A Pilot Study Using Machine Learning Algorithms and Wearable Technology for the Early Detection of Postoperative Complications After Cardiothoracic Surgery.

OBJECTIVE: To evaluate whether a machine learning algorithm (i.e. the "NightSignal" algorithm) can be used for the detection of postoperative complications prior to symptom onset after cardiothoracic surgery. SUMMARY BACKGROUND DATA: Methods that enable the early detection of postoperative complications after cardiothoracic surgery are needed. METHODS: This was a prospective observational cohort study conducted from July 2021 to February 2023 at a single academic tertiary care hospital. Patients aged 18 years or older scheduled to undergo cardiothoracic surgery were recruited. Study participants wore a Fitbit watch continuously for at least 1 week preoperatively and up to 90-days postoperatively. The ability of the NightSignal algorithm-which was previously developed for the early detection of Covid-19-to detect postoperative complications was evaluated. The primary outcomes were algorithm sensitivity and specificity for postoperative event detection. RESULTS: A total of 56 patients undergoing cardiothoracic surgery met inclusion criteria, of which 24 (42.9%) underwent thoracic operations and 32 (57.1%) underwent cardiac operations. The median age was 62 (IQR: 51-68) years and 30 (53.6%) patients were female. The NightSignal algorithm detected 17 of the 21 postoperative events a median of 2 (IQR: 1-3) days prior to symptom onset, representing a sensitivity of 81%. The specificity, negative predictive value, and positive predictive value of the algorithm for the detection of postoperative events were 75%, 97%, and 28%, respectively. CONCLUSIONS: Machine learning analysis of biometric data collected from wearable devices has the potential to detect postoperative complications-prior to symptom onset-after cardiothoracic surgery.

Extended ischemic time (>15 hours) using controlled hypothermic storage in lung transplantation: A multicenter experience.

Static ice storage has long been the standard-of-care for lung preservation, although freezing injury limits ischemic time (IT). Controlled hypothermic storage (CHS) at elevated temperature could safely extend IT. This retrospective analysis assesses feasibility and safety of CHS with IT > 15 hours. Three lung transplant (LuTx) centers (April-October 2023) included demographics, storage details, IT, and short-term outcome from 13 LuTx recipients (8 male, 59 years old). Donor lungs were preserved in a portable CHS device at 7 (5-9.3)°C. Indication was overnight bridging and/or long-distance transport. IT of second-implanted lung was 17.3 (15.1-22) hours. LuTx were successful, 4/13 exhibited primary graft dysfunction grade 3 within 72 hours and 0/13 at 72 hours. Post-LuTx mechanical ventilation was 29 (7-442) hours. Intensive care unit stay was 9 (5-28) and hospital stay 30 (16-90) days. Four patients needed postoperative extracorporeal membrane oxygenation (ECMO). One patient died (day 7) following malpositioning of an ECMO cannula. This multicenter experience demonstrates the possibility of safely extending IT > 15 hours by CHS.

Preemptive antiviral therapy in lung transplantation from hepatitis C donors results in a rapid and sustained virologic response.

Objective: The study objective was to assess the safety and efficacy of a preemptive direct-acting antiviral therapy in lung transplants from hepatitis C virus donors to uninfected recipients. Methods: This study is a prospective, open-label, nonrandomized, pilot trial. Recipients of hepatitis C virus nucleic acid test positive donor lungs underwent preemptive direct-acting antiviral therapy with glecaprevir 300 mg/pibrentasvir 120 mg for 8 weeks from January 1, 2019, to December 31, 2020. Recipients of nucleic acid test positive lungs were compared with recipients of lungs from nucleic acid test negative donors. Primary end points were Kaplan-Meier survival and sustained virologic response. Secondary outcomes included primary graft dysfunction, rejection, and infection. Results: Fifty-nine lung transplantations were included: 16 nucleic acid test positive and 43 nucleic acid test negative. Twelve nucleic acid test positive recipients (75%) developed hepatitis C virus viremia. Median time to clearance was 7 days. All nucleic acid test positive patients had undetectable hepatitis C virus RNA by week 3, and all alive patients (n = 15) remained negative during follow-up with 100% sustained virologic response at 12 months. One nucleic acid test positive patient died of primary graft dysfunction and multiorgan failure. Three of 43 nucleic acid test negative patients (7%) had hepatitis C virus antibody positive donors. None of them developed hepatitis C virus viremia. One-year survival was 94% for nucleic acid test positive recipients and 91% for nucleic acid test negative recipients. There was no difference in primary graft dysfunction, rejection, or infection. One-year survival for nucleic acid test positive recipients was similar to a historical cohort of the Scientific Registry of Transplant Recipients (89%). Conclusions: Recipients of hepatitis C virus nucleic acid test positive lungs have similar survival as recipients of nucleic acid test negative lungs. Preemptive direct-acting antiviral therapy results in rapid viral clearance and sustained virologic response at 12 months. Preemptive direct-acting antiviral may partially prevent hepatitis C virus transmission.

Is Transplantation With Coronavirus Disease 2019-Positive Donor Lungs Safe? A US Nationwide Analysis.

BACKGROUND: Since the beginning of the pandemic, coronavirus disease 2019 (COVID-19) has caused debilitating lung failure in many patients. Practitioners have understandably been hesitant to use lungs from donors with COVID-19 for transplantation. This study aimed to analyze the characteristics and short-term outcomes of lung transplantation from donors with recent positive COVID-19 testing results. METHODS: Lung transplantations performed between January 2020 and June 2022 were queried from the United Network for Organ Sharing database. Pediatric, multiorgan, and repeat lung transplantations were excluded. Propensity scoring matched recipients of lungs from donors with recent positive COVID-19 testing results to recipients of lungs from donors with negative COVID-19 testing results, and comparisons of 30-day mortality, 3-month mortality, and perioperative outcomes were performed. RESULTS: A total of 5270 patients underwent lung transplantation during the study dates, including 51 patients who received lungs from donors with recent positive COVID-19 testing results. Forty-five recipients of lungs from donors with recent positive COVID-19 testing results were matched with 135 recipients of lungs from donors with negative COVID-19 testing results. After matching, there was no difference in 30-day (log-rank P = .42) and 3-month (log-rank P = .42) mortality. The incidence of other perioperative complications was similar between the groups. CONCLUSIONS: The 30-day and 3-month survival outcomes were similar between recipients of lungs from donors with recent positive COVID-19 testing results and recipients of lungs from donors with negative COVID-19 testing results. This finding suggests that highly selected COVID-19-positive donors without evidence of active infection may be safely considered for lung transplantation. Further studies should explore long-term outcomes to provide reassurance about the safety of this practice.

Building a successful minimally invasive mitral valve repair program before introducing the robotic approach: The Massachusetts General Hospital experience.

Background: Patients with mitral valve prolapse (MVP) requiring surgical repair (MVr) are increasingly operated using minimally invasive strategies. Skill acquisition may be facilitated by a dedicated MVr program. We present here our institutional experience in establishing minimally invasive MVr (starting in 2014), laying the foundation to introduce robotic MVr. Methods: We reviewed all patients that had undergone MVr for MVP via sternotomy or mini-thoracotomy between January 2013 and December 2020 at our institution. In addition, all cases of robotic MVr between January 2021 and August 2022 were analyzed. Case complexity, repair techniques, and outcomes are presented for the conventional sternotomy, right mini-thoracotomy and robotic approaches. A subgroup analysis comparing only isolated MVr cases via sternotomy vs. right mini-thoracotomy was conducted using propensity score matching. Results: Between 2013 and 2020, 799 patients were operated for native MVP at our institution, of which 761 (95.2%) received planned MVr (263 [34.6%] via mini-thoracotomy) and 38 (4.8%) received planned MV replacement. With increasing proportions of minimally invasive procedures (2014: 14.8%, 2020: 46.5%), we observed a continuous growth in overall institutional volume of MVP (n = 69 in 2013; n = 127 in 2020) and markedly improved institutional rates of successful MVr, with 95.4% in 2013 vs. 99.2% in 2020. Over this period, a higher complexity of cases were treated minimally-invasively and increased use of neochord implantation ± limited leaflet resection was observed. Patients operated minimally invasively had longer aortic cross-clamp times (94 vs. 88 min, p = 0.001) but shorter ventilation times (4.4 vs. 4.8 h, p = 0.002) and hospital stays (5 vs. 6 days, p < 0.001) than those operated via sternotomy, with no significant differences in other outcome variables. A total of 16 patients underwent robotically assisted MVr with successful repair in all cases. Conclusion: A focused approach towards minimally invasive MVr has transformed the overall MVr strategy (incision; repair techniques) at our institution, leading to a growth in MVr volume and improved repair rates without significant complications. On this foundation, robotic MVr was first introduced at our institution in 2021 with excellent outcomes. This emphasizes the importance of building a competent team to perform these challenging operations, especially during the initial learning curve.

Impact of Moderate Aortic Stenosis in Patients With Heart Failure With Reduced Ejection Fraction.

BACKGROUND: Afterload from moderate aortic stenosis (AS) may contribute to adverse outcomes in patients with heart failure with reduced ejection fraction (HFrEF). OBJECTIVES: The authors evaluated clinical outcomes in patients with HFrEF and moderate AS relative to those without AS and with severe AS. METHODS: Patients with HFrEF, defined by left ventricular ejection fraction (LVEF) <50% and no, moderate, or severe AS were retrospectively identified. The primary endpoint, defined as a composite of all-cause mortality and heart failure (HF) hospitalization, was compared across groups and within a propensity score-matched cohort. RESULTS: We included 9,133 patients with HFrEF, of whom 374 and 362 had moderate and severe AS, respectively. Over a median follow-up time of 3.1 years, the primary outcome occurred in 62.7% of patients with moderate AS vs 45.9% with no AS (P < 0.0001); rates were similar with severe and moderate AS (62.0% vs 62.7%; P = 0.68). Patients with severe AS had a lower incidence of HF hospitalization (36.2% vs 43.6%; P < 0.05) and were more likely to undergo AVR within the follow-up period. Within a propensity score-matched cohort, moderate AS was associated with an increased risk of HF hospitalization and mortality (HR: 1.24; 95% CI: 1.04-1.49; P = 0.01) and fewer days alive outside of the hospital (P < 0.0001). Aortic valve replacement (AVR) was associated with improved survival (HR: 0.60; CI: 0.36-0.99; P < 0.05). CONCLUSIONS: In patients with HFrEF, moderate AS is associated with increased rates of HF hospitalization and mortality. Further investigation is warranted to determine whether AVR in this population improves clinical outcomes.

Induction therapy in lung transplantation: A contemporary analysis of trends and outcomes.

OBJECTIVES: We provide a contemporary consideration of long-term outcomes and trends of induction therapy use following lung transplantation in the United States. METHODS: We reviewed the United Network for Organ Sharing registry from 2006 to 2018 for first-time, adult, lung-only transplant recipients. Long-term survival was compared between induction classes (Interleukin-2 inhibitors, monoclonal or polyclonal cell-depleting agents, and no induction therapy). A 1:1 propensity score match was performed, pairing patients who received basiliximab with similar risk recipients who did not receive induction therapy. Outcomes in matched populations were compared using Cox, Kaplan-Meier and Logistic regression modeling. MEASUREMENTS AND MAIN RESULTS: 22 025 recipients were identified; 8003 (36.34%) were treated with no induction therapy, 11 045 (50.15%) with basiliximab, 1556 (7.06%) with alemtuzumab and 1421 (6.45%) with anti-thymocyte globulin. Compared with those who received no induction, patients receiving basiliximab, alemtuzumab or anti-thymocyte globulin were found on multivariable Cox-regression analyses to have lower long-term mortality (all p < .05). Following propensity score matching of basiliximab and no induction populations, analyses demonstrated a statistically significant association between basiliximab use and long- term survival (p < .001). Basiliximab was also associated with a lower risk of acute rejection (p < .001) and renal failure (p = .002). CONCLUSION: Induction therapy for lung transplant recipients-specifically basiliximab-is associated with improved long-term survival and a lower risk of renal failure or acute rejection.

Patient- and Process-Related Contributors to the Underuse of Aortic Valve Replacement and Subsequent Mortality in Ambulatory Patients With Severe Aortic Stenosis.

Background Many patients with severe aortic stenosis (AS) and an indication for aortic valve replacement (AVR) do not undergo treatment. The reasons for this have not been well studied in the transcatheter AVR era. We sought to determine how patient- and process-specific factors affected AVR use in patients with severe AS. Methods and Results We identified ambulatory patients from 2016 to 2018 demonstrating severe AS, defined by aortic valve area [Formula: see text]1.0 cm2. Propensity scoring analysis with inverse probability of treatment weighting was used to evaluate associations between predictors and the odds of undergoing AVR at 365 days and subsequent mortality at 730 days. Of 324 patients with an indication for AVR (79.3±9.7 years, 57.4% men), 140 patients (43.2%) did not undergo AVR. The odds of AVR were reduced in patients aged >90 years (odds ratio [OR], 0.24 [95% CI, 0.08-0.69]; P=0.01), greater comorbid conditions (OR, 0.88 per 1-point increase in Combined Comorbidity Index [95% CI, 0.79-0.97]; P=0.01), low-flow, low-gradient AS with preserved left ventricular ejection fraction (OR, 0.11 [95% CI, 0.06-0.21]), and low-gradient AS with reduced left ventricular ejection fraction (OR, 0.18 [95% CI, 0.08-0.40]) and were increased if the transthoracic echocardiogram ordering provider was a cardiologist (OR, 2.46 [95% CI, 1.38-4.38]). Patients who underwent AVR gained an average of 85.8 days of life (95% CI, 40.9-130.6) at 730 days. Conclusions The proportion of ambulatory patients with severe AS and an indication for AVR who do not receive AVR remains significant. Efforts are needed to maximize the recognition of severe AS, especially low-gradient subtypes, and to encourage patient referral to multidisciplinary heart valve teams.

Trends in Utilization of Aortic Valve Replacement for Severe Aortic Stenosis.

BACKGROUND: Despite the rapid growth of aortic valve replacement (AVR) for aortic stenosis (AS), limited data suggest symptomatic severe AS remains undertreated. OBJECTIVES: This study sought to investigate temporal trends in AVR utilization among patients with a clinical indication for AVR. METHODS: Patients with severe AS (aortic valve area <1 cm2) on transthoracic echocardiograms from 2000 to 2017 at 2 large academic medical centers were classified based on clinical guideline indications for AVR and divided into 4 AS subgroups: high gradient with normal left ventricular ejection fraction (LVEF) (HG-NEF), high gradient with low LVEF (HG-LEF), low gradient with normal LVEF (LG-NEF), and low gradient with low LVEF (LG-LEF). Utilization of AVR was examined and predictors identified. RESULTS: Of 10,795 patients, 6,150 (57%) had an indication or potential indication for AVR, of whom 2,977 (48%) received AVR. The frequency of AVR varied by AS subtype with LG groups less likely to receive an AVR (HG-NEF: 70%, HG-LEF: 53%, LG-NEF: 32%, LG-LEF: 38%, P < 0.001). AVR volumes grew over the 18-year study period but were paralleled by comparable growth in the number of patients with an indication for AVR. In patients with a Class I indication, younger age, coronary artery disease, smoking history, higher hematocrit, outpatient index transthoracic echocardiogram, and LVEF ≥0.5 were independently associated with an increased likelihood of receiving an AVR. AVR was associated with improved survival in each AS-subgroup. CONCLUSIONS: Over an 18-year period, the proportion of patients with an indication for AVR who did not receive AVR has remained substantial despite the rapid growth of AVR volumes.

Outcomes of Lung Transplantation From Hepatitis C Viremic Donors.

BACKGROUND: Direct-acting antiviral (DAA) therapy for hepatitis C virus (HCV) has encouraged lung transplantation with HCV positive donors. Early trials have been promising; however, nationwide data have not been previously examined. METHODS: The United Network for Organ Sharing registry was queried for adult patients receiving lung transplants from 2016 to 2019. We excluded multiorgan transplants, incomplete data, and loss to follow-up. Nucleic acid testing (NAT) determined HCV status. Propensity matching was performed for comparison of outcomes. RESULTS: Hepatitis C virus NAT-positive lungs were transplanted in 189 patients, compared with 9511 recipients of NAT-negative lungs. The HCV NAT-positive donors were younger (mean 33 vs 35 years, P = .017) with higher rates of Pao2/Fio2 greater than 300 (83.6% vs 76.5%, P = .029). Recipients of NAT-positive lungs had lower lung allocation scores (mean 39.3 vs 42.4, P = .009). Distance traveled was significantly further for HCV viremic donor lungs (mean 416 vs 206 miles, P < .001). Kaplan-Meier survival analysis demonstrated no difference in survival (P = .56). There were no differences in airway dehiscence (P = .629), acute rejection (P > .999), or reintubation (P = .304). At mean follow-up of 395 days, 63 recipients of NAT-positive lungs (40%) seroconverted, 14 with viremia. One-year mortality rates among seroconverted patients was 6% and did not differ significantly from 14% in nonseroconverted patients or 13.2% in recipients of HCV-negative lungs. CONCLUSIONS: Short-term outcomes of lung transplantation from HCV viremic donors are promising, with no difference in early complications or survival. The effects of seroconversion and long-term outcomes including chronic rejection and infection need to be further explored.

Rationale and Design of the Randomized Controlled Trial of New Oral Anticoagulants Versus Warfarin for Post Cardiac Surgery Atrial Fibrillation: The NEW-AF Trial.

OBJECTIVE: This manuscript describes the rationale and design of a randomized, controlled trial comparing outcomes with Warfarin vs Novel Oral Anticoagulant (NOAC) therapy in patients with new onset atrial fibrillation after cardiac surgery. BACKGROUND: New onset atrial fibrillation commonly occurs after cardiac surgery and is associated with increased rates of stroke and mortality. in nonsurgical patients with atrial fibrillation, NOACs have been shown to confer equivalent benefits for stroke prevention with less bleeding risk and less tedious monitoring requirements compared with Warfarin. However, NOAC use has yet to be adopted widely in cardiac surgery patients. METHODS: The NEW-AF study has been designed as a pragmatic, prospective, randomized controlled trial that will compare financial, convenience and safety outcomes for patients with new onset atrial fibrillation after cardiac surgery that are treated with NOACs versus Warfarin. RESULTS: Study results may contribute to optimizing the options for stroke prophylaxis in cardiac surgery patients and catalyze more widespread application of NOAC therapy in this patient population. CONCLUSIONS: The study is ongoing and actively enrolling at the time of the publication. The trial is registered with clinicaltrials.gov under registration number NCT03702582.

Association Between Hospital Cardiovascular Procedural Volumes and Transcatheter Mitral Valve Repair Outcomes.

BACKGROUND: Cardiovascular procedural volumes can serve as metrics of hospital infrastructure and quality, and are the basis for thresholds for initiating transcatheter mitral valve repair (TMVr) programs. Whether hospital volumes of TMVr, surgical mitral valve replacement or repair (SMVRr), and percutaneous coronary intervention (PCI) are indicators of TMVr quality of care is not known. METHODS: We used the 2017 Nationwide Readmissions Database to identify hospitals that performed at least 5 TMVr procedures. Hospitals were divided into quartiles of TMVr volume. Associations of hospital TMVr, SMVRr, and PCI volumes, as well as SMVRr and PCI outcomes with TMVr outcomes were examined. Outcomes studied were risk-standardized in-hospital mortality rate (RSMR) and 30-day readmission rate (RSRR). RESULTS: The study included 3404 TMVr procedures performed across 150 hospitals in the US. The median hospital TMVr volume was 17 (IQR 10, 28). The mean hospital-level RSMR and RSRR for TMVr were 3.0% (95% CI 2.5%, 3.4%) and 14.8% (95% CI 14.5%, 15.0%), respectively. There was no significant association between hospital TMVr volume (as quartiles or as a continuous variable) and TMVr RSMR or RSRR (P > 0.05). Similarly, there was weak or no correlation between hospital SMVRr and PCI volumes and outcomes with TMVr RSMR or RSRR (Pearson correlation coefficients, r = -0.199 to 0.269). CONCLUSION: In this study, we found no relationship between hospital TMVr, SMVRr, and PCI volume and TMVr outcomes. Further studies are needed to determine more appropriate structure and process measures to assess the performance of established and new TMVr centers.

Influence of left ventricular ejection fraction on morbidity and mortality after aortic root replacement.

OBJECTIVE: To better understand morbidity and mortality in patients with a low left ventricular ejection fraction (LVEF) undergoing aortic root replacement. METHODS: All patients who underwent aortic root replacement at our institution between 2005 and 2013 (n = 595) were retrospectively reviewed and included in the study. The primary outcome was mortality. Secondary outcomes were in-hospital mortality and perioperative morbidity. Restricted cubic spline analysis showed a relatively linear inverse relationship between LVEF and the hazard ratio for mortality in patients with an LVEF <50% with no unique cutoff. Therefore, LVEF was treated as a continuous variable. Patients were divided into 3 groups (LVEF <40%, LVEF 40%-49%, and LVEF ≥50%) in order to illustrate the impact of LVEF on mortality. RESULTS: LVEF <40% patients had greater in-hospital mortality (14.0% vs 5.0% vs 1.0%, P < .001) and longer median hospital and intensive care unit stays (10.5 vs 8 vs 6 days, P < .001 and 4 vs 2 vs 2 days, P < .001) than patients with LVEF 40% to 49% or greater than 50%, respectively. Patients with LVEF <40% had more reoperations for bleeding (18% vs 5.0% vs 5.8%, P = .004), postoperative respiratory failure (16% vs 6.7% vs 4.9%, P = .008), and need for mechanical circulatory support (8.0% vs 5.0% vs 1.4%, P = .005). Using multivariable Cox proportional hazards analysis, we found that reduced LVEF, age, previous, cardiac surgery, and type A dissection were independent predictors of mortality. CONCLUSIONS: Reduced LVEF negatively impacts mortality as well as in-hospital death and perioperative morbidity after aortic root replacement. Careful patient selection and risk discussion are vital in this high-risk population.