Assessment of preoperative cardiac risk with magnetic resonance imaging

Safety and feasibility of dobutamine stress cardiac magnetic resonance for cardiovascular assessment prior to renal transplantation

AIMS

Current guidelines recommend cardiovascular risk assessment prior to renal transplantation. There is currently no evidence for the role of cardiovascular magnetic resonance (CMR) in this population, despite an established evidence base in the non-chronic kidney disease (CKD) population. Our aim is to determine the feasibility and safety of dobutamine stress CMR (DSCMR) imaging in the risk stratification of CKD patients awaiting renal transplantation.

METHODS

CKD patients who were deemed at high risk for coronary artery disease (CAD) and awaiting renal transplantation underwent DSCMR.

RESULTS

Forty-one patients whose median age was 56 years (range 28–73 years) underwent DSCMR. Nineteen were undergoing haemodialysis, 10 peritoneal dialysis and 12 pre-dialysis. The aetiology of the renal failure was diabetes mellitus in 29%, glomerulonephritis in 24%, hypertension in 22% and autosomal dominant polycystic kidney disease in 10%. Thirty-eight patients (93%) achieved the end point, either positive for ischaemia or negative, achieving at least 85% of age-predicted heart rate. Two of them did not achieve target heart rate and one was discontinued because of severe headache. Of the 38 patients who achieved the end point, 35 (92%) were negative for inducible wall motion abnormalities and four (10%) were positive. There were no serious adverse effects.

CONCLUSION

DSCMR is a well tolerated and viable investigation for the cardiovascular risk stratification of high-risk CKD patients prior to renal transplantation. DSCMR already has an established evidence base in the non-CKD population with superiority over other noninvasive techniques. Larger studies with outcome data are now required to define its true utility in the CKD population.

Cardiac risk assessment before non-cardiac surgery

Cardiovascular events account for half of the deaths related to non-cardiac surgery. Identification of a patient's risk and perioperative management appropriate to that risk is important to optimize the clinical outcome of surgery. Key concepts of preoperative cardiac risk assessment are contained within American and European guidelines. Risk indices stratify patients according to clinical and surgery-specific predictors. The most widely used is the Lee index; however, all have limitations. Patients at intermediate and high risk following risk index stratification and assessment of functional capacity require further non-invasive assessment to detect myocardial ischaemia using, for instance, exercise electrocardiography, myocardial perfusion scintigraphy, or stress echocardiography. It can be difficult, however, to decide which technique and predictor is most effective and local practice differs. Invasive coronary angiography is not recommended unless it would be performed in the absence of surgery. Appropriate pain management should be considered in all patients and beta-blockade may improve the outcome in intermediate- and high-risk patients. Identifying patients with risk factors or previously undiagnosed coronary artery disease enables the preoperative cardiac risk assessment to guide long-term treatment.

Assessment of myocardial ischemia with cardiovascular magnetic resonance

Assessment of myocardial ischemia in symptomatic patients remains a common and challenging clinical situation faced by physicians. Risk stratification by presence of ischemia provides important utility for both prognostic assessment and management. Unfortunately, current noninvasive modalities possess numerous limitations and have limited prognostic capacity. More recently, ischemia assessment by cardiovascular magnetic resonance (CMR) has been shown to be a safe, available, and potentially cost-effective alternative with both high diagnostic and prognostic accuracy. Cardiovascular magnetic resonance has numerous advantages over other noninvasive methods, including high temporal and spatial resolution, relatively few contraindications, and absence of ionizing radiation. Furthermore, studies assessing the clinical utility and cost effectiveness of CMR in the short-term setting for patients without evidence of an acute myocardial infarction have also demonstrated favorable results. This review will cover techniques of ischemia assessment with CMR by both stress-induced wall motion abnormalities as well as myocardial perfusion imaging. The diagnostic and prognostic performance studies will also be reviewed, and the use of CMR for ischemia assessment will be compared with other commonly used noninvasive modalities.

Pharmacological stress cardiovascular magnetic resonance

Over the past decade, cardiovascular magnetic resonance (CMR) has evolved into a cardiac stress testing modality that can be used to diagnose myocardial ischemia using intravenous dobutamine or vasodilator perfusion agents such as adenosine or dipyridamole. Because CMR produces high-resolution tomographic images of the human heart in multiple imaging planes, it has become a highly attractive noninvasive testing modality for those suspected of having myocardial ischemia. The purpose of this article is to review the clinical, diagnostic, and prognostic utility of stress CMR testing for patients with (or suspected of having) coronary artery disease.

[Detection of induced myocardial ischemia during stress cardiovascular magnetic resonance]

In the past decade, cardiovascular magnetic resonance (CMR) has evolved considerably. Its clinical applications enable the diagnosis and prognostic assessment of patients with ischemic heart disease. CMR is safe, with absence of any ionizing radiation, and offers the greatest information from a single test, allowing the assessment of myocardial morphology, myocardial function and viability. Stress-CMR can be used for detection and quantification of ischemia. This article analyses the technical approach, the limits and reviews the available literature about diagnostic performance of stress CMR testing and its results in the prognostication of cardiac patients. With further improvements in CMR techniques and the establishment of a standardized study protocol, stress-CMR will play a pivotal role in managing patients with ischemic heart disease.

Preoperative cardiac risk management

Approximately 100 million people undergo noncardiac surgery annually worldwide. It is estimated that around 3% of patients undergoing noncardiac surgery experience a major adverse cardiac event. Although cardiac events, like myocardial infarction, are major cause of perioperative morbidity or mortality, its true incidence is difficult to assess. The risk of perioperative cardiac complications depends mainly on two conditions: (1) identified risk factors, and (2) the type of the surgical procedure. On that basis, different scoring systems have been developed in order to accurately assess the perioperative cardiac risk and to improve the patient management. Importantly, patients with estimated high risk should be tested preoperatively by non-invasive cardiac imaging modalities. According to test results, they can proceed directly to planed surgery with the use of cardioprotective drugs (beta-blockers, statins, aspirin), or to myocardial revascularization prior to non-cardiac surgery. In this review, we discuss the role of clinical cardiac risk factors, laboratory measurements, additional non-invasive cardiac testing, and consequent strategies in perioperative management of patients undergoing noncardiac surgery.

Resource utilization after introduction of a standardized clinical assessment and management plan

INTRODUCTION

A Standardized Clinical Assessment and Management Plan (SCAMP) is a novel quality improvement initiative that standardizes the assessment and management of all patients who carry a predefined diagnosis. Based on periodic review of systemically collected data the SCAMP is designed to be modified to improve its own algorithm. One of the objectives of a SCAMP is to identify and reduce resource utilization and patient care costs.

METHODS

We retrospectively reviewed resource utilization in the first 93 arterial switch operation (ASO) SCAMP patients and 186 age-matched control ASO patients. We compared diagnostic and laboratory testing obtained at the initial SCAMP clinic visit and control patient visits. To evaluate the effect of the SCAMP over time, the number of clinic visits per patient year and echocardiograms per patient year in historical control ASO patients were compared to the projected rates for ASO SCAMP participants.

RESULTS

Cardiac magnetic resonance imaging (MRI), stress echocardiogram, and lipid profile utilization were higher in the initial SCAMP clinic visit group than in age-matched control patients. Total echocardiogram and lung scan usage were similar. Chest X-ray and exercise stress testing were obtained less in SCAMP patients. ASO SCAMP patients are projected to have 0.5 clinic visits and 0.5 echocardiograms per year. Historical control patients had more clinic visits (1.2 vs. 0.5 visits/patient year, P<.01) and a higher echocardiogram rate (0.92 vs. 0.5 echocardiograms/patient year, P<.01)

CONCLUSION

Implementation of a SCAMP may initially lead to increased resource utilization, but over time resource utilization is projected to decrease.

The 20 year evolution of dobutamine stress cardiovascular magnetic resonance

Over the past 20 years, investigators world-wide have developed and utilized dobutamine magnetic resonance stress testing procedures for the purpose of identifying ischemia, viability, and cardiac prognosis. This article traces these developments and reviews the data utilized to substantiate this relatively new noninvasive imaging procedure.

Cardiac magnetic resonance imaging in patients with coronary disease

Cardiac magnetic resonance (CMR) has emerged as a versatile noninvasive tool for the comprehensive evaluation of patients with suspected or established coronary artery disease (CAD). In a single imaging session, CMR can assess left ventricular anatomy and function, myocardial perfusion, viability, and coronary luminal stenosis. Using specific pulse sequences, left ventricular global and regional function can be assessed by cine CMR at rest and in response to inotropic stress; first-pass perfusion quantified by vasodilator stress; myocardial viability evaluated by delayed enhancement imaging and also by functional reserve; and coronary artery stenosis assessed by angiography. All these modalities can be achieved with high spatial resolution and image contrast, without exposure to ionizing radiation, and within a reasonable time frame of about 1 hour of scan time. Also, the imaging planes can be programmed to provide identical views of the heart for each type of image, thereby facilitating intermodality comparisons. There is early but accumulating evidence that the accuracy and prognostic values of many of these modalities are comparable or superior to radionuclide scintigraphy and echocardiography in head-to-head studies. Current limitations unique to CMR include the inability to perform exercise stress testing inside the CMR suite and exclusion of patients with indwelling metallic devices such as defibrillators and pacemakers. Despite these limitations, CMR is unique in its multifaceted approach that can be specifically tailored to the clinical question at hand, making it arguably the best tool for the diagnosis and management of CAD. With the rapid pace of advancement in CMR hardware and pulse sequence technologies, the clinical use of this powerful technique is likely to grow even greater in this area.

Assessment of myocardial ischemia and viability using cardiac magnetic resonance

In the past decade, cardiac magnetic resonance (CMR) has evolved dramatically. Its clinical applications are now a major tool in the diagnosis and prognostic assessment of patients with ischemic heart disease. CMR can be used for detection and quantification of ischemia and for viability assessment using different techniques that are now well validated. Scar can be easily detected using contrast enhancement (late gadolinium enhancement). Ischemia detection is usually achieved with stress CMR techniques, whereas prediction for the recovery of function (detection of dysfunctional but viable myocardial segments) can be deduced from scar and stress imaging. Although determination of which approach is better may depend on the population group, the major advantage of CMR is the ability to integrate different information about anatomy, wall motion, myocardial perfusion, and tissue characterization in a single comprehensive examination.

Risk stratification for therapeutic management and prognosis

In coronary artery disease (CAD), cardiac magnetic resonance (CMR) imaging can integrate several types of pulse-sequence examinations (eg, myocardial perfusion, cine wall motion, T2-weighted imaging for myocardial edema, late gadolinium enhancement, and CMR angiography) that can provide anatomic, functional, and physiologic information about the heart in a single imaging session. Because of this ability to interrogate myocardial physiology using different pulse sequence techniques within a single CMR session, this technique has been recognized increasingly in many centers as the test of choice for assessing patients who present with cardiomyopathy of undetermined cause. This article first reviews the current evidence supporting the prognosticating role of CMR in assessing CAD and then discusses CMR applications and prognostication in many non-coronary cardiac conditions.

Feasibility of dobutamine stress cardiovascular magnetic resonance imaging in children

PURPOSE

To evaluate the feasibility of dobutamine stress magnetic resonance (DSMR) in pediatric patients.

MATERIALS AND METHODS

The medical records of all DSMR studies performed on patients < or =22 years old at a single institution were retrospectively reviewed. The DSMR protocol included dobutamine doses up to 40 microg/kg/minute and atropine to attain the target heart rate [0.85 . (220 - age)].

RESULTS

Thirty-two DSMR studies were performed in 28 patients (median age = 7.3 years; range = 0.8-22 years). Twenty of the studies were performed under general anesthesia. The protocol was completed in 26 studies, technical problems and interruptions were few, and image quality scores (1-5) for all ventricular wall segments were high (mean = 4.2). A heart rate > or =160 bpm was attained in 84% of the studies, a rate pressure product > or =20,000 beats . mm Hg in 87%, and a heart rate greater than or equal to the target heart rate in 19%. No serious adverse events occurred. One patient had an inducible wall motion abnormality. Interobserver agreement was 100% (kappa = 1.0) for test positivity and 92% (kappa = 0.72) for wall motion scores.

CONCLUSION

DSMR in pediatric patients is feasible and provides high-quality imaging of all ventricular wall segments with low interobserver variability. Further exploration of DSMR in pediatric patients is warranted, particularly for those children who are unable to cooperate sufficiently for exercise stress or have poor acoustic windows.

Dobutamine cardiac magnetic resonance results predict cardiac prognosis in women with known or suspected ischemic heart disease

OBJECTIVES

The purpose of this study was to determine the prognostic utility of dobutamine cardiac magnetic resonance (DCMR) stress test results in women.

BACKGROUND

To date, the preponderance of studies reporting the utility of DCMR stress results for predicting cardiac prognosis have been performed in men. We sought to determine the utility of DCMR results for predicting cardiac prognosis in women.

METHODS

Two hundred sixty-six consecutively referred women underwent DCMR in which left ventricular wall motion (LVWM) was assessed at rest and after intravenous dobutamine and atropine. Inducible LVWM abnormalities were identified during testing. Women were contacted to determine the post-DCMR occurrence of a cardiac event. All events were substantiated according to defined criteria and then were verified after a thorough medical record review by individuals blinded to testing data.

RESULTS

Women were contacted an average of 6.2 +/- 1.6 (median 6.2, range 0.8 to 10.4) years after DCMR; 27% of the women experienced an inducible LVWM abnormality during testing. In those with and without inducible LVWM abnormalities, the proportion of women with cardiac events were 63% versus 30%, respectively, (hazard ratio [HR]: 2.7; 95% confidence interval [CI]: 1.8 to 4.3 for the presence of inducible LVWM abnormalities p < 0.0001). The proportion of women with myocardial infarction (MI) and cardiac death were 33.3% and 7.5%, respectively. This resulted in a HR for MI and cardiac death of 4.1 (95% CI: 2.2 to 9.4) for those with versus those without inducible LVWM abnormalities; p < 0.0001. A subgroup analysis was performed in women without a history of coronary artery disease and in those with LVWM abnormalities, DCMR remained an adverse predictor of cardiac events (HR: 4.0, 95% CI: 1.8 to 9.0, p = 0.003).

CONCLUSIONS

Inducible LVWM abnormalities during DCMR predict cardiac death and MI in women. Similar to men, these results indicate that DCMR is a valuable noninvasive stress imaging modality for identifying cardiac risk in women with known or suspected ischemic heart disease.

Assessment of ventricular function with cardiovascular magnetic resonance

The high spatial and temporal resolution of cardiovascular magnetic resonance (CMR) images makes it well-suited for use in the assessment of right ventricular and left ventricular function in patients who have cardiovascular disorders. This article reviews CMR methods used to assess regional and global ventricular function.

Prognostic value of cardiac magnetic resonance stress tests: adenosine stress perfusion and dobutamine stress wall motion imaging

BACKGROUND

Adenosine stress magnetic resonance perfusion (MRP) and dobutamine stress magnetic resonance (DSMR) wall motion analyses are highly accurate for the detection of myocardial ischemia. However, knowledge about the prognostic value of stress MR examinations is limited. We sought to determine the value of MRP and DSMR, as assessed during a single-session examination, in predicting the outcome of patients with known or suspected coronary artery disease.

METHODS AND RESULTS

In 513 patients (with known or suspected coronary disease, prior coronary artery bypass graft, or percutaneous coronary intervention), a combined single-session magnetic resonance stress examination (MRP and DSMR) was performed at 1.5 T. For first-pass perfusion imaging, the standard adenosine stress imaging protocol (140 microg x kg(-1) x min(-1) for 6 minutes, 3-slice turbo field echo-echo-planar imaging or steady-state free precession sequence, 0.05 mmol/kg Gd-DTPA) was applied, and for DSMR, the standard high-dose dobutamine/atropine protocol (steady-state free-precession cine sequence) was applied. Stress testing was classified as pathological if at MRP > or = 1 segment showed an inducible perfusion deficit > 25% transmurality or if at DSMR > or = 1 segment showed an inducible wall motion abnormality. During a median follow-up of 2.3 years (range, 0.06 to 4.55 years), 19 cardiac events occurred (4.1%; 9 cardiac deaths, 10 nonfatal myocardial infarctions). The 3-year event-free survival was 99.2% for patients with normal MRP and DSMR and 83.5% for those with abnormal MRP and DSMR. Univariate analysis showed ischemia identified by MRP and DSMR to be predictive of cardiac events (hazard ratio, 12.51; 95% confidence interval, 3.64 to 43.03; and hazard ratio, 5.42; 95% confidence interval, 2.18 to 13.50; P<0.001, respectively); other predictors were diabetes mellitus, known coronary artery disease, and the presence of resting wall motion abnormality. By multivariate analysis, ischemia on magnetic resonance stress testing (MRP or DSMR) was an independent predictor of cardiac events. In a stepwise multivariate model (Cox regression), an abnormal magnetic resonance stress test result had significant incremental value over clinical risk factors and resting wall motion abnormality (P<0.001).

CONCLUSIONS

In patients with known or suspected coronary artery disease, myocardial ischemia detected by MRP and DSMR can be used to identify patients at high risk for subsequent cardiac death or nonfatal myocardial infarction. For patients with normal MRP and DSMR, the 3-year event-free survival was 99.2%. MR stress testing provides important incremental information over clinical risk factors and resting wall motion abnormalities.

Dobutamine Stress Magnetic Resonance Imaging

Measurements of left ventricular function with cardiovascular magnetic resonance (CMR) at rest and during intravenous dobutamine are useful for identifying myocardial ischemia, viability, and the risk of subsequent cardiovascular events. Without ionizing radiation, intravascular iodinated contrast administration, or acoustic window limitations, CMR has emerged as a useful adjunct to transthoracic echocardiography for assessing patients with or suspected of having coronary artery disease.

Accelerated 4D dobutamine stress MR imaging with k-t BLAST: feasibility and diagnostic performance

PURPOSE

To prospectively determine feasibility and diagnostic performance (with angiography as reference standard) of k-space and time (k-t) broad-use linear acquisition speed-up technique (k-t BLAST) cine imaging during dobutamine stress for identification of inducible cardiac wall motion abnormalities.

MATERIALS AND METHODS

The study was conducted according to standards of the Charité and Virchow-Klinikum Ethics Committee. Patients gave written consent. Dobutamine stress magnetic resonance (MR) imaging was conducted in 65 patients (mean age, 63 years +/- 9 [standard deviation]; 49 men) with conventional cine steady-state free precession (SSFP). Accelerated four-dimensional (4D) k-t BLAST single-breath-hold imaging with complete left ventricular (LV) coverage was also performed at rest and during stress. For the cine SSFP and accelerated cine techniques, duration of imaging at rest and LV end-diastolic volume and ejection fraction were assessed. Segmental agreement for resting and inducible wall motion abnormalities was determined. In a subgroup (n = 40), direct comparison between SSFP and accelerated cine was performed for coronary stenosis detection. A paired Student t test was used to assess significance of continuous variables. Pearson correlation was used to test correlation between the techniques. Sensitivity, specificity, and diagnostic accuracy were calculated (standard definitions). For quantitative measurement of agreement, Cohen kappa was applied.

RESULTS

For accelerated cine, imaging duration at rest was shortened by 40%. Correlations between cine SSFP and accelerated cine for LV parameters were 135 mL +/- 37 versus 129 mL +/- 31 (r = 0.89) for end-diastolic volume and 59% +/- 8 versus 58% +/- 7 (r = 0.95) for ejection fraction. kappa Values for segmental wall motion at rest and stress ranged from 0.77 to 0.91. Sensitivity, specificity, and diagnostic accuracy for coronary stenosis (>or=50%) detection based on arterial territory were 82%, 87%, and 86%, respectively, for cine SSFP and 82%, 86%, and 85%, respectively, for accelerated cine imaging.

CONCLUSION

Accelerated 4D k-t BLAST wall motion imaging at rest and at dobutamine stress is rapid and feasible; LV measurements were nearly identical between the imaging approaches. Segmental wall motion analysis at rest and at stress show excellent agreement and reliable depiction of myocardial territories supplied by coronary arteries with 50% or more luminal narrowing.

Cardiac stress MR imaging with dobutamine

Stress testing for detection of ischemia-induced wall-motion abnormalities has become a mainstay for noninvasive diagnosis and risk stratification of patients with suspected coronary artery disease (CAD). Recent technical developments in magnetic resonance imaging (MRI), including the adoption of balanced steady-state free precession (b-SSFP) sequences-preferentially in combination with parallel imaging techniques-have led to a significant reduction of imaging time and improved patient safety. The stress protocol includes application of high-dose dobutamine (up to 40 microg/kg/min) combined with fractionated atropine (up to a maximal dose of 1.0 mg). High-dose dobutamine stress MRI revealed good sensitivity (83-96%) and specificity (80-100%) for detection of significant CAD. Myocardial tagging methods have been shown to further increase sensitivity for CAD detection. Severe complications (sustained tachycardia, ventricular fibrillation, myocardial infarction, cardiogenic shock) are rare but may be expected in 0.1-0.3% of patients. Dobutamine stress MRI has emerged as a reliable and safe clinical alternative for noninvasive assessment of CAD. New pulse sequences, such as real-time imaging, might obviate the need for breath holding and electrocardiogram (ECG) triggering in patients with severe dyspnoea and cardiac arrhythmias, which may further improve the clinical impact and acceptance of stress MRI in the future.

Cardiovascular magnetic resonance in the quantitative assessment of left ventricular mass, volumes and contractile function

Cardiovascular magnetic resonance is a well validated, highly accurate and reproducible technique for the assessment of ventricular volumes, function and mass. State of the art cardiovascular magnetic resonance practice is capable of a ventricular assessment that includes not only systolic but also diastolic function. Thus, it provides an insight into the complex changes in ventricular morphology, physiology and function in cardiovascular disease. This has produced great interest not only in its clinical utilization but also as an important research tool. As refinement of the technique continues to incorporate hardware and software developments, the technique becomes quicker, more accurate and easier to analyse. Here, we review recent developments and current practice.

Dobutamine cardiovascular magnetic resonance: A review

Dobutamine cardiovascular magnetic resonance (DCMR) is useful for identifying myocardial ischemia and viability in patients with known or suspected coronary artery disease (CAD). This article reviews the performance and utility of DCMR, its association with dobutamine stress echocardiography (DSE), and areas of active investigative research.

Reproducibility and Inter-observer Variability of Dobutamine Stress CMR in Patients with Severe Coronary Disease: Implications for Clinical Research

PURPOSE

The purpose of this study was to analyze reproducibility and inter-observer variability of dobutamine stress cardiac magnetic resonance imaging (dobutamine CMR) and its implications on serial studies.

METHODS

Nineteen consecutive patients underwent two dobutamine CMR each (median 12 days apart), as part of eligibility criteria for phase I/II stem cell therapy trial. These patients had Canadian Cardiovascular Society Class III/IV angina despite maximal therapy. The two studies were compared for reproducibility of stress response. To assess inter-observer variability, 29 randomly selected dobutamine CMR studies were analyzed by three experienced observers and Kappa values were computed to measure the agreement.

RESULTS

Dobutamine CMR studies were completed without any major complications. The left ventricular function, dobutamine and atropine dose, hemodynamic response, symptomatic response and the results of wall motion and perfusion abnormalities were highly reproducible between the two studies (p = .91). Sample size calculations suggested that a clinical trial using dobutamine CMR to detect an endpoint of resolution of two ischemic segments would require a sample size of 20 subjects and to detect an improvement in perfusion of two segments would require a sample size of 8 subjects. Inter-observer variability between individual and consensus interpretation of dobutamine CMR was good to very good (kappa = 0.81 for wall motion and 0.70 for perfusion).

CONCLUSION

Dobutamine CMR is a highly reproducible technique with very good inter-observer variability and could be used as a specific endpoint in a relatively small clinical trial.

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.

Evaluation of ischemic heart disease with cardiac magnetic resonance and computed tomography

Ischemic heart disease is the most common cardiac problem encountered by physicians in their daily practice. In the last few years, computed tomography and magnetic resonance have emerged as robust imaging modalities with great potential for the comprehensive evaluation of patients with this disorder. This article reviews current evidence of the applications where these techniques have demonstrated their usefulness and provides guidance for their use in the clinical management of coronary artery disease.

Assessment of myocardial ischemia and viability using cardiac magnetic resonance

Cardiac magnetic resonance (CMR) is a burgeoning area of noninvasive cardiac imaging. Today, its clinical utility spans from the qualitative and quantitative assessment of cardiac function and morphology to the challenging task of determining the severity and reversibility of coronary heart disease. Advances in magnet and coil design, pulse sequence, and contrast media have contributed greatly, helping CMR become the multipurpose tool of today's cardiac imaging. This article reviews and explores some of the most exciting clinical applications of CMR in the assessment of coronary artery disease.

MRI for the diagnosis of myocardial ischemia and viability

Assessment of myocardial ischemia and viability plays a crucial role in the clinical management of patients with coronary artery disease. Recently, cardiovascular MRI has emerged as an important noninvasive diagnostic modality in the assessment of coronary artery disease. MRI is able to evaluate both myocardial perfusion as well as myocardial contractile reserve. 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 myocardial ischemia and viability, and may well emerge as the premier noninvasive technique in the assessment of patients with coronary artery disease. The authors review the rapidly expanding recent literature that has now established cardiovascular MRI (including dobutamine cine MRI and vasodilator perfusion MRI techniques) as an ideal choice in the evaluation of myocardial ischemia and delayed contrast-enhanced MRI and low-dose dobutamine cine MRI for evaluation of viability. Comparisons with more established techniques such as dobutamine stress echocardiography, single photon emission computed tomography perfusion imaging, and positron emission tomography are reviewed.

Magnetic resonance imaging assessment of cardiac function

Measurements of left ventricular function at rest and during stress are useful for identifying myocardial ischemia, injury, and the risk of subsequent myocardial infarction. Without ionizing radiation or intravascular contrast administration, magnetic resonance imaging techniques can be used to acquire precise measurements of left ventricular function. This relatively new development may enhance a physician's ability to provide care to patients with cardiovascular disease.