Mitochondrial Sequencing Identifies Long Non-Coding RNA Features that Promote Binding to PNPase.

Extranuclear localization of long non-coding RNAs (lncRNAs) is poorly understood. Based on machine learning evaluations, we propose a lncRNA-mitochondrial interaction pathway where Polynucleotide Phosphorylase (PNPase), through domains that provide specificity for primary sequence and secondary structure, binds nuclear-encoded lncRNAs to facilitate mitochondrial import. Using FVB/NJ mouse and human cardiac tissues, RNA from isolated subcellular compartments (cytoplasmic and mitochondrial) and crosslinked immunoprecipitate (CLIP) with PNPase within the mitochondrion were sequenced on the Illumina HiSeq and MiSeq, respectively. LncRNA sequence and structure were evaluated through supervised (Classification and Regression Trees (CART) and Support Vector Machines, (SVM)) machine learning algorithms. In HL-1 cells, qPCR of PNPase CLIP knockout mutants (KH and S1) were performed. In vitro fluorescence assays assessed PNPase RNA binding capacity and verified with PNPase CLIP. 112 (mouse) and 1,548 (human) lncRNAs were identified in the mitochondrion with Malat1 being the most highly expressed. Most non-coding RNAs binding PNPase were lncRNAs, including Malat1. LncRNA fragments bound to PNPase compared against randomly generated sequences of similar length showed stratification with SVM and CART algorithms. The lncRNAs bound to PNPase were used to create a criterion for binding, with experimental validation revealing increased binding affinity of RNA designed to bind PNPase compared to control RNA. Binding of lncRNAs to PNPase was decreased through knockout of RNA binding domains KH and S1. In conclusion, sequence and secondary structural features identified by machine learning enhance the likelihood of nuclear-encoded lncRNAs to bind to PNPase and undergo import into the mitochondrion.

Manipulation of the miR-378a/mt-ATP6 regulatory axis rescues ATP synthase in the diabetic heart and offers a novel role for lncRNA Kcnq1ot1.

Diabetes mellitus has been linked to an increase in mitochondrial microRNA-378a (miR-378a) content. Enhanced miR-378a content has been associated with a reduction in mitochondrial genome-encoded mt-ATP6 abundance, supporting the hypothesis that miR-378a inhibition may be a therapeutic option for maintaining ATP synthase functionality during diabetes mellitus. Evidence also suggests that long noncoding RNAs (lncRNAs), including lncRNA potassium voltage-gated channel subfamily Q member 1 overlapping transcript 1 (Kcnq1ot1), participate in regulatory axes with microRNAs (miRs). Prediction analyses indicate that Kcnq1ot1 has the potential to bind miR-378a. This study aimed to determine if loss of miR-378a in a genetic mouse model could ameliorate cardiac dysfunction in type 2 diabetes mellitus (T2DM) and to ascertain whether Kcnq1ot1 interacts with miR-378a to impact ATP synthase functionality by preserving mt-ATP6 levels. MiR-378a was significantly higher in patients with T2DM and 25-wk-old Db/Db mouse mitochondria, whereas mt-ATP6 and Kcnq1ot1 levels were significantly reduced when compared with controls. Twenty-five-week-old miR-378a knockout Db/Db mice displayed preserved mt-ATP6 and ATP synthase protein content, ATP synthase activity, and preserved cardiac function, implicating miR-378a as a potential therapeutic target in T2DM. Assessments following overexpression of the 500-bp Kcnq1ot1 fragment in established mouse cardiomyocyte cell line (HL-1) cardiomyocytes overexpressing miR-378a revealed that Kcnq1ot1 may bind and significantly reduce miR-378a levels, and rescue mt-ATP6 and ATP synthase protein content. Together, these data suggest that Kcnq1ot1 and miR-378a may act as constituents in an axis that regulates mt-ATP6 content, and that manipulation of this axis may provide benefit to ATP synthase functionality in type 2 diabetic heart.

Robotic Aortic Valve Replacement: First 50 Cases.

BACKGROUND: Existing management challenges in selecting transcatheter vs surgical aortic valve replacement (SAVR) include bicuspid stenosis, low clinical risk, horizontal valve position, aortic insufficiency (AI), and need for concomitant procedures or mechanical valves. To address these gaps, we present our early experience with fully robotic-assisted aortic valve replacement (RAVR). METHODS: Between January 2020 and February 2021, 50 consecutive RAVR operations were performed using a 3- to 4-cm lateral mini-thoracotomy 3-port technique with transthoracic aortic clamping, similar to our robotic mitral platform. Conventional SAVR prostheses were implanted with interrupted braided sutures in all cases. RESULTS: The 50 patients were a median age of 67.5 years, body mass index was 29 kg/m2, calcified bicuspid disease was present in 28 (56%), and severe AI in 8 (16%). Ejection fraction was 0.55 ± 0.08 (mean ± SD), and The Society of Thoracic Surgeons predicted risk of mortality was 1.54% ± 0.7%. Mechanical prostheses were used in 16 of 50 (32%), and 7 required concomitant procedures, including Cox maze in 3, aortic root enlargement in 2, and left atrial appendage clipping, mitral repair, and left atrial myxoma excision in 1 each. Median times (minutes) were 166 for cardiopulmonary bypass, 117 for cross-clamp, 4 for valvectomy, 20 for annular sutures, and 31 for aortotomy closure. All times plateaued after the initial 5 cases. Extubation occurred in 42 of 50 patients (84%) in the operating room, and within 4 hours in the remaining 8 (16%). There was no 30-day operative mortality or stroke. All had 30-day echocardiography demonstrating no valvular or perivalvular abnormalities. CONCLUSIONS: RAVR appears to have procedural safety and short-term outcomes to rival alternatives. Incremental experience may facilitate the safe performance of concomitant procedures as deemed necessary.

Robotic assisted cryothermic biatrial Cox-Maze.

INTRODUCTION: Robotic cryothermic Cox-Maze (CM) IV is a minimally invasive procedure that reliably replicates the biatrial lesion set of the CM III by utilizing cryothermia as a single power source. METHODS: Herein we describe a step by step creation of the biatrial CM III lesion sets utilizing the minimally invasive robotic platform. RESULTS: Technical details are reviewed for this single incision, single stage, highly effective option for stand-alone or concomitant surgical ablation of atrial fibrillation (AF). CONCLUSION: Robotic cryothermic CM IV can be safely performed as a stand-alone or concomitant procedure, and offers a comprehensive surgical ablation solution for patients with AF.

Association between surgical volume and clinical outcomes following coronary artery bypass grafting in contemporary practice.

BACKGROUND: Studies assessing the association between surgical volume and coronary artery bypass grafting (CABG) outcomes yielded conflicting results. Given the substantial recent decrease in CABG volume, we sough to examine the volume-outcomes effect in contemporary practice. METHODS: The National Readmission Database was queried to identify patients undergoing CABG between January 1, 2015 and December 31, 2016. Risk-adjusted in-hospital morbidity, mortality, length-of-stay, cost, and 30-day readmission were compared between low-, intermediate-, and high-volume centers. RESULTS: A total of 411 159 CABG hospitalizations at 1558 hospitals were included. Hospitals were classified into three tertiles (high > 250, intermediate 100-250, and low-volume < 100). Hospitals in the highest tertile (n = 568) performed 73.9% of all CABG operations, while those in the intermediate (n = 452), and low (n = 538) volume tertiles performed only 21.7% and 4.4% of all CABGs, respectively. The median number of CABGs performed at high-, intermediate-, and low-volume hospitals was 45 316 335, respectively. After risk adjustment, undergoing CABG at low- or intermediate- volume hospital (vs high-volume hospitals) was associated with higher in-hospital death (odd ratio [OR] = 1.31, 95% confidence interval [CI], 1.19-1.44, and OR = 1.11, 95% CI, 1.05-1.17, respectively, P < .001). Similarly, adjusted odds of stroke, acute kidney injury, and blood transfusion were higher at low- and intermediate-volume centers compared with high-volume centers. Undergoing CABG at a low-volume center was associated with 50% higher adjusted cost and 77% higher adjusted 30-day readmissions. CONCLUSIONS: In contemporary practice, in which one-third of CABG-capable hospitals perform < 100 CABG operations annually, a strong relationship is observed between surgical volume and adjusted in-hospital morbidity, mortality, cost, and 30-day readmission.

Incidence, Predictors, and Outcomes of Early Acute Myocardial Infarction Following Coronary Artery Bypass Grafting.

Large-scale data on early postdischarge acute myocardial infarction (AMI) after coronary artery bypass grafting (CABG) are lacking. We queried the National Readmission Database (2015 to 2016) to identify patients who underwent CABG between January 1 and June 31 (i.e., had 6 months of follow-up). The study's end points were the incidence, predictors, and outcomes of early post-CABG AMI. Of the 203,760 included patients, 3,829 (1.8%) were readmitted for AMI. Compared with patients without readmissions for AMI, those with AMI were younger (65 ± 11 vs 66 ± 10 years), had more females (35.5% vs 25.1%), and higher prevalence of hypertension, diabetes, obstructive lung disease, anemia, vascular disease, renal insufficiency, and liver cirrhosis, but less atrial fibrillation (p <0.001). They also had a distinctive profile of their index CABG surgery. The strongest predictors of post-CABG AMI readmission were female gender (odds ratio [OR] 1.46, 95% confidence interval [CI] = 1.36 to 1.57), heart failure (OR 1.37, 95% CI = 1.27 to 1.50), dialysis (OR 1.5%, 95% CI = 1.25 to 1.78), cirrhosis (OR 1.61, 95% CI = 1.14 to 2.27), nonelective CABG (OR 1.70, 95% CI = 1.57 to 1.84), perioperative mechanical circulatory support (OR 1.37, 95% CI = 1.23 to 1.51), low-volume centers (OR 1.36, 95% CI = 1.18 to 1.56), and nonhome discharge after CABG (OR 1.47, 95% CI = 1.35 to 1.59). In the patients who were readmitted for AMI, 86.3% had non-ST-elevation AMI and 13.7% had ST-elevation AMI. Coronary angiography was performed in 2,096 patients (54.7%). Of those, 63.5% received percutaneous coronary intervention, and 1.7% had redo-CABG. Readmissions for AMI were associated with significant in-hospital mortality (5.7%), acute kidney injury (22.1%), and new dialysis (2.1%). Median length-of-stay was 3 days (25th/75th percentile 2,6), and the mean hospital cost was $22,207 ± 29,071.

Machine-learning to stratify diabetic patients using novel cardiac biomarkers and integrative genomics.

BACKGROUND: Diabetes mellitus is a chronic disease that impacts an increasing percentage of people each year. Among its comorbidities, diabetics are two to four times more likely to develop cardiovascular diseases. While HbA1c remains the primary diagnostic for diabetics, its ability to predict long-term, health outcomes across diverse demographics, ethnic groups, and at a personalized level are limited. The purpose of this study was to provide a model for precision medicine through the implementation of machine-learning algorithms using multiple cardiac biomarkers as a means for predicting diabetes mellitus development. METHODS: Right atrial appendages from 50 patients, 30 non-diabetic and 20 type 2 diabetic, were procured from the WVU Ruby Memorial Hospital. Machine-learning was applied to physiological, biochemical, and sequencing data for each patient. Supervised learning implementing SHapley Additive exPlanations (SHAP) allowed binary (no diabetes or type 2 diabetes) and multiple classification (no diabetes, prediabetes, and type 2 diabetes) of the patient cohort with and without the inclusion of HbA1c levels. Findings were validated through Logistic Regression (LR), Linear Discriminant Analysis (LDA), Gaussian Naïve Bayes (NB), Support Vector Machine (SVM), and Classification and Regression Tree (CART) models with tenfold cross validation. RESULTS: Total nuclear methylation and hydroxymethylation were highly correlated to diabetic status, with nuclear methylation and mitochondrial electron transport chain (ETC) activities achieving superior testing accuracies in the predictive model (~ 84% testing, binary). Mitochondrial DNA SNPs found in the D-Loop region (SNP-73G, -16126C, and -16362C) were highly associated with diabetes mellitus. The CpG island of transcription factor A, mitochondrial (TFAM) revealed CpG24 (chr10:58385262, P = 0.003) and CpG29 (chr10:58385324, P = 0.001) as markers correlating with diabetic progression. When combining the most predictive factors from each set, total nuclear methylation and CpG24 methylation were the best diagnostic measures in both binary and multiple classification sets. CONCLUSIONS: Using machine-learning, we were able to identify novel as well as the most relevant biomarkers associated with type 2 diabetes mellitus by integrating physiological, biochemical, and sequencing datasets. Ultimately, this approach may be used as a guideline for future investigations into disease pathogenesis and novel biomarker discovery.

Contemporary trends and outcomes of mitral valve surgery for infective endocarditis.

BACKGROUND: Contemporary data on mitral valve (MV) surgery in patients with infective endocarditis (IE) are limited. METHODS: The National Inpatient Sample was queried to identify patients with IE who underwent MV surgery between 2003 and 2016. We assessed (a) temporal trends in the incidence of MV surgery for IE, (b) morbidity, mortality, and cost of MV repair vs replacement, and (c) predictors of in-hospital mortality. RESULTS: The proportion of MV operations involving patients with IE increased from 5.4% in 2003 to 7.3%, and the proportion of MV repair among those undergoing surgery for IE increased from 15.2% to 25.0% (Ptrend < .001). In-hospital mortality was higher in the replacement group (11.3% vs 8.1%; P < .001), and this excess mortality persisted after propensity score matching (11.2% vs 8.1%; P < .001), and in sensitivity analyses excluding concomitant surgery (unadjusted 11.3% vs 4.8%; adjusted 8.5% vs 4.5%; P < .001), and stratifying patients by the time of operation (within 7 days, 11.3% vs 6.8%; P < .001 and >7 days, 11.9% vs 9.1%; P = .012). In the propensity-matched cohorts, shock and need for tracheostomy were more frequent in the replacement group, but rates of stroke, pacemaker implantation, new dialysis, and blood transfusion were similar. Mitral valve repair was, however, associated with shorter hospitalizations, more home discharges, and less cost. In a multivariate regression analysis, age above 70 and chronic dialysis were the strongest predictors of in-hospital mortality. CONCLUSION: Mitral valve repair in IE patients is associated with lower in-hospital mortality, resource utilization, and cost compared with MV replacement.

Surgical Techniques for Mitral Valve Repair: A Pathoanatomic Grading System.

Mitral valve surgery has evolved over 4 decades from one based on the principles of prosthetic replacement to a subspecialty with a foundation based on the principles of repair. This review will attempt to enumerate the contemporary techniques of mitral valve repair and a pathoanatomically directed approach with which to apply them by focusing on degenerative disease and associated complexities.

Robotic mitral valve operations by experienced surgeons are cost-neutral and durable at 1 year.

BACKGROUND: Robotic mitral valve surgery has potential advantages in patient satisfaction and 30-day outcome. Cost concerns and repair durability limit wider adoption of robotic technology. This study examined detailed cost differences between robotic and sternotomy techniques in relation to outcomes and durability following robotic mitral program initiation. METHODS: Between April 2013 and October 2015, 30-day and 1-year outcomes of 328 consecutive patients undergoing robotic or sternotomy mitral valve repair or replacement by experienced surgeons were examined. Multivariable logistic regression informed propensity matching to derive a cohort of 182 patients. Echocardiographic follow-up was completed at 1 year in all robotic patients. Detailed activity-based cost accounting was applied to include direct, semidirect, and indirect costs with special respect to robotic depreciation, maintenance, and supplies. A quantitative analysis of all hospital costs was applied directly to each patient encounter for comparative financial analyses. RESULTS: Mean predicted risk of mortality was similar in both the robotic (n = 91) and sternotomy (n = 91) groups (0.9% vs 0.8%; P > .431). The total costs of robotic mitral operations were similar to those of sternotomy ($27,662 vs $28,241; P = .273). Early direct costs were higher in the robotic group. There was a marked increase in late indirect cost with the sternotomy cohort related to increased length of stay, transfusion requirements, and readmission rates. Robotic repair technique was associated with no echocardiographic recurrence greater than trace to only mild regurgitation at 1 year. CONCLUSIONS: Experienced mitral surgeons can initiate a robotic program in a cost-neutral manner that maintains clinical outcome integrity as well as repair durability.

Meta-analysis Comparing Transcatheter and Surgical Treatments of Paravalvular Leaks.

Percutaneous paravalvular leak (PVL) closure has emerged as a feasible alternative to redo valve surgery. However, comparative data on percutaneous and surgical treatment of PVL are scarce. We performed a systematic review and a meta-analysis of studies on percutaneous and surgical treatments of PVL. Of the 2,267 studies screened, 22 eligible studies were analyzed. Primary end points were technical success, 30-day mortality, stroke, and length of stay. Secondary end points were 1-year mortality, readmission for heart failure, reoperation, and symptomatic improvement at follow-up. A total of 2,373 patients were included, of whom 1,511 (63.7%) underwent percutaneous closure. Technical success was higher with surgery (96.7% vs 72.1%, odds ratio [OR] 9.7, p <0.001) but at the cost of higher 30-day mortality (8.6% vs 6.8%, OR 1.90, p <0.001), a trend toward higher stroke (3.3% vs 1.4%, OR 1.94, p = 0.069), and longer hospitalizations. However, surgery was associated with similar 1-year mortality (17.3% vs 17.2%, OR 1.07, p = 0.67), reoperation (9.1% vs 9.9%, OR 0.72, p = 0.1), readmission for heart failure (13.3% vs 26.4%, OR 0.51, p = 0.29), and improvement in New York Heart Association classification (67.4% vs 56%, OR 1.37, p = 0.74), compared with percutaneous closure. A sensitivity analysis including comparative studies only yielded similar results. Surgical treatment of PVL achieves higher technical success rates but is associated with higher early morbidity and mortality compared with percutaneous closure. Nevertheless, mortality rates and clinical efficacy parameters were similar at midterm with both procedures. Further studies are warranted to identify the ideal management approach to patients with symptomatic PVL.

Aortic clamping strategy and postoperative stroke.

OBJECTIVE: The effect of aortic clamping strategy on short-term stroke during proximal graft construction for coronary artery bypass grafting (CABG) remains undefined. The aim of this study was to test the hypothesis that partial occluding clamp (POC) technique does not increase incidence of postoperative stroke compared with single clamp (SC) technique for performing proximal coronary anastomoses. METHODS: We identified 52,611 patients who underwent on-pump CABG in the Society of Thoracic Surgeons Adult Cardiac Surgery Database from July 1, 2014 to March 31, 2015. Propensity scores for POC were calculated on the basis of validated Society of Thoracic Surgeons predicted risk of postoperative stroke scores and used to adjust for intergroup differences to derive 17,819 matched pairs for analysis. RESULTS: Despite a similar number of total bypass grafts between matched SC versus POC groups, myocardial ischemic times were shorter (74.1 ± 29.2 minutes vs 57.0 ± 23.3 minutes; P < .0001) as were cardiopulmonary bypass times (95.0 ± 35.0 minutes vs 89.7 ± 34.4 minutes; P < .0001) for the POC group. Postoperative stroke rates were similar between SC versus POC (0.9% vs 1.1%; risk ratio, 1.1; 95% confidence interval, 0.9-1.4; P = .3) as were mortality rates (1.3% vs 1.3%; risk ratio, 1.0; 95% confidence interval, 0.8-1.2; P = .9). CONCLUSIONS: Aortic clamping strategy for constructing proximal anastomoses in CABG procedures does not affect short-term incidence of postoperative stroke or mortality. The use of POC incurred shorter myocardial ischemic and perfusion times compared with the SC technique with similar total number of bypass grafts.