The Relationship Between Diastolic Blood Pressure And Coronary Collateral Circulation In Patients With CTO Lesion

Background Coronary collateral circulation (CCC) development involves capillarycollaterals develop and muscular collateral arteries develop (arteriogenesis). Arteriogenesisplays an important role in alleviating myocardial ischemia. The most significantbiomechanical trigger of arteriogenesis is the increased tangential fluid shear stress (FSS)at the endothelial surface. The tangential FSS is closely related to the fluid flow velocityand it is known to all that blood pressure determines the blood flow velocity in vivo. Thecoronary circulation is unique in that most of the coronary blood flow to the myocardiumoccurs in diastole, so the diastolic blood pressure (DBP) may influence the tangential FSSof the endothelial surface by influencing the coronary artery blood flow velocity in diastole,and thus affecting the development of CCC. The “J-curve” relationship between the DBPand adverse cardiovascular events had been reported in many studies. The range of DBPwith the lowest incidence of adverse cardiovascular events is called “J point”.Objective1. Examining the predictors of the existence of well collateral circulation inpatients with stable angina pectoris (SAP) and chronic total occlusion (CTO).2.Establishing the more precise relationship between DBP and CCC to see whether there is a“J-curve” relationship between DBP to CCC and where the “J point” is.MethodsFirst part The study group consisted of222patients with SAP and CTO. The extent ofCCC to the area perfused by the CTO-related artery was graded as poorly (n=38) or well(n=184) developed collaterals, assessed by Rentrop classification. Univariate and logisticmultivariate analysis were performed on all clinical and angiographic factors to identifysignificant predictors of the presence of well-developed collateral circulation.Second part We conducted a study of671patients with CTO lesion. The patients weredivided into six groups for their DBP level (<65mmHg, n=53;>65mm-≤75mmHg, n=103;>75mm-≤85mmHg, n=256;>85-≤95mmHg, n=147;>95-≤105mmHg, n=82; >105mmHg, n=30). We compared the poor CCC incidences of different DBP groups to seewhether the “J-curve” relationship existed between the DBP and CCC. We would identifythe “J-point” according to the DBP group with the lowest poor CCC incidence.ResultsUnivariate analysis showed no statistically significant difference between the studysubgroups in terms of gender, age, body mass index, left-ventricular ejection fraction,diabetes mellitus, hypertensive disease, smoking, duration of coronary artery occlusion,history of myocardial infarction, SBP, pulse pressure, mean arterial pressure, use ofantihypertensive medication, serum fast blood glucose, total cholesterol,high-density-lipoprotein-cholesterol, low-density-lipoprotein-cholesterol, triglyceride,creatinine, hematocrit, position of CTO lesion, coronary vessels diseased or in thecondition combined with left main coronary artery disease. There was a significantdifference between the subgroups in terms of the prevalence of high DBP and in meanDBP.In multiple regression analysis with clinical and angiographic variables, high DBPwas the only independent positive predictor of well-developed CCC (p=0.0079).The incidence of poorly developed collaterals reduced from49.1%to25.2%, whenthe DBP level increased from≤65mmHg to>85mmHg-≤95mmHg. Then theincidence of poorly developed collaterals increased from25.2%to56.7%, when the DBPlevel increased from>85mmHg-95mmHg to>105mmHg. The DBP waving from75-95mmHg had the lowest incidence of poorly developed collaterals.Conclusion1. DBP is an independent predictor of CCC in patients with SAP and CTO. And thereis a “J-curve” relationship between the degree of CCC and the level of DBP in patientswith CTO lesion.2. The DBP waving from75mmHg to95mmHg is the optimal “J point” for the welldevelopment of CCC.