Studies On Coronary Collateral Circulation In Patients With Stable Angina Pectoris And Chronic Total Occlusion And In Animal Hindlimb Models

Coronary collateral circulation is an alternative source of blood supply to myocardiumin the presence of advanced coronary artery disease. Despite complete interruption ofantegrade blood flow caused by heavy atherosclerotic plaque burden or arterial thrombosis,the frequency of myocardial infarction in areas subtended by chronic total occlusion variesconsiderably, and the degree of myocardial injury downstream of epicardial chronic totalocclusion is inversely correlated with the degree of angiographic coronary collateralcirculation. Well-developed coronary collaterals have the potential to alleviate myocardialischemia, preserve residual contractility, reduce cardiovascular events, and even save livesin patients with severe coronary artery occlusion. The complex mechanism mediating thedevelopment of coronary collateral vessels in the heart is still not well-understood. Theextent of coronary collateralization is affected by multiple clinical, angiographic andbiochemical factors and inflammatory cytokines.Therefore, we conducted this study which included4parts: to determine the clinicaland angiographic features and soluble vascular endothelial growth factor receptorsassociated with coronary collateralization in patients with stable angina and chronic totalcoronary occlusion; to compare the differential role of estimating glomerular filtration ratewith creatinine-and cystatin C-based equations in detecting the presence of poor coronarycollaterals in these patients. Finally, the effects of type1diabetes on arteriogenesis wereexamined in a C57BL/6J male mice model with low-limb ischemic injury.Part I: Determination of clinical and angiographic features influencing coronarycollateralization in patients with stable angina pectoris and chronic coronary totalocclusion. Background and objective：In this study, we investigated the influence of clinicalcharacteristics and angiographic features on coronary collateralization in patients withstable angina pectoris and chronic coronary total occlusion.Methods： Demographic and clinical variables, biochemical results, and coronaryangiographic findings were collected in478patients with stable angina and chronic totalocclusion. The presence and extent of collaterals supplying the distal aspect of a totalcoronary occlusion from the contra-lateral vessel were graded from0to3according to theRentrop scoring system.Results：Low（Rentrop grade0/1）and high (Rentrop grade2/3）coronary collateralizationwas detected in186and292patients, respectively. Despite similar age, percentage ofcigarette smoking, and use of cardiovascular medications, patients with lowcollateralization were female in high proportion, had more hyperlipidemia, renaldysfunction and diabetes, and were less hypertensive. In addition, angiography showedthat single vessel coronary disease was common, but right coronary occlusion was lessfrequent in patients with low collateralization. Multivariate Logistic regression analysisrevealed that age>65years, female gender, diabetes, hyperlipidemia, moderate to severerenal insufficiency, elevated serum high-sensitivity C-reactive protein were independentrisk factors for poor coronary collateralization in patients with chronic total occlusion.Conclusions: Approximately40%of patients with stable angina and chronic totalocclusion had poor coronary collateral circulation, which is related to baseline clinicalcharacteristics and angiographic features.Part II: Association between elevated soluble vascular endothelial growth factorreceptor in serum and low coronary collateralization in patients with stablecoronary artery diseaseBackground and objective: Soluble vascular endothelial growth factor receptor(sVEGFR)-1has been shown to be a negative endogenous modulator of angiogenesis by binding and sequestering vascular endothelial growth factor (VEGF). Increased expressionand secretion of sVEGFR-1prevents capillary growth and angiogenesis in both in vivoand in intro studies. The present study investigated whether serum levels of sVEGFR-1,-2and-3are related to low coronary collateralization in patients with stable coronary arterydisease.Methods：Serum levels of sVEGFR-1,-2, and-3, placenta growth factor (PLGF), andVEGF were determined in403patients with chronic total or subtotal occlusion of at leastone epicardial coronary arteries using ELISA technique. The Rentrop scoring system wasapplied to assess the presence and extent of collaterals supplying the distal aspect of a totalcoronary occlusion from the contra-lateral vessel.Results：Poo（rRentrop grade0/1）and good (Rentrop grade2/3）coronary collateralizationwas detected in161and242patients, respectively. Compared with patients with goodcollateralization, those with poor coronary collateralization had significantly higher serumlevels of sVEGFR-1, sVEGFR-2, and high-sensitivity C-reactive protein (hs-CRP), andlower PLGF and VEGF levels (for all such comparisons, P＜0.05). For diabetic andnon-diabetic patients，the differences in serum levels of VEGFR-1,PLGF, and VEGFpersisted between patients with good collateralization and those with poor collateralization.Multivariate Logistic regression analysis showed that diabetes, hyperlipidemia, elevatedserum levels of sVEGFR-1, and reduced levels of PLGF and VEGF were independentlyassociated with poor coronary collateralization.Conclusion：Increased serum levels of sVEGFR-1correlate positively with the presenceof poor coronary collateralization in patients with stable coronary artery disease. Type2diabetes is an important factor which adversely affects coronary collateral growth in thesepatients.Part III. Comoparative value of cystatin C-versus creatinine-based renaldysfunction in the evaluation of coronary collateralization in patients with stableangina and chronic total occlusion Background: Renal impairment with decreased estimated glomerular filtration rate(eGFR) represents an independent risk factor for poor coronary collateral development.We investigated whether eGFR determined with cystatin C-based equation (eGFRcys) issuperior to that with creatinine-based formula (eGFRcr) for evaluating coronarycollateralization in patients with stable angina and chronic total occlusion.Methods: We determined eGFRs with cystatin C-and creatinine-based equations in427patients with stable angina and angiographic total occlusion of at least one major coronaryartery. GFRcr(mL/min/1.73m2)=[186.3x creatinine-1.354(mg/dl) x age-0.203x0.742(iffemale)][13,26]; GFRcys(mL/min/1.73m2)=[133x cystatin C/0.8-0.499(mg/L) x0.996agex0.932(if female)], when serum cystatin C≤0.8mg/L or GFRcys=133x cystatin C/0.8-1.328(mg/L) x0.996agex0.932(if female)], when serum cystatin C>0.8mg/L. The degree ofcollaterals supplying the distal aspect of a total occlusion from the contra-lateral vesselwas graded as poor (Rentrop score of0or1) or good collateralization (Rentrop score of2or3).Results: Both eGFRcrand eGFRcyswere lower in patients with poor (n=157) than in thosewith good collateralization (n=270). However, eGFRcyscorrelated more closely withRentrop score than eGFRcr(Spearmen’s r=0.39vs. Spearmen’s r=0.28, P=0.048). Thearea under the curve of eGFRcyswas larger compared with that of eGFRcr(0.75vs.0.67, P=0.001) for detecting poor collateralization (72.2%vs.66.7%), along with a netreclassification improvement of11.8%(P=0.044) and an integrated discriminationimprovement of8.8%(P <0.001). The result patterns did not change when subgroupswere stratified by presence or absence of diabetes, hypertension, and dyslipidemia.Conclusions: Cystatin C-based definition of renal dysfunction indicates a potential betterclinical utility than creatinine-based equation for detecting poor coronary collaterals inpatients with stable angina and chronic total occlusion.Part IV. Effects of type1diabetes on arteriogenesis in a C57BL/6J male rat modelwith low-limb ischemic injuryPurpose：We assessed the effects of type1diabetes on arteriogenesis using a C57BL/6J male mice model with low-limb ischemic injury.Methods:In C57BL/6J male mice, type1diabetes model was established by intraperitoneal injection of streptozococin, and low-limb ischemic injury was created by ligation of the right femoral artery. After3weeks, the degree of low-limb ischemic injury was assessed using HE staining of the cross-sectional area for the right gastrocnemius muscles and arteriogenesis was evaluated by assessing collateral morphology using HE staining of the right gracilis muscles. Western blot was performed to determine the expression of VEGFR-1and sVEGFR-1proteins in gastrocnemius muscles.Results:Three weeks after ligation of the right femoral artery, HE staining revealed that ischemia injury of right gastrocnemius muscles was mild in control mice, but became more obvious in type1diabetic mice. The cross-sectional area was doubled in control mice, but was unchanged in type1diabetic mice. Western blotting showed that the expression of VEGFR-1and sVEGFR-1proteins was higher in right gastrocnemius muscles than that in left gastrocnemius muscles.Conclusion:This study indicates that expression of VEGFR-1and sVEGFR-1is significantly increased in the ischemic gastrocnemius muscles. Type1diabetes adversely affects collateral remodeling in hindlimb mice.