Magnetic resonance imaging in the assessment of coronary artery disease

Magnetic resonance imaging (MRI) is gaining importance in cardiology as the noninvasive test of choice for patients with a multitude of cardiovascular problems. Recently, cardiovascular MRI has emerged as an important noninvasive diagnostic modality in the assessment of coronary artery disease. Because of its superior spatial resolution, integration of qualitative and quantitative methodology, and excellent reproducibility, MRI has advantages over conventional noninvasive modalities currently used in the evaluation of coronary artery disease. This article reviews the rapidly expanding recent literature that has now established cardiovascular MRI as an ideal choice in the evaluation of myocardial ischemia (including dobutamine cine MRI and vasodilator perfusion MRI techniques). We further discuss the role of delayed contrast-enhanced MRI and low-dose dobutamine cine MRI for evaluation of myocardial viability. Comparisons with more established techniques, such as dobutamine stress echocardiography, single-photon emission computed tomography perfusion imaging, and positron emission tomography, are reviewed.     

Usefulness of cardiac magnetic resonance imaging for coronary artery disease detection

Cardiac magnetic resonance imaging (cMRI) is a promising non-invasive technique to assess the presence of coronary artery disease (CAD), which is free of ionizing radiation and iodine contrast. cMRI can detect CAD by angiographic methods or indirectly by perfusion stress techniques. While coronary angiography by cMRI remains limited to research protocols, stress perfusion cMRI is currently being applied worldwide in the clinical setting. Studies have shown good correlation between adenosine-induced stress myocardial perfusion cMRI and single-photon-emission computed tomography or positron emission tomography to detect CAD. Quantitative methods to analyze cMRI perfusion data have been developed in an attempt to provide a more objective imaging interpretation. Standardization of such quantitative methods, with minimal operator dependency, would be useful for clinical and research applications. Myocardial perfusion reserve (MPR), calculated using Fermi deconvolution technique, has been compared with well established anatomical and physiological CAD detection techniques. MPR appears to be the most accurate quantitative index to detect anatomical and hemodynamically significant CAD. Beyond physiological assessment of CAD, cMRI provides information regarding regional and global left ventricular function and morphology, myocardial infarction size, transmurality and viability. Such comprehensive information would require the performance of multiple tests if other modalities were used. This article describes current applications of cMRI for evaluation of patients with CAD.     

Environmental impact of cardiac imaging tests for the diagnosis of coronary artery disease

The use of cardiovascular imaging is growing inexorably and concerns have been expressed about its cost and radiation safety. In this study, the relative environmental impact of MRI, single photon emission tomography and cardiac ultrasound (echo) for the diagnosis of coronary artery disease were examined. The results emphasise that echo causes the least environmental impact at each stage of its life cycle. The effect of one echo on human health, ecosystem effects and resource use was of the order of 1-20% of those of the alternative methods. Although there are circumstances in which one imaging modality is preferred on clinical grounds, when everything else is equal, these results support the selection of echocardiography as the preferred test on environmental grounds.     

Rapid cardiac hybrid imaging with minimized radiation dose for accurate non-invasive assessment of ischemic coronary artery disease

Background

Ischemic coronary artery disease (CAD) is a major cause for morbidity and mortality resulting in a continuously increasing number of diagnostic interventions. We have validated a new hybrid imaging method using minimized radiation dose for rapid non-invasive prediction of invasive coronary angiography (CA) findings with regard to coronary lesion detection and revascularization.

Methods

Forty patients referred for elective invasive coronary angiography (CA) due to suspected CAD were prospectively enrolled to undergo a low-dose CTCA with prospective ECG-triggering and a stress-only SPECT-MPI scan administering half of the standard low-dose stress ^99mTc-tetrofosmin activity. The latter was acquired immediately after adenosine stress (omitting the standard 30-60 min waiting time). After fusing CTCA and SPECT-MPI decisions towards conservative management versus revascularization strategy based on hybrid images were compared to the decisions taken by the interventional operator in the catheterization laboratory based on CA. The latter served as standard of reference.

Results

Hybrid images yielded sensitivity, specificity, positive and negative predictive values and accuracy of 100%, 96.0%, 100%, 93.8% and 97.5% for predicting coronary revascularization. The estimated mean effective radiation doses were significantly lower for hybrid imaging (4.7 ± 1.0 mSv) than for invasive CA (8.7 ± 4.2 mSv; P < 0.001 vs. hybrid). Total non-invasive protocol time was below 60 min, comparing favourably to standard SPECT protocols.

Conclusions

Rapid cardiac hybrid imaging allows accurate prediction of invasive CA findings and of treatment decision despite minimized radiation dose and protocol time.     

多巴酚丁胺负荷超声心动图结合组织多普勒应变率成像技术诊断老年人冠心病的研究

目的探讨多巴酚丁胺负荷超声心动图(DSE)结合组织多普勒应变率成像技术(SRI)诊断老年人冠心病的临床价值。方法 98例老年疑诊冠心病的患者行DSE+SRI检查,测定不同多巴酚丁胺负荷剂量时各心室壁中段收缩期心肌峰值应变率(SRpeak),2周内完成冠状动脉造影(CAG),对比分析SRpeak和CAG对老年人冠心病的诊断价值。结果与CAG相比,SRpeak诊断老年人冠心病敏感度、特异度、准确度分别为71.7%、82.2%、78.0%;SRpeak在不同多巴酚丁胺负荷剂量时诊断的敏感度和特异度不同,在40μg·kg~(-1)·min~(-1)负荷剂量时最高,分别为75.0%、90.4%;对于三支冠状动脉血管的定位诊断均表现为高特异度。结论多巴酚丁胺负荷定量应变率成像是一项安全、有效、无创诊断老年人冠心病的方法。     

多巴酚丁胺负荷组织多普勒诊断老年冠心病的临床价值

目的 探讨多巴酚丁胺负荷超声心动图(DSE)与定量组织多普勒技术(TDI)相结合诊断老年冠心病的临床价值. 方法 98例老年患者行DSE与TDI相结合检查,测定不同多巴酚丁胺负荷剂量时各室壁中段收缩期心肌运动峰值速度(Vpeak)、收缩期心肌峰值位移(Dpeak)、收缩期峰值应变率(SRpeak)、收缩期峰值应变(Speak),2周内完成冠状动脉造影. 结果 和冠状动脉造影相比,Vpeak、Dpeak、SRpeak、Speak诊断老年人冠心病的敏感性、特异性、精确性分别为Vpeak82.4％、61.7％ 、72.4％,Dpeak 82.4％、59.5％、71.4％,SRpeak 71.7％、82.2％、78％,Speak 78.6％、72.3％、74.7％.DSE+ TDI不良反应轻. 结论 DSE与TDI是一项安全、有效、无创诊断老年冠心病的方法,具有较高的敏感性和特异性.     

腺苷负荷试验心肌灌注显像在老年人冠心病中的临床应用

目的 评价腺苷负荷试验心肌灌注显像在诊断老年人冠心病的准确性及临床应用的特点.方法 63例临床疑诊冠心病或已诊断但病情不稳定需介入治疗老年患者,住院后分别行腺苷负荷试验心肌灌注显像和冠状动脉(冠动)造影检查.腺苷负荷试验心肌灌注采用单光子发射断层显像图像采集系统,腺苷以140μg·kg-1·min-1静脉注射,用药时间6 min,注射过程中全程监测心电图、血压及患者的症状.于注射腺苷3 min末,静脉注射核素显像剂99cm Tc-MIBI 925 MBq,1.5 h后行心肌灌注断层显像,若显像异常,次日行静息心肌显像.冠脉造影按常规程序,在腺苷负荷试验心,肌灌注显像前后1周内进行.结果 63例中,53例冠脉造影阳性,10例阴性,而腺苷负荷试验心肌灌注显像51例阳性,7例阴性.腺苷负荷试验心肌灌注显像诊断老年人冠心病的总体敏感性为96.2%,特异性为70.0%,阳性预测值94.4%,阴性预测值77.8%,准确性为92.1%.53例冠脉造影显示,冠脉狭窄病变中,单支病变29例,二支14例,三支10例;累及左前降支(LAD)44支,左回旋支(LCX)18支,右冠脉(RCA)25支.腺苷负荷试验心肌灌注显像判断血管病变以LAD敏感性最高,达到95.5%;RCA次之,为84.0%;LCX最差,仅为55.6%;但特异性可达100%.监测过程中,32例(50.0%)患者发生胸闷、胸痛、头晕、头痛等不良反应,无严重事件发生.结论 腺苷负荷心肌灌注显像诊断老年人冠心病的敏感性、特异性高,尤其对探查和定位严重的冠脉病变准确性更高;腺苷负荷试验过程中副作用小,且因检查无创,因此在老年人冠心病的临床诊断应用中具有重要的价值.     

老年稳定型冠心病患者的衰弱评估与预后分析

目的评估稳定型老年冠心病(CAD)患者衰弱的发生情况,分析与衰弱相关的指标,以及研究衰弱对稳定型CAD患者短期预后的影响。方法连续入选2014年12月1日至2015年4月30日期间在北京协和医院心内科及老年医学科门诊就诊的老年患者153例,进行老年综合评估及临床衰弱量表(《2FS)评估,运用CAD特异性指数来量化共存基础疾病的影响。随访患者非常规就诊(URV)及全因死亡发生率。结果依据CFS评估结果,将153例患者分为两组:衰弱组(n=69,45.10%)和非衰弱组(n=84,54.90%)。其中,中-重度衰弱患者33例,占21.57%(33/153)。与非衰弱组相比,衰弱组患者的握力和步速显著降低,而炎症指标超敏C-反应蛋白(hs-CRP)和白细胞介素-6(IL-6)显著增高,差异均具有统计学意义(P0.05)。步速的衰弱诊断界值为:男性0.879 m/s;女性0.870 m/s。握力的衰弱诊断界值为:男性29.85 kg;女性19.50 kg。,Cox回归分析显示,CFS评分是稳定型CAD患者URV(HR:3.312;95%CI:1.439~7.621;P=0.005)的独立风险预测因子。结论老年CAD患者衰弱的发生率较高,尤其中-重度衰弱患者需要得到关注。步速和握力均可作为衰弱评估的指标。CFS评分是老年冠心病患者URV的独立风险预测因子。     

Invasive treatment for coronary artery disease in the elderly

The widespread availability of coronary artery bypass grafting and percutaneous transluminal coronary angioplasty presents important treatment options for the older patient. The findings from a number of surgical series of coronary artery bypass grafting and percutaneous transluminal coronary angioplasty are summarized. Certain trends are evident. Perioperative mortality, cardiovascular morbidity, and other complications, while declining, remain somewhat higher in elderly patients. However, the impact of age alone is slight. In both coronary artery bypass grafting and percutaneous transluminal coronary angioplasty, complications are more closely correlated with the presence of serious concomitant disease. Long-term survival and pain relief after coronary artery bypass grafting are excellent in older patients, and percutaneous transluminal coronary angioplasty may be the treatment of choice in some elderly patients with coronary artery disease. As in younger patients, prolongation of survival should not be the exclusive goal. Rather, a focus on quality of life and freedom from dependency should be seriously considered.     

Magnetic resonance imaging in detection and functional assessment of coronary artery disease

The past few years have brought significant improvements in the field of cardiovascular magnetic resonance imaging (MRI), which evolved from an experimental technique to a clinically accepted method of coronary artery disease detection (stress MRI) and viability assessment. In this article, we describe current MRI technology for detection and functional assessment of ischemia, such as dobutamine/atropine MRI, perfusion techniques, viability, and flow reserve in native coronary arteries and grafts. With further refinement in the technology, wide acceptance of cardiovascular MRI is anticipated in clinical practice.     

Atherosclerosis imaging and calcified plaque: coronary artery disease risk assessment

Over the last decade, there has been increased recognition that atherosclerosis imaging adds greatly to the ability to identify patients at high risk for cardiac events. Technologies such as electron beam computed tomography and carotid intimal media thickness have contributed significantly to our understanding of the prevalence of preclinical atherosclerosis and its consequences. Guidelines and policy toward these modalities have shifted, with increased recognition of the importance among experts in cardiology, lipidology, and preventive medicine. Because most adverse events related to atherosclerosis occur in individuals at an intermediate risk, data suggest that it will be most cost-effective to concentrate screening efforts on this group of patients. This article reviews the current understanding of the value of coronary artery calcium screening in asymptomatic and symptomatic patients. The validity of measuring coronary artery calcium with new multislice computed tomography scanners is also reviewed. Accurate measurement of subclinical coronary atherosclerosis should significantly improve the accuracy of global cardiovascular risk prediction and allow for tracking of atherosclerosis burden as well as better prediction of future cardiovascular events.     

衰弱评估在老年冠心病患者心脏康复治疗中的应用

随着医疗技术水平的进步,人类预期寿命大大增加,然而随着年龄的增加衰弱与心血管疾病的患病率也不断上升,老年人尤其如此。目前,国内关于衰弱与心血管疾病相关性的研究报道尚不多。本文重点关注衰弱评估中的肌力评估与步速评估在老年冠心病患者心脏康复治疗中的应用,以期说明衰弱评估对于预测老年冠心病患者心脏康复预后的重要性,希望能够引起临床各相关学科的重视,旨在为老年冠心病患者心脏康复的诊疗及预防提供新思路。     

Noninvasive imaging for coronary artery disease: a technology assessment for the Medicare Coverage Advisory Commission

This report describes a review of the available scientific evidence through 2005 on direct noninvasive imaging tests (NITs) for coronary artery disease. In particular, the report addresses 6 key questions provided by the Agency for Healthcare Research and Quality and the Centers for Medicare and Medicaid Services. The questions examine the degree to which current evidence supports confident judgments about the use of NITs in the assessment of native coronary artery stenosis in clinical practice. The 2 NITs that are examined in detail in this report are 16 (and higher)-multidetector computed tomography angiography and 1.5-T magnetic resonance angiography to evaluate for stenosis in native coronary arteries. Reported sensitivity of NITs ranged from 68% to 100%; reported specificity ranged from 57% to 100% (patient-based analysis). Limitations include the exclusion of significant numbers of segments and patients, with often only the proximal coronary segments visualized. There is no direct evidence assessing the clinical use of NITs in terms of the incremental benefits or risks compared to alternative testing strategies. Although the ability of noninvasive direct coronary imaging technologies is promising-particularly the 64-multidetector computed tomography angiography-the evidence does not provide strong guidance on whether and how such technologies should be used in the population generally, or for Medicare beneficiaries specifically. Informed clinical and policy decision making will require further study of these technologies in well-characterized clinical contexts, in typical practice settings, and with attention to impact on management and health outcomes.     

老年冠心病患者冠状动脉病变特点

目的探讨老年冠心病患者冠状动脉的病变特点。方法临床诊断冠心病患者602例,其中老年女性207例(老年女性组),经冠状动脉造影确诊123例,中青年女性129例(中青年女性组),老年男性266例(老年男性组)。对比分析老年女性组与中青年女性组患者冠状动脉造影阳性率,老年女性组与老年男性组患者冠状动脉病变的不同特点。结果老年女性组不稳定性心绞痛和急性心肌梗死冠状动脉造影阳性率显著高于中青年女性组(77.3%vs57.7%,95.8%vs66.7%,P<0.01),两组患者稳定性心绞痛和陈旧性心肌梗死无统计学差异((78.2%vs76.5%,95.0%vs100.0%,P>0.05)。冠状动脉造影阳性的老年女性组与老年男性组患者不同临床类型的冠状动脉病变血管支数无统计学差异(P>0.05),老年女性组稳定性心绞痛和陈旧性心肌梗死冠状动脉Gensini积分均显著高于老年男性组[(54±7)分vs(46±5)分,(78±9)分vs(68±4)分,P<0.05],两组患者冠状动脉病变分布无统计学差异(P>0.05)。结论老年女性患者冠状动脉病变阳性率高于中青年女性,部分老年女性患者冠状动脉病变程度较老年男性患者重。     

The treatment of coronary artery disease in the elderly

Changing population demographics dictate that in the next decade physicians will be increasingly faced with treating coronary artery disease in the elderly. Despite this, there is a paucity of data to guide management decisions in this population. Currently, it appears that "low-risk" or mild coronary artery disease can be treated medically so long as appropriate adjustments are made for aging changes in renal function, hepatic metabolism, noncompliance, multisystem disease, etc. Unfortunately, most elderly patients have "high-risk" or severe coronary artery disease. Balloon dilatation can yield excellent results in certain highly selected "high-risk" patients, but its role in the frequently encountered multivessel disease patient is unclear until current studies are completed. Coronary bypass grafting in selected patients clearly prolongs survival, but careful patient selection and meticulous preoperative and postoperative is required. Finally, the importance of issues such as quality of life, function independence, and cost must be addressed in more detail if physicians are to make rational decisions in treating this expanding population.     

Noninvasive assessment of coronary artery disease

This study determines whether a mathematical model can be used to assess noninvasively the extent of coronary artery disease (CAD). The model was based on stepwise multivariate discriminant analysis of data obtained in 99 patients from clinical and nonhemodynamic exercise variables, or from radionuclide determination of left ventricular function at rest or during exercise, or both. The extent of CAD was assessed by a scoring system and by the number of diseased vessels.The variables selected by this method (Q-wave infarction, exercise LV ejection fraction, change in systolic blood pressure from rest to exercise, sex and diabetes mellitus) yielded a predictive accuracy of 82% for the identification of patients with extensive CAD (score ≥ 35). Slightly better results were achieved by a subgroup of 77 patients who had adequate exercise end points (exercise heart rate ≥ 120 beats/min, or angina or ST depression during exercise). In these patients, the predictive accuracy was 84%. The model also identified patients with “light” CAD (score ≤ 10) with a predictive accuracy of 82%.Thus, noninvasive assessment of the extent of CAD is possible with a stepwise multivariate discriminant analysis of clinical, electrocardiographic and left ventricular function assessed by radionuclide ventriculography at rest and during exercise. The scoring system was superior to the conventional method of classifying patients according to the number of diseased vessels.     

Myocardial perfusion imaging in coronary artery disease

Radionuclide myocardial perfusion imaging (MPI) can be used to demonstrate the presence of coronary heart disease and to risk stratify and guide management of patients with known disease. It has the ability to localize hemodynamically important coronary stenoses, and assess the extent and severity of coronary obstruction by the presence and extent of perfusion defects. A normal stress MPI indicates the absence of coronary obstruction and hence of clinically significant disease. Cardiac PET has the advantage from SPECT of higher spatial and temporal resolution, and a decreased radiation exposure to patients. Hybrid cardiac imaging combining SPECT or PET with CT data appears to offer superior diagnostic and prognostic information in patients with intermediate risk for CAD. A significant progress in better quantification of myocardial blood flow and coronary flow reserve has recently been seen. Also several studies have demonstrated that the combination of imaging apoptosis and matrix metalloproteinases production can help imaging vulnerable plaque and identifying the group of high-risk asymptomatic patients who will benefit most by an imaging procedure.     

Tissue Doppler imaging for the diagnosis of coronary artery disease

PURPOSE OF REVIEW: Tissue Doppler imaging (TDI) is a diagnostic method that provides quantitative data about myocardial function. The present review discusses the most recent developments in the application of TDI in coronary artery disease. RECENT FINDINGS: The most widely used TDI modality is velocity imaging, and systolic function is measured as peak velocity during LV ejection. Several recent studies show that TDI measurements during the LV isovolumic phases provide unique information regarding myocardial dysfunction. Since velocity imaging is confounded by influence from velocities in other segments, the TDI-based modalities strain- and strain rate imaging (SRI) have been introduced to measure regional shortening fraction and shortening rate, respectively.Velocity imaging during stress echocardiography has been validated clinically and appears equivalent, but not superior to conventional visual assessment of grey scale images. Potentially, more comprehensive evaluation that includes the use of SRI may improve the diagnostic power of TDI further. Preliminary reports suggest that TDI may have an important role in the assessment of viability in acute coronary occlusion, but this needs to be demonstrated in appropriately designed clinical trials. SUMMARY: At the present time tissue Doppler velocity imaging can be recommended for clinical use, especially the pulsed mode. Strain rate imaging may be useful as additional imaging, but needs further refinement before it is ready for routine clinical use.     

Efficacy of coronary artery bypass grafting in elderly patients with coronary artery disease

A consecutive series of 121 patients 70 years of age and older who underwent aortocoronary artery saphenous vein bypass grafting without other cardiac procedures during a 5 year period was analyzed and follow-up status ascertained. This group was compared with a consecutive series of 2,850 patients under the age of 70 who underwent aortocoronary bypass during the same period. The patients aged 70 years or greater had a higher incidence of unstable angina pectoris, congestive heart fallure and cardlomegaly on roentgenography. They had more severe coronary obstruction with a 29 percent incidence rate of left main coronary disease versus a 15 percent incidence rate in the patients aged less than 70 years (P < 0.001). The hospital mortality rate for patients aged less than 70 years was 1.1 percent (31 of 2,850) and for those aged 70 years or greater was 1.6 percent (2 of 121). The 119 patients aged 70 years or greater who survived surgery had a significantly greater incidence of postoperative stroke (3 patients), supraventricular tachycardia (28 patients), transient postoperative psychosis (9 patients), heart block requiring permanent pacing (2 patients), intraaortic balloon pumping (5 patients) and pulmonary embolism (4 patients) than patients aged less than 70 years. Both groups had significant symptomatic improvement: More than 95 percent of the survivors in each group were angina-free or in improved condition at late follow-up. Survival at 36 months was 95 percent for the patients in both age groups. A subgroup of patients aged 75 years or greater had comparable symptomatic results and survival. Patients aged 70 years or greater need not be denied the benefits of coronary bypass surgery on the basis of advanced age alone, although these patients have complfcations of surgery more frequently. However, severe calcification of the ascending aorta is a relative contraindication to saphenous vein bypass surgery in this age group.     

A contemporary role of coronary artery calcium scoring in the assessment of the risk for coronary artery disease

The growing prevalence of coronary artery disease, also in younger population, inspires constant development of coronary atherogenesis risk stratification and early diagnosis methods. The coronary artery calcium score is a simple parameter, requiring only a relatively small radiation dose to obtain in computed tomography. So far completed studies have provided consistent evidence in support of its specificity to exclude coronary artery disease, along with its predictive value for future cardiac events. Our paper is a review of peerviewed journals regarding in coronary artery calcium scoring, including the most recent guidelines on its use in establishing a diagnosis of coronary artery disease.