Loss of Independent Living in Patients Undergoing Transcatheter or Surgical Aortic Valve Replacement: A Retrospective Cohort Study.

BACKGROUND: The recommendation for transcatheter aortic valve replacement (TAVR) or surgical aortic valve replacement (SAVR) in patients 65 to 80 years of age is equivocal, leaving patients with a difficult decision. We evaluated whether TAVR compared to SAVR is associated with reduced odds for loss of independent living in patients ≤65, 66 to 79, and ≥80 years of age. Further, we explored mechanisms of the association of TAVR and adverse discharge. METHODS: Adult patients undergoing TAVR or SAVR within a large academic medical system who lived independently before the procedure were included. A multivariable logistic regression model, adjusting for a priori defined confounders including patient demographics, preoperative comorbidities, and a risk score for adverse discharge after cardiac surgery, was used to assess the primary association. We tested the interaction of patient age with the association between aortic valve replacement (AVR) procedure and loss of independent living. We further assessed whether the primary association was mediated (ie, percentage of the association that can be attributed to the mediator) by the procedural duration as prespecified mediator. RESULTS: A total of 1751 patients (age median [quartiles; min-max], 76 [67, 84; 23-100]; sex, 56% female) were included. A total of 27% (222/812) of these patients undergoing SAVR and 20% (188/939) undergoing TAVR lost the ability to live independently. In our cohort, TAVR was associated with reduced odds for loss of independent living compared to SAVR (adjusted odds ratio [OR adj ] 0.19 [95% confidence interval {CI}, 0.14-0.26]; P < .001). This association was attenuated in patients ≤65 years of age (OR adj 0.63 [0.26-1.56]; P = .32) and between 66 and 79 years of age (OR adj 0.23 [0.15-0.35]; P < .001), and magnified in patients ≥80 years of age (OR adj 0.16 [0.10-0.25]; P < .001; P -for-interaction = .004). Among those >65 years of age, a shorter procedural duration mediated 50% (95% CI, 28-76; P < .001) of the beneficial association of TAVR and independent living. CONCLUSIONS: Patients >65 years of age undergoing TAVR compared to SAVR had reduced odds for loss of independent living. This association was partly mediated by shorter procedural duration. No association between AVR approach and the primary end point was found in patients ≤65 years of age.

Pembrolizumab Improves Survival After Resection of Intracardiac Metastatic Cervical Carcinoma.

Intracardiac metastasis of cervical squamous cell carcinoma (C-SCC) is rare, with historically poor long-term survival. We report the case of a 55-year-old woman with prior metastatic C-SCC who was found to have a right ventricular mass causing functional pulmonic stenosis and multiple pulmonary emboli 19 months after her initial diagnosis. She underwent surgical resection to prevent further embolization and heart failure. Pathology confirmed metastatic C-SCC and she was maintained on adjuvant pembrolizumab. She remained well 32 months later without further disease progression. Surgical resection of intracardiac metastasis of C-SCC combined with pembrolizumab therapy may result in improved postoperative life expectancy.

Carbon monoxide and a change of heart.

The relationship between carbon monoxide and the heart has been extensively studied in both clinical and preclinical settings. The Food and Drug Administration (FDA) is keenly focused on the ill effects of carbon monoxide on the heart when presented with proposals for clinical trials to evaluate efficacy of this gasotransmitter in a various disease settings. This review provides an overview of the rationale that examines the actions of the FDA when considering clinical testing of CO, and contrast that with the continued accumulation of data that clearly show not only that CO can be used safely, but is potently cardioprotective in clinically relevant small and large animal models. Data emerging from Phase I and Phase II clinical trials argues against CO being dangerous to the heart and thus it needs to be redefined and evaluated as any other substance being proposed for use in humans. More than twenty years ago, the belief that CO could be used as a salutary molecule was ridiculed by experts in physiology and medicine. Like all agents designed for use in humans, careful pharmacology and safety are paramount, but continuing to hinder progress based on long-standing dogma in the absence of data is improper. Now, CO is being tested in multiple clinical trials using innovative delivery methods and has proven to be safe. The hope, based on compelling preclinical data, is that it will continue to be evaluated and ultimately approved as an effective therapeutic.

Update: Gender differences in CABG outcomes-Have we bridged the gap?

BACKGROUND: Appreciation of unique presentation, patterns and underlying pathophysiology of coronary artery disease in women has driven gender based risk stratification and risk reduction efforts over the last decade. Data regarding whether these advances have resulted in unequivocal improvements in outcomes of CABG in women is conflicting. The objective of our study was to assess gender differences in post-operative outcomes following CABG. METHODS: Retrospective analyses of institutional data housed in the Society of Thoracic Surgeons (STS) database for patients undergoing CABG between 2002 and 2020 were conducted. Multivariable regression analysis was conducted to investigate gender differences in post-operative outcomes. P-values were adjusted using Bonferroni correction to reduce type-I errors. RESULTS: Our final cohort of 6,250 patients had fewer women than men (1,339 vs. 4,911). more women were diabetic (52.0% vs. 41.2%, p<0.001) and hypertensive (89.1% vs. 84.0%, p<0.001). Women had higher adjusted odds of developing ventilator dependence >48 hours (OR: 1.65 [1.21, 2.45], p = 0.002) and cardiac readmissions (OR: 1.56 [1.27, 2.30], p = 0.003). After adjustment for comorbidity burden, mortality rates in women were comparable to those of age-matched men. CONCLUSION: The findings of our study indicate that despite apparent reduction of differences in mortality, the burden of postoperative morbidity is still high among women.

Intraoperative Oxygen Concentration and Neurocognition after Cardiac Surgery.

BACKGROUND: Despite evidence suggesting detrimental effects of perioperative hyperoxia, hyperoxygenation remains commonplace in cardiac surgery. Hyperoxygenation may increase oxidative damage and neuronal injury leading to potential differences in postoperative neurocognition. Therefore, this study tested the primary hypothesis that intraoperative normoxia, as compared to hyperoxia, reduces postoperative cognitive dysfunction in older patients having cardiac surgery. METHODS: A randomized double-blind trial was conducted in patients aged 65 yr or older having coronary artery bypass graft surgery with cardiopulmonary bypass. A total of 100 patients were randomized to one of two intraoperative oxygen delivery strategies. Normoxic patients (n = 50) received a minimum fraction of inspired oxygen of 0.35 to maintain a Pao2 above 70 mmHg before and after cardiopulmonary bypass and between 100 and 150 mmHg during cardiopulmonary bypass. Hyperoxic patients (n = 50) received a fraction of inspired oxygen of 1.0 throughout surgery, irrespective of Pao2 levels. The primary outcome was neurocognitive function measured on postoperative day 2 using the Telephonic Montreal Cognitive Assessment. Secondary outcomes included neurocognitive function at 1, 3, and 6 months, as well as postoperative delirium, mortality, and durations of mechanical ventilation, intensive care unit stay, and hospital stay. RESULTS: The median age was 71 yr (interquartile range, 68 to 75), and the median baseline neurocognitive score was 17 (16 to 19). The median intraoperative Pao2 was 309 (285 to 352) mmHg in the hyperoxia group and 153 (133 to 168) mmHg in the normoxia group (P < 0.001). The median Telephonic Montreal Cognitive Assessment score on postoperative day 2 was 18 (16 to 20) in the hyperoxia group and 18 (14 to 20) in the normoxia group (P = 0.42). Neurocognitive function at 1, 3, and 6 months, as well as secondary outcomes, were not statistically different between groups. CONCLUSIONS: In this randomized controlled trial, intraoperative normoxia did not reduce postoperative cognitive dysfunction when compared to intraoperative hyperoxia in older patients having cardiac surgery. Although the optimal intraoperative oxygenation strategy remains uncertain, the results indicate that intraoperative hyperoxia does not worsen postoperative cognition after cardiac surgery.

Cardiopulmonary Bypass Suppresses Forkhead Box O3 and Downstream Autophagy in the Diabetic Human Heart.

BACKGROUND: Autophagy is an integral component of cellular homeostasis and metabolism. The exact mechanism of impaired autophagy in diabetes mellitus is unknown. Forkhead Box O3 (FOXO3α) is a key regulator of oxidative stress-related responses. We hypothesize FOXO3α is a direct upstream regulator of the autophagy pathway, and its upregulation is compromised in diabetic patients during stress of cardiopulmonary bypass (CPB). METHODS: The study enrolled 32 diabetic and 33 nondiabetic patients undergoing a cardiac surgical procedure on CPB. Right atrial tissue and serum samples were collected before and after CPB per protocol. A set of key components were quantitatively assessed and compared by microarray, immunoblotting, and immunohistochemistry studies. Data were analyzed using paired or unpaired student test. A P of <.05 or less was considered significant. RESULTS: Serum microarray showed FOXO3α was upregulated in the diabetic vs nondiabetic group after CPB (P = .033), autophagy-related 4B gene and Beclin 1 gene were greatly upregulated in the nondiabetic group (P = .028 and P = .002, respectively). On immunoblotting, there was upregulation of FOXO3α in the nondiabetic patients after CPB (P = .003). There were increased levels of Beclin-1, Bcl-2, and light chain 3B after CPB in the nondiabetic group only (P = .016, P = .005, P = .002, respectively). Sirtuin 1, Unc-51-like autophagy activating kinase 1 (ULK1), peroxisome proliferator-activated receptor gamma coactivator 1α (PGC1α), and mammalian target of rapamycin (mTOR) were not significantly changed in the nondiabetic group after CPB. CONCLUSIONS: Compared with nondiabetic patients, there was no significant upregulation of FOXO3α in diabetic patients, which could possibly explain the lack of upregulation of the autophagy process after CPB. FOXO3α could potentially serve as a therapeutic target to improve cellular homeostasis.

Prevalence and Outcomes of Isolated Tricuspid Valve Surgery Among Medicare Beneficiaries.

We sought to characterize the clinical outcomes and to identify predictors of mortality undergoing isolated tricuspid valve surgery in the United States. We identified 5,164 patients undergoing isolated tricuspid valve surgery from the Centers for Medicare and Medicaid Services Medicare Provider Analysis and Review data between January 2003 and December 2014. The primary outcome was all cause 1-year mortality. A backward elimination method was performed to identify predictors of 1-year mortality. Tricuspid valve repair was performed in 2,494 (48.3%) patients and tricuspid valve replacement was performed in 2,670 (51.7%) patients. Perioperative and 1-year mortality rates were 9.9% and 24.1%, respectively. Predictors of 1-year mortality were age (p <0.001), chronic heart failure (p = 0.001, cirrhosis (p <0.001), carcinoid syndrome (p <0.001), chronic kidney disease (p = 0.001), secondary pulmonary hypertension (p = 0.023), endocarditis (p = 0.005), decubitus ulcer (p <0.001), malnutrition (p <0.001), replacement (p = 0.013), emergency procedure (p <0.001), and preprocedural shock (p <0.001). The C-statistic for 1-year mortality was 0.70 (95% confidence interval, 0.67 to 0.73). In conclusion, isolated tricuspid valve surgery is infrequently performed in the United States, and is associated with high 1-year mortality. Patients at higher risk for mortality can be identified based on the presence of a number of comorbidities at the time of surgery.

Association of Hospital Surgical Aortic Valve Replacement Quality With 30-Day and 1-Year Mortality After Transcatheter Aortic Valve Replacement.

Importance: Hospital outcomes for transcatheter aortic valve replacement (TAVR) may be dependent on the quality of evaluation, personnel, and procedural and postprocedural care common to patients undergoing cardiac surgery. Objectives: We sought to assess whether those hospitals with better patient outcomes for surgical aortic valve replacement (SAVR) subsequently achieved better TAVR outcomes after launching TAVR programs. Design, Setting, and Participants: This national cohort included US patients 65 years and older. The analysis used the Centers for Medicare and Medicaid Services' Medicare Provider and Review data collected between January 1, 2010, and September 29, 2015. Only hospitals performing at least 1 SAVR prior to September 1, 2011, and performing at least 1 TAVR after this date were included in the analysis. Data analysis was completed from June 2018 to August 2018. Interventions: Isolated aortic valve replacements. Main Outcomes and Measures: Hospital risk-adjusted 30-day mortality for SAVR in the pre-TAVR period was used as a surrogate for SAVR quality. Thirty-day and 1-year TAVR mortality rates were examined after stratification by quartile of baseline hospital risk-adjusted SAVR mortality. Results: A total of 51 924 TAVR procedures were performed in 519 hospitals, of which 19 798 were performed at hospitals in quartile 1 (the lowest risk-adjusted SAVR mortality rate), 7663 were performed in quartile 2, 10 180 were performed in quartile 3, and 14 283 were performed in quartile 4 (the highest risk-adjusted SAVR mortality rate). Observed mortality rates at 30 days consistently increased with increasing baseline hospital SAVR risk-adjusted mortality (quartile 1, 917 patients [4.6%]; quartile 2, 381 [5.0%]; quartile 3, 521 [5.1%]; quartile 4, 800 [5.6%]; P < .001). The same pattern was observed in 1-year mortality (quartile 1, 3359 [17.0%]; quartile 2, 1337 [17.5%]; quartile 3, 1852 [18.2%]; quartile 4, 2652 [18.6%]; P < .001). After multivariable analysis, compared with the lowest quartile of SAVR mortality, undergoing TAVR at a hospital with higher baseline SAVR mortality continued to be associated with higher 30-day mortality (odds ratios: quartile 2, 1.02 [95% CI, 0.87-1.21]; quartile 3, 1.13 [95% CI, 1.02-1.26]; quartile 4, 1.23 [95% CI, 1.07-1.40]; P = .02) and 1-year mortality (hazard ratios: quartile 2, 1.04 [95% CI, 0.92-1.17]; quartile 3, 1.14 [95% CI, 1.02-1.28]; quartile 4, 1.16 [95% CI, 1.05-1.28]; P = .02). Conclusions and Relevance: Hospitals with higher SAVR mortality rates also had higher short-term and long-term TAVR mortality after initiating TAVR programs. Quality of cardiac surgical care may be associated with a hospital's performance with new structural heart disease programs.

Initiation of a Multidisciplinary, Rapid Response Team to Massive and Submassive Pulmonary Embolism.

Pulmonary embolism (PE) can result in rapid clinical decompensation in many patients. With increasing patient complexity and advanced treatment options for PE, multidisciplinary, rapid response teams can optimize risk stratification and expedite management strategies. The Massive And Submassive Clot On-call Team (MASCOT) was created at our institution, which comprised specialists from cardiology, pulmonology, hematology, interventional radiology, and cardiac surgery. MASCOT offers rapid consultation 24 hours a day with a web-based conference call to review patient data and discuss management of patients with high-risk PE. We reviewed patient data collected from MASCOT's registry to analyze patient clinical characteristics and outcomes and describe the composition and operation of the team. Between August 2015 and September 2016, MASCOT evaluated 72 patients. Seventy of the 72 patients were admitted to our institution, accounting for 32% of all patients discharged with a primary diagnosis of PE. Average age was 62 ± 17 years with a female predominance (63%). Active malignancy (31%), recent surgery or trauma (21%), and recent hospitalization (24%) were common. PE clinical severity was massive in 16% and submassive in 83%. Patients were managed with anticoagulation alone in 65% (n = 46), systemic fibrinolysis in 11% (n = 8), catheter-directed therapy in 18% (n = 13), extracorporeal membrane oxygenation in 3% (n = 2), and an inferior vena cava filter was placed in 15% (n = 11). Thirteen percent (n = 9) experienced a major bleed with no intracranial hemorrhage. Survival to discharge was 89% (64% with massive PE and 93% with submassive PE). In conclusion, multidisciplinary, rapid response PE teams offer a unique coordinated approach to patient care.

Alcohol attenuates myocardial ischemic injury.

BACKGROUND: Moderate alcohol consumption is cardioprotective but the mechanism of action remains unclear. Nuclear factor κ-B regulates the expression of genes involved in inflammation, stress, and apoptosis. We used a swine model of diet-induced metabolic syndrome to investigate the effects of red wine and vodka on nuclear factor κ-B signaling and cytokine activity in chronically ischemic myocardium. METHODS: Yorkshire swine were given a high-fat diet for 4 weeks; an ameroid constrictor was then placed on the left circumflex artery. The high-fat diet was continued and the swine were divided into 3 groups for 7 weeks: hypercholesterolemic diet alone (control, n = 8), hypercholesterolemic diet with vodka (vodka, n = 8), and hypercholesterolemic diet with wine (wine, n = 8). Ischemic myocardium was analyzed by Western blot and cytokine array. RESULTS: Administration of alcohol was associated with decreased expression of inhibitor of κ-B kinase complex α, inhibitor of κ-B kinase complex ß, and phosphorylated inhibitor of κ-B ß in the ischemic myocardium compared with the control group. Alcohol administration demonstrated an increase in nuclear factor κ-B in the ischemic myocardium. Both wine and vodka demonstrated a significant decrease in leptin, interleukin-1α, IL-13, IL-15, and interferon-γ. Vodka demonstrated a significant decrease in phosphorylated BCL-2 and caspase-9. CONCLUSION: In ischemic myocardium, alcohol modulates the nuclear factor κ-B pathway, which may contribute to the adaptive response of tissues to the stress of ischemia. Furthermore, both wine and vodka decreased multiple proinflammatory cytokines. This study provides a mechanism by which alcohol may be cardioprotective in ischemic myocardium.

Preoperative gene expression may be associated with neurocognitive decline after cardiopulmonary bypass.

OBJECTIVE: Despite advances in surgical techniques, neurocognitive decline after cardiopulmonary bypass remains a common and serious complication. We have previously demonstrated that patients with neurocognitive decline have unique genetic responses 6 hours after cardiopulmonary bypass when compared with normal patients. We used genomic microarray to objectively investigate whether patients with neurocognitive decline had associated preoperative gene expression profiles and how these profiles changed up to 4 days after surgery. METHODS: Patients undergoing cardiac surgery underwent neurocognitive assessments preoperatively and 4 days after surgery. Skeletal muscle was collected intraoperatively. Whole blood collected before cardiopulmonary bypass, 6 hours after cardiopulmonary bypass, and on postoperative day 4 was hybridized to Affymetrix Gene Chip U133 Plus 2.0 microarrays (Affymetrix Inc, Santa Clara, Calif). Gene expression in patients with neurocognitive decline was compared with gene expression in the normal group using JMP Genomics (SAS Institute Inc, Cary, NC). Only genes that were commonly expressed in the 2 groups with a false discovery rate of 0.05 and a fold change greater than 1.5 were carried forward to pathway analysis using Ingenuity Pathway Analysis (Ingenuity Systems, Redwood City, Calif). Microarray gene expression was validated by Green real-time polymerase chain reaction and Western blotting. RESULTS: Neurocognitive decline developed in 17 of 42 patients. A total of 54,675 common transcripts were identified on microarray in each group across all time points. Preoperatively, there were 140 genes that were significantly altered between the normal and neurocognitive decline groups (P < .05). Pathway analysis demonstrated that preoperatively, patients with neurocognitive decline had increased regulation in genes associated with inflammation, cell death, and neurologic dysfunction. Of note, the number of significantly regulated genes between the 2 groups changed over each time point and decreased from 140 preoperatively to 64 six hours after cardiopulmonary bypass and to 25 four days after surgery. There was no correlation in gene expression between the blood and the skeletal muscle. CONCLUSIONS: Patients in whom neurocognitive decline developed after cardiopulmonary bypass had increased differential gene expression before surgery versus patients in whom neurocognitive decline did not develop. Although significant differences in gene expression also existed postoperatively, these differences gradually decreased over time. Preoperative gene expression may be associated with neurologic injury after cardiopulmonary bypass. Further investigation into these genetic pathways may help predict patient outcome and guide patient selection.

Atorvastatin regulates apoptosis in chronically ischemic myocardium.

BACKGROUND: We previously demonstrated that atorvastatin upregulates proangiogenic proteins and increases arteriolar density in ischemic myocardium. Despite this, there was a lack of collateral-dependent perfusion, possibly related to apoptosis. We utilized a swine model of metabolic syndrome and chronic myocardial ischemia to investigate the effects of atorvastatin on apoptosis. MATERIALS AND METHODS: Sixteen Ossabaw miniswine were fed a high-cholesterol diet for 14 weeks then underwent surgical placement of an ameroid constrictor to their circumflex artery inducing chronic ischemia. Eight pigs additionally received supplemental atorvastatin (1.5 mg/kg daily). Myocardium was harvested six months later for western blotting and TUNEL staining. RESULTS: Animals supplemented with atorvastatin had significant increases in markers associated with apoptosis including p-38, BAX, and caspase 3 (p < 0.05). Atorvastatin supplementation also resulted in significant increases in expression of cell survival proteins Bcl-2 and P-ERK and an overall decrease in apoptosis demonstrated by TUNEL staining (p < 0.05). CONCLUSIONS: Atorvastatin acts on multiple pathways and its effects on angiogenesis remain unclear. Although there is increased expression in several markers of apoptosis, key anti-apoptotic proteins were also upregulated with an overall decrease in apoptosis. Further investigation of these pathways may provide insight into the role of statins on myocardial protection after ischemia.

Differential effects of atorvastatin on autophagy in ischemic and nonischemic myocardium in Ossabaw swine with metabolic syndrome.

OBJECTIVES: The perioperative administration of pleomorphic statin drugs has been implicated in improving outcomes after cardiac surgery. Adaptive autophagy is a highly conserved cellular process that allows for the elimination of dysfunctional cell components in response to stress and survival under starving conditions. We sought to investigate the effects of the statin drug atorvastatin on autophagy in ischemic and nonischemic myocardia using a clinically relevant porcine model of metabolic syndrome. METHODS: Male Ossabaw swine were fed a regular diet (n = 8), a high-cholesterol diet (n = 8), or a high-cholesterol diet with supplemental atorvastatin (1.5 mg/kg/d) (n = 8). After 14 weeks, all animals underwent surgical placement of an ameroid constrictor to the circumflex coronary artery to induce chronic ischemia. Nonischemic and ischemic myocardia were harvested 6 months after initiation of the diet and processed for Western blotting. RESULTS: In the nonischemic myocardium, Western blot results demonstrate that a high cholesterol diet resulted in a statistically significant decrease in autophagy as indicated by an increase in mammalian target of rapamycin and the accumulation of several essential autophagy markers, including Beclin-1, light chain 3B-I, and light chain 3B-II. Atorvastatin supplementation prevented these changes and resulted in an increase in autophagy as indicated by a decrease in autophagy flux marker P62. In the ischemic myocardium, atorvastatin had the opposite effect, with a decrease in autophagy flux as indicated by an increase in p62 and an accumulation of light chain 3B-I, light chain B-II, and lysosome-associated membrane protein 2. CONCLUSIONS: Atorvastatin administration has differential effects on autophagy in ischemic and nonischemic myocardia. In the setting of metabolic syndrome, atorvastatin stimulates autophagy in nonischemic myocardium while partly inhibiting autophagy in ischemic myocardium. The differential regulation on autophagy may, in part, explain the cardioprotective effect of statins in both ischemic and nonischemic myocardia, and these findings may have implications in the setting of cardiac surgery.

Metabolic syndrome impairs notch signaling and promotes apoptosis in chronically ischemic myocardium.

OBJECTIVE: Impaired angiogenesis is a known consequence of metabolic syndrome (MetS); however, the mechanism is not fully understood. Recent studies have shown that the notch signaling pathway is an integral component of cardiac angiogenesis. We tested, in a clinically relevant swine model, the effects of MetS on notch and apoptosis signaling in chronically ischemic myocardium. METHODS: Ossabaw swine were fed either a regular diet (control [CTL], n = 8) or a high-cholesterol diet (MetS, n = 8) to induce MetS. An ameroid constrictor was placed to induce chronic myocardial ischemia. Eleven weeks later, the wine underwent cardiac harvest of the ischemic myocardium. RESULTS: Downregulation of pro-angiogenesis proteins notch2, notch4, jagged2, angiopoietin 1, and endothelial nitric oxide synthase were found in the MetS group compared with the CTL group. Also, upregulation of pro-apoptosis protein caspase 8 and downregulation of anti-angiogenesis protein phosphorylated forkhead box transcription factor 03 and pro-survival proteins phosphorylated P38 and heat shock protein 90 were present in the MetS group. Cell death was increased in the MetS group compared with the CTL group. Both CTL and MetS groups had a similar arteriolar count and capillary density, and notch3 and jagged1 were both similarly concentrated in the smooth muscle wall. CONCLUSIONS: MetS in chronic myocardial ischemia significantly impairs notch signaling by downregulating notch receptors, ligands, and pro-angiogenesis proteins. MetS also increases apoptosis signaling, decreases survival signaling, and increases cell death in chronically ischemic myocardium. Although short-term angiogenesis appears unaffected in this model of early MetS, the molecular signals for angiogenesis are impaired, suggesting that inhibition of notch signaling might underlie the decreased angiogenesis in later stages of MetS.

Metformin mitigates apoptosis in ischemic myocardium.

BACKGROUND: Epidemiologic data has shown that metformin confers a survival advantage in patients with cardiovascular disease. Although the underlying cardioprotective mechanism is unclear, it appears to be independent of metformin's insulin-sensitizing effect. The purpose of this study was to evaluate the effect of metformin on the apoptosis pathway in the ischemic and nonischemic cardiac tissue in a swine model of metabolic syndrome. MATERIALS AND METHODS: Ossabaw miniswine were fed either a regular diet (Ossabaw control, n = 8), a high-cholesterol diet (Ossabaw high cholesterol, n = 8), or a high-cholesterol diet supplemented with metformin (Ossabaw high-cholesterol metformin, n = 8). After 9 wk, all animals underwent placement of an ameroid constrictor to the left circumflex coronary artery to induce chronic ischemia. Seven weeks after ameroid placement, animals underwent cardiac harvest. RESULTS: In the chronically ischemic myocardium, metformin significantly upregulates prosurvival proteins: extracellular signal-regulated kinases, nuclear factor κB, phosphorylated endothelial nitric oxide synthase, and P38. Metformin also significantly inhibits or downregulates proapoptosis proteins: FOXO3 and caspase 3. Metformin decreased the percent apoptotic cells in the ischemic and nonischemic myocardium. There was no difference in arteriolar density, capillary density, intramyocardial fibrosis, or collagen deposition in the ischemic or nonischemic myocardium. CONCLUSIONS: Metformin selectively alters the apoptosis pathway by inhibiting FOXO3 and decreasing the active form of caspase 3, cleaved caspase 3. Metformin also upregulates mitogen-activated kinase proteins p38 and extracellular signal-regulated protein kinases 1 and 2, which are considered cardioprotective during ischemic preconditioning. Perhaps, the altered activation of the apoptosis pathway in ischemic myocardium is one mechanism by which metformin is cardioprotective.

Microvascular notch signaling is upregulated in response to vascular endothelial growth factor and chronic myocardial ischemia.

BACKGROUND: Notch signaling is a highly conserved pathway that promotes vascular and myocardial growth. The hypothesis that exogenous vascular endothelial growth factor (VEGF) administration to ischemic myocardium would enhance the neovascular response and upregulate Notch signaling was assessed. METHODS AND RESULTS: Fourteen male Yorkshire swine underwent placement of an ameroid constrictor on the left circumflex artery to induce chronic myocardial ischemia with half of the animals receiving perivascular VEGF to the ischemic area. The remote territory served as the normal ventricle control (NV), while the 2 experimental groups consisted of the area at risk of the non-VEGF animals (AAR) and the area at risk of animals treated with VEGF (VEGF). Capillary and arteriolar density was significantly increased in the VEGF group as compared to both NV and AAR. Expression of Notch receptors and pro-neovascular Notch ligands was significantly higher in the VEGF group. Both Jagged 1 and Notch 3 were the most highly concentrated in the smooth muscle wall of arterioles. CONCLUSIONS: VEGF administration to chronically ischemic myocardium significantly augmented the neovascular response by an increase in both capillary and arteriolar density, and resulted in an upregulation of several Notch receptors and ligands, which were not upregulated with ischemia alone. These findings suggest that the augmented neovascular response seen with VEGF administration was through the VEGF-induced upregulation of Notch signaling.

Altered apoptosis-related signaling after cardioplegic arrest in patients with uncontrolled type 2 diabetes mellitus.

BACKGROUND: We investigated the effects of cardioplegic arrest and reperfusion (CP/Rep) on myocardial apoptosis and key apoptotic mediators, such as apoptosis-inducing factor, caspase 3, caspase 8, caspase 9, poly(adenosine diphosphate-ribose) polymerase, B-cell lymphoma 2 (Bcl-2) family proteins, and protein kinase C (PKC), in uncontrolled type 2 diabetic, controlled type 2 diabetic, and nondiabetic patients. METHODS AND RESULTS: Right atrial tissue was harvested pre- and post-CP/Rep from uncontrolled type 2 diabetic patients (hemoglobin A1c=9.6 ± 0.25), controlled type 2 diabetic patients (hemoglobin A1c=6.5 ± 0.15), and nondiabetic patients (hemoglobin A1c=5.4 ± 0.12) undergoing coronary artery bypass grafting (n=8/group). Terminal deoxynucleotidyl transferase dUTP nick-end labeling staining was used for the identification of apoptotic cells. Total and modified apoptosis-inducing factor, Bcl-2 family proteins, phospho-PKC-α, phospho-PKC-ß1, and poly(adenosine diphosphate-ribose) polymerase were quantified by immunoblotting or immunohistochemistry. At baseline, the number of apoptotic cells and expression of total apoptosis-inducing factor, Bcl-2, Bak, and Bax in the pre-CP/Rep atrial tissue from uncontrolled type 2 diabetic patients were significantly increased compared with those of nondiabetic or controlled type 2 diabetic patients (P<0.05). After CP/Rep, the amount of apoptotic cells, apoptosis-inducing factor, phospho-Bad, phospho-PKC-α, phospho-PKC-ß1, and cleaved poly(adenosine diphosphate-ribose) polymerase in post-CP/Rep atrial tissue were increased in all 3 groups compared with pre-CP/Rep. These increases after CP/Rep were more pronounced in the uncontrolled type 2 diabetic group. In addition, there were significant increases in the expression of cleaved caspase 8 and caspase 9 in the basal and post-CP/Rep atrium of uncontrolled type 2 diabetic group compared with nondiabetic or controlled type 2 diabetic group. CONCLUSIONS: Uncontrolled diabetes mellitus is associated with increases in myocardial apoptosis and expression of key apoptosis mediators at baseline and in the setting of CP/Rep.

The pig as a valuable model for testing the effect of resveratrol to prevent cardiovascular disease.

Resveratrol is a naturally occurring polyphenol found in the skin of red grapes, peanuts, and red wine that has been shown to modify many cardiovascular risk factors. Small animal models have been extensively used to investigate cardiovascular disease, but the results often fail to translate in clinical trials. Disease-specific pig models are emerging as clinically useful tools that may offer insight into cardiovascular disease and the effect of drugs such as resveratrol on cardiovascular health. In this paper, we discuss the advantage of using clinically relevant pig models of diabetes, hypercholesterolemia, and myocardial ischemia to investigate the role of resveratrol in cardiovascular disease prevention.

Mechanism for reduced pericardial adhesion formation in hypercholesterolemic swine supplemented with alcohol.

OBJECTIVE: Previous experiments in Yorkshire swine demonstrated significantly fewer pericardial adhesions and intramyocardial collagen deposition at reoperative sternotomy in animals supplemented with vodka but not with red wine. The purpose of this experiment was to determine a mechanism for adhesion reduction. METHODS: Twenty-seven male Yorkshire swine were fed a high-cholesterol diet to simulate conditions of coronary artery disease followed by the surgical placement of an ameroid constrictor to the left circumflex coronary artery to induce chronic ischaemia. Postoperatively, control pigs continued their high-fat/cholesterol diet alone, whereas the two experimental groups had diets supplemented with either red wine or vodka for 7 weeks followed by reoperative sternotomy and cardiac harvest. RESULTS: The expression of related adhesion focal tyrosine kinase (RAFTK) and caspase 3 in the sodium dodecyl sulphate (SDS)-soluble myocardial fraction was significantly higher only in the vodka-supplemented group. In the more soluble fraction, the expression of caspase 3, cleaved caspase 3 and caspase 9 was lower in both the vodka and red wine treatment groups. CONCLUSIONS: In the SDS-soluble lysate fraction, likely representing the transmembrane/cell-extracellular matrix (ECM), a significant increase in RAFTK and caspase 3 expression was seen only in the vodka-treated animals, which may explain why this group demonstrated significantly fewer pericardial adhesions. Caspase expression/signalling was not increased in the more soluble myocardial lysate, suggesting that the increased apoptotic signalling was specific to the epicardial-ECM.

Metformin alters the insulin signaling pathway in ischemic cardiac tissue in a swine model of metabolic syndrome.

OBJECTIVE: The purpose of this study is to evaluate the effect of metformin on insulin signaling in ischemic cardiac tissue in a swine model of metabolic syndrome. METHODS: Ossabaw miniswine were fed either a regular diet (Ossabaw control [OC]) or a hypercaloric diet (Ossabaw high cholesterol [OHC], Ossabaw high cholesterol with metformin [OHCM]). After 9 weeks, all animals underwent placement of an ameroid constrictor to the left circumflex artery to induce chronic ischemia. OHC animals were continued on a hypercaloric diet alone; the OHCM group was supplemented with metformin in addition to the hypercaloric diet. Seven weeks after ameroid placement, myocardial perfusion was measured and ischemic cardiac tissue was harvested for protein expression and histologic analysis. RESULTS: The OHC and OHCM groups had significantly higher body mass indices and serum insulin levels compared with the OC group. There were no differences in myocardial perfusion in the chronically ischemic territories. In the OHC group, there was upregulation of both an activator of insulin signaling insulin receptor substrate 1, and an inhibitor of insulin signaling phosphorylated insulin receptor substrate 2. In the OHCM group, there was upregulation of activators of insulin signaling including phosphorylated adenosine monophosphate-activated protein kinase α, protein kinase B, phosphorylated protein kinase B, mammalian target of rapamycin, phosphorylated mammalian target of rapamycin, and phosphoinostitide 3-kinase, and upregulation of inhibitors including phosphorylated insulin receptor substrate 1, phosphorylated insulin receptor substrate 2, and retinol binding protein 4. Histologic analysis demonstrated increased expression of glucose transporter 1 at the plasma membrane in the OHCM group, but there was no difference in cardiomyocyte glycogen stores among groups. CONCLUSIONS: Metformin treatment in the context of metabolic syndrome and myocardial ischemia dramatically upregulates the insulin signaling pathway in chronically ischemic myocardium, which is at the crossroads of known metabolic and survival benefits of metformin.