Objective Human brown adipose tissue (BAT) is a thermogenic tissue activated by the sympathetic nervous system in response to cold. It contributes to energy expenditure (EE) and takes up glucose and lipids from the circulation. Studies in rodents suggest that BAT contributes to the transient rise in EE after food intake, so called diet-induced thermogenesis (DIT). We investigated the relationship between human BAT activity and DIT in response to glucose intake in 17 healthy volunteers. Methods We assessed DIT, cold induced thermogenesis (CIT) and maximum BAT activity at three separate study visits within two weeks. DIT was measured by indirect calorimetry during an oral glucose tolerance-test. CIT was assessed as the difference in EE after cold exposure of two hours duration as compared to warm conditions. Maximal activity of BAT was assessed by ¹⁸F-FDG-PET/MRI after cold exposure and concomitant pharmacological stimulation with Mirabegron. Results 17 healthy men (mean age 23.4 years, mean BMI 23.2 kg/m²) participated in the study. EE increased from 1908 (±181) kcal/24 hours to 2128 (±277) kcal/24 hours (p<0.0001, +11.5%) after mild cold exposure. An oral glucose load increased EE from 1911 (±165) kcal/24 hours to 2096 (±167) kcal/24 hours at 60 minutes (p<0.0001, +9.7%). The increase in EE in response to cold was significantly associated with BAT activity (R²=0.43, p=0.004). However, DIT was not associated with BAT activity (R²=0.015, p=0.64). Conclusion DIT after an oral glucose load was not associated with stimulated ¹⁸F-FDG uptake into BAT suggesting that DIT is independent from BAT activity in humans.

This study investigates the prognostic impact of albumin levels in patients with cardiogenic shock (CS). Intensive care unit (ICU) related mortality in CS patients remains unacceptably high despite improvement concerning the treatment of CS patients. Limited data regarding the prognostic value of albumin in patients with CS is available. All consecutive patients with CS from 2019 to 2021 were included at one institution. Laboratory values were retrieved from the day of disease onset (day 1) and days 2, 3, 4, and 8 thereafter. The prognostic impact of albumin was tested for 30-day all-cause mortality. Moreover, the prognostic performance of albumin decline during ICU treatment was examined. Statistical analyses included univariable t-test, Spearman’s correlation, Kaplan–Meier analyses, multivariable mixed analysis of variance (ANOVA), C-Statistics, and Cox proportional regression analyses. In total, 230 CS patients were included, with an overall all-cause mortality at 30 days of 54%. The median albumin on day 1 was 30.0 g/L. Albumin on day 1 was able to discriminate between 30-day survivors and non-survivors (area under the curve (AUC) 0.607; 0.535–0.680; p = 0.005). CS patients with albumin < 30.0 g/L were associated with an increased risk of 30-day all-cause mortality (63% vs. 46%; log-rank p = 0.016; HR = 1.517; 95% CI 1.063–2.164; p = 0.021), which was demonstrated even after multivariable adjustment. Moreover, a decrease of albumin levels by ≥20% from day 1 to day 3 was accompanied by a higher risk of 30-days all-cause mortality (56% vs. 39%; log-rank p = 0.036; HR = 1.645; 95% CI 1.014–2.669; p = 0.044). Especially when combined with lactate, creatinine, and cardiac troponin I, reliable discrimination of 30-day all-cause mortality was observed, including albumin in CS risk stratification models (AUC = 0.745; 95% CI 0.677–0.814; p = 0.001). In conclusion, low baseline albumin levels as well as a decay of albumin levels during the course of ICU treatment, deteriorate prognostic outcomes in CS patients. The additional assessment of albumin levels may further improve risk stratification in CS patients.

Objective: Energy expenditure (EE) increases in response to cold exposure, which is called cold induced thermogenesis (CIT). Brown adipose tissue (BAT) has been shown to contribute significantly to CIT in human adults. BAT activity and CIT are acutely influenced by ambient temperature. In the present study, we investigated the long-term effect of seasonal temperature variation on human CIT. Materials and Methods: We measured CIT in 56 healthy volunteers by indirect calorimetry. CIT was determined as difference between EE during warm conditions (EE_warm) and after a defined cold stimulus (EE_cold). We recorded skin temperatures at eleven anatomically predefined locations, including the supraclavicular region, which is adjacent to the main human BAT depot. We analyzed the relation of EE, CIT and skin temperatures to the daily minimum, maximum and mean outdoor temperature averaged over 7 or 30 days, respectively, prior to the corresponding study visit by linear regression. Results: We observed a significant inverse correlation between outdoor temperatures and EE_cold and CIT, respectively, while EE_warm was not influenced. The daily maximum temperature averaged over 7 days correlated best with EE_cold (R² = 0.123, p = 0.008) and CIT (R² = 0.200, p = 0.0005). The mean skin temperatures before and after cold exposure were not related to outdoor temperatures. However, the difference between supraclavicular and parasternal skin temperature after cold exposure was inversely related to the average maximum temperature during the preceding 7 days (R² = 0.07575, p = 0.0221). Conclusion: CIT is significantly related to outdoor temperatures indicating dynamic adaption of thermogenesis and BAT activity to environmental stimuli in adult humans. Clinical Trial Registration: www.ClinicalTrials.gov, Identifier NCT02682706.

Pulmonary vein isolation (PVI) using radiofrequency (RF) ablation is an effective treatment option for patients with atrial fibrillation (AF). This study aims to investigate the safety of high-power short duration (HPSD) with emphasis on oesophageal lesions after PVI. Consecutive patients undergoing AF ablation with HPSD (50 W; ablation index (AI)-guided; target AI 350 for posterior wall ablation, AI 450 for anterior wall ablation) using the ThermoCool SmartTouch SF catheter were included. Patients underwent post-ablation oesophageal endoscopy to detect and categorize thermal oesophageal injury (EDEL). Occurrence and risk factors of oesophageal lesions and perforating complications were analysed. A total of 1033 patients underwent AF ablation with HPSD. Of them, 953 patients (67.6 ± 9.6 years; 58% male; 43% paroxysmal AF; 68% first PVI) underwent post-procedural oesophageal endoscopy and were included in further analyses. Median procedure time was 82.8 ± 24.4 min with ablation times of 16.1 ± 9.2 min. Thermal oesophageal injury was detected in 58 patients (6%) (n = 29 Category 1 erosion, n = 29 Category 2 ulcerous). One patient developed oesophageal perforation (redo, 4th AF ablation). No patient died. Using multivariable regression models, increased total ablation time [odds ratio (OR) 1.029, P = 0.010] and history of stroke (OR 2.619, P = 0.033) were associated with increased incidence of EDEL after AF ablation, whereas increased body mass index was protective (OR 0.980, P = 0.022). Thermal oesophageal lesions occur in 6% of HPSD AF ablations. The risk for development of perforating complications seems to be low. Incidence of atrio-oesophageal fistula (0.1%) is comparable to other reported series about RF ablation approaches.

This study examines the prognostic impact of C-reactive protein (CRP) and white blood cell (WBC) counts in patients with cardiogenic shock (CS). Data regarding the prognostic impact of inflammatory biomarkers in CS are scarce. All consecutive patients with CS from 2019 to 2021 admitted to a cardiac intensive care unit (ICU) were included at one institution. Laboratory measurements were retrieved from the day of admission (i.e., day 1), as well as days 2, 3, 4, and 8. The primary endpoint was 30-day all-cause mortality. Statistical analyses included univariate t-tests, Spearman’s correlations, C-statistics, Kaplan–Meier, and Cox regression analyses. From a total of 240 consecutive patients admitted with CS, 55% died within 30 days. CRP levels on days 3 to 8 were associated with reliable discrimination for 30-day all-cause mortality (area under the curve (AUC): 0.623–0.754), whereas CRP on day 1 was not (AUC = 0.514). In line, CRP > 100 mg/L on day 3 (56% vs. 37%; log-rank p = 0.023; HR = 1.702; 95% CI 1.060–2.735; p = 0.028) and especially a CRP increase of at least 200% from days 1 to day 3 (51% vs. 35%; log-rank p = 0.040; HR = 1.720; 95% CI 1.006–2.943; p = 0.048) were associated with an increased risk of all-cause mortality. Furthermore, WBC on day 1 discriminated 30-day all-cause mortality (AUC = 0.605; p = 0.005) with an increased risk of all-cause mortality in patients admitted with WBC > 10 × 10⁶/mL (59% vs. 40%; log-rank p = 0.036; HR = 1.643; 95% CI 1.010–2.671; p = 0.045). In conclusion, WBC count on admission as well as CRP levels during the course of ICU treatment were associated with 30-day all-cause mortality. Specifically, an increase of CRP levels by at least 200% from day 1 to day 3 during the course of ICU treatment was associated with an increased risk of 30-day all-cause mortality. The present study is one of the first to describe the prognostic value of inflammatory biomarkers in consecutive all-comer CS patients treated at a cardiac ICU.