Inflammation and Its Consequences After Surgical Versus Transcatheter Aortic Valve Replacement

Immune response following transcatheter aortic valve procedure

Aortic valve stenosis is the most common type of heart valve disease in the United States and Europe and calcific aortic stenosis (AS) affects 2-7% of people aged 65 years and older. Aortic valve replacement (AVR) is the only effective treatment for individuals with this condition. Transcatheter Aortic Valve Replacement (TAVR) has been widely accepted as a minimally invasive therapeutic approach for addressing symptomatic AS in patients who are considered to have a high risk for traditional surgical intervention. TAVR procedure may have a paradoxical effect on the immune system and inflammatory status. A major portion of these immune responses is regulated by activating or inhibiting inflammatory monocytes and the complement system with subsequent changes in inflammatory cytokines. TAVR has the potential to induce various concurrent exposures, including disruption of the native valve, hemodynamic changes, antigenicity of the bioprosthesis, and vascular damage, which finally lead to the development of inflammation. On the other hand, it is important to acknowledge that TAVR may also have anti-inflammatory effects by helping in the resolution of stenosis.The inflammation and immune response following TAVR are complex processes that significantly impact procedural outcomes and patient well-being. Understanding the underlying mechanisms, identifying biomarkers of inflammation, and exploring therapeutic interventions to modulate these responses are crucial for optimizing TAVR outcomes. Further research is warranted to elucidate the precise immunological dynamics and develop tailored strategies to attenuate inflammation and enhance post-TAVR healing while minimizing complications.

Procalcitonin for the diagnosis of postoperative bacterial infection after adult cardiac surgery: a systematic review and meta-analysis

BACKGROUND AND AIMS

Patients undergoing cardiac surgery are subject to infectious complications that adversely affect outcomes. Rapid identification is essential for adequate treatment. Procalcitonin (PCT) is a noninvasive blood test that could serve this purpose, however its validity in the cardiac surgery population is still debated. We therefore performed a systematic review and meta-analysis to estimate the accuracy of PCT for the diagnosis of postoperative bacterial infection after cardiac surgery.

METHODS

We included studies on adult cardiac surgery patients, providing estimates of test accuracy. Search was performed on PubMed, EmBase and WebOfScience on April 12th, 2023 and rerun on September 15th, 2023, limited to the last 10 years. Study quality was assessed with the QUADAS-2 tool. The pooled measures of performance and diagnostic accuracy, and corresponding 95% Confidence Intervals (CI), were calculated using a bivariate regression model. Due to the variation in reported thresholds, we used a multiple-thresholds within a study random effects model for meta-analysis (diagmeta R-package).

RESULTS

Eleven studies were included in the systematic review, and 10 (2984 patients) in the meta-analysis. All studies were single-center with observational design, five of which with retrospective data collection. Quality assessment highlighted various issues, mainly concerning lack of prespecified thresholds for the index test in all studies. Results of bivariate model analysis using multiple thresholds within a study identified the optimal threshold at 3 ng/mL, with a mean sensitivity of 0.67 (0.47-0.82), mean specificity of 0.73 (95% CI 0.65-0.79), and AUC of 0.75 (IC95% 0.29-0.95). Given its importance for practice, we also evaluated PCT's predictive capability. We found that positive predictive value is at most close to 50%, also with a high prevalence (30%), and the negative predictive value was always > 90% when prevalence was < 20%.

CONCLUSIONS

These results suggest that PCT may be used to help rule out infection after cardiac surgery. The optimal threshold of 3 ng/mL identified in this work should be confirmed with large, well-designed randomized trials that evaluate the test's impact on health outcomes and on the use of antibiotic therapy. PROSPERO Registration number CRD42023415773. Registered 22 April 2023.

Inflammatory Status Assessment by Machine Learning Techniques to Predict Outcomes in Patients with Symptomatic Aortic Stenosis Treated by Transcatheter Aortic Valve Replacement

(1) Background: Although transcatheter aortic valve replacement (TAVR) significantly improves long-term outcomes of symptomatic severe aortic stenosis (AS) patients, long-term mortality rates are still high. The aim of our study was to identify potential inflammatory biomarkers with predictive capacity for post-TAVR adverse events from a wide panel of routine biomarkers by employing ML techniques. (2) Methods: All patients diagnosed with symptomatic severe AS and treated by TAVR since January 2016 in a tertiary center were included in the present study. Three separate analyses were performed: (a) using only inflammatory biomarkers, (b) using inflammatory biomarkers, age, creatinine, and left ventricular ejection fraction (LVEF), and (c) using all collected parameters. (3) Results: A total of 338 patients were included in the study, of which 56 (16.5%) patients died during follow-up. Inflammatory biomarkers assessed using ML techniques have predictive value for adverse events post-TAVR with an AUC-ROC of 0.743 and an AUC-PR of 0.329; most important variables were CRP, WBC count and Neu/Lym ratio. When adding age, creatinine and LVEF to inflammatory panel, the ML performance increased to an AUC-ROC of 0.860 and an AUC-PR of 0.574; even though LVEF was the most important predictor, inflammatory parameters retained their value. When using the entire dataset (inflammatory parameters and complete patient characteristics), the ML performance was the highest with an AUC-ROC of 0.916 and an AUC-PR of 0.676; in this setting, the CRP and Neu/Lym ratio were also among the most important predictors of events. (4) Conclusions: ML models identified the CRP, Neu/Lym ratio, WBC count and fibrinogen as important variables for adverse events post-TAVR.

Postoperative delirium after transcatheter aortic valve replacement: An updated systematic review and meta-analysis

AIMS

To perform an updated systematic review and meta-analysis of postoperative delirium (POD) after transcatheter aortic valve replacement (TAVR).

METHODS

We conducted a systematic literature search of PubMed, Embase, and Cochrane Library databases from the time of the first human TAVR procedure in 2002 until December 24, 2021, which was supplemented by manual searches of bibliographies. Data were collected on incidence rates, risk factors, and/or associated mortality of POD after TAVR. Pooled analyses were conducted using random effects models to yield mean differences, odds ratios, hazard ratios, and risk ratios, with 95% confidence intervals.

RESULTS

A total of 70 articles (69 studies) comprising 413,389 patients were included. The study heterogeneity was substantial. The pooled mean incidence of POD after TAVR in all included studies was 9.8% (95% CI: 8.7%-11.0%), whereas that in studies using validated tools to assess for delirium at least once a day for at least 2 consecutive days after TAVR was 20.7% (95% CI: 17.8%-23.7%). According to the level of evidence and results of meta-analysis, independent preoperative risk factors with a high level of evidence included increased age, male sex, prior stroke or transient ischemic attack, atrial fibrillation/flutter, weight loss, electrolyte abnormality, and impaired Instrumental Activities of Daily Living; intraoperative risk factors included non-transfemoral access and general anesthesia; and acute kidney injury was a postoperative risk factor. POD after TAVR was associated with significantly increased mortality (pooled unadjusted RR: 2.20, 95% CI: 1.79-2.71; pooled adjusted RR: 1.62, 95% CI: 1.25-2.10), particularly long-term mortality (pooled unadjusted HR: 2.84, 95% CI: 1.91-4.23; pooled adjusted HR: 1.88, 95% CI: 1.30-2.73).

CONCLUSIONS

POD after TAVR is common and is associated with an increased risk of mortality. Accurate identification of risk factors for POD after TAVR and implementation of preventive measures are critical to improve prognosis.

Association between haematological parameters and outcomes following transcatheter aortic valve implantation at mid-term follow-up

BACKGROUND

Patients undergoing transcatheter aortic valve implantation (TAVI) often have multiple comorbidities, such as anaemia and chronic inflammatory disorders. We sought to investigate the association between preoperative and postoperative haematological parameters and clinical outcomes in TAVI patients at mid-term follow-up.

METHODS

In the present study, consecutive patients (N=908) who underwent TAVI at the Cleveland Clinic between 2017 and 2019 with available complete blood counts were studied. Data were collected on preoperative and postoperative anaemia and elevations in neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR). Survival analysis was used to study the association of haematologic parameters with all-cause mortality and major adverse cardiac and cerebrovascular events (MACCE).

RESULTS

We found that preoperative anaemia and elevated NLR were significantly associated with a higher risk of all-cause mortality (aHR=1.6 (95% CI: 1.1 to 2.0) and 1.4 (95% CI: 1.1 to 1.6), respectively) and MACCE (aHR=1.9 (95% CI: 1.3 to 2.8) and 1.6 (95% CI: 1.1 to 2.4), respectively). While an elevated preoperative PLR was not associated with increased mortality risk, it had a significant association with MACCE risk (aHR: 1.6 (95% CI: 1.1 to 2.4)). Further, postoperative anaemia, elevated NLR and PLR were associated with increased risks of all-cause mortality and MACCE.

CONCLUSION

Pathological alterations in haematological parameters were associated with higher risks of post-TAVI mortality and MACCE at mid-term follow-up. Our findings advocate for further incorporating haematological parameters in the preoperative evaluation of TAVI candidates.

Presepsin predicts 1-year all-cause mortality better than N-terminal pro-B-type natriuretic peptide in patients undergoing transcatheter aortic valve implantation

Aim: Presepsin is a sensitive biomarker for the diagnosis and estimation of prognosis in septic patients. The prognostic role of presepsin in patients undergoing transcatheter aortic valve implantation (TAVI) has never been investigated. Patients, materials & methods: In 343 patients, presepsin and N-terminal pro-B-type natriuretic peptide were measured before TAVI. One-year all-cause mortality was used as outcome measure. Results: Patients with high presepsin levels were more likely to succumb than patients with low presepsin values (16.9% vs 12.3%; p = 0.015). Elevated presepsin remained a significant predictor of 1-year all-cause mortality (odds ratio: 2.2 [95% CI: 1.12-4.29]; p = 0.022) after adjustment. N-terminal pro-B-type natriuretic peptide did not predict 1-year all-cause mortality. Conclusion: Elevated baseline presepsin levels are an independent predictor of 1-year mortality in TAVI patients.

Uncoupling the Vicious Cycle of Mechanical Stress and Inflammation in Calcific Aortic Valve Disease

Calcific aortic valve disease (CAVD) is a common acquired valvulopathy, which carries a high burden of mortality. Chronic inflammation has been postulated as the predominant pathophysiological process underlying CAVD. So far, no effective medical therapies exist to halt the progression of CAVD. This review aims to outline the known pathways of inflammation and calcification in CAVD, focussing on the critical roles of mechanical stress and mechanosensing in the perpetuation of valvular inflammation. Following initiation of valvular inflammation, dysregulation of proinflammatory and osteoregulatory signalling pathways stimulates endothelial-mesenchymal transition of valvular endothelial cells (VECs) and differentiation of valvular interstitial cells (VICs) into active myofibroblastic and osteoblastic phenotypes, which in turn mediate valvular extracellular matrix remodelling and calcification. Mechanosensitive signalling pathways convert mechanical forces experienced by valve leaflets and circulating cells into biochemical signals and may provide the positive feedback loop that promotes acceleration of disease progression in the advanced stages of CAVD. Mechanosensing is implicated in multiple aspects of CAVD pathophysiology. The mechanosensitive RhoA/ROCK and YAP/TAZ systems are implicated in aortic valve leaflet mineralisation in response to increased substrate stiffness. Exposure of aortic valve leaflets, endothelial cells and platelets to high shear stress results in increased expression of mediators of VIC differentiation. Upregulation of the Piezo1 mechanoreceptor has been demonstrated to promote inflammation in CAVD, which normalises following transcatheter valve replacement. Genetic variants and inhibition of Notch signalling accentuate VIC responses to altered mechanical stresses. The study of mechanosensing pathways has revealed promising insights into the mechanisms that perpetuate inflammation and calcification in CAVD. Mechanotransduction of altered mechanical stresses may provide the sought-after coupling link that drives a vicious cycle of chronic inflammation in CAVD. Mechanosensing pathways may yield promising targets for therapeutic interventions and prognostic biomarkers with the potential to improve the management of CAVD.

Postoperative delirium and quality of life after transcatheter and surgical aortic valve replacement: A prospective observational study

OBJECTIVE

In older patients, postoperative delirium is a frequently occurring complication after surgical aortic valve replacement, leading to an excess in postoperative morbidity and mortality. It remains controversial whether transcatheter aortic valve implantation and minimally invasive surgical aortic valve replacement can reduce the risk of postoperative delirium. This study aimed to compare the incidence of postoperative delirium after transcatheter aortic valve implantation and surgical aortic valve replacement and the impact on long-term outcomes.

METHODS

Between September 2018 and January 2020, we conducted an observational, prospective cohort study in patients aged 70 years or more undergoing transcatheter aortic valve implantation or surgical aortic valve replacement. The primary end point was the incidence of in-hospital postoperative delirium during 5 postoperative days assessed with the Confusion Assessment Method. Secondary end points included perioperative inflammation, postoperative complications, health status (EuroQol 5-dimensional questionnaire 5 levels), and mortality up to 6 months. Transcatheter aortic valve implantation and surgical aortic valve replacement were compared using propensity weighting to account for important baseline differences (European System for Cardiac Operative Risk Evaluation II, age, and frailty).

RESULTS

We included 250 patients with a mean (standard deviation) age of 80 (±5.8) years and a European System for Cardiac Operative Risk Evaluation score of 5 (±4.7). In the propensity-weighted analysis, those undergoing surgical aortic valve replacement (N = 166) had a higher incidence of postoperative delirium compared with transcatheter aortic valve implantation (N = 84) (51% vs 15%: P < .0001). Furthermore, patients undergoing surgical aortic valve replacement experienced more inflammation, a greater depth of anesthesia, and more intraoperative hypotension. After surgical aortic valve replacement, 41% of patients experienced an improved health status compared with 12% after transcatheter aortic valve implantation (P < .0001). No outcome differences were noted within the surgical aortic valve replacement groups.

CONCLUSIONS

Transcatheter aortic valve implantation is associated with a lower risk for postoperative delirium. Nevertheless, patients undergoing surgical aortic valve replacement experience the greatest improvement in quality of life. Heart teams should consider these outcomes in shared decision-making in the choice of transcatheter aortic valve implantation or surgical aortic valve replacement.

Transcatheter aortic valve replacement during the COVID-19 pandemic-A Dutch single-center analysis

Background and Aim of the Study

The coronavirus disease 2019 (COVID‐19) pandemic has put an enormous strain on healthcare systems and intensive care unit (ICU) capacity, leading to suspension of most elective procedures, including transcatheter aortic valve replacement (TAVR). However, deferment of TAVR is associated with significant wait‐time mortality in patients with severe aortic valve stenosis. Conversely, there is currently no data available regarding the safety and feasibility of a continued TAVR program during this unprecedented crisis. The aim of this study is to evaluate the safety and feasibility of patients undergoing TAVR during the COVID‐19 pandemic in our center, with specific emphasis on COVID‐19 related outcomes.

Methods

All patients who underwent TAVR in our center between February 27, 2020, and June 30, 2020, were evaluated. Clinical outcomes were described in terms of Valve Academic Research Consortium 2 definitions. Patient follow‐up was done by chart review and telephone survey.

Results

A total of 71 patients have undergone TAVR during the study period. Median age was 80 years, 63% were men, and 25% were inpatients. Procedural success was 99%. After TAVR, 30% involved admission to the ICU, and 94% were ultimately discharged to the cardiac care unit on the same day. Two patients (3%) had confirmed COVID‐19 a few days after TAVR, and both died of COVID‐19 pneumonia within 2 weeks after hospital discharge.

Conclusions

A continued TAVR program during the COVID‐19 pandemic is feasible despite limited hospital resources. However, COVID‐19 related mortality after TAVR is of concern.

Effect of Transcatheter Aortic Valve Implantation on the Immune Response Associated With Surgical Aortic Valve Replacement

The immune response after transcatheter aortic valve implantation (TAVI) in comparison to that after surgical aortic valve replacement (SAVR) remains to be fully elucidated. In a 2-part study, we assessed laboratory data obtained before, immediately after, and 24 and 48 hours after SAVR (128 patients; age ≥80 [mean 82] years) or transfemoral TAVI (102 patients; age ≥80 [mean 86] years) performed for aortic stenosis. In-hospital mortalities were similar (3% vs 0%), but leukocyte counts and aspartate aminotransferase and creatine kinas concentrations were decreased immediately and 24 hours after surgery (all, p <0.001). We performed cytokine profiling in a SAVR group (11 patients; mean age, 77 years) and transfemoral TAVI group (12 patients; mean age, 84 years). By measuring normalized concentrations of 71 cytokines at 3 time points, we found a significant difference (defined as fold change >1.7 and p <0.05 [by Mann-Whitney U-test]) in 23 cytokines. The differentially expressed cytokines fell into 3 hierarchical clusters: cluster A (high increase after SAVR and suppressed increase after TAVI only immediately after surgery [CCL2, CCL4, and 2 others]), cluster B (high increase after SAVR and suppressed increase after TAVI at 2 time points [IL-1Ra, IL-6, IL-8, IL-10, and 5 others]), and cluster C (various patterns [TRAIL, CCL11, and 8 others]). Gene enrichment analysis identified multiple pathways associated with the inflammatory responses in SAVR and altered responses in TAVI, including cellular responses to tumor necrosis factor (p = 0.0035) and interleukin-1 (p = 0.0062). In conclusion, a robust inflammatory response follows SAVR, and a comparatively attenuated response follows TAVI.

Transcatheter Aortic Valve Implantation Represents an Anti-Inflammatory Therapy Via Reduction of Shear Stress-Induced, Piezo-1-Mediated Monocyte Activation

BACKGROUND

Aortic valve stenosis is an increasingly prevalent degenerative and inflammatory disease. Transcatheter aortic valve implantation (TAVI) has revolutionized its treatment, thereby avoiding its life-threatening/disabling consequences. Whether aortic valve stenosis is accelerated by inflammation and whether it is itself a cause of inflammation are unclear. We hypothesized that the large shear forces exerted on circulating cells, particularly on the largest circulating cells, monocytes, while passing through stenotic aortic valves result in proinflammatory effects that are resolved with TAVI.

METHODS

TAVI provides a unique opportunity to compare the activation status of monocytes under high shear stress (before TAVI) and under low shear stress (after TAVI). The activation status of monocytes was determined with a single-chain antibody, MAN-1, which is specific for the activated β₂-integrin Mac-1. Monocyte function was further characterized by the adhesion of myocytes to stimulated endothelial cells, phagocytic activity, uptake of oxidized low-density lipoprotein, and cytokine expression. In addition, we designed a microfluidic system to recapitulate the shear rate conditions before and after TAVI. We used this tool in combination with functional assays, Ca²⁺ imaging, siRNA gene silencing, and pharmacological agonists and antagonists to identify the key mechanoreceptor mediating the shear stress sensitivity of monocytes. Last, we stained for monocytes in explanted stenotic aortic human valves.

RESULTS

The resolution of high shear stress through TAVI reduces Mac-1 activation, cellular adhesion, phagocytosis, oxidized low-density lipoprotein uptake, and expression of inflammatory markers in monocytes and plasma. Using microfluidics and pharmacological and genetic studies, we could recapitulate high shear stress effects on isolated human monocytes under highly controlled conditions, showing that shear stress-dependent calcium influx and monocyte adhesion are mediated by the mechanosensitive ion channel Piezo-1. We also demonstrate that the expression of this receptor is shear stress dependent and downregulated in patients receiving TAVI. Last, we show monocyte accumulation at the aortic side of leaflets of explanted aortic valves.

CONCLUSIONS

We demonstrate that high shear stress, as present in patients with aortic valve stenosis, activates multiple monocyte functions, and we identify Piezo-1 as the mainly responsible mechanoreceptor, representing a potentially druggable target. We demonstrate an anti-inflammatory effect and therefore a novel therapeutic benefit of TAVI.

Peri-procedural hemostasis disorders in surgical and transcatheter aortic valve implantation

Introduction

Despite their high effectiveness, surgical aortic valve replacement (AVR) and transcatheter aortic valve implantation (TAVI) are associated with substantial risk of bleeding. Although procedure-related hemostasis disorders might be crucial for safety of both procedures, the amount of data on the peri-procedural status of hemostasis in patients with aortic valve stenosis (AS) subjected to AVR and TAVI is negligible.

Aim

To investigate the profile of peri-procedural hemostasis in elderly patients with AS, subjected to aortic valve prosthesis implantation.

Material and methods

We performed a prospective analysis of global hemostasis using ROTEM thromboelastometry and platelet reactivity assessment using impedance aggregometry in 30 consecutive patients ≥ 70 years old subjected to AVR and TAVI. All tests were performed within 24 h before, directly and 24 h after the procedures.

Results

Surgical aortic valve replacement was characterized by transient hypofibrinogenemia and von Willebrand factor (vWF) depletion, which quickly recovered within 24 h after AVR. Transcatheter aortic valve implantation was characterized by substantial alteration of platelet function and vWF depletion with significant platelet reactivity impairment and increase in platelet sensitivity to antiplatelet agent, early after the procedure. TAVI-related hemostasis alterations were not recovered at 24 h after the procedure.

Conclusions

Surgical and transcatheter aortic valve replacement procedures are associated with substantial and diverse peri-procedural hemostasis disorders. Since hemostasis disorders related to TAVI are mainly characterized by impaired platelet function, early dual antiplatelet prophylaxis after TAVI requires careful consideration.

Changes in thromboinflammatory profiles across the generations of transcatheter aortic heart valves

The transcatheter aortic valve replacement (TAVR) procedure was developed to provide patients with severe aortic stenosis an alternative to the surgical aortic valve replacement. Since the approval of the original SAPIEN the technology has rapidly evolved. While several approaches can be used for valve deployment, as delivery systems have become smaller and more flexible, the transfemoral approach has become the dominant technique for valve deployment. One hundred and forty five patients undergoing TAVR receiving one of four valve types (Sapien, Sapien XT, Sapien3 or CoreValve) via the femoral artery were included in this study. Platelet count, white blood cells count (WBC), Interleukin-6 (IL-6), and Serum Amyloid A (SAA) were determined before and after TAVR. Platelet counts declined after the procedure regardless of the valve type and were dependent upon the baseline platelet count. Use of conscious sedation blunted the decline in platelet count. With the newer generation valves, the rise in WBC post-TAVR was lower than observed with the Sapien, in keeping with less systemic inflammation. Consistent with WBC, IL-6 levels were lower following deployment of the newer generation valves. Elevations in plasma SAA, which occur following myocardial injury, were not reduced with the newer valves. Evolution of the TAVR technology has occurred rapidly over the last 5 years. The newer devices and smaller delivery systems are associated with less systemic inflammation, as reflected in WBC and plasma IL-6 levels. However, the acute phase reactant SAA remains unchanged, possibly reflecting different triggers for SAA following TAVR.

Artificial Organs 2018: A Year in Review

In this Editor's Review, articles published in 2018 are organized by category and summarized. We provide a brief reflection of the research and progress in artificial organs intended to advance and better human life while providing insight for continued application of these technologies and methods. Artificial Organs continues in the original mission of its founders "to foster communications in the field of artificial organs on an international level." Artificial Organs continues to publish developments and clinical applications of artificial organ technologies in this broad and expanding field of organ Replacement, Recovery, and Regeneration from all over the world. Peer-reviewed special issues this year included contributions from the 13th International Conference on Pediatric Mechanical Circulatory Support Systems and Pediatric Cardiopulmonary Perfusion edited by Dr. Akif Undar, and the 25th Congress of the International Society for Mechanical Circulatory Support edited by Dr. Marvin Slepian. Additionally, many editorials highlighted the worldwide survival differences in hemodialysis and perspectives on mechanical circulatory support and stem cell therapies for cardiac support. We take this time also to express our gratitude to our authors for offering their work to this journal. We offer our very special thanks to our reviewers who give so generously of time and expertise to review, critique, and especially provide meaningful suggestions to the author's work whether eventually accepted or rejected. Without these excellent and dedicated reviewers the quality expected from such a journal could not be possible. We also express our special thanks to our Publisher, John Wiley & Sons for their expert attention and support in the production and marketing of Artificial Organs. We look forward to reporting further advances in the coming years.