Noteworthy in Cardiothoracic Surgery 2023.

Noteworthy in Cardiothoracic Surgery 2023 summarizes a few of the most high-impact trials and provocative trends in cardiothoracic surgery and transplantation this past year. Transplantation using organs procured from donation after circulatory death (DCD) continues to increase, and the American Society of Transplant Surgeons released recommendations on best practices in 2023. We review a summary of data on the impact of DCD on heart and lung transplantation. There has been increased interest in extracorporeal life support (ECLS), particularly after the COVID-19 pandemic, and we review the results of the highly discussed ECLS-SHOCK trial, which randomized patients in cardiogenic shock with planned revascularization to ECLS vs usual care. With improving survival outcomes in complex aortic surgery, there is a need for higher-quality evidence to guide which cooling and cerebral perfusion strategies may optimize cognitive outcomes in these patients. We review the short-term outcomes of the GOT ICE trial (Cognitive Effects of Body Temperature During Hypothermic Circulatory Arrest), a multicenter, randomized controlled trial of three different nadir temperatures, evaluating outcomes in cognition and associated changes in functional magnetic resonance imaging. Finally, both the Society of Thoracic Surgeons (STS) and the American College of Cardiology, American Heart Association, American College of Chest Physicians and Heart Rhythm Society (ACC/AHA/ACCP/HRS) updated atrial fibrillation guidelines in 2023, and we review surgically relevant updates to the guidelines and the evidence behind them.

Personalizing Patient Risk of a Life Altering Event: An Application of Machine Learning to Hemiarch Surgery.

OBJECTIVE: To assess a machine learning model's ability to predict the occurrence of life altering events (LAE) in hemiarch surgery and determine contributing patient characteristics and intraoperative factors. METHODS: In total, 602 patients who underwent hemiarch replacement at a high-volume, aortic center from 2009-2022 were included. Patients were randomly divided into training (80%) and testing (20%) sets with various eXtreme gradient boosting (XGBoost) candidate models constructed to predict the risk of experiencing LAE, including stroke, mortality, or new renal replacement therapy requirement. 64 input parameters from the index hospitalization were identified, including 24 demographic characteristics as well as 8 pre-operative and 32 intra-operative variables. A SHapley Additive exPlanation (SHAP) beeswarm plot was generated to identify and interpret the impact of individual features on the predictions of the final model. RESULTS: A LAE was noted in 15% (90/602) of patients who underwent hemiarch replacement, including urgent/emergent cases and dissections. The final XGBoost model demonstrated a cross-validation accuracy of 88% on the testing set and was well-calibrated as evidenced by a low Brier score of 0.12. The best performing model achieved an area under the receiver-operating characteristic curve of 0.76 and an area under the precision-recall curve of 0.55. The SHAP beeswarm plot provided insights into key features that significantly influenced model prediction. CONCLUSIONS: Machine learning demonstrated superior accuracy in predicting hemiarch patients that would experience a LAE. This model may help to guide patients and clinicians in stratifying risk on an individual basis, which may in turn influence clinical decision-making.

One-Year Results of a Low-Profile Endograft in Acute, Complicated Type B Aortic Dissection.

BACKGROUND: The safety and effectiveness of the RelayPro endograft (Terumo Aortic) was assessed for the treatment of acute, complicated type B aortic dissection (TBAD). METHODS: A prospective pivotal trial analyzed a primary end point of all-cause mortality at 30 days. Secondary end points included technical success, major adverse events (disabling stroke, renal failure, and paraplegia/paralysis), endoleaks, patency, rupture, device integrity, false lumen perfusion, reinterventions, aortic expansion, and migration evaluated to 5 years. RESULTS: The study involved 22 United States centers and enrolled 56 patients (mean age, 59.5 ± 11.4 years) from 2017 to 2021; of whom, 73.2% were men and 53.6% were African American. TBAD was complicated by malperfusion of the kidneys (51.8%), lower extremities (35.7%), and viscera (33.9%), and rupture (10.7%). Dissection extended proximally to zones 1/2 (14.3%) and zone 3 (78.6%) and distally to the iliac arteries (67.3%). Most procedures were percutaneous (85.5%). Technical success was 100%. Median hospitalization was 7 days (interquartile range, 5-12 days). All-cause mortality at 30 days was 1.8% (1 of 56; upper 95% CI, 8.2%; P < .0001). Seven major adverse events occurred in 6 patients (10.7%), consisting of paraplegia (n = 3), paraparesis (n = 2), disabling stroke (n = 1), and renal failure (n = 1). All paraplegia/paraparesis resolved with lumbar drainage. Kaplan-Meier analysis estimated a freedom from major adverse events of 89.1% at each interval from 30 days to 3 years. There was 1 endoleak (Type Ia), 2 retrograde dissections, and aortic diameter growth occurred in 2. There has been no rupture, fistula, component separation, patency loss, stenosis, kinking, twisting, bird beak, loss of device integrity, or fracture. CONCLUSIONS: RelayPro is safe and effective in acute, complicated TBAD. Follow-up is ongoing to evaluate longer-term outcomes and durability.

Prolonged travel time to transplantation center is associated with poor outcomes following heart transplantation.

BACKGROUND: This study aims to examine the impact of home-to-transplantation center travel time as a potential barrier to healthcare accessibility. METHODS: Observational study examined adult heart transplant recipients who received a graft between 2012 and 2022 in the United States. Travel time was calculated using the Google Distance Matrix API between the recipient's residence and transplantation center. A multivariable parametric survival model was fitted to minimize confounding bias. RESULTS: Among the 25,923 recipients that met the selection criteria, the median travel time was 51 â€‹min and 95 â€‹% of recipients lived within a 5-h radius of their center. White recipients experienced longer median travel times (62 â€‹min, p â€‹< â€‹0.001) compared to Black (36 â€‹min) or Hispanic (40 â€‹min) recipients. A travel time of 1-2 â€‹h (survival time ratio [STR] 0.867, p â€‹= â€‹0.035) or >2 â€‹h (STR 0.873, p â€‹= â€‹0.026) away from the transplantation center was independently associated with lower long-term survival rates. CONCLUSION: Extended travel times to transplantation centers may negatively impact long-term survival outcomes for heart transplant recipients, suggesting the need to address this potential barrier to healthcare accessibility.

Evaluation of the efficacy and safety of amustaline/glutathione pathogen-reduced RBCs in complex cardiac surgery: the Red Cell Pathogen Inactivation (ReCePI) study-protocol for a phase 3, randomized, controlled trial.

BACKGROUND: Red blood cell (RBC) transfusion is a critical supportive therapy in cardiovascular surgery (CVS). Donor selection and testing have reduced the risk of transfusion-transmitted infections; however, risks remain from bacteria, emerging viruses, pathogens for which testing is not performed and from residual donor leukocytes. Amustaline (S-303)/glutathione (GSH) treatment pathogen reduction technology is designed to inactivate a broad spectrum of infectious agents and leukocytes in RBC concentrates. The ReCePI study is a Phase 3 clinical trial designed to evaluate the efficacy and safety of pathogen-reduced RBCs transfused for acute anemia in CVS compared to conventional RBCs, and to assess the clinical significance of treatment-emergent RBC antibodies. METHODS: ReCePI is a prospective, multicenter, randomized, double-blinded, active-controlled, parallel-design, non-inferiority study. Eligible subjects will be randomized up to 7 days before surgery to receive either leukoreduced Test (pathogen reduced) or Control (conventional) RBCs from surgery up to day 7 post-surgery. The primary efficacy endpoint is the proportion of patients transfused with at least one study transfusion with an acute kidney injury (AKI) diagnosis defined as any increased serum creatinine (sCr) level ≥ 0.3 mg/dL (or 26.5 µmol/L) from pre-surgery baseline within 48 ± 4 h of the end of surgery. The primary safety endpoints are the proportion of patients with any treatment-emergent adverse events (TEAEs) related to study RBC transfusion through 28 days, and the proportion of patients with treatment-emergent antibodies with confirmed specificity to pathogen-reduced RBCs through 75 days after the last study transfusion. With ≥ 292 evaluable, transfused patients (> 146 per arm), the study has 80% power to demonstrate non-inferiority, defined as a Test group AKI incidence increase of no more than 50% of the Control group rate, assuming a Control incidence of 30%. DISCUSSION: RBCs are transfused to prevent tissue hypoxia caused by surgery-induced bleeding and anemia. AKI is a sensitive indicator of renal hypoxia and a novel endpoint for assessing RBC efficacy. The ReCePI study is intended to demonstrate the non-inferiority of pathogen-reduced RBCs to conventional RBCs in the support of renal tissue oxygenation due to acute anemia and to characterize the incidence of treatment-related antibodies to RBCs.

Spinal cord protection for thoracoabdominal aortic aneurysm repair: from bench to bedside.

This keynote lecture and corresponding presentation discuss the anatomy and pathophysiology surrounding spinal cord injury in aortic surgery. This article will discuss risk factors and mechanisms for spinal cord injury, including loss of direct and collateral spinal cord perfusion and ischemia-reperfusion injury. This review will examine these elements in both the laboratory and clinical setting, in addition to other neuroprotective strategies applied in clinical practice. Addressing spinal cord injury requires an integrated and considerate approach to simultaneously optimize spinal cord blood flow, promote collateralization and improve ischemic tolerance. Given the catastrophic clinical consequences for both the patient and their caregivers, continuing to investigate and examine spinal cord injury is of the utmost importance.

Safety and efficacy of a kaolin-impregnated hemostatic gauze in cardiac surgery: A randomized trial.

Objective: A kaolin-based nonresorbable hemostatic gauze, QuikClot Control+, has demonstrated effective hemostasis and safety when used for severe/life-threatening (grade 3/4) internal organ space bleeding. We evaluated the efficacy and safety of this gauze for mild to moderate (grade 1-2) bleeding in cardiac surgery compared with control gauze. Methods: This was a randomized, controlled, single-blinded study of patients who underwent cardiac surgery between June 2020 and September 2021 across 7 sites with 231 subjects randomized 2:1 to QuikClot Control+ or control. The primary efficacy end point was hemostasis rate (ie, subjects achieving grade 0 bleed) through up to 10 minutes of bleeding site application, assessed using a semiquantitative validated bleeding severity scale tool. The secondary efficacy end point was the proportion of subjects achieving hemostasis at 5 and 10 minutes. Adverse events, assessed up to 30 days postsurgery, were compared between arms. Results: The predominant procedure was coronary artery bypass grafting, and 69.7% and 29.4% were sternal edge and surgical site (suture line)/other bleeds, respectively. Of the QuikClot Control+ subjects, 121 of 153 (79.1%) achieved hemostasis within 5 minutes, compared with 45 of 78 (58.4%) controls (P < .001). At 10 minutes, 137 of 153 patients (89.8%) achieved hemostasis compared with 52 of 78 controls (68.4%) (P < .001). At 5 and 10 minutes, hemostasis was achieved in 20.7% and 21.4% more QuikClot Control+ subjects, respectively, compared with controls (P < .001). There were no significant differences in safety or adverse events between treatment arms. Conclusions: QuikClot Control+ demonstrated superior performance in achieving hemostasis for mild to moderate cardiac surgery bleeding compared with control gauze. The proportion of subjects achieving hemostasis was more than 20% higher in QuikClot Control+ subjects at both timepoints compared with controls, with no significant difference in safety outcomes.

Direct and indirect activation of the adenosine triphosphate-sensitive potassium channel to induce spinal cord ischemic metabolic tolerance.

OBJECTIVES: The mitochondrial adenosine triphosphate-sensitive potassium channel is central to pharmacologically induced tolerance to spinal cord injury. We hypothesized that both direct and nitric oxide-dependent indirect activation of the adenosine triphosphate-sensitive potassium channel contribute to the induction of ischemic metabolic tolerance. METHODS: Spinal cord injury was induced in adult male C57BL/6 mice through 7 minutes of thoracic aortic crossclamping. Pretreatment consisted of intraperitoneal injection 3 consecutive days before injury. Experimental groups were sham (no pretreatment or ischemia, n = 10), spinal cord injury control (pretreatment with normal saline, n = 27), Nicorandil 1.0 mg/kg (direct and indirect adenosine triphosphate-sensitive potassium channel opener, n = 20), Nicorandil 1 mg/kg + carboxy-PTIO 1 mg/kg (nitric oxide scavenger, n = 21), carboxy-PTIO (n = 12), diazoxide 5 mg/kg (selective direct adenosine triphosphate-sensitive potassium channel opener, n = 25), and DZ 5 mg/kg+ carboxy-PTIO 1 mg/kg, carboxy-PTIO (n = 23). Limb motor function was assessed using the Basso Mouse Score (0-9) at 12-hour intervals for 48 hours after ischemia. RESULTS: Motor function was significantly preserved at all time points after ischemia in the Nicorandil pretreatment group compared with ischemic control. The addition of carboxy-PTIO partially attenuated Nicorandil's motor-preserving effect. Motor function in the Nicorandil + carboxy-PTIO group was significantly preserved compared with the spinal cord injury control group (P < .001), but worse than in the Nicorandil group (P = .078). Motor preservation in the diazoxide group was similar to the Nicorandil + carboxy-PTIO group. There was no significant difference between the diazoxide and diazoxide + carboxy-PTIO groups. CONCLUSIONS: Both direct and nitric oxide-dependent indirect activation of the mitochondrial adenosine triphosphate-sensitive potassium channel play an important role in pharmacologically induced motor function preservation.

Early results of geometric ring annuloplasty for bicuspid aortic valve repair during aortic aneurysm surgery.

Objectives: Geometric ring annuloplasty has shown promise during bicuspid aortic valve repair for aortic insufficiency. This study examined early outcomes of bicuspid aortic valve repair associated with proximal aortic aneurysm replacement. Methods: From September 2017 to November, 2021, 127 patients underwent bicuspid aortic valve repair with concomitant proximal aneurysm reconstruction. Patient age was 50.6 ± 12.7 years (mean ± standard deviation), male gender was 83%, New York Heart Association Class was 2 (1-2) (median [interquartile range]), and preoperative aortic insufficiency grade was 3 (2-4). Ascending aortic diameter was 50 (46-54) mm, and all patients had ascending aortic replacement. Forty patients had sinus diameters greater than 45 mm, prompting remodeling root procedures. A total of 105 patients had Sievers type 1 valves, 3 patients had type 0, and 7 patients had type 2. A total of 118 patients had primarily right/left fusion, 8 patients had right/nonfusion, and 1 patient had left/nonfusion. Leaflet reconstruction used central leaflet plication and cleft closure, with limited ultrasonic decalcification in 31 patients. Results: Ring size was 23 (21-23) mm, and 26 of 40 root procedures were selective nonfused sinus replacements. Aortic clamp time was 139 (112-170) minutes, and bypass time was 178 (138-217) minutes. Postrepair aortic insufficiency grade was 0 (0-0) (P < .0001), and mean valve gradient was 10 (7-14) mm Hg. No early and 1 late mortality occurred. Four patients required reoperation for bleeding, and 4 patients required pacemakers. At a mean follow-up of 20 months (maximal 93), there were no valve-related complications, 5 late repair failures prompting valve replacement, and 1 death due to Coronavirus Disease 2019. Conclusions: Geometric ring annuloplasty for bicuspid aortic valve repair with proximal aortic aneurysm reconstruction is safe and associated with good early outcomes. Further experience and follow-up will help inform long-term durability.

Evaluating the risk of spinal cord ischemia in zone 2 frozen elephant trunk replacement.

BACKGROUND: The appropriate stent length in frozen elephant trunk replacements (FET) remains debated relative to the risk for paraplegia. However, landing the distal end of the stent beyond the curve of the arch facilitates distal reintervention, which is commonly beyond the 10 cm stent coverage when deployed proximal to the left subclavian artery. The aim of this study was to evaluate outcomes following the use of 15 cm stent grafts in zone 2 (z2, distal to the left common carotid). METHODS: Using our single institution-maintained database, 103 zone 2 FET performed from 2016 to 2020 were reviewed. RESULTS: Of the 103 z2, a 15 cm stent graft was used in 51 operations. The indications for FET included acute and chronic aortic dissection, arch aneurysms, and pseudoaneurysms. The incidence of SCI was 0%. Seven deaths (13.7%) occurred. CONCLUSIONS: The data demonstrates the incidence of post-operative paraplegia to be 0% with 15 cm z2 FET. The understanding of SCI in FET should not only include the stent length but also from where it begins.

A Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial of Preoperative Antithrombin Supplementation in Patients at Risk for Antithrombin Deficiency After Cardiac Surgery.

BACKGROUND: Antithrombin (AT) activity is reduced during cardiac operations with cardiopulmonary bypass (CPB), which is associated with adverse outcomes. Preoperative AT supplementation, to achieve >58% and <100% AT activity, may potentially reduce postoperative morbidity and mortality in cardiac operations with CPB. This prospective, multicenter, randomized, double-blind, placebo-controlled study was designed to evaluate the safety and efficacy of preoperative treatment with AT supplementation in patients at risk for low AT activity after undergoing cardiac surgery with CPB. METHODS: A total of 425 adult patients were randomized (1:1) to receive either a single dose of AT (n = 213) to achieve an absolute increase of 20% above pretreatment AT activity or placebo (n = 212) before surgery. The study duration was approximately 7 weeks. The primary efficacy end point was the percentage of patients with any component of a major morbidity composite (postoperative mortality, stroke, acute kidney injury [AKI], surgical reexploration, arterial or venous thromboembolic events, prolonged mechanical ventilation, and infection) in the 2 groups. Secondary end points included AT activity, blood loss, transfusion requirements, duration of intensive care unit (ICU), and hospital stays. Safety was also assessed. RESULTS: Overall, 399 patients (men, n = 300, 75.2%) with a mean (standard deviation [SD]) age of 66.1 (11.7) years, with the majority undergoing complex surgical procedures (n = 266, 67.9%), were analyzed. No differences in the percentage of patients experiencing morbidity composite outcomes between groups were observed (AT-treated 68/198 [34.3%] versus placebo 58/194 [29.9%]; P = .332; relative risk, 1.15). After AT infusion, AT activity was significantly higher in the AT group (108% [42-143]) versus placebo group (76% [40-110]), and lasted up to postoperative day 2. At ICU, the frequency of patients with AT activity ≥58% in the AT group (81.5%) was significantly higher ( P < .001) versus placebo group (43.2%). Secondary end point analysis did not show any advantage of AT over placebo group. There were significantly more patients with AKI ( P < .001) in the AT group (23/198; 11.6%) than in the placebo group (5/194, 2.6%). Safety results showed no differences in treatment-emergent adverse events nor bleeding events between groups. CONCLUSIONS: AT supplementation did not attenuate adverse postoperative outcomes in our cohort of patients undergoing cardiac surgery with CPB.

Noteworthy Cardiac Literature From 2021: Coronary Guideline Change Without New Data, Heart Transplant Donation After Cardiac Death, Covid Effects on Global Cardiac Surgery, and Attempt to Improve Dissection Remodeling.

Cardiac surgery continues to evolve. The last year has been notable for many reasons. The guidelines for coronary revascularization introduced significant discord. The pandemic continues to affect the care on a global scale. Advances in organ procurement and dissection care move forward with better understanding and better technology.