Prognostic value of myocardial contrast delayed enhancement with 64-slice multidetector computed tomography after acute myocardial infarction

Clinical impact of multimodality assessment of myocardial viability

Coronary artery disease (CAD) is a prevalent cause of left ventricular dysfunction. Nevertheless, effective elective revascularization, particularly surgical revascularization, can enhance long-term outcomes and, in selected cases, global left ventricular contractility. The assessment of myocardial viability and scars is still relevant in guiding treatment decisions and selecting patients who are likely to benefit most from blood flow restoration. Although the most recent randomized studies challenge the notion of "hibernating myocardium" and the clinical usefulness of assessing myocardial viability, the advancement of imaging techniques still renders this assessment valuable in specific situations. According to the guidelines of the European Society of Cardiology, non-invasive stress imaging may be employed to define myocardial ischemia and viability in patients with CAD and heart failure before revascularization. Currently, several non-invasive imaging techniques are available to evaluate the presence and extent of viable myocardium. The selection of the most suitable technique should be based on the patient, clinical context, and resource availability. This narrative review evaluates the characteristics of available imaging modalities for assessing myocardial viability to determine the most appropriate therapeutic strategy.

Preprocedural imaging with cardiac computed tomography for endo-epicardial ventricular tachycardia ablation

BACKGROUND

Studies evaluating the systematic use of cardiac computed tomography (CCT) for the preprocedural assessment of myocardial fibrosis are limited. Their implementation in the electrophysiology workflow has not been extensively described.

OBJECTIVE

This study aimed to explore the degree of concordance between CCT and electroanatomic mapping (EAM) for the evaluation of cardiac fibrosis in patients undergoing endo-epicardial ventricular tachycardia (VT) ablation.

METHODS

From November 2017 to December 2021, patients undergoing endo-epicardial VT catheter ablation with CCT as the only source of preprocedural scar assessment were prospectively enrolled. After image integration, myocardial fibrosis detected with CCT was compared with low-voltage areas identified by endo-epicardial EAM. Postprocedural VT recurrences of this approach were evaluated after at least 1 year of follow-up.

RESULTS

The study enrolled 35 patients (mean age, 60.7 ± 13.2 years; 94.2% male). The most common underlying arrhythmic substrate was dilated cardiomyopathy (48.6%). CCT was employed for contraindications to cardiac magnetic resonance, such as unstable VTs (31.4%) or nonconditional implantable cardioverter-defibrillators (28.6%), but also for patients' and operators' preferences (14.3%-25.7%). Myocardial fibrosis was correctly identified by CCT and EAM, with strong agreement between these techniques both overall (Cohen κ for agreement, 0.933) and in per-segment analysis (κ ranging from 0.796 to 1.0). Ischemic patients showed the best correlation (κ = 1.000), whereas myocarditis showed the worst (κ = 0.750). After a median follow-up of 14 (12-24) months, 1-year freedom from recurrences was achieved in 74.3% patients; overall freedom from recurrences was 60.0%.

CONCLUSION

A CCT-based preprocedural assessment before VT ablation is feasible, showing high diagnostic concordance with EAM in detecting myocardial fibrosis.

Simultaneous Viability Assessment and Invasive Coronary Angiography Using a Therapeutic CT System in Chronic Myocardial Infarction Patients

PURPOSE

In a preclinical study using a swine myocardial infarction (MI) model, a delayed enhancement (DE)-multi-detector computed tomography (MDCT) scan was performed using a hybrid system alongside diagnostic invasive coronary angiography (ICA) without the additional use of a contrast agent, and demonstrated an excellent correlation in the infarct area compared with histopathologic specimens. In the present investigation, we evaluated the feasibility and diagnostic accuracy of a myocardial viability assessment by DE-MDCT using a hybrid system comprising ICA and MDCT alongside diagnostic ICA without the additional use of a contrast agent.

MATERIALS AND METHODS

We prospectively enrolled 13 patients (median age: 67 years) with a previous MI (>6 months) scheduled to undergo ICA. All patients underwent cardiac magnetic resonance (CMR) imaging before diagnostic ICA. MDCT viability scans were performed concurrently with diagnostic ICA without the use of additional contrast. The total myocardial scar volume per patient and average transmurality per myocardial segment measured by DE-MDCT were compared with those from DE-CMR.

RESULTS

The DE volume measured by MDCT showed an excellent correlation with the volume measured by CMR (r=0.986, p<0.0001). The transmurality per segment by MDCT was well-correlated with CMR (r=0.900, p<0.0001); the diagnostic performance of MDCT in differentiating non-viable from viable myocardium using a 50% transmurality criterion was good with a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 87.5%, 99.5%, 87.5%, 99.5%, and 99.1%, respectively.

CONCLUSION

The feasibility of the DE-MDCT viability assessment acquired simultaneously with conventional ICA was proven in patients with chronic MI using DE-CMR as the reference standard.

Coronary Computed Tomography Angiography: Beyond Obstructive Coronary Artery Disease

Nowadays, coronary computed tomography angiography (CCTA) has a role of paramount importance in the diagnostic algorithm of ischemic heart disease (IHD), both in stable coronary artery disease (CAD) and acute chest pain. Alongside the quantification of obstructive coronary artery disease, the recent technologic developments in CCTA provide additional relevant information that can be considered as "novel markers" for risk stratification in different settings, including ischemic heart disease, atrial fibrillation, and myocardial inflammation. These markers include: (i) epicardial adipose tissue (EAT), associated with plaque development and the occurrence of arrhythmias; (ii) late iodine enhancement (LIE), which allows the identification of myocardial fibrosis; and (iii) plaque characterization, which provides data about plaque vulnerability. In the precision medicine era, these emerging markers should be integrated into CCTA evaluation to allow for the bespoke interventional and pharmacological management of each patient.

Comprehensive Evaluation of Left Ventricle Dysfunction by a New Computed Tomography Scanner: The E-PLURIBUS Study

BACKGROUND

Although cardiac magnetic resonance (CMR) is considered the gold standard for myocardial fibrosis detection, cardiac computed tomography (CCT) is emerging as a promising alternative.

OBJECTIVES

The purpose of this study was to assess feasibility and diagnostic accuracy of a comprehensive functional and anatomical evaluation with CCT as compared with CMR in patients with newly diagnosed left ventricular dysfunction (LVD).

METHODS

A total of 128 consecutive patients with newly diagnosed LVD were screened. Based on the exclusion criteria, 28 cases were excluded. CCT was performed within 10 days from CMR. Biventricular volumes and ejection fraction, and presence and pattern of delayed enhancement (DE), were determined, along with evaluation of coronary arteries among patients undergoing invasive angiography in the 6 months after CCT.

RESULTS

Six cases were excluded because of claustrophobia at CMR. Among the 94 patients who formed the study population, the concordance between CCT and CMR in suggesting the cause of the LVD was high (94.7%, 89/94 patients) in the overall population and was 100% for identifying ischemic cardiomyopathy. The CCT diagnostic rate for DE assessment was also high (96.7%, 1,544/1,598 territories) and similar to that of CMR (97.4%; P = 0.345, CCT vs CMR). Moreover, CCT showed high diagnostic accuracy in the detection of DE (94.8%, 95% CI: 93.6%-95.8%) in a territory-based analysis. Biventricular volumes and function parameters as measured by CCT and CMR were similar, without significant differences with the exception of a modest difference in RV volume. CCT was confirmed to be accurate for assessing arterial coronary circulation. The mean radiation exposure of the whole CCT was 7.78 ± 2.53 mSv (0.84 ± 0.24 mSv for DE).

CONCLUSIONS

CCT performed with low-dose whole-heart coverage scanner and high-concentration contrast agent appears an effective noninvasive tool for a comprehensive assessment of patients with newly diagnosed LVD.

Live integration of comprehensive cardiac CT with electroanatomical mapping in patients with refractory ventricular tachycardia

BACKGROUND

Aim of the present study was to verify the feasibility and accuracy of live integration of myocardial fibrosis evaluated at CCT with EAM (electro-anatomical mapping).

METHODS

We prospectively enrolled a consecutive cohort of patients with clinical indication to EAM before radiofrequency catheter ablation (RFCA) of refractory ventricular tachycardia (VT) and an absolute contraindication to cardiac magnetic resonance. All patients underwent per protocol CCT for myocardial fibrosis and coronary anatomy evaluation. Diagnostic performance was assessed for myocardial fibrosis evaluation with CCT vs EAM. Live integration feasibility of CCT vs EAM was evaluated for every patients.

RESULTS

A total of 19 patients were included in the present study with 323 myocardial segments analyzed for myocardial fibrosis at CCT. In all patients CCT data were successfully integrated with EAM during RFCA procedure. All patients had myocardial fibrosis correctly identified at CCT vs EAM on a per-patients basis. A diagnostic accuracy on a per-segment basis of 94.1% for detection of any type of myocardial fibrosis at CCT vs EAM was recorded.

CONCLUSIONS

CCT identification of myocardial fibrosis is feasible and accurate vs EAM in a very selected high risk patients with clinical indication to RFCA of VT and contraindication to CMR.

Enhancement patterns detected by multidetector computed tomography are associated with the long-term prognosis of patients with acute myocardial infarction

The present study investigated the clinical value of myocardial contrast-delayed enhancement (DE) with multidetector computed tomography (MDCT) without iodine re-injection immediately after primary percutaneous coronary intervention (PCI) for predicting future cardiovascular events after acute myocardial infarction (AMI). We performed a prospective study in which 263 consecutive patients with first AMI successfully treated with primary PCI were enrolled. Sixty-four-slice MDCT without the re-injection of contrast medium was performed immediately after PCI. Myocardial DE was considered to be transmural when involving myocardial thickness ≥ 75% (Group A; n = 104), subendocardial (< 75%, Group B; n = 108), or normal (Group C; n = 51). A semiquantitative scale score was defined for 17 left ventricular segments to investigate the extent of the DE area assessed. We examined the relationship between the presence or absence of transmural DE and long-term cardiovascular event rates. The median follow-up period was 3.5 years. Kaplan-Meier survival curves showed that patient prognosis was poorer in the group with Group A than that in the group with Group B, which was equivalent to that with Group C. A multivariate analysis identified the presence of transmural DE as the strongest predictor for future cardiovascular events (hazard ratio: 3.7; P = 0.023). Transmural myocardial DE immediately following primary PCI without an iodine re-injection for AMI is a major risk factor for future cardiovascular events.

State of the art paper: Cardiovascular CT for planning ventricular tachycardia ablation procedures

In the last 20 years coronary computed tomography angiography (CCTA) gained a pivotal role in the evaluation of patients with suspected coronary artery disease (CAD) as finally recognized by the ESC guidelines on stable CAD. Technological advances have progressively improved the temporal resolution of CT scanners, contemporary reducing acquisition time, radiation dose and contrast volume needed for the whole heart volume acquisition, further expanding the role of cardiac CT beyond coronary anatomy evaluation. Aim of the present review is to discuss use and benefit of cardiac CT for the planning and preparation of VT ablation.

Impact of delayed hyperenhancement obtained by non-contrast computed tomography following coronary angiography in patients undergoing extracorporeal cardiopulmonary resuscitation

Background

Extracorporeal cardiopulmonary resuscitation (ECPR) has the potential to improve outcomes in patients with refractory cardiac arrest. However, the outcome is difficult to predict on admission. Recent reports have described early evaluation of myocardial damage in patients with acute myocardial infarction by detecting delayed enhancement in non-contrast computed tomography (CT) following coronary angiography (CAG). We investigated the impact of delayed hyperenhancement obtained by non-contrast CT following CAG in patients with ischaemic and non-ischaemic cardiovascular diseases who underwent ECPR for refractory cardiac arrest.

Methods

Forty-two patients who underwent ECPR, CAG, and postprocedural CT for refractory cardiac arrest in our institute were retrospectively enrolled. Two blinded readers independently and semi-quantitatively judged whether hyperenhancement was present or absent in non-contrast axial CT images following CAG. We evaluated the relationship between in-hospital death and delayed hyperenhancement.

Results

The identification of delayed hyperenhancement was highly consistent between the two readers (kappa ​= ​0.71). The survival rate was 21.4% in this cohort. The only significant difference between the survival group and in-hospital death group was the presence of delayed hyperenhancement, which was detected only in the in-hospital death group (p ​= ​0.03). The prevalence of cardiac death was higher in patients with than without delayed hyperenhancement. Delayed hyperenhancement was observed even in areas perfused by non-obstructive coronary arteries.

Conclusions

Delayed hyperenhancement of the left ventricular wall on non-contrast CT imaging following CAG might help to predict in-hospital death in patients undergoing ECPR for refractory cardiac arrest.

STRA-MI-VT (STereotactic RadioAblation by Multimodal Imaging for Ventricular Tachycardia): rationale and design of an Italian experimental prospective study

Background

Ventricular tachycardia (VT) is a life-threatening condition, which usually implies the need of an implantable cardioverter defibrillator in combination with antiarrhythmic drugs and catheter ablation. Stereotactic body radiotherapy (SBRT) represents a common form of therapy in oncology, which has emerged as a well-tolerated and promising alternative option for the treatment of refractory VT in patients with structural heart disease.

Objective

In the STRA-MI-VT trial, we will investigate as primary endpoints safety and efficacy of SBRT for the treatment of recurrent VT in patients not eligible for catheter ablation. Secondary aim will be to evaluate SBRT effects on global mortality, changes in heart function, and in the quality of life during follow-up.

Methods

This is a spontaneous, prospective, experimental (phase Ib/II), open-label study (NCT04066517); 15 patients with structural heart disease and intractable VT will be enrolled within a 2-year period. Advanced multimodal cardiac imaging preceding chest CT-simulation will serve to elaborate the treatment plan on different linear accelerators with target and organs-at-risk definition. SBRT will consist in a single radioablation session of 25 Gy. Follow-up will last up to 12 months.

Conclusions

We test the hypothesis that SBRT reduces the VT burden in a safe and effective way, leading to an improvement in quality of life and survival. If the results will be favorable, radioablation will turn into a potential alternative option for selected patients with an indication to VT ablation, based on the opportunity to treat ventricular arrhythmogenic substrates in a convenient and less-invasive manner.

Computed tomography for myocardial characterization in ischemic heart disease: a state-of-the-art review

This review provides an overview of the currently available computed tomography (CT) techniques for myocardial tissue characterization in ischemic heart disease, including CT perfusion and late iodine enhancement. CT myocardial perfusion imaging can be performed with static and dynamic protocols for the detection of ischemia and infarction using either single- or dual-energy CT modes. Late iodine enhancement may be used for the analysis of myocardial infarction. The accuracy of these CT techniques is highly dependent on the imaging protocol, including acquisition timing and contrast administration. Additionally, the options for qualitative and quantitative analysis and the accuracy of each technique are discussed.

Assessment of Left Ventricular Myocardial Diseases with Cardiac Computed Tomography

Rapid advances in cardiac computed tomography (CT) have enabled the characterization of left ventricular (LV) myocardial diseases based on LV anatomical morphology, function, density, and enhancement pattern. Global LV function and regional wall motion can be evaluated using multi-phasic cine CT images. CT myocardial perfusion imaging facilitates the identification of hemodynamically significant coronary artery disease. CT delayed-enhancement imaging is used to detect myocardial scar in myocardial infarction and to measure the extracellular volume fraction in non-ischemic cardiomyopathy. Multi-energy cardiac CT allows the mapping of iodine distribution in the myocardium. This review summarizes the current techniques of cardiac CT for LV myocardial assessment, highlights the key findings in various myocardial diseases, and presents future applications to complement echocardiography and cardiovascular magnetic resonance.

Left ventricular wall findings in non-electrocardiography-gated contrast-enhanced computed tomography after extracorporeal cardiopulmonary resuscitation

Background

Few studies have reported left ventricular wall findings in contrast-enhanced computed tomography (CE-CT) after extracorporeal cardiopulmonary resuscitation (ECPR). This study examined left ventricular wall CE-CT findings after ECPR and evaluated the association between these findings and the results of coronary angiography and prognosis.

Methods

We evaluated out-of-hospital cardiac arrest patients who were treated with ECPR and subsequently underwent both non-electrocardiography-gated CE-CT and coronary angiography at our center between January 2011 and April 2018. Left ventricular wall CE-CT findings were classified as follows: (1) homogeneously enhanced (HE; the left ventricular wall was homogeneously enhanced), (2) segmental defect (SD; the left ventricular wall was not segmentally enhanced according to the coronary artery territory), (3) total defect (TD; the entire left ventricular wall was not enhanced), and (4) others. Successful weaning from extracorporeal membrane oxygenation, survival to hospital discharge, and predictive ability of significant stenosis on coronary angiography were compared among patients with HE, SD, and TD patterns.

Results

A total of 74 patients (median age, 59 years) were eligible, 50 (68%) of whom had initial shockable rhythm. Twenty-three (31%) patients survived to hospital discharge. HE, SD, TD, and other patterns were observed in 19, 33, 11, and 11 patients, respectively. The rates of successful weaning from extracorporeal membrane oxygenation (84% vs. 39% vs. 9%, p < 0.01) and survival to hospital discharge (47% vs. 27% vs. 0%, p = 0.02) were significantly different among patients with HE, SD, and TD patterns. In post hoc analysis, patients with HE patterns had a significantly higher success rate of weaning from extracorporeal membrane oxygenation than those with SD and TD patterns. SD predicted significant stenosis with a sensitivity of 74% and specificity of 94%.

Conclusions

Homogenously enhanced left ventricular wall might be a predictor of good left ventricular function recovery. In contrast, total enhancement defect in the entire left ventricular wall was associated with poor outcomes. Contrast defect matching the coronary artery territory could predict significant coronary artery stenosis with good specificity. The left ventricular wall findings in non-electrocardiography-gated CE-CT after ECPR might be useful for diagnosis and prognostic prediction.

Emerging role of cardiac computed tomography in heart failure

Despite medical advancements, the prognosis of patients with heart failure remains poor. While echocardiography and cardiac magnetic resonance imaging remain at the forefront of diagnosing and monitoring patients with heart failure, cardiac computed tomography (CT) has largely been considered to have a limited role. With the advancements in scanner design, technology, and computer processing power, cardiac CT is now emerging as a valuable adjunct to clinicians managing patients with heart failure. In the current manuscript, we review the current applications of cardiac CT to patients with heart failure and also the emerging areas of research where its clinical utility is likely to extend into the realm of treatment, procedural planning, and advanced heart failure therapy implementation.

Assessment of Remote Myocardium Heterogeneity in Patients with Ventricular Tachycardia Using Texture Analysis of Late Iodine Enhancement (LIE) Cardiac Computed Tomography (cCT) Images

Purpose

Diffuse remodeling of myocardial extra-cellular matrix is largely responsible for left ventricle (LV) dysfunction and arrhythmias. Our hypothesis is that the texture analysis of late iodine enhancement (LIE) cardiac computed tomography (cCT) images may improve characterization of the diffuse extra-cellular matrix changes. Our aim was to extract volumetric extracellular volume (ECV) and LIE texture features of non-scarred (remote) myocardium from cCT of patients with recurrent ventricular tachycardia (rVT), and to compare these radiomic features with LV-function, LV-remodeling, and underlying cardiac disease.

Procedures

Forty-eight patients suffering from rVT were prospectively enrolled: 5/48 with idiopathic VT (IVT), 23/48 with post-ischemic dilated cardiomyopathy (ICM), 9/48 with idiopathic dilated cardiomyopathy (IDCM), and 11/48 with scars from a previous healed myocarditis (MYO). All patients underwent echocardiography to assess LV systolic and diastolic function and cCT with pre-contrast, angiographic, and LIE scan to obtain end-diastolic volume (EDV), ECV, and first-order texture parameters of Hounsfield Unit (HU) of remote myocardium in LIE [energy, entropy, HU-mean, HU-median, standard deviation (SD), and mean absolute deviation (MAD)].

Results

Energy, HU mean, and HU median by cCT texture analysis correlated with ECV (rho = 0.5650, rho = 0.5741, rho = 0.5068; p < 0.0005). cCT-derived ECV, HU-mean, HU-median, SD, and MAD correlated directly to EDV by cCT and inversely to ejection fraction by echocardiography (p < 0.05). SD and MAD correlated with diastolic function by echocardiography (rho = 0.3837, p = 0.0071; rho = 0.3330, p = 0.0208). MYO and IVT patients were characterized by significantly lower values of SD and MAD when compared with ICM and IDCM patients, independently of LV-volume systolic and diastolic function.

Conclusions

Texture analysis of LIE may expand cCT capability of myocardial characterization. Myocardial heterogeneity (SD and MAD) was associated with LV dilatation, systolic and diastolic function, and is able to potentially identify the different patterns of structural remodeling characterizing patients with rVT of different etiology.

Role of Cardiac Computed Tomography in the Diagnosis of Left Ventricular Myocardial Diseases

Multimodality imaging is indicated for the evaluation of left ventricular (LV) myocardial diseases. Cardiac magnetic resonance (CMR) allows morphological and functional assessment of the LV along with soft tissue characterization. Technological advances in cardiac computed tomography (CT) have led to the development of techniques for diagnostic acquisition in LV myocardial disease. Cardiac CT facilitates the characterization of LV myocardial disease based on anatomy, function, and enhancement pattern. LV regional and global functional parameters are evaluated using multi-phasic cine CT images. CT myocardial perfusion facilitates the identification of hemodynamically significant coronary artery stenosis. Cardiac CT with delayed enhancement is used to detect myocardial scarring or fibrosis in myocardial infarction and non-ischemic cardiomyopathy, and for the measurement of extracellular volume fraction in non-ischemic cardiomyopathy. In this review, we review imaging techniques and key imaging features of cardiac CT used for the evaluation of myocardial diseases, along with CMR findings.

Myocardial Assessment with Cardiac CT: Ischemic Heart Disease and Beyond

PURPOSE OF REVIEW

The aim of this review is to highlight recent advancements, current trends, and the expanding role for cardiac CT (CCT) in the evaluation of ischemic heart disease, nonischemic cardiomyopathies, and some specific congenital myocardial disease states.

RECENT FINDINGS

CCT is a highly versatile imaging modality for the assessment of numerous cardiovascular disease states. Coronary CT angiography (CCTA) is now a well-established first-line imaging modality for the exclusion of significant coronary artery disease (CAD); however, CCTA has modest positive predictive value and specificity for diagnosing obstructive CAD in addition to limited capability to evaluate myocardial tissue characteristics.

SUMMARY

CTP, when combined with CCTA, presents the potential for full functional and anatomic assessment with a single modality. CCT is a useful adjunct in select patients to both TTE and CMR in the evaluation of ventricular volumes and systolic function. Newer applications, such as dynamic CTP and DECT, are promising diagnostic tools offering the possibility of more quantitative assessment of ischemia. The superior spatial resolution and volumetric acquisition of CCT has an important role in the diagnosis of other nonischemic causes of cardiomyopathies.

Infarct characterization using CT

Myocardial infarction (MI) is a major cause of death and disability worldwide. The incidence is not expected to diminish, despite better prevention, diagnosis and treatment, because of the ageing population in industrialized countries and unhealthy lifestyles in developing countries. Nowadays it is highly requested an imaging tool able to evaluate MI and viability. Technology improvements determined an expansion of clinical indications from coronary plaque evaluation to functional applications (perfusion, ischemia and viability after MI) integrating additional phases and information in the mainstream examination. Cardiac computed tomography (CCT) and cardiac MR (CMR) employ different contrast media, but may characterize MI with overlapping imaging findings due to the similar kinetics and tissue distribution of gadolinium and iodinated contrast media. CCT may detect first-pass perfusion defects, dynamic perfusion after pharmacological stress, and delayed enhancement (DE) of non-viable territories.

Delayed enhancement cardiac computed tomography for the assessment of myocardial infarction: from bench to bedside

A large number of studies support the increasingly relevant prognostic value of the presence and extent of delayed enhancement (DE), a surrogate marker of fibrosis, in diverse etiologies. Gadolinium and iodinated based contrast agents share similar kinetics, thus leading to comparable myocardial characterization with cardiac magnetic resonance (CMR) and cardiac computed tomography (CT) at both first-pass perfusion and DE imaging. We review the available evidence of DE imaging for the assessment of myocardial infarction (MI) using cardiac CT (CTDE), from animal to clinical studies, and from 16-slice CT to dual-energy CT systems (DECT). Although both CMR and gadolinium agents have been originally deemed innocuous, a number of concerns (though inconclusive and very rare) have been recently issued regarding safety issues, including DNA double-strand breaks related to CMR, and gadolinium-associated nephrogenic systemic fibrosis and deposition in the skin and certain brain structures. These concerns have to be considered in the context of non-negligible rates of claustrophobia, increasing rates of patients with implantable cardiac devices, and a number of logistic drawbacks compared with CTDE, such as higher costs, longer scanning times, and difficulties to scan patients with impaired breath-holding capabilities. Overall, these issues might encourage the role of CTDE as an alternative for DE-CMR in selected populations.

Functional Evaluation of Coronary Disease by CT Angiography

In recent years, several technical developments in the field of cardiac computed tomography (CT) have made possible the extraction of functional information from an anatomy-based examination. Several different lines have been explored and will be reviewed in the present paper, namely: 1) myocardial perfusion imaging; 2) transluminal attenuation gradients and corrected coronary opacification indexes; 3) fractional flow reserve computed from CT; and 4) extrapolation from atherosclerotic plaque characteristics. In view of these developments, cardiac CT has the potential to become in the near future a truly 2-in-1 noninvasive evaluation for coronary artery disease.

Update on Computed Tomography Myocardial Perfusion Imaging

PURPOSE OF REVIEW

Computed tomography (CT) coronary angiography is a well-validated non-invasive technique for accurate and expedient diagnosis of coronary artery disease (CAD). However, a limitation of coronary CT angiography (CCTA) is its limited capability to identify physiologically significant stenoses, which may eventuate the need for further functional testing. Stress CT myocardial perfusion imaging (CT-MPI) is an emerging technique that has the ability to identify flow-limiting stenoses.

RECENT FINDINGS

The combination of CCTA coronary and CT-MPI has transformed the modality from a tool to assess anatomy and morphology to a modality capable of simultaneous assessment of coronary stenoses and their physiologic significance. A growing number of studies have demonstrated the feasibility and diagnostic accuracy of CT-MPI in comparison to a number of reference standard modalities for CAD diagnosis, including single-photon emission CT, cardiovascular magnetic resonance imaging, and invasive coronary angiography with and without fractional flow-reserve testing.

SUMMARY

While there is still a need for consensus regarding acquisition techniques as well as analysis and interpretation of CT-MPI, with further validation, it is likely to become a powerful adjunctive tool to CCTA in the management of patients with suspected coronary disease.

Non-contrast cardiac CT immediately after percutaneous coronary intervention: does it predict the risk of left ventricular remodeling in patients with ST-elevation myocardial infarction?

To assess the clinical utility of non-contrast cardiac CT (CCT) immediately after successful percutaneous coronary intervention (PCI) for predicting the risk of left ventricle (LV) remodeling in the management of patients with acute myocardial infarction (AMI), 35 patients with AMI underwent non-contrast CCT immediately after PCI. Volume and transmural extent of myocardial delayed enhancement (DE) were assessed on non-contrast CCT. Serial echocardiography and serologic biomarkers were evaluated at baseline and at 2 and 12 months after AMI. Based on an increase in left ventricular end-diastolic volume (LVEDV) ≥20 % at 2 months, patients were classified into two groups: LV remodeling (group 1, n = 14) and no LV remodeling (group 2, n = 21). Clinical characteristics, imaging parameters, and serologic biomarkers were compared between the two groups. Higher incidence of hypertension, longer time to reperfusion, and higher Killip classification at admission were observed for group 1 than for group 2, but these differences were not statistically significant (P > 0.05). Greater volume and transmural extent of DE on non-contrast CCT and poorer resolution of ST-segment elevation on ECG were observed in group 1 compared to group 2, but these results were not statistically significant (P > 0.05). Measurement of biochemical markers showed that probrain natriuretic peptide (proBNP), initial high sensitivity C reactive protein (hs-CRP), and maximum troponin T level were significantly higher in group 1 than in group 2 (P < 0.05) at 2 months. Based on the trend of greater volume and transmural extent of DE in group 1 compared to group 2, non-contrast CCT immediately after PCI, in combination with serologic biomarkers (proBNP, hs-CRP, and troponin T) might be useful for managing patients with AMI.

Enhancement patterns detected by multidetector computed tomography are associated with microvascular obstruction and left ventricular remodelling in patients with acute myocardial infarction

AIMS

This study evaluated the clinical value of myocardial contrast-delayed enhancement (DE) with multidetector computed tomography (MDCT) for detecting microvascular obstruction (MVO) and left ventricular (LV) remodelling revealed by DE magnetic resonance imaging after acute myocardial infarction (AMI).

METHODS AND RESULTS

In 92 patients with first AMI, MDCT without iodine reinjection was performed immediately following successful percutaneous coronary intervention (PCI). Delayed-enhancement magnetic resonance imaging performed in the acute and chronic phases was used to detect MVO and LV remodelling (any increase in LV end-systolic volume at 6 months after infarction compared with baseline). Patients were divided into two groups according to the presence (n = 33) or absence (n = 59) of heterogeneous enhancement (HE). Heterogeneous enhancement was defined as concomitant presence of hyper- and hypoenhancement within the infarcted myocardium on MDCT. Microvascular obstruction and LV remodelling were detected in 49 (53%) and 29 (32%) patients, respectively. In a multivariable analysis, HE and a relative CT density >2.20 were significant independent predictors for MVO [odds ratio (OR) 13.5; 95% confidence interval (CI), 2.15-84.9; P = 0.005 and OR 12.0; 95% CI, 2.94-49.2; P < 0.001, respectively). The presence of HE and relative CT density >2.20 showed a high positive predictive value of 93%, and the absence of these two findings yielded a high negative predictive value of 90% for the predictive value of MVO. Heterogeneous enhancement was significantly associated with LV remodelling (OR 6.75; 95% CI, 1.56-29.29; P = 0.011).

CONCLUSION

Heterogeneous enhancement detected by MDCT immediately after primary PCI may provide promising information for predicting MVO and LV remodelling in patients with AMI.

The Relationship among N-Terminal Pro-B-Type Natriuretic Peptide, High-Sensitivity C-Reactive Protein and Infarct Size in Patients with Acute ST-Elevation Myocardial Infarction

Background and Objectives

We sought to investigate the relationship between levels of high-sensitivity C-reactive protein (hs-CRP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) and the infarct size and left ventricular (LV) volume after acute myocardial infarction (MI).

Subjects and Methods

Eighty-six patients with acute ST-elevation MI underwent delayed enhancement multidetector computed tomography immediately after they underwent percutaneous coronary intervention to determine the infarct size. LV function and remodeling were assessed by echocardiography. Hs-CRP and NT-proBNP were measured at admission, 24 hours and two months later.

Results

Both hs-CRP and NT-proBNP at 24 hours showed a positive correlation with infarct size and a negative correlation with LV ejection fraction at the baseline and two months later. NT-proBNP at two months correlated with infarct size, LV ejection fraction, and LV end diastolic and systolic volume indices at two months. In patients with high NT-proBNP levels at 24 hours and two months, infarct size was larger and LV ejection fraction was lower. NT-proBNP was higher in patients who developed LV remodeling at two months: 929 pg/mL vs. 134 pg/mL, p=0.002. In contrast, hs-CRP at two months showed no relationship to infarct size, LV function, or LV volumes at two months.

Conclusion

Elevated hs-CRP level 24 hours after the onset of acute MI is associated with infarct size and LV dysfunction, whereas elevated levels of NT-proBNP 24 hours and two months after the onset of acute MI are both correlated with infarct size, LV dysfunction, and LV remodeling.

Viability assessment after conventional coronary angiography using a novel cardiovascular interventional therapeutic CT system: Comparison with gross morphology in a subacute infarct swine model

BACKGROUND

Given the lack of promptness and inevitable use of additional contrast agents, the myocardial viability imaging procedures have not been used widely for determining the need to performing revascularization.

OBJECTIVE

This study is aimed to evaluate the feasibility of myocardial viability assessment, consecutively with diagnostic invasive coronary angiography (ICA) without use of additional contrast agent, using a novel hybrid system comprising ICA and multislice CT (MSCT).

METHODS

In all, 14 Yucatan miniature swine models (female; age, 3 months; weight, 28-30 kg) were subjected to ICA followed by balloon occlusion (90 minutes) and reperfusion of the left anterior descending coronary artery. Two weeks after induction of myocardial infarction, delayed hyperenhancement (DHE) images were obtained, using a novel combined machine comprising ICA and 320-channel MSCT scanner (Aquilion ONE, Toshiba), after 2, 5, 7, 10, 15, and 20 minutes after conventional ICA. The heart was sliced in 10-mm consecutive sections in the short-axis plane and was embedded in a solution of 1% triphenyltetrazolium chloride (TTC). Infarct size was determined as TTC-negative areas as a percentage of total left ventricular area. On MSCT images, infarct size per slice was calculated by dividing the DHE area by the total slice area (%) and compared with histochemical analyses.

RESULTS

Serial MSCT scans revealed a peak CT attenuation of the infarct area (222.5 ± 36.5 Hounsfield units) with a maximum mean difference in CT attenuation between the infarct areas and normal myocardium of at 2 minutes after contrast injection (106.4; P for difference = 0.002). Furthermore, the percentage difference of infarct size by MSCT vs histopathologic specimen was significantly lower at 2 (8.5% ± 1.8%) and 5 minutes (9.5% ± 1.9%) than those after 7 minutes. Direct comparisons of slice-matched DHE area by MSCT demonstrated excellent correlation with TTC-derived infarct size (r = 0.952; P < .001). Bland-Altman plots of the differences between DHE by MSCT and TTC-derived infarct measurements plotted against their means showed good agreement between the 2 methods.

CONCLUSION

The feasibility of myocardial viability assessment by DHE using MSCT after conventional ICA was proven in experimental models, and the optimal viability images were obtained after 2 to 5 minutes after the final intracoronary injection of contrast agent for conventional ICA.

Role of cardiac multidetector computed tomography beyond coronary angiography

Cardiac multidetector computed tomography (MDCT) has become a useful noninvasive modality for anatomical imaging of coronary artery disease (CAD). Currently, the main clinical advantage of coronary computed tomography angiography (CCTA) appears to be related to its high negative predictive value at low or intermediate pretest probability for CAD. With the development of technical aspects of MDCT, clinical practice and research are increasingly shifting toward defining the clinical implication of plaque morphology, myocardial perfusion, and patient outcomes. The presence of positive vessel remodeling, low-attenuation plaques, napkin-ring sign, or spotty calcification on CCTA could be useful information on high-risk vulnerable plaques. The napkin-ring sign, especially, showed higher accuracy for the detection of thin-cap fibroatheroma. Recently, it was reported that cardiac 3D single-photon emission tomography/CT fusion imaging, noninvasive fractional flow reserve computed from CT, and integrated CCTA and CT myocardial perfusion were associated with improved diagnostic accuracy for the detection of hemodynamically significant CAD. Furthermore, several randomized, large clinical trials have evaluated the clinical value of CCTA for chest pain triage in the emergency department or long-term reduction in death, myocardial infarction, or hospitalization for unstable angina. In this review we discuss the role of cardiac MDCT beyond coronary angiography, including a comparison with other currently available imaging modalities used to examine atherosclerotic plaque and myocardial perfusion.

CV imaging: what was new in 2012?

Echocardiography, single-photon emission computed tomography (SPECT), positron emission tomography (PET), cardiac magnetic resonance, and cardiac computed tomography can be used for anatomic and functional imaging of the heart. All 4 methods are subject to continuous improvement. Echocardiography benefits from the more widespread availability of 3-dimensional imaging, strain and strain rate analysis, and contrast applications. SPECT imaging continues to provide very valuable prognostic data, and PET imaging, on the one hand, permits quantification of coronary flow reserve, a strong prognostic predictor, and, on the other hand, can be used for molecular imaging, allowing the analysis of extremely small-scale functional alterations in the heart. Magnetic resonance is gaining increasing importance as a stress test, mainly through perfusion imaging, and continues to provide very valuable prognostic information based on late gadolinium enhancement. Magnetic resonance coronary angiography does not substantially contribute to clinical cardiology at this point in time. Computed tomography imaging of the heart mainly concentrates on the imaging of coronary artery lumen and plaque and has made substantial progress regarding outcome data. In this review, the current status of the 5 imaging techniques is illustrated by reviewing pertinent publications of the year 2012.

Myocardial perfusion imaging with cardiac computed tomography: state of the art

Cardiac computed tomography (CCT) has become an important tool for the anatomic assessment of patients with suspected coronary disease. Its diagnostic accuracy for detecting the presence of underlying coronary artery disease and ability to risk stratify patients are well documented. However, the role of CCT for the physiologic assessment of myocardial perfusion during resting and stress conditions is only now emerging. With the addition of myocardial perfusion imaging to coronary imaging, CCT has the potential to assess both coronary anatomy and its functional significance with a single non-invasive test. In this review, we discuss the current state of CCT myocardial perfusion imaging for the detection of myocardial ischemia and myocardial infarction and examine its complementary role to CCT coronary imaging.

Evaluation of myocardial infarction patients after coronary revasculation by dual-phase multi-detector computed tomography: Now and in future

Multidetector-row computed tomography (MDCT) has become one of the major tools in diagnosing and evaluating patients with coronary artery disease in recent years. In selected patients, MDCT has been shown to provide more reliable accuracy in detection of stent patency than invasive coronary angiography. Chiou et al reported a delicate infarcted myocardium at-risk score. According to their results, the MDCT-based myocardium at-risk score had a good correlation with the thallium 201 ST-segment elevation myocardial infarction-based summed difference score (r = 0.841, P < 0.001). They claimed that dual-phase MDCT is useful in detecting different patterns of obstructive lesions and the extent of myocardium at risk. In this commentary, we discuss the current status of the clinical application of MDCT in patients with myocardial infarction in relation to evaluating the myocardial perfusion defect, detecting reversible myocardial ischemia, assessing myocardial viability, estimating target lesion restenosis, and calculating of fractional flow reserve from MDCT.