47, p = 0.30) or groups of combined socioeconomic deprivation (high vs low degree of deprivation, adjusted HR 0.86 95% CI 0.50-1.46, p = 0.56) were not significantly associated with rates of advanced HF therapy. CONCLUSIONS: Patients with a lower level of education might be disfavored for advanced HF therapies and could require specific attention in the advanced HF care center.

Long-Term Medical Treatment and Adherence in Patients With Left Ventricular Assist Devices: A Danish Nationwide Cohort Study.

The use of a left ventricular assist device (LVAD) in treating advanced heart failure has increased. However, data regarding medical treatment and adherence following LVAD implantation is sparse, particularly whether socioeconomic factors (cohabitation status, educational level, employment status, and income) and multimorbidity influence these aspects, which are known to impact adherence in heart failure patients. We performed a nationwide cohort study of 119 patients with LVAD implanted between January 1, 2006, and December 31, 2018, who were discharged alive with LVAD therapy. We linked individual-level data from clinical LVAD databases, the Scandiatransplant Database, and Danish medical and administrative registers. Medical treatment 90-day pre-LVAD and 720-day post-LVAD were assessed using descriptive statistics in 90-day intervals. Medication adherence (proportion of days covered ≥80%) was assessed 181- to 720-day post-LVAD. The proportions of patients using angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (88.7%), beta-blockers (67.0%), mineralocorticoid receptor antagonists (62.9%), warfarin (87.6%), and aspirin (55.7%) within 90-day post-LVAD were higher than pre-LVAD and were stable during follow-up. Medication adherence ranged from 86.7% (aspirin) to 97.8% (warfarin). Socioeconomic factors and multimorbidity did not influence medical medication use and adherence. Among LVAD patients, medical treatment and adherence are at high levels, regardless of socioeconomic background and multimorbidity.

Initiation of eplerenone or spironolactone, treatment adherence, and associated outcomes in patients with new-onset heart failure with reduced ejection fraction: a nationwide cohort study.

BACKGROUND: The mineralocorticoid receptor antagonists (MRAs) eplerenone and spironolactone are beneficial in heart failure with reduced ejection fraction (HFrEF), but have not been prospectively compared. We compared clinical outcomes, daily dosages, and discontinuation rates for the two drugs in a nationwide cohort. METHODS: We identified all patients with HFrEF in the period 2016-2020, who were alive and had initiated MRA treatment at study start, 180 days after HF diagnosis. We estimated the 2-year risk of a composite of death and HF hospitalization, as well as each component separately, using Kaplan-Meier, cumulative incidence functions, and Cox proportional hazards models adjusted for age, sex, and comorbidities. Secondly, we assessed treatment withdrawal, cross-over, and daily drug dosage. RESULTS: We included 7479 patients; 653 (9%) on eplerenone and 6840 (91%) on spironolactone. Patients in the eplerenone group were younger (median age 65 vs. 69 years), and more often men (91% vs. 68%), both P < 0.001. In adjusted analyses, with spironolactone as reference, there were no differences in the risk of the composite of all-cause death and HF hospitalization (HR 1.02, 95% CI 0.82-1.27), all-cause death (HR 0.93, 95% CI 0.67-1.30), or HF hospitalization (HR 1.10, 95% CI 0.84-1.42). Treatment withdrawal occurred in 34% in the eplerenone group and 53% in the spironolactone group (P < 0.001), treatment cross-over in 3%, and 10%, respectively. Daily dose >25 mg at 12 months, was observed in 230 patients (37%) in the eplerenone group and 771 patients (12%) in the spironolactone (P < 0.001). CONCLUSIONS: In a contemporary nationwide cohort of patients with new-onset HFrEF who initiated MRA, we found no differences in clinical outcomes associated with initiation of eplerenone vs. spironolactone. Treatment was more frequently withdrawn, and daily drug dosage was lower among patients treated with spironolactone.

Combining endocannabinoids with retigabine for enhanced M-channel effect and improved KV7 subtype selectivity.

Retigabine is unique among anticonvulsant drugs by targeting the neuronal M-channel, which is composed of KV7.2/KV7.3 and contributes to the negative neuronal resting membrane potential. Unfortunately, retigabine causes adverse effects, which limits its clinical use. Adverse effects may be reduced by developing M-channel activators with improved KV7 subtype selectivity. The aim of this study was to evaluate the prospect of endocannabinoids as M-channel activators, either in isolation or combined with retigabine. Human KV7 channels were expressed in Xenopus laevis oocytes. The effect of extracellular application of compounds with different properties was studied using two-electrode voltage clamp electrophysiology. Site-directed mutagenesis was used to construct channels with mutated residues to aid in the mechanistic understanding of these effects. We find that arachidonoyl-L-serine (ARA-S), a weak endocannabinoid, potently activates the human M-channel expressed in Xenopus oocytes. Importantly, we show that ARA-S activates the M-channel via a different mechanism and displays a different KV7 subtype selectivity compared with retigabine. We demonstrate that coapplication of ARA-S and retigabine at low concentrations retains the effect on the M-channel while limiting effects on other KV7 subtypes. Our findings suggest that improved KV7 subtype selectivity of M-channel activators can be achieved through strategically combining compounds with different subtype selectivity.

Polyunsaturated Fatty Acids as Modulators of KV7 Channels.

Voltage-gated potassium channels of the KV7 family are expressed in many tissues. The physiological importance of KV7 channels is evident from specific forms of disorders linked to dysfunctional KV7 channels, including variants of epilepsy, cardiac arrhythmia and hearing impairment. Thus, understanding how KV7 channels are regulated in the body is of great interest. This Mini Review focuses on the effects of polyunsaturated fatty acids (PUFAs) on KV7 channel activity and possible underlying mechanisms of action. By summarizing reported effects of PUFAs on KV7 channels and native KV7-mediated currents, we conclude that the generally observed effect is a PUFA-induced increase in current amplitude. The increase in current is commonly associated with a shift in the voltage-dependence of channel opening and in some cases with increased maximum conductance. Auxiliary KCNE subunits, which associate with KV7 channels in certain tissues, may influence PUFA effects, though findings are conflicting. Both direct and indirect activating PUFA effects have been described, direct effects having been most extensively studied on KV7.1. The negative charge of the PUFA head-group has been identified as critical for electrostatic interaction with conserved positively charged amino acids in transmembrane segments 4 and 6. Additionally, the localization of double bonds in the PUFA tail tunes the apparent affinity of PUFAs to KV7.1. Indirect effects include those mediated by PUFA metabolites. Indirect inhibitory effects involve KV7 channel degradation and re-distribution from lipid rafts. Understanding how PUFAs regulate KV7 channels may provide insight into physiological regulation of KV7 channels and bring forth new therapeutic strategies.

KCNE1 tunes the sensitivity of KV7.1 to polyunsaturated fatty acids by moving turret residues close to the binding site.

The voltage-gated potassium channel KV7.1 and the auxiliary subunit KCNE1 together form the cardiac IKs channel, which is a proposed target for future anti-arrhythmic drugs. We previously showed that polyunsaturated fatty acids (PUFAs) activate KV7.1 via an electrostatic mechanism. The activating effect was abolished when KV7.1 was co-expressed with KCNE1, as KCNE1 renders PUFAs ineffective by promoting PUFA protonation. PUFA protonation reduces the potential of PUFAs as anti-arrhythmic compounds. It is unknown how KCNE1 promotes PUFA protonation. Here, we found that neutralization of negatively charged residues in the S5-P-helix loop of KV7.1 restored PUFA effects on KV7.1 co-expressed with KCNE1 in Xenopus oocytes. We propose that KCNE1 moves the S5-P-helix loop of KV7.1 towards the PUFA-binding site, which indirectly causes PUFA protonation, thereby reducing the effect of PUFAs on KV7.1. This mechanistic understanding of how KCNE1 alters KV7.1 pharmacology is essential for development of drugs targeting the IKs channel.

Biaryl sulfonamide motifs up- or down-regulate ion channel activity by activating voltage sensors.

Voltage-gated ion channels are key molecules for the generation of cellular electrical excitability. Many pharmaceutical drugs target these channels by blocking their ion-conducting pore, but in many cases, channel-opening compounds would be more beneficial. Here, to search for new channel-opening compounds, we screen 18,000 compounds with high-throughput patch-clamp technology and find several potassium-channel openers that share a distinct biaryl-sulfonamide motif. Our data suggest that the negatively charged variants of these compounds bind to the top of the voltage-sensor domain, between transmembrane segments 3 and 4, to open the channel. Although we show here that biaryl-sulfonamide compounds open a potassium channel, they have also been reported to block sodium and calcium channels. However, because they inactivate voltage-gated sodium channels by promoting activation of one voltage sensor, we suggest that, despite different effects on the channel gates, the biaryl-sulfonamide motif is a general ion-channel activator motif. Because these compounds block action potential-generating sodium and calcium channels and open an action potential-dampening potassium channel, they should have a high propensity to reduce excitability. This opens up the possibility to build new excitability-reducing pharmaceutical drugs from the biaryl-sulfonamide scaffold.

Fatty acid analogue N-arachidonoyl taurine restores function of IKs channels with diverse long QT mutations.

About 300 loss-of-function mutations in the IKs channel have been identified in patients with Long QT syndrome and cardiac arrhythmia. How specific mutations cause arrhythmia is largely unknown and there are no approved IKs channel activators for treatment of these arrhythmias. We find that several Long QT syndrome-associated IKs channel mutations shift channel voltage dependence and accelerate channel closing. Voltage-clamp fluorometry experiments and kinetic modeling suggest that similar mutation-induced alterations in IKs channel currents may be caused by different molecular mechanisms. Finally, we find that the fatty acid analogue N-arachidonoyl taurine restores channel gating of many different mutant channels, even though the mutations are in different domains of the IKs channel and affect the channel by different molecular mechanisms. N-arachidonoyl taurine is therefore an interesting prototype compound that may inspire development of future IKs channel activators to treat Long QT syndrome caused by diverse IKs channel mutations.