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Revascularization of chronic hibernating myocardium stimulates myocyte proliferation and partially reverses chronic adaptations to ischemia.

ABSTRACT: The time course and extent of recovery after revascularization of viable dysfunctional myocardium are variable. Although fibrosis is a major determinant, myocyte structural and molecular remodeling may also play important roles.This study sought to determine whether persistent myocyte loss and/or irreversibility of protein changes that develop in hibernating myocardium have an impact on functional recovery in the absence of infarction.Swine implanted with a chronic left anterior descending artery (LAD) stenosis to produce hibernating myocardium underwent percutaneous revascularization, with serial functional recovery evaluated for 1 month (n = 12). Myocardial tissue was evaluated to assess myocyte size, nuclear density, and proliferation indexes in comparison with those of normal animals and nonrevascularized controls. Proteomic analysis by 2-dimensional differential in-gel electrophoresis was used to determine the reversibility of molecular adaptations of hibernating myocytes.At 3 months, physiological features of hibernating myocardium were confirmed, with depressed LAD wall thickening and no significant infarction. Revascularization normalized LAD flow reserve, with no immediate change in LAD wall thickening. Regional LAD wall thickening slowly improved but remained depressed 1 month post-percutaneous coronary intervention. Surprisingly, revascularization was associated with histological evidence of myocytes re-entering the growth phase of the cell cycle and increases in the number of c-Kit(+) cells. Myocyte nuclear density returned to normal, whereas regional myocyte hypertrophy regressed. Proteomic analysis demonstrated heterogeneous effects of revascularization. Up-regulated stress and cytoskeletal proteins normalized, whereas reduced contractile and metabolic proteins persisted.Delayed recovery of hibernating myocardium in the absence of scar may reflect persistent reductions in the amounts of contractile and metabolic proteins. Although revascularization appeared to stimulate myocyte proliferation, the persistence of small immature myocytes may have contributed to delayed functional recovery.

SUBMITTER: Page BJ

PROVIDER: S-EPMC4328140 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature

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Revascularization of chronic hibernating myocardium stimulates myocyte proliferation and partially reverses chronic adaptations to ischemia.

Page Brian J BJ Banas Michael D MD Suzuki Gen G Weil Brian R BR Young Rebeccah F RF Fallavollita James A JA Palka Beth A BA Canty John M JM

Journal of the American College of Cardiology 20150201 7

<h4>Background</h4>The time course and extent of recovery after revascularization of viable dysfunctional myocardium are variable. Although fibrosis is a major determinant, myocyte structural and molecular remodeling may also play important roles.<h4>Objectives</h4>This study sought to determine whether persistent myocyte loss and/or irreversibility of protein changes that develop in hibernating myocardium have an impact on functional recovery in the absence of infarction.<h4>Methods</h4>Swine i ...[more]

PMID: 25677430

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Project description:ObjectiveThe Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system was developed to stratify the risk of 1-year major amputation. Recently, the WIfI scores were used to define the estimated revascularization benefit quartiles ranging from high benefit (Q1) to questionable benefit (Q4). The aim of our study was to evaluate the revascularization benefit quartiles in a cohort of diabetic patients presenting with chronic limb-threatening ischemia (CLTI).MethodsAll diabetic patients presenting to our multidisciplinary diabetic foot and wound clinic (June 2012 to May 2020) who underwent lower extremity revascularization for CLTI were included. The affected limbs were graded using the WIfI system and assigned to an estimated benefit of revascularization quartile as previously published. One-year major amputation, complete foot healing, secondary patency, and amputation-free survival were calculated among the quartiles using Kaplan-Meier curve analyses and compared using Cox proportional hazards models.ResultsOverall, 136 diabetic patients underwent revascularization of 187 limbs (mean age, 64.9 ± 11.2 years; 63.2% male; 58.8% black). The limbs were revascularized using an endovascular approach for 66.8% and open surgery for 33.2%. Of the 187 limbs, 27.3% had a high estimated benefit of revascularization (Q1), 31.6% had a moderate estimate benefit of revascularization (Q2), 20.3% had a low estimated benefit of revascularization (Q3), and 20.9% had a questionable benefit of revascularization (Q4). The estimated 1-year major amputation rates were 7.2% ± 4.1% for Q1, 3.8% ± 2.6% for Q2, 7.0% ± 4.8% for Q3, and 25.7% ± 7.5% for Q4 (P = .006). The estimated 1-year foot healing rates were 87.3% ± 5.7% for Q1, 84.8% ± 5.6% for Q2, 83.8% ± 7.4% for Q3, and 68.2% ± 9.1% for Q4 (P = .06). The overall secondary patency (P = .23) and amputation-free survival (P = .33) did not significantly differ among the groups. Using Cox proportional hazard modeling, the Q4 group had a significantly greater risk of major amputation compared with Q1 (hazard ratio, 4.26; 95% confidence interval, 1.15-15.70). Of the 14 limbs requiring major amputation, 9 (56.3%) had a patent revascularization at the time of amputation, including one of three limbs in Q1, two of two limbs in Q2, no limb in Q3, and six of nine limbs in Q4.ConclusionsThe questionable estimated revascularization benefit quartile using the WIfI classification system is significantly associated with 1-year major amputation in diabetic patients presenting with CLTI. Limbs with a questionable benefit of revascularization (Q4) will frequently require major amputation despite a patent revascularization, suggesting that the wound size and infection burden are the driving factors behind the elevated risk of major amputation in this group. Our findings support the previously described use of the WIfI classification system to predict revascularization benefit among diabetic patients with CLTI.

Project description:Background and objectiveDiabetes mellitus associates with poor outcomes in chronic limb threatening ischemia but data on different hypoglycemic regimens and outcomes are lacking. We analyzed insulin-treated diabetes mellitus, non-insulin-treated diabetes mellitus, and patients without diabetes mellitus.MethodsAll patients with peripheral artery disease and/or diabetes mellitus and infrapopliteal revascularization in the Department of Vascular Surgery, Turku University Hospital during 2007-2015 were included. Tibial atherosclerosis was categorized into crural index classes of I-IV.ResultsOf the 497 patients, 180 were insulin-treated diabetes mellitus, 94 non-insulin-treated diabetes mellitus, and 223 patients without diabetes mellitus groups (diabetes mellitus 55.1%). Insulin-treated diabetes mellitus was the most ill, youngest (insulin-treated diabetes mellitus-median: 72.4, interquartile range: 64.0-79.5 versus non-insulin-treated diabetes mellitus-76.0, interquartile range: 67.9-83.6 versus patients without diabetes mellitus-77.3, interquartile range: 68.5-83.7, p < 0.001), had the highest body mass index (insulin-treated diabetes mellitus-median: 27.7, interquartile range: 24.0-31.8 versus non-insulin-treated diabetes mellitus-26.3, interquartile range: 23.2-30.3 versus patients without diabetes mellitus-23.9, interquartile range: 21.5-26.9, p < 0.001), and Charlson comorbidity index (insulin-treated diabetes mellitus-65.6% versus non-insulin-treated diabetes mellitus-46.8% versus patients without diabetes mellitus-10.8%, p < 0.001). After endovascular revascularization, limb salvage was poorer for insulin-treated diabetes mellitus (p = 0.046) and non-insulin-treated diabetes mellitus groups (p = 0.011) compared to surgery, but not for patients without diabetes mellitus (p = 0.15). Patients with crural index IV in insulin-treated diabetes mellitus (p = 0.001) and non-insulin-treated diabetes mellitus (p = 0.013) had higher mortality after revascularization. Crural index IV was a risk factor for limb loss (hazard ratio: 1.37, 95% confidence interval: 1.08-1.74, p = 0.008).ConclusionsLimb salvage after bypass is better for insulin and non-insulin diabetics, compared to the endovascular approach. Extensive tibial atherosclerosis is an independent risk factor for limb loss. It associates with increased mortality in both insulin and non-insulin diabetics.

Project description:ObjectiveHistorically, open surgical bypass provided a durable repair among diabetic patients with chronic limb-threatening ischemia (CLTI). In the current endovascular era, however, the difference in long-term outcomes between first-time revascularization strategies among patients with insulin-dependent diabetes mellitus (IDDM) is poorly understood.MethodsWe reviewed the records of all patients with IDDM undergoing a first-time infrainguinal bypass graft (BPG) or percutaneous transluminal angioplasty with or without stenting (PTA/S) for CLTI at our institution from 2005 to 2014. We defined IDDM as use of chronic insulin administration at baseline to control blood glucose levels and recorded the most recent glycated hemoglobin value available within 3 months before the procedure and fasting blood glucose level on the day of the procedure. We compared rates of wound healing, restenosis, reintervention, major amputation, and mortality between BPG and PTA/S in our population using χ2, Kaplan-Meier, and Cox regression analyses. As a sensitivity analysis, we calculated propensity scores and employed inverse probability weighting to account for nonrandom assignment to BPG vs PTA/S.ResultsOf 2869 infrainguinal revascularizations from 2005 to 2014, 655 limbs (316 BPG, 339 PTA/S) in 580 patients fit our criteria and underwent a first-time revascularization for CLTI. Patients undergoing BPG, compared with PTA/S, were similar in age (69 vs 68 years; P = .55), had similar rates of tissue loss (87% vs 91%; P = .07) and dialysis dependence (26% vs 28%; P = .55), were less likely to be hypertensive (84% vs 92%; P < .001), and were more likely to be current smokers (21% vs 14%; P = .02). There were no differences between BPG and PTA/S patients in mean glycated hemoglobin levels (8.1% vs 8.0%; P = .51) or mean fasting blood glucose levels (158 vs 150 mg/dL; P = .18). Although total hospital length of stay was significantly longer among BPG patients (11 vs 8 days; P < .001), perioperative complications did not differ, including acute kidney injury (19% vs 23%; P = .24), hematoma (6.0% vs 3.8%; P = .20), acute myocardial infarction (1.3% vs 2.1%; P = .43), and mortality (3.8% vs 3.0%; P = .55). BPG-first patients had significantly lower unadjusted 6-month rates of incomplete wound healing (49% vs 57%) and 5-year rates of restenosis (53% vs 72%) and reintervention (47% vs 58%; all P < .05). After adjustment, multivariable analysis suggested PTA/S-first intervention to be significantly associated with higher risk of restenosis (hazard ratio, 1.9; 95% confidence interval, 1.3-2.7) and reintervention (1.9 [1.2-2.7]). These results remained robust after inverse probability weighting.ConclusionsAmong patients with IDDM and CLTI, a bypass-first strategy is associated with similar 30-day outcomes and lower restenosis and reintervention rates. These data suggest that a bypass-first approach may best serve appropriately selected, anatomically suitable patients with IDDM and pedal ischemia that requires revascularization.

Project description:RationaleAllogeneic bone marrow-derived mesenchymal stem cells (MSCs) and cardiosphere-derived cells (CDCs) have each entered clinical trials, but a direct comparison of these cell types has not been performed in a large animal model of hibernating myocardium.ObjectiveUsing completely blinded methodology, we compared the efficacy of global intracoronary allogeneic MSCs (icMSCs, ≈35×10(6)) and CDCs (icCDCs, ≈35×10(6)) versus vehicle in cyclosporine-immunosuppressed swine with a chronic left anterior descending coronary artery stenosis (n=26).Methods and resultsStudies began 3 months after instrumentation when wall thickening was reduced (left anterior descending coronary artery % wall thickening [mean±SD], 38±11% versus 83±26% in remote; P<0.01) and similar among groups. Four weeks after treatment, left anterior descending coronary artery % wall thickening increased similarly after icCDCs and icMSCs, whereas it remained depressed in vehicle-treated controls (icMSCs, 51±13%; icCDCs, 51±17%; vehicle, 34±3%, treatments P<0.05 versus vehicle). There was no change in myocardial perfusion. Both icMSCs and icCDCs increased left anterior descending coronary artery myocyte nuclear density (icMSCs, 1601±279 nuclei/mm(2); icCDCs, 1569±294 nuclei/mm(2); vehicle, 973±181 nuclei/mm(2); treatments P<0.05 versus vehicle) and reduced myocyte diameter (icMSCs, 16.4±1.5 μm; icCDCs, 16.8±1.2 μm; vehicle, 20.2±3.7 μm; treatments P<0.05 versus vehicle) to the same extent. Similar changes in myocyte nuclear density and diameter were observed in the remote region of cell-treated animals. Cell fate analysis using Y-chromosome fluorescent in situ hybridization demonstrated rare cells from sex-mismatched donors.ConclusionsAllogeneic icMSCs and icCDCs exhibit comparable therapeutic efficacy in a large animal model of hibernating myocardium. Both cell types produced equivalent increases in regional function and stimulated myocyte regeneration in ischemic and remote myocardium. The activation of endogenous myocyte proliferation and regression of myocyte cellular hypertrophy support a common mechanism of cardiac repair.

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Revascularization of chronic hibernating myocardium stimulates myocyte proliferation and partially reverses chronic adaptations to ischemia.

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Revascularization of chronic hibernating myocardium stimulates myocyte proliferation and partially reverses chronic adaptations to ischemia.

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