ABSTRACT
Cardiovascular disease is one of the most serious diseases endangering human life and health. In China, 2 out of every 5 people die of cardiovascular diseases. Myocardial ischemia is one of the important cardiovascular diseases. Fractional flow reserve (FFR) is used to quantify myocardial ischemia in epicardial stenoses. Index of microvascular resistance (IMR) is an invasive index for quantitative evaluation of coronary microcirculation. Traditional FFR and IMR measurements rely on guide wires to perform interventional measurements under the maximum hyperemia state,so as to assist the diagnosis of myocardial ischemia clinically. Coronary angiography-derived FFR and IMR without using invasive pressure-wire measurement, hyperemic stimulus and contraindications can assist the diagnosis and treatment of percutaneous coronary intervention by fast simultaneous calculation of FFR and IMR. In this review, the research progress of coronary angiography-derived FFR and IMR as well as other coronary physiological evaluation in recent years were summarized. It is of great clinical value to further study the combination of coronary angiography-derived FFR and IMR in functional research of coronary circulation from macro to micro.
ABSTRACT
The dysfunction of coronary microcirculation is an important cause of coronary artery disease (CAD). The index of microcirculatory resistance (IMR) is a quantitative evaluation of coronary microcirculatory function, which provides a significant reference for the prediction, diagnosis, treatment, and prognosis of CAD. IMR also plays a key role in investigating the interaction between epicardial and microcirculatory dysfunctions, and is closely associated with coronary hemodynamic parameters such as flow rate, distal coronary pressure, and aortic pressure, which have been widely applied in computational studies of CAD. However, there is currently a lack of consensus across studies on the normal and pathological ranges of IMR. The relationships between IMR and coronary hemodynamic parameters have not been accurately quantified, which limits the application of IMR in computational CAD studies. In this paper, we discuss the research gaps between IMR and its potential applications in the computational simulation of CAD. Computational simulation based on the combination of IMR and other hemodynamic parameters is a promising technology to improve the diagnosis and guide clinical trials of CAD.
Subject(s)
Humans , Coronary Angiography , Coronary Artery Disease , Coronary Circulation , Microcirculation , Predictive Value of Tests , Vascular ResistanceABSTRACT
Objective@#To explore the value of index of microcirculatory resistance (IMR) for early prediction of periprocedural myocardial injury (PMI) in patients with stable angina pectoris (SAP) and acute coronary syndrome (ACS) after PCI.@*Methods@#It was a prospective study. One hundred and sixty-four patients who had single coronary lesion were consecutively enrolled from May 2014 to December 2017 at Nanjing Hospital affiliated to Nanjing Medical University. According to clinical manifestation, patients were divided into SAP group (n=81) and ACS group (n=83). IMR was determined by thermal dilution with pressure guide wire. Basic clinical characteristics, coronary angiographic results, PCI procedural details, IMR after PCI, ΔIMR (IMR=post-PCI-IMR pre-PCI), levels of myocardial biomarkers before and after PCI were compared between the two groups. Multivariate logistic regression was used to analyze the relation of PMI with IMR and ΔIMR, and the predictive ability was evaluated by receiver operating characteristic (ROC).@*Results@#The levels of total cholesterol and low density lipoprotein cholesterol were significantly higher in ACS group than in SAP group (P<0.05), other clinical data at baseline were similar between the two groups (P>0.05). Quantitative coronary angiography (QCA) results and PCI related data were also similar between the two groups before PCI (P>0.05). Values of mean transit time (Tmn) of intracoronary injection with room temperature saline, post-PCI IMR and ΔIMR were significantly higher in ACS group than in SAP group after PCI (P<0.05). Plasma creatine kinase isoenzyme-MB difference (ΔCK-MB) (ΔCK-MB=CK-MB post-PCI-CK-MB pre-PCI) and cardiac troponin-I (cTnI) difference (ΔcTnI=cTnI post-PCI-cTnI pre-PCI) were significantly larger in ACS group than in SAP group (P<0.05). Multivariate logistic regression analysis showed that coronary artery disease (CHD) type (SAP and ACS) (OR=1.301, 95%CI 1.083-1.562), age (OR=1.007, 95%CI 1.000-1.013), ΔIMR (OR=1.009, 95%CI 1.000-1.017) and post-PCI IMR (OR=1.008, 95%CI 1.001-1.014) were independent predictors of PMI (P<0.05). The area under the ROC curve (AUC) of ΔIMR was 0.763 to predict PMI (P<0.05), the optimum cut-off value of ΔIMR was 5.485 with 70.0% sensitivity and 77.4% specificity. ΔIMR was positively correlated with ΔcTnI (r=0.592, P<0.05).@*Conclusions@#ΔIMR serves as an early predictor of PMI in CHD patients after PCI. As compared with SAP patients, ACS patients are more likely to develop PMI.
ABSTRACT
Objective To evaluate the impact of cardiovascular risk factors on index of microvascular resistance (IMR)and coronary flow reserve (CFR) and to explore the characteristics of IMR and CFR and the relationship between IMR and angiographic features in patients with intermediate coronary stenosis and chest pain.Methods Fractional flow reserve (FFR),CFR,and IMR were measured in patients who underwent invasive coronary angiography with 40％-70％ stenosis by visual assessment.All patients with FFR＞0.75 were enrolled and grouped with the cut-off points of IMR≥25 and CFR≤2.0.Patients with IMR≥25 were group H,including two sub-groups (high IMR-low CFR,group H1 and high IMR-high CFR,group H2),while those with IMR＜25 were group N.The thrombolysis in myocardial infarction (TIMI) frame were counted.Results A total of 34 patients with FFR＞0.75 were enrolled with 61.8％(21 cases) of males and 38.2％ (13 cases) of females.The mean age was (57.3±8.1) years old.High IMR accounted for 47.1％ of all cases.There was significant difference between group H and N in TIMI frame (33.0 vs.20.8,P=0.031).There were significant differences between group H1 and H2 in homocysteine (17.8 μmol/L vs.12.0 μmol/L,P=0.005) and IMRcorr (58.0 vs.36.1,P=0.002).IMRcorrwas correlated to TIMI frame (r=0.40,P=0.012) for all cases.The sensitivity and specificity of inferring IMR≥35.3 by TIMI frame were 0.75 and 0.65 (P=0.049) with TIMI frame over 40.5.Conclusions High IMR may be one of the reasons for chest pain in patients with intermediate coronary stenosis.There is no correlation between vascular risk factors and IMR or CFR,while there is positive correlation between TIMI frame and IMR.The specificity is 65％ for inferring IMR rise with TIMI frame over 40.5.
ABSTRACT
Objective To evaluate the status of microcirculation and to compare the short-term prognosis after elective PCI for AMI between patients with poorly controlled type2 diabetes and patients without type 2 diabetes. Methods According to the clinical history and HbA1c values,all patients were divided into 2 groups:diabetic group (group A,n=24) and non-diabetic group (group B,n=32).Basic clinical data, left ventricular end diastolic diameter (LVEDD) and left ventricular shot ejection fraction (LVEF)immediately and 3 months after operation measured by echocardiography and the result of coronary angiography were compared between the two groups. The rate of MACE 3 months after PCI was also compared. A pressure-temperature sensor wire was used to measure the index of microcirculation resistance(IMR)immediately after PCI. Results 1.The mean IMR value in group A was higher than group B(29.12±7.45)vs.(22.74±6.87);P=0.011.The HbA1c levels has positive correlation with the IMR value(r=0.324;P=0.048). 2. The mean LVEDD and the mean LVEF Rad no signifi cant diff erence between two groups before PCI. The mean LVEDD of group A at 3 months after PCI was significantly larger than group B(52.3±4.8)mm vs.(48.6±5.1)mm,P=0.019,the mean LVEF of group A 3 months post PCI was lower than that of group B(48.6±7.3)% vs.(56.1±4.7)%,P=0.003.The mean increase in LVEDD at 3 months after PCI in group A was higher than group B(4.1±6.3)mm vs.(0.8±4.4)mm, p=0.005 and the mean increase in LVEF in group A was significantly lower than in group B(–1.9±6.8)% vs. (4.3±5.4)%,P=0.007. 3. HbA1chad positive correlation with LVEDD(r=0.324,p=0.048)and its increase at 3 months postoperatively(r=–0.422,P=0.005).4. Risk estimation found type 2 diabetes was an independent risk factor for poor recovery of LVEF. The MACE rate was signifi cantly higher in Group A than in Group B(35.7% vs.9.4%,P=0.018).Conclusions Patients with type2 diabetes were more prone to suffer from coronary microcirculatory dysfunction and had poor recovery of cardiac function. Poorly controlled type 2 diabetes was an independent risk factor for poor recovery of cardiac function and short-term prognosis was worse in diabetic patients who had elective PCI.
ABSTRACT
Objective To investigate the correlation between morning blood pressure surge and Coronary Microvascular Dysfunction.Methods 58 cases of patients with hypertension in our hospital were given 24 h ambu-latory blood pressure monitoring(ambulatory blood pressure monitoring,ABPM).The coronary microvascular dys-function was estimated by the index of microcirculatory resistance(IMR). All cases were given biochemical test-ing,included TCH,TG,HDL-c,LDL-c and SUA.Results According to whether ABMP was arise,the patient were divided into MBPS group(n=21)and the Non-MBPS group(n=37).24 h,day,night and morning peak of systolic blood pressure were significantly higher in the morning peak group than in the average morning peak group. Multiple linear regression analysis showed that,MBPS,24 h average systolic blood pressure,day average systolic blood pressure,night average systolic blood pressure,and age were independent risk factors for coronary artery disease.Conclusion Morning blood pressure surge is closely related to severity of coronary microcirculation dysfunction. It is an independent risk factor for coronary microcirculation dysfunction. To control the blood pres-sure in patients with hypertension effectively can reduce morning peak target organ damage.
ABSTRACT
We investigated the importance of comprehensive physiologic assessment about culprit vessel in STEMI in estimating long-term clinical outcomes after complete revascularization. Comprehensive physiologic assessment provides additional information about microvascular function in coronary artery disease. This assessment includes three indices, fractional flow reserve (FFR), index of microcirculatory resistance (IMR) and coronary flow reserve (CFR). We have performed the comprehensive physiologic assessment in culprit vessels after successful primary PCI in STEMI patients. Both cases were thrombotic total occlusion in mid right coronary artery with inferior wall STEMI, successfully revascularized with stent implantation after thrombus suction. However, in post PCI physiologic assessment, one case showed overt microvascular damage. CFR was 1.1, and IMR was 75U, which was defined as a combined criterion of low CFR (<2.0) and high IMR (≥25U) in culprit vessel, but the other case showed 2.2 in CFR and 24U in IMR, which suggested no overt microvascular damage. Moreover, we can validate these findings by cardiac MR after primary PCI. Previous studies presented that the presence of overt microvascular damage was significantly associated with worse clinical outcome in patients with coronary artery disease. We suggest that comprehensive physiologic evaluation provides important information about the degree of microvascular damage and long-term clinical outcomes after complete revascularization in culprit vessel in STEMI.
Subject(s)
Humans , Coronary Artery Disease , Coronary Vessels , Myocardial Infarction , Percutaneous Coronary Intervention , Stents , Suction , ThrombosisABSTRACT
Objective To investigate the clinical value of the index of microcirculation resistance(IMR) in the prediction of major adverse cardiac events after PCI in the patients with ST segment elevation myocardial infarction.Methods Forty-eight inpa tients with acute ST segment elevation myocardial infarction(STEMI) in the cardiology department CCU of our hospital from December 2013 to June 2015 were selected,including 38 males and 10 females,and divided into 3 groups according to the measured IMR value after PCI operation:the group A,IMR≤25(n=18);group B,IMR 25 ～ 32 (n =16);group C,IMR≥32 (n =14).Serum NT-ProBNP was collected,and the data in cardiac color ultrasound after PCI and at postoperative 1 year:left ventricular ejection fraction(LVEF) and left ventricular end diastolic diameter(LVEDD),and major adverse cardiac events within 1 years after PCI were also collected.Results The serum of concentrations NT-ProBNP were compared among the three groups[(2 734.83 ± 1 009.40) vs.(4 929.68±611.52) vs.(7 480.64±2 082.78)],and the difference among 3 groups was statistically significant (F=35.449,P=0.000).The difference of LVEF among the three groups had statistal significance[(54.00-±-5.99) vs.(52.31 ± 4.35)vs.(49.29 ±4.68),F=3.376,P=0.043)],and there was no statistical difference among the three groups in LVEDD(P＞0.05).The difference of LVEF at postoperative 1 year among 3 groups had statistical significance[(57.28 ± 5.21)vs.(54.43 ±3.69)vs.(46.43±5.33),F=16.744,P=0.000],and the difference of LVEDD (48.94±1.95)vs.(50.63±2.68)vs.(52.14±2.69) among 3 groups was statistically significant(F=6.875,P=0.002).The differences in the major adverse cardiac events,cases of cardiac death and cases of heart failure after postoperative 1 year among 3 groups were statistically significant(x2 value=6.707,P=0.035;x2 value=6.084,P=0.048);the occurrence of again ACS,again PCI and malignant arrhythmia had no statistical difference among 3 groups(P＞0.05).Conclusion Measurement of IMR after PCI in the patients with STEMI can effectively predict the heart function and the risk of major adverse cardiac events within 1 year.
ABSTRACT
PURPOSE: We aimed to discover clinical and angiographic predictors of microvascular dysfunction using the index of microcirculatory resistance (IMR) in patients with ST-segment elevation myocardial infarction (STEMI). MATERIALS AND METHODS: We enrolled 113 patients with STEMI (age, 56+/-11 years; 95 men) who underwent primary percutaneous coronary intervention (PCI). The IMR was measured with a pressure sensor/thermistor-tipped guidewire after primary PCI. The patients were divided into three groups based on IMR values: Low IMR [31 U (48.1+/-17.1 U), n=37]. RESULTS: The age of the Low IMR group was significantly lower than that of the Mid and High IMR groups. The door-to-balloon time was <90 minutes in all patients, and it was not significantly different between groups. Meanwhile, the symptom-onset-to-balloon time was significantly longer in the High IMR group, compared to the Mid and Low IMR groups (p<0.001). In the high IMR group, the culprit lesion was found in a proximal location significantly more often than in a non-proximal location (p=0.008). In multivariate regression analysis, age and symptom-onset-to-balloon time were independent determinants of a high IMR (p=0.013 and p=0.003, respectively). CONCLUSION: Our data suggest that age and symptom-onset-to-balloon time might be the major predictors of microvascular dysfunction in STEMI patients with a door-to-balloon time of <90 minutes.