Multiomics of Tissue Extracellular Vesicles Identifies Unique Modulators of Atherosclerosis and Calcific Aortic Valve Stenosis.

BACKGROUND: Fewer than 50% of patients who develop aortic valve calcification have concomitant atherosclerosis, implying differential pathogenesis. Although circulating extracellular vesicles (EVs) act as biomarkers of cardiovascular diseases, tissue-entrapped EVs are associated with early mineralization, but their cargoes, functions, and contributions to disease remain unknown. METHODS: Disease stage-specific proteomics was performed on human carotid endarterectomy specimens (n=16) and stenotic aortic valves (n=18). Tissue EVs were isolated from human carotid arteries (normal, n=6; diseased, n=4) and aortic valves (normal, n=6; diseased, n=4) by enzymatic digestion, (ultra)centrifugation, and a 15-fraction density gradient validated by proteomics, CD63-immunogold electron microscopy, and nanoparticle tracking analysis. Vesiculomics, comprising vesicular proteomics and small RNA-sequencing, was conducted on tissue EVs. TargetScan identified microRNA targets. Pathway network analyses prioritized genes for validation in primary human carotid artery smooth muscle cells and aortic valvular interstitial cells. RESULTS: Disease progression drove significant convergence (P<0.0001) of carotid artery plaque and calcified aortic valve proteomes (2318 proteins). Each tissue also retained a unique subset of differentially enriched proteins (381 in plaques; 226 in valves; q<0.05). Vesicular gene ontology terms increased 2.9-fold (P<0.0001) among proteins modulated by disease in both tissues. Proteomics identified 22 EV markers in tissue digest fractions. Networks of proteins and microRNA targets changed by disease progression in both artery and valve EVs revealed shared involvement in intracellular signaling and cell cycle regulation. Vesiculomics identified 773 proteins and 80 microRNAs differentially enriched by disease exclusively in artery or valve EVs (q<0.05); multiomics integration found tissue-specific EV cargoes associated with procalcific Notch and Wnt signaling in carotid arteries and aortic valves, respectively. Knockdown of tissue-specific EV-derived molecules FGFR2, PPP2CA, and ADAM17 in human carotid artery smooth muscle cells and WNT5A, APP, and APC in human aortic valvular interstitial cells significantly modulated calcification. CONCLUSIONS: The first comparative proteomics study of human carotid artery plaques and calcified aortic valves identifies unique drivers of atherosclerosis versus aortic valve stenosis and implicates EVs in advanced cardiovascular calcification. We delineate a vesiculomics strategy to isolate, purify, and study protein and RNA cargoes from EVs entrapped in fibrocalcific tissues. Integration of vesicular proteomics and transcriptomics by network approaches revealed novel roles for tissue EVs in modulating cardiovascular disease.

Patient-, Clinician-, and Institution-level Variation in Inotrope Use for Cardiac Surgery: A Multicenter Observational Analysis.

BACKGROUND: Conflicting evidence exists regarding the risks and benefits of inotropic therapies during cardiac surgery, and the extent of variation in clinical practice remains understudied. Therefore, the authors sought to quantify patient-, anesthesiologist-, and hospital-related contributions to variation in inotrope use. METHODS: In this observational study, nonemergent adult cardiac surgeries using cardiopulmonary bypass were reviewed across a multicenter cohort of academic and community hospitals from 2014 to 2019. Patients who were moribund, receiving mechanical circulatory support, or receiving preoperative or home inotropes were excluded. The primary outcome was an inotrope infusion (epinephrine, dobutamine, milrinone, dopamine) administered for greater than 60 consecutive min intraoperatively or ongoing upon transport from the operating room. Institution-, clinician-, and patient-level variance components were studied. RESULTS: Among 51,085 cases across 611 attending anesthesiologists and 29 hospitals, 27,033 (52.9%) cases received at least one intraoperative inotrope, including 21,796 (42.7%) epinephrine, 6,360 (12.4%) milrinone, 2,000 (3.9%) dobutamine, and 602 (1.2%) dopamine (non-mutually exclusive). Variation in inotrope use was 22.6% attributable to the institution, 6.8% attributable to the primary attending anesthesiologist, and 70.6% attributable to the patient. The adjusted median odds ratio for the same patient receiving inotropes was 1.73 between 2 randomly selected clinicians and 3.55 between 2 randomly selected institutions. Factors most strongly associated with increased likelihood of inotrope use were institutional medical school affiliation (adjusted odds ratio, 6.2; 95% CI, 1.39 to 27.8), heart failure (adjusted odds ratio, 2.60; 95% CI, 2.46 to 2.76), pulmonary circulation disorder (adjusted odds ratio, 1.72; 95% CI, 1.58 to 1.87), loop diuretic home medication (adjusted odds ratio, 1.55; 95% CI, 1.42 to 1.69), Black race (adjusted odds ratio, 1.49; 95% CI, 1.32 to 1.68), and digoxin home medication (adjusted odds ratio, 1.48; 95% CI, 1.18 to 1.86). CONCLUSIONS: Variation in inotrope use during cardiac surgery is attributable to the institution and to the clinician, in addition to the patient. Variation across institutions and clinicians suggests a need for future quantitative and qualitative research to understand variation in inotrope use affecting outcomes and develop evidence-based, patient-centered inotrope therapies.

Preoperative Tricuspid Regurgitation Is Associated With Long-Term Mortality and Is Graded More Severe Than Intraoperative Tricuspid Regurgitation.

OBJECTIVES: To determine whether preoperative (preop) tricuspid regurgitation (TR) severity grade was associated with postoperative mortality, to examine the correlation between pre-op and intraoperative (intraop) TR grades, and to understand which TR grade had better prognostic predictability in cardiac surgery patients. DESIGN: Retrospective. SETTING: Single institution. PARTICIPANTS: Patients. INTERVENTIONS: Preop and intraop echocardiography TR grades of 4,232 patients who had undergone cardiac surgeries between 2004 and 2014 were examined. MEASUREMENTS AND MAIN RESULTS: Kaplan-Meier curves and Cox proportional hazard models were used to determine the association between TR grades and the primary endpoint of all-cause mortality. The Wilcoxon signed-rank test and Spearman's rank correlation were analyzed to assess the similarity and correlation between preop and intraop-grade pairs. Multivariate logistic regression models of the area under the curve characteristics were compared for prognostic implications. Kaplan-Meier curves demonstrated a strong relationship between preop grades and survival. Multivariate models showed significantly increased mortality starting at mild preop TR (mild TR: hazard ratio [HR] 1.24; 95% CI 1.05-1.46, p = 0.013; moderate TR: HR 1.60; 95% CI 1.05-1.97, p < 0.001; severe TR: HR 2.50; 95% CI 1.74-3.58, p < 0.001). Preop TR grades were mostly higher than intraop grades. Spearman's correlation was 0.55 (p < 0.001). The area under the curves of preop and intraop TR-based models were almost identical (0.704 v 0.702 1-year mortality and 0.704 v 0.700 2-year mortality). CONCLUSIONS: The authors found that echocardiographically-determined preop TR grade at the time of surgical planning was associated with long-term mortality, starting even at a mild grade. Preop grades were higher than intraop grades, with a moderate correlation. Preop and intraop grades exhibited similar prognostic implications.

Genome-wide association study reveals novel genetic loci: a new polygenic risk score for mitral valve prolapse.

AIMS: Mitral valve prolapse (MVP) is a common valvular heart disease with a prevalence of >2% in the general adult population. Despite this high incidence, there is a limited understanding of the molecular mechanism of this disease, and no medical therapy is available for this disease. We aimed to elucidate the genetic basis of MVP in order to better understand this complex disorder. METHODS AND RESULTS: We performed a meta-analysis of six genome-wide association studies that included 4884 cases and 434 649 controls. We identified 14 loci associated with MVP in our primary analysis and 2 additional loci associated with a subset of the samples that additionally underwent mitral valve surgery. Integration of epigenetic, transcriptional, and proteomic data identified candidate MVP genes including LMCD1, SPTBN1, LTBP2, TGFB2, NMB, and ALPK3. We created a polygenic risk score (PRS) for MVP and showed an improved MVP risk prediction beyond age, sex, and clinical risk factors. CONCLUSION: We identified 14 genetic loci that are associated with MVP. Multiple analyses identified candidate genes including two transforming growth factor-ß signalling molecules and spectrin ß. We present the first PRS for MVP that could eventually aid risk stratification of patients for MVP screening in a clinical setting. These findings advance our understanding of this common valvular heart disease and may reveal novel therapeutic targets for intervention.

Sex Differences in In-Hospital Mortality After Open Cardiac Valve Surgery.

BACKGROUND: Cardiac valvular disease affects millions of people worldwide and is a major cause of morbidity and mortality. Female patients have been shown to experience inferior clinical outcomes after nonvalvular cardiac surgery, but recent data are limited regarding open valve surgical cohorts. The primary objective of our study was to assess whether female sex is associated with increased in-hospital mortality after open cardiac valve operations. METHODS: Utilizing the Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases (SID), we conducted a retrospective cohort study of patients who underwent open cardiac valve surgery from 2007 to 2018 in Washington, Maryland, Kentucky, and Florida; from 2007 to 2011 in California; and from 2007 to 2016 in New York. The primary objective of this study was to estimate the confounder-adjusted association between sex and in-hospital mortality (as recorded and coded by SID HCUP) after open cardiac valve surgery. We used multilevel multivariable models to account for potential confounders, including intrahospital practice patterns. RESULTS: A total of 272,954 patients (108,443 women; 39.73% of sample population with mean age of 67.6 ± 14.3 years) were included in our analysis. The overall mortality rates were 3.8% for male patients and 5.1% for female patients. The confounder-adjusted odds ratio (OR) for in-hospital mortality for female patients compared to male patients was 1.41 (95% confidence interval [CI], 1.35-1.47; P < .001). When stratifying by surgical type, female patients were also at increased odds of in-hospital mortality ( P < .001) in populations undergoing aortic valve replacement (adjusted OR [aOR], 1.38; 95% CI, 1.25-1.52); multiple valve surgery (aOR, 1.38; 95% CI, 1.22-1.57); mitral valve replacement (aOR, 1.22; 95% CI, 1.12 - 1.34); and valve surgery with coronary artery bypass grafting (aOR, 1.64; 95% CI, 1.54 - 1.74; all P < .001). Female patients did not have increased odds of in-hospital mortality in populations undergoing mitral valve repair (aOR, 1.26; 95% CI, 0.98 - 1.64; P = .075); aortic valve repair (aOR, 0.87; 95% CI, 0.67 - 1.14; P = .32); or any other single valve repair (aOR, 1.10; 95% CI, 0.82 - 1.46; P = .53). CONCLUSIONS: We found an association between female patients and increased confounder-adjusted odds of in-hospital mortality after open cardiac valve surgery. More research is needed to better understand and categorize these important outcome differences. Future research should include observational analysis containing granular and complete patient- and surgery-specific data.

Inconsistent Methodology as a Barrier to Meaningful Research Outputs From Studies of Atrial Fibrillation After Cardiac Surgery.

Atrial fibrillation after cardiac surgery (AFACS) is a serious postoperative complication. There is significant research interest in this field but also relevant heterogeneity in reported AFACS definitions and approaches used for its identification. Few data exist on the extent of this variation in clinical studies. The authors reviewed the literature since 2001 and included manuscripts reporting outcomes of AFACS in adults. They excluded smaller studies and studies in which patients did not undergo a sternotomy. The documented protocol in each manuscript was analyzed according to six different categories to determine how AFACS was defined, which techniques were used to identify it, and the inclusion and/or exclusion criteria. They also noted when a category was not described in the documented protocol. The authors identified 302 studies, of which 92 were included. Sixty-two percent of studies were randomized controlled trials. There was significant heterogeneity in the manuscripts, including the exclusion of patients with preoperative AF, the definition and duration of AF needed to meet the primary endpoint, the type of screening approach (continuous, episodic, or opportunistic), the duration of monitoring during the study period in days, the diagnosis with predefined electrocardiogram criteria, and the requirement for independent confirmation by study investigators. Furthermore, the definitions of these criteria frequently were not described. Consistent reporting standards for AFACS research are needed to advance scientific progress in the field. The authors here propose pragmatic standards for trial design and reporting standards. These include adequate sample size estimation, a clear definition of the AFACS endpoints, and a protocol for AFACS detection.

Association of Factor V Leiden With Subsequent Atherothrombotic Events: A GENIUS-CHD Study of Individual Participant Data.

BACKGROUND: Studies examining the role of factor V Leiden among patients at higher risk of atherothrombotic events, such as those with established coronary heart disease (CHD), are lacking. Given that coagulation is involved in the thrombus formation stage on atherosclerotic plaque rupture, we hypothesized that factor V Leiden may be a stronger risk factor for atherothrombotic events in patients with established CHD. METHODS: We performed an individual-level meta-analysis including 25 prospective studies (18 cohorts, 3 case-cohorts, 4 randomized trials) from the GENIUS-CHD (Genetics of Subsequent Coronary Heart Disease) consortium involving patients with established CHD at baseline. Participating studies genotyped factor V Leiden status and shared risk estimates for the outcomes of interest using a centrally developed statistical code with harmonized definitions across studies. Cox proportional hazards regression models were used to obtain age- and sex-adjusted estimates. The obtained estimates were pooled using fixed-effect meta-analysis. The primary outcome was composite of myocardial infarction and CHD death. Secondary outcomes included any stroke, ischemic stroke, coronary revascularization, cardiovascular mortality, and all-cause mortality. RESULTS: The studies included 69 681 individuals of whom 3190 (4.6%) were either heterozygous or homozygous (n=47) carriers of factor V Leiden. Median follow-up per study ranged from 1.0 to 10.6 years. A total of 20 studies with 61 147 participants and 6849 events contributed to analyses of the primary outcome. Factor V Leiden was not associated with the combined outcome of myocardial infarction and CHD death (hazard ratio, 1.03 [95% CI, 0.92-1.16]; I2=28%; P-heterogeneity=0.12). Subgroup analysis according to baseline characteristics or strata of traditional cardiovascular risk factors did not show relevant differences. Similarly, risk estimates for the secondary outcomes including stroke, coronary revascularization, cardiovascular mortality, and all-cause mortality were also close to identity. CONCLUSIONS: Factor V Leiden was not associated with increased risk of subsequent atherothrombotic events and mortality in high-risk participants with established and treated CHD. Routine assessment of factor V Leiden status is unlikely to improve atherothrombotic events risk stratification in this population.

Sex differences in gene expression in response to ischemia in the human left ventricular myocardium.

Sex differences exist in the prevalence, presentation and outcomes of ischemic heart disease (IHD). Females have higher risk of heart failure post-myocardial infarction relative to males and are two to three times more likely to die after coronary artery bypass grafting surgery. We examined sex differences in human myocardial gene expression in response to ischemia. Left ventricular biopsies from 68 male/46 female patients undergoing aortic valve replacement surgery were obtained at baseline and after a median 74 min of cold cardioplegic arrest/ischemia. Transcriptomes were quantified by RNA-sequencing. Cell-type enrichment analysis was used to estimate the identity and relative proportions of different cell types in each sample. A sex-specific response to ischemia was observed for 271 genes. Notably, the expression FAM5C, PLA2G4E and CYP1A1 showed an increased expression in females compared to males due to ischemia and DIO3, MT1G and CMA1 showed a decreased expression in females compared to males due to ischemia. Functional annotation analysis revealed sex-specific modulation of the oxytocin signaling pathway and common pathway of fibrin clot formation. Expression quantitative trait locus (eQTL) analysis identified variant-by-sex interaction eQTLs, indicative of sex differences in the genotypic effects on gene expression. Cell-type enrichment analysis showed sex-bias in proportion of specific cell types. Common lymphoid progenitor cells and M2 macrophages were found to increase in female samples from pre- to post-ischemia, but no change was observed in male samples. These differences in response to myocardial ischemia provide insight into the sexual dimorphism of IHD and may aid in the development of sex-specific therapies that reduce myocardial injury.

Retinoids Repress Human Cardiovascular Cell Calcification With Evidence for Distinct Selective Retinoid Modulator Effects.

OBJECTIVE: Retinoic acid (RA) is a ligand for nuclear receptors that modulate gene transcription and cell differentiation. Whether RA controls ectopic calcification in humans is unknown. We tested the hypothesis that RA regulates osteogenic differentiation of human arterial smooth muscle cells and aortic valvular interstitial cells that participate in atherosclerosis and heart valve disease, respectively. Approach and Results: Human cardiovascular tissue contains immunoreactive RAR (RA receptor)-a retinoid-activated nuclear receptor directing multiple transcriptional programs. RA stimulation suppressed primary human cardiovascular cell calcification while treatment with the RAR inhibitor AGN 193109 or RARα siRNA increased calcification. RA attenuated calcification in a coordinated manner, increasing levels of the calcification inhibitor MGP (matrix Gla protein) while decreasing calcification-promoting TNAP (tissue nonspecific alkaline phosphatase) activity. Given that nuclear receptor action varies as a function of distinct ligand structures, we compared calcification responses to cyclic retinoids and the acyclic retinoid peretinoin. Peretinoin suppressed human cardiovascular cell calcification without inducing either secretion of APOC3 (apolipoprotein-CIII), which promotes atherogenesis, or reducing CYP7A1 (cytochrome P450 family 7 subfamily A member 1) expression, which occurred with cyclic retinoids all-trans RA, 9-cis RA, and 13-cis RA. Additionally, peretinoin did not suppress human femur osteoblast mineralization, whereas all-trans RA inhibited osteoblast mineralization. CONCLUSIONS: These results establish retinoid regulation of human cardiovascular calcification, provide new insight into mechanisms involved in these responses, and suggest selective retinoid modulators, like acyclic retinoids may allow for treating cardiovascular calcification without the adverse effects associated with cyclic retinoids.

Nanoscale Technologies for Prevention and Treatment of Heart Failure: Challenges and Opportunities.

The adult myocardium has a limited regenerative capacity following heart injury, and the lost cells are primarily replaced by fibrotic scar tissue. Suboptimal efficiency of current clinical therapies to resurrect the infarcted heart results in injured heart enlargement and remodeling to maintain its physiological functions. These remodeling processes ultimately leads to ischemic cardiomyopathy and heart failure (HF). Recent therapeutic approaches (e.g., regenerative and nanomedicine) have shown promise to prevent HF postmyocardial infarction in animal models. However, these preclinical, clinical, and technological advancements have yet to yield substantial enhancements in the survival rate and quality of life of patients with severe ischemic injuries. This could be attributed largely to the considerable gap in knowledge between clinicians and nanobioengineers. Development of highly effective cardiac regenerative therapies requires connecting and coordinating multiple fields, including cardiology, cellular and molecular biology, biochemistry and chemistry, and mechanical and materials sciences, among others. This review is particularly intended to bridge the knowledge gap between cardiologists and regenerative nanomedicine experts. Establishing this multidisciplinary knowledge base may help pave the way for developing novel, safer, and more effective approaches that will enable the medical community to reduce morbidity and mortality in HF patients.

Novel and Annotated Long Noncoding RNAs Associated with Ischemia in the Human Heart.

BACKGROUND: Long noncoding RNAs (lncRNAs) have been implicated in the pathogenesis of cardiovascular diseases. We aimed to identify novel lncRNAs associated with the early response to ischemia in the heart. METHODS AND RESULTS: RNA sequencing data gathered from 81 paired left ventricle samples from patients undergoing cardiopulmonary bypass was collected before and after a period of ischemia. Novel lncRNAs were validated with Oxford Nanopore Technologies long-read sequencing. Gene modules associated with an early ischemic response were identified and the subcellular location of selected lncRNAs was determined with RNAscope. A total of 2446 mRNAs, 270 annotated lncRNAs and one novel lncRNA differed in response to ischemia (adjusted p < 0.001, absolute fold change >1.2). The novel lncRNA belonged to a gene module of highly correlated genes that also included 39 annotated lncRNAs. This module associated with ischemia (Pearson correlation coefficient = -0.69, p = 1 × 10-23) and activation of cell death pathways (p < 6 × 10-9). A further nine novel cardiac lncRNAs were identified, of which, one overlapped five cis-eQTL eSNPs for the gene RWD Domain-Containing Sumoylation Enhancer (RWDD3) and was itself correlated with RWDD3 expression (Pearson correlation coefficient -0.2, p = 0.002). CONCLUSION: We have identified 10 novel lncRNAs, one of which was associated with myocardial ischemia and may have potential as a novel therapeutic target or early marker for myocardial dysfunction.

Joint analysis of left ventricular expression and circulating plasma levels of Omentin after myocardial ischemia.

BACKGROUND: Omentin-1, also known as Intelectin-1 (ITLN1), is an adipokine with plasma levels associated with diabetes, obesity, and coronary artery disease. Recent studies suggest that ITLN1 can mitigate myocardial ischemic injury but the expression of ITLN1 in the heart itself has not been well characterized. The purpose of this study is to discern the relationship between the expression pattern of ITLN1 RNA in the human heart and the level of circulating ITLN1 protein in plasma from the same patients following myocardial ischemia. METHODS: A large cohort of patients (n = 140) undergoing elective cardiac surgery for aortic valve replacement were enrolled in this study. Plasma and left ventricular biopsy samples were taken at the beginning of cardiopulmonary bypass and after an average of 82 min of ischemic cross clamp time. The localization of ITLN1 in epicardial adipose tissue (EAT) was also further characterized with immunoassays and cell fate transition studies. RESULTS: mRNA expression of ITLN1 decreases in left ventricular tissue after acute ischemia in human patients (mean difference 280.48, p = 0.001) whereas plasma protein levels of ITLN1 increase (mean difference 5.24, p < 0.001). Immunohistochemistry localized ITLN1 to the mesothelium or visceral pericardium of EAT. Epithelial to mesenchymal transition in mesothelial cells leads to a downregulation of ITLN1 expression. CONCLUSIONS: Myocardial injury leads to a decrease in ITLN1 expression in the heart and a corresponding increase in plasma levels. These changes may in part be due to an epithelial to mesenchymal transition of the cells that express ITLN1 following ischemia. Trial Registration Clinicaltrials.gov ID: NCT00985049.

Length Polymorphisms in Heme Oxygenase-1 and AKI after Cardiac Surgery.

Heme oxygenase-1 (HO-1) catalyzes the degradation of heme, which may be involved in the pathogenesis of AKI. Length polymorphisms in the number of GT dinucleotide repeats in the HO-1 gene (HMOX1) promoter inversely associate with HMOX1 mRNA expression. We analyzed the association between allelic frequencies of GT repeats in the HMOX1 gene promoter and postoperative AKI in 2377 white patients who underwent cardiac surgery with cardiopulmonary bypass. We categorized patients as having the short allele (S; <27 GT repeats) or long allele (L; ≥27 GT repeats), and defined AKI as an increase in serum creatinine ≥0.3 mg/dl within 48 hours or ≥50% within 5 days, or the need for RRT. Compared with patients with the SS genotype, patients with the LL genotype had 1.58-fold (95% confidence interval, 1.06 to 2.34; P=0.02) higher odds of AKI. After adjusting for baseline and operative characteristics, the odds ratio for AKI per L allele was 1.26 (95% confidence interval, 1.05 to 1.50; P=0.01). In conclusion, longer GT repeats in the HMOX1 gene promoter associate with increased risk of AKI after cardiac surgery, consistent with heme toxicity as a pathogenic feature of cardiac surgery-associated AKI, and with HO-1 as a potential therapeutic target.

Integrated microRNA and mRNA responses to acute human left ventricular ischemia.

MicroRNAs (miRNAs) play a significant role in ischemic heart disease. Animal models of left ventricular (LV) ischemia demonstrate a unique miRNA profile; however, these models have limitations in describing human disease. In this study, we performed next-generation miRNA and mRNA sequencing on LV tissue from nine patients undergoing cardiac surgery with cardiopulmonary bypass and cardioplegic arrest. Samples were obtained immediately after aortic cross clamping (baseline) and before aortic cross clamp removal (postischemic). Of 1,237 identified miRNAs, 21 were differentially expressed between baseline and postischemic LV samples including the upregulated miRNAs miR-339-5p and miR-483-3p and the downregulated miRNA miR-139-5p. Target prediction analysis of these miRNAs was integrated with mRNA expression from the same LV samples to identify anticorrelated miRNA-mRNA pairs. Gene enrichment studies of candidate mRNA targets demonstrated an association with cardiovascular disease, cell death, and metabolism. Therapeutics that intervene on these miRNAs and their downstream targets may lead to novel mechanisms of mitigating the damage caused by ischemic insults on the human heart.

Using next-generation RNA sequencing to examine ischemic changes induced by cold blood cardioplegia on the human left ventricular myocardium transcriptome.

BACKGROUND: The exact mechanisms that underlie the pathological processes of myocardial ischemia in humans are unclear. Cardiopulmonary bypass with cardioplegic arrest allows the authors to examine the whole transcriptional profile of human left ventricular myocardium at baseline and after exposure to cold cardioplegia-induced ischemia as a human ischemia model. METHODS: The authors obtained biopsies from 45 patients undergoing aortic valve replacement surgery at baseline and after an average of 79 min of cold cardioplegic arrest. Samples were RNA sequenced and analyzed with the Partek Genomics Suite (Partek Inc., St. Louis, MO) for differential expression. Ingenuity Pathway Analysis (Ingenuity Systems, Redwood City, CA) and Biobase ExPlain (Biobase GmbH, Wolfenbuettel, Germany) systems were used for functional and pathway analyses. RESULTS: Of the 4,098 genes with a mean expression value greater than 5, 90% were down-regulated and 9.1% were up-regulated. Of those, 1,241 were significantly differentially expressed. Gene ontology analysis revealed significant down-regulation in immune inflammatory response and complement activation categories and highly consistent was the down-regulation of intelectin 1, proteoglycan, and secretory leukocyte peptidase inhibitor. Up-regulated genes of interest were FBJ murine osteosarcoma viral oncogene homolog and the hemoglobin genes hemoglobin α1 (HBA1) and hemoglobin ß. In addition, analysis of transcription factor-binding sites revealed interesting targets in factors regulating reactive oxygen species production, apoptosis, immunity, cytokine production, and inflammatory response. CONCLUSIONS: The authors have shown that the human left ventricle exhibits significant changes in gene expression in response to cold cardioplegia-induced ischemia during cardiopulmonary bypass, which provides great insight into the pathophysiology of ventricular ischemia, and thus, may help guide efforts to reduce myocardial damage during surgery.

Genetic Variants Associated With Atrial Fibrillation and PR Interval Following Cardiac Surgery.

OBJECTIVE: The authors hypothesized that genetic association between atrial fibrillation (AF)-associated and PR-associated genetic loci was biologically mediated through slower conduction velocities for some or all of these loci. DESIGN: Prospectively collected cohort study. SETTING: Single tertiary care university hospital. PARTICIPANTS: A total of 1227 Caucasian patients who underwent coronary artery bypass grafting (CABG). INTERVENTIONS: A total of 677 single nucleotide polymorphisms previously associated with ambulatory AF or PR interval were tested for association with postoperative atrial fibrillation (poAF) and preoperative PR interval, maximum PR interval, maximum change in PR interval, and maximum change in PR interval from preoperative PR interval. MEASUREMENTS AND MAIN RESULTS: The incidence of new-onset poAF was 31%. All of the PR interval variables were longer in the poAF cohort. Two variants on 1q21 and 12 on 4q25 were associated with poAF after adjustment for false discovery rate (FDR), but no variants were associated with PR interval variables after adjustment for FDR. Several variants were associated with both poAF and PR interval variables at p<0.05, but none of them remained significant after adjusting for FDR. CONCLUSION: It was found that patients with poAF have significantly longer PR interval. Genetic variants in both the 1q21 and 4q25 regions associate with poAF after CABG surgery, but the authors were unable to find association between these variants and PR interval after adjusting for FDR.