The impact of pre-existing chronic heart failure on the intensive care treatment and outcome of old intensive care patients suffering from COVID-19

Background

Patients suffering from COVID-19 with pre-existing chronic heart failure (CHF) are considered to have a significant risk regarding morbidity and mortality. Similarly, older patients on the intensive care unit (ICU) constitute another vulnerable subgroup. This study investigated the association between pre-existing CHF and clinical practice in critically ill older ICU patients with COVID-19.

Methods

Patients with severe COVID-19 and who were ≥70 years old were recruited from this prospective multicenter international study. Patients' treatment, follow-up, and pre-existing heart failure data were collected during ICU stay. Univariate and multivariate logistic regression analyses examined the association between pre-existing heart failure and the primary endpoint of 30-day mortality.

Results

The study included 3,917 patients, with 407 patients (17%) evidencing pre-existing CHF. These patients were older (77±5 versus 76±5, p<0.001) and more frail (Clinical Frailty Scale 4±2 versus 3±2, p<0.0001). The other comorbidities were also significantly more common in CHF patients. Before hospital admission, CHF patients suffered fewer days from symptoms (5 days (3–8) versus 7 days (4–10), p<0.001), but there was no difference in the days in the hospital before ICU admission (2 days (1–5) versus 2 (1–5) days, p=0.21). At ICU admission, disease severity assessed by SOFA scores was significantly higher in CHF patients (7±3 versus 5±3). During ICU-stay, intubation, mechanical ventilation, and tracheostomy occurred significantly more often in patients without CHF (63% versus 69%, p=0.017; and 13% versus 18%, p=0.002, respectively). In contrast, there was no difference regarding non-invasive ventilation (28% versus 27%, p=0.20), and the need for vasoactive drugs (66% versus 64, p=0.30). Regarding the limitation of life-sustaining therapy, therapy was significantly more often withheld (32% versus 25%, p=0.001) but not withdrawn (18% versus 17%, p=0.21) in CHF patients. Length of ICU stay was significantly shorter in CHF patients (166 (72–336) hours versus 260 hours (120–528), p<0.001). CHF patients had significantly higher ICU- (52% versus 46%, p=0.007), 30-day mortality (60% vs. 48%, p<0.001; OR 1.87, 95% CI 1.5–2.3) and 3-month mortality (69% vs. 56%, p<0.001). In the univariate regression analysis, having pre-existing CHF was significantly associated with 30-day mortality (OR 1.89, 95% CI 1.5–2.3; p<0.001), but after adjusting for confounders (SOFA, age, gender, frailty), heart failure was not independently associated any more (aOR 1.2, 95% CI 0.5–1.5; p=0.137).

Conclusion

In critically ill old COVID-19 patients, pre-existing chronic heart failure is associated with significantly increased short- and long-term mortality, but heart failure is not independently associated with increased 30-day mortality when adjusted for confounders.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): This study was endorsed by the ESICM. Free support for running the electronic database and was granted from the dep. of Epidemiology, University of Aarhus, Denmark. The support of the study in France by a grant from “Fondation Assistance Publique-Hôpitaux de Paris pour la recherche” is greatly appreciated. In Norway, the study was supported by a grant from the Health Region West. In addition, the study was supported by a grant from the European Open Science Cloud (EOSC). EOSCsecretariat.eu has received funding from the European Union's Horizon Programme call H2020-INFRAEOSC-05-2018-2019, grant agreement number 831644. This work was supported by the Forschungskommission of the Medical Faculty of the Heinrich-Heine-University Düsseldorf, No. 2018-32 to GW and No. 2020-21 to RRB for a Clinician Scientist Track.

Snow microbiome functional analyses reveal novel aspects of microbial metabolism of complex organic compounds

Microbes active in extreme cold are not as well explored as those of other extreme environments. Studies have revealed a substantial microbial diversity and identified cold-specific microbiome molecular functions. We analyzed the metagenomes and metatranscriptomes of 20 snow samples collected in early and late spring in Svalbard, Norway using mi-faser, our read-based computational microbiome function annotation tool. Our results reveal a more diverse microbiome functional capacity and activity in the early- vs. late-spring samples. We also find that functional dissimilarity between the same-sample metagenomes and metatranscriptomes is significantly higher in early than late spring samples. These findings suggest that early spring samples may contain a larger fraction of DNA of dormant (or dead) organisms, while late spring samples reflect a new, metabolically active community. We further show that the abundance of sequencing reads mapping to the fatty acid synthesis-related microbial pathways in late spring metagenomes and metatranscriptomes is significantly correlated with the organic acid levels measured in these samples. Similarly, the organic acid levels correlate with the pathway read abundances of geraniol degradation and inversely correlate with those of styrene degradation, suggesting a possible nutrient change. Our study thus highlights the activity of microbial degradation pathways of complex organic compounds previously unreported at low temperatures.

Over Winter Microbial Processes in a Svalbard Snow Pack: An Experimental Approach

Snow packs cover large expanses of Earth’s land surface, making them integral components of the cryosphere in terms of past climate and atmospheric proxies, surface albedo regulators, insulators for other Arctic environments and habitats for diverse microbial communities such as algae, bacteria and fungi. Yet, most of our current understanding of snow pack environments, specifically microbial activity and community interaction, is limited to the main microbial growing season during spring ablation. At present, little is known about microbial activity and its influence on nutrient cycling during the subfreezing temperatures and 24-h darkness of the polar winter. Here, we examined microbial dynamics in a simulated cold (−5°C), dark snow pack to determine polar winter season microbial activity and its dependence on critical nutrients. Snow collected from Ny-Ålesund, Svalbard was incubated in the dark over a 5-week period with four different nutrient additions, including glacial mineral particles, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and a combined treatment of DIN plus DIP. Data indicate a consumption of dissolved inorganic nutrients, particularly DIN, by heterotrophic communities, suggesting a potential nitrogen limitation, contradictory to phosphorus limitations found in most aquatic environments. 16S amplicon sequencing also reveal a clear difference in microbial community composition in the particulate mineral treatment compared to dissolved nutrient treatments and controls, suggesting that certain species of heterotrophs living within the snow pack are more likely to associate with particulates. Particulate phosphorus analyses indicate a potential ability of heterotrophic communities to access particulate sources of phosphorous, possibly explaining the lack of phosphorus limitation. These findings have importance for understanding microbial activity during the polar winter season and its potential influences on the abundance and bioavailability of nutrients released to surface ice and downstream environments during the ablation season.

Do Organic Substrates Drive Microbial Community Interactions in Arctic Snow?

The effect of nutrients on microbial interactions, including competition and collaboration, has mainly been studied in laboratories, but their potential application to complex ecosystems is unknown. Here, we examined the effect of changes in organic acids among other parameters on snow microbial communities in situ over 2 months. We compared snow bacterial communities from a low organic acid content period to that from a higher organic acid period. We hypothesized that an increase in organic acids would shift the dominant microbial interaction from collaboration to competition. To evaluate microbial interactions, we built taxonomic co-variance networks from OTUs obtained from 16S rRNA gene sequencing. In addition, we tracked marker genes of microbial cooperation (plasmid backbone genes) and competition (antibiotic resistance genes) across both sampling periods in metagenomes and metatranscriptomes. Our results showed a decrease in the average connectivity of the network during late spring compared to the early spring that we interpreted as a decrease of cooperation. This observation was strengthened by the significantly more abundant plasmid backbone genes in the metagenomes from the early spring. The modularity of the network from the late spring was also found to be higher than the one from the early spring, which is another possible indicator of increased competition. Antibiotic resistance genes were significantly more abundant in the late spring metagenomes. In addition, antibiotic resistance genes were also positively correlated to the organic acid concentration of the snow across both seasons. Snow organic acid content might be responsible for this change in bacterial interactions in the Arctic snow community.

Proteolysis in septic shock patients: plasma peptidomic patterns are associated with mortality

BACKGROUND

Uncontrolled proteolysis contributes to cell injury and organ dysfunction in animal models of circulatory shock. We investigated in humans the relationship between septic shock, proteolysis, and outcome.

METHODS

Intensive care patients with septic shock (n=29) or sepsis (n=6) and non-hospitalised subjects (n=9) were recruited as part of the prospective observational trial 'ShockOmics' (ClinicalTrials.gov Identifier NCT02141607). A mass spectrometry-based approach was used to analyse the plasma peptidomes and the origin of circulating peptides from proteolysis in the enrolled subjects.

RESULTS

Evidence of systemic proteolysis was indicated by a larger number of circulating peptides in septic shock patients, compared with septic patients and non-hospitalised healthy subjects. The peptide count and abundance in the septic shock patients were greater in patients who died (n=6) than in survivors (n=23), suggesting an association between magnitude of proteolysis and outcome. In silico analysis of the peptide sequences and of the sites of cleavage on the proteins of origin indicated a predominant role for serine proteases, such as chymotrypsin, and matrix metalloproteases in causing the observed proteolytic degradation.

CONCLUSIONS

Systemic proteolysis is a novel fundamental pathological mechanism in septic shock. Plasma peptidomics is proposed as a new tool to monitor clinical trajectory in septic shock patients.

CLINICAL TRIAL REGISTRATION

NCT02141607.