Comparison of Outcomes After Transcatheter Aortic Valve Replacement vs Surgical Aortic Valve Replacement Among Patients With Aortic Stenosis at Low Operative Risk

Importance:  Transcatheter aortic valve replacement (TAVR) has been shown to be a valid alternative to surgical aortic valve replacement (SAVR) in patients at high operative risk with severe aortic stenosis (AS). However, the evidence of the benefits and harms of TAVR in patients at low operative risk is still scarce.Objective:  To compare the short-term and midterm outcomes after TAVR and SAVR in low-risk patients with AS.Design, Setting, and Participants:  This retrospective comparative effectiveness cohort study used data from the Nationwide Finnish Registry of Transcatheter and Surgical Aortic Valve Replacement for Aortic Valve Stenosis of patients at low operative risk who underwent TAVR or SAVR with a bioprosthesis for severe AS from January 1, 2008, to November 30, 2017. Low operative risk was defined as a Society of Thoracic Surgeons Predicted Risk of Mortality score less than 3% without other comorbidities of clinical relevance. One-to-one propensity score matching was performed to adjust for baseline covariates between the TAVR and SAVR cohorts.Exposures:  Primary TAVR or SAVR with a bioprosthesis for AS with or without associated coronary revascularization.Main Outcomes and Measures:  The primary outcomes were 30-day and 3-year survival.Results:  Overall, 2841 patients (mean [SD] age, 74.0 [6.2] years; 1560 [54.9%] men) fulfilled the inclusion criteria and were included in the analysis; TAVR was performed in 325 patients and SAVR in 2516 patients. Propensity score matching produced 304 pairs with similar baseline characteristics. Third-generation devices were used in 263 patients (86.5%) who underwent TAVR. Among these matched pairs, 30-day mortality was 1.3% after TAVR and 3.6% after SAVR (P = .12). Three-year survival was similar in the study cohorts (TAVR, 85.7%; SAVR, 87.7%; P = .45). Interaction tests found no differences in terms of 3-year survival between the study cohorts in patients younger than vs older than 80 years or in patients who received recent aortic valve prostheses vs those who did not.Conclusions and Relevance:  Transcatheter aortic valve replacement using mostly third-generation devices achieved similar short- and mid-term survival compared with SAVR in low-risk patients. Further studies are needed to assess the long-term durability of TAVR prostheses before extending their use to low-risk patients.</p

Blood Transfusion and Outcome After Transfemoral Transcatheter Aortic Valve Replacement

Objective: To investigate the prognostic impact of red blood cell (RBC) transfusion on the outcome after transfemoral transcatheter aortic valve replacement (TAVR).Design: Nationwide, retrospective multicenter study.Setting: Five University Hospitals.Participants: The nationwide FinnValve registry included data from 2,130 patients who underwent TAVR for aortic stenosis from 2008 to 2017. After excluding patients who underwent TAVR through nontransfemoral accesses, 1,818 patients were selected for this analysis.Intervention: TAVR with or without coronary revascularization.Measurements and Main Results: RBCs were transfused in 293 patients (16.1%). Time-trend analysis showed that the rates of RBC transfusion decreased significantly from 27.5% in 2012 to 10.0% in 2017 (p Conclusions: Patients who received blood transfusion after TAVR had an increased risk of early and late adverse events. These adverse effects were particularly evident with increasing amount of RBC transfusion and operations for excessive bleeding.</p

Acute Kidney Injury Following Aortic Valve Replacement in Patients Without Chronic Kidney Disease

acceptedVersionPeer reviewe

Environmental drivers of increased ecosystem respiration in a warming tundra

Arctic and alpine tundra ecosystems are large reservoirs of organic carbon1,2. Climate warming may stimulate ecosystem respiration and release carbon into the atmosphere3,4. The magnitude and persistency of this stimulation and the environmental mechanisms that drive its variation remain uncertain5–7. This hampers the accuracy of global land carbon–climate feedback projections7,8. Here we synthesize 136 datasets from 56 open-top chamber in situ warming experiments located at 28 arctic and alpine tundra sites which have been running for less than 1 year up to 25 years. We show that a mean rise of 1.4 °C [confidence interval (CI) 0.9–2.0 °C] in air and 0.4 °C [CI 0.2–0.7 °C] in soil temperature results in an increase in growing season ecosystem respiration by 30% [CI 22–38%] (n = 136). Our findings indicate that the stimulation of ecosystem respiration was due to increases in both plant-related and microbial respiration (n = 9) and continued for at least 25 years (n = 136). The magnitude of the warming effects on respiration was driven by variation in warming-induced changes in local soil conditions, that is, changes in total nitrogen concentration and pH and by context-dependent spatial variation in these conditions, in particular total nitrogen concentration and the carbon:nitrogen ratio. Tundra sites with stronger nitrogen limitations and sites in which warming had stimulated plant and microbial nutrient turnover seemed particularly sensitive in their respiration response to warming. The results highlight the importance of local soil conditions and warming-induced changes therein for future climatic impacts on respiration