Extent of left ventricular scar predicts outcomes in ischemic cardiomyopathy patients with significantly reduced systolic function: a delayed hyperenhancement cardiac magnetic resonance study

Detection of Recent Myocardial Infarction Using Native T1 Mapping in a Swine Model: A Validation Study

Late gadolinium enhancement (LGE) imaging is the currently the gold standard for in-vivo detection of myocardial infarction. However, gadolinium contrast administration is contraindicated in patients with renal insufficiency. We aim to evaluate the diagnostic sensitivity and specificity of this contrast-free MRI technique, native T1 mapping, in detecting recent myocardial infarction versus a reference histological gold standard. Ten pigs underwent CMR at 2 weeks after induced MI. The infarct size and transmural extent of MI was calculated using native T1 maps and LGE images. Histological validation was performed using triphenyl tetrazolium chloride (TTC) staining in the corresponding ex-vivo slices. The infarct size and transmural extent of myocardial infarction assessed by T1 mapping correlated well with that assessed by LGE and TTC images. Using TTC staining as the reference, T1 mapping demonstrated underestimation of infarct size and transmural extent of infarction. Additionally, there was a slight but not significant difference found in the diagnostic performance between the native T1 maps and LGE images for the location of MI. Our study shows that native T1 mapping is feasible alternative method to the LGE technique for the assessment of the size, transmural extent, and location of MI in patients who cannot receive gadolinium contrast.

Epicardial delivery of autologous atrial appendage micrografts during coronary artery bypass surgery-safety and feasibility study

Background

The atrial appendages are a tissue reservoir for cardiac stem cells. During on-pump coronary artery bypass graft (CABG) surgery, part of the right atrial appendage can be excised upon insertion of the right atrial cannula of the heart-lung machine. In the operating room, the removed tissue can be easily cut into micrografts for transplantation. This trial aims to assess the safety and feasibility of epicardial transplantation of atrial appendage micrografts in patients undergoing CABG surgery.

Methods/design

Autologous cardiac micrografts are made from leftover right atrial appendage during CABG of 6 patients. Atrial appendage is mechanically processed to micrografts consisting of atrial appendage-derived cells (AADCs) and their extracellular matrix (ECM). The micrografts are epicardially transplanted in a fibrin gel and covered with a tissue-engineered ECM sheet. Parameters including echocardiography—reflecting cardiac insufficiency—are studied pre- and post-operatively as well as at 3 and 6 months of the follow-up. Cardiac functional magnetic resonance imaging is performed preoperatively and at 6-month follow-up. The primary outcome measures are patient safety in terms of hemodynamic and cardiac function over time and feasibility of therapy administration in a clinical setting. Secondary outcome measures are left ventricular wall thickness, change in the amount of myocardial scar tissue, changes in left ventricular ejection fraction, plasma concentrations of N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, New York Heart Association class, days in hospital, and changes in the quality of life. Twenty patients undergoing routine CAGB surgery will be recruited to serve as a control group.

Discussion

This study aims to address the surgical feasibility and patient safety of epicardially delivered atrial appendage micrografts during CABG surgery. Delivery of autologous micrografts and AADCs has potential applications for cell and cell-based gene therapies.

Trial registration

ClinicalTrials.gov Identifier: NCT02672163. Date of registration: 02.02.2016

Role of cardiovascular magnetic resonance in the management of patients with stable coronary artery disease

Cardiovascular magnetic resonance (CMR) assesses cardiac function, ischaemia, viability and tissue characterisation, all within a single scan. Many studies regarding the role of CMR in stable coronary artery disease (CAD) have been published over the last decade providing important technical advances, large-scale clinical validation and prognostic data. As a result, CMR has emerged as a highly accurate technique for diagnosis and risk stratification in stable CAD and has been incorporated into national and international guidelines. Furthermore, clinical pathways utilising CMR have been shown to be the most cost-effective in several healthcare systems. In this review, we summarise the key roles and guideline recommendations for CMR in stable CAD supported by contemporary clinical evidence.

Serum apolipoprotein B is inversely associated with eccentric left ventricular hypertrophy in peritoneal dialysis patients

OBJECTIVES

The study aimed to examine the relationship of serum apolipoprotein B level with left ventricular (LV) structural and functional characteristics, in particular, LV remodeling parameters in peritoneal dialysis (PD) patients.

METHODS

A total of 182 patients with end-stage renal disease (ESRD) receiving PD were identified. Conventional echocardiography was performed for each patient, and echocardiographic characteristics were analyzed according to apo B quartile groups. Multivariate linear regression models were used to determine the associations between serum apo B and LV remodeling indices.

RESULTS

A high serum apo B level was significantly related to the reduction in left atrium dimension (r = - 0.20, P = 0.011), LV dimensions (end-diastolic: r = - 0.27, P = 0.001; end-systolic: r = - 0.24, P = 0.003), peak velocities of early filling divided by peak velocities of atrial filling (r = - 0.38, P < 0.001), and LV volumetric dimension (end-diastolic: r = - 0.27, P < 0.001; end-systolic: r = - 0.28, P < 0.001). After adjustment for clinical confounding factors, the effect of serum apo B on LV eccentric remodeling modestly weakened but remained statistically significant (P = 0.038), while other associations were not significant. In multivariate linear regression analysis, conventional lipid profiles were not significantly associated with LV eccentric remodeling, whereas serum apo B was an independent determinant of LV dilatation (β: - 42.10, 95% CI - 74.82 to - 9.38, P = 0.012).

CONCLUSIONS

Serum apo B was significantly and inversely associated with LV dilatation, independently of conventional lipids and other CV risk factors in our ESRD patients undergoing PD. It suggested that low serum apo B level could be a powerful risk marker for eccentric left ventricular geometry remodeling and could be potentially used to risk-stratify PD patients.

Can Functional Testing for Ischemia and Viability Guide Revascularization?

Cardiac imaging procedures are a cornerstone of the diagnosis and management of patients with cardiac disease. The optimal management of the patient with stable ischemic heart disease or ischemic heart failure often rests on the totality of symptom burden, patient risk, and disease severity, whether assessed anatomically or functionally. Recent trials have demonstrated the power of flow measurements to direct revascularization as well as the strengths and limitations of ischemia and viability/hibernation imaging as markers of risk to direct interventions. They have also highlighted the challenges in evaluating imaging or functional testing to direct therapies, because imaging does not directly affect outcome itself, rather it affects the management decisions that may result in a positive outcome. Ongoing studies with randomized designs, such as FAME 3 (Fractional Flow Reserve versus Angiography for Multivessel Evaluation), ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches), and AIMI-HF (Alternative Imaging Modalities in Ischemic Heart Failure) (IMAGE-HF [Imaging Modalities to Assist with Guiding Therapy in The Evaluation of Patients with Heart Failure]), will provide the highest level of evidence to support practice changes that may further clarify the role of cardiac imaging in the evaluation of these patients and result in improved patient outcomes.

T1 and T2 Mapping in Cardiology: “Mapping the Obscure Object of Desire”

The increasing use of cardiovascular magnetic resonance (CMR) is based on its capability to perform biventricular function assessment and tissue characterization without radiation and with high reproducibility. The use of late gadolinium enhancement (LGE) gave the potential of non-invasive biopsy for fibrosis quantification. However, LGE is unable to detect diffuse myocardial disease. Native T1 mapping and extracellular volume fraction (ECV) provide knowledge about pathologies affecting both the myocardium and interstitium that is otherwise difficult to identify. Changes of myocardial native T1 reflect cardiac diseases (acute coronary syndromes, infarction, myocarditis, and diffuse fibrosis, all with high T1) and systemic diseases such as cardiac amyloid (high T1), Anderson-Fabry disease (low T1), and siderosis (low T1). The ECV, an index generated by native and post-contrast T1 mapping, measures the cellular and extracellular interstitial matrix (ECM) compartments. This myocyte-ECM dichotomy has important implications for identifying specific therapeutic targets of great value for heart failure treatment. On the other hand, T2 mapping is superior compared with myocardial T1 and ECM for assessing the activity of myocarditis in recent-onset heart failure. Although these indices can significantly affect the clinical decision making, multicentre studies and a community-wide approach (including MRI vendors, funding, software, contrast agent manufacturers, and clinicians) are still missing.

Red blood cell distribution width and myocardial scar burden in coronary artery disease

INTRODUCTION

Red blood cell distribution width (RDW) is a novel independent marker of cardiovascular disease including heart failure, coronary artery disease and myocardial ischaemia. The aim of the study was to investigate a possible relationship between RDW and myocardial scar burden, as assessed by a MIBI viability scan. A secondary objective was to assess whether there is an association between RDW and left ventricular ejection fraction (LVEF).

METHODS

The study comprised 123 subjects with ischaemic heart disease who underwent a myocardial viability scan between June 2008 and July 2014. Haemoglobin, mean corpuscular volume, RDW, platelet count, mean platelet volume (MPV), estimated glomerular filtration rate, fasting blood glucose, liver and lipid profiles were evaluated for all patients. The extent of myocardial scarring and LVEF were noted. Data were analysed using IBM SPSS Statistics 22.0. Univariate followed by multivariate analyses were performed to assess for independent predictors of myocardial scarring and LVEF, respectively.

RESULTS

The mean age of the study population was 63.5 years; most of the subjects were men. The median LVEF was 31% and median percentage of myocardial scarring was 8.7%. Multivariate analyses revealed that RDW, HDL-cholesterol and alanine transaminase were independent predictors of myocardial scarring while RDW, MPV, LDL-cholesterol and gamma-glutamyl transpeptidase were independent predictors of LVEF.

CONCLUSIONS

Increased RDW is an independent predictor both of myocardial scar burden and of impaired left ventricular function in subjects with coronary artery disease.

Intra-procedural determination of viability by myocardial deformation imaging: a randomized prospective study in the cardiac catheter laboratory

BACKGROUND

The benefit of revascularization for functional recovery depends on the presence of viable myocardial tissue.

OBJECTIVE

Myocardial deformation imaging allows determination of myocardial viability.

METHODS

In a first approach, we assessed the optimal cutoff value to determine preserved viability by layer-specific echocardiographic myocardial deformation imaging at rest and low-dose dobutamine (DSE) echocardiography: regional endocardial circumferential strain (eCS) <-19% at rest was as accurate as eCS at DSE. In a main study, 123 patients (66% men, age 59 ± 6 years) with relevant coronary stenoses and corresponding severe regional myocardial dysfunction were included and randomized in 2 groups after coronary angiography: group A: intra-procedural myocardial deformation imaging in the cardiac catheter laboratory (CLab), determination of myocardial viability by regional eCS <-19%, in case of positive viability immediate coronary intervention in the same session. Group B: two-step determination of myocardial viability by cardiovascular magnetic resonance (CMR), in case of positive viability coronary intervention. After 18 months follow-up an analysis of the endpoints regarding cardiovascular events, left ventricular (LV) function, and comparison of cost was performed.

RESULTS

Group A (N = 61) and group B (N = 62) showed no differences concerning localization of the coronary stenosis, comorbidities, or medical therapy. Cardiovascular events at 18-month follow-up were as follows: group A 13% (N = 10) vs. group B 14% (N = 9, p = 0.288); improvement of LV function: group A: +7 ± 2% vs. group B: +7 ± 3%, p = 0.963; costs: group A: 3096 Dollar vs. group B: 6043 Dollar, p < 0.001.

CONCLUSION

Intra-procedural determination of myocardial viability by myocardial deformation imaging in the CLab is feasible, safe, and cost effective and may become an emerging alternative to the current practice of two-stage viability diagnostics.

Native T1 value in the remote myocardium is independently associated with left ventricular dysfunction in patients with prior myocardial infarction

PURPOSE

To compare remote myocardium native T₁ in patients with chronic myocardial infarction (MI) and controls without MI and to elucidate the relationship of infarct size and native T₁ in the remote myocardium for the prediction of left ventricular (LV) systolic dysfunction after MI.

MATERIALS AND METHODS

A total of 41 chronic MI (18 anterior MI) patients and 15 age-matched volunteers with normal LV systolic function and no history of MI underwent cardiac magnetic resonance imaging (MRI) at 1.5T. Native T₁ map was performed using a slice interleaved T₁ mapping and late gadolinium enhancement (LGE) imaging. Cine MR was acquired to assess LV function and mass.

RESULTS

The remote myocardium native T₁ time was significantly elevated in patients with prior MI, compared to controls, for both anterior MI and nonanterior MI (anterior MI: 1099 ± 30, nonanterior MI: 1097 ± 39, controls: 1068 ± 25 msec, P < 0.05). Remote myocardium native T₁ moderately correlated with LV volume, mass index, and ejection fraction (r = 0.38, 0.50, -0.49, respectively, all P < 0.05). LGE infarct size had a moderate correlation with reduced LV ejection fraction (r = -0.33, P < 0.05), but there was no significant association between native T₁ and infarct size. Native T₁ time in the remote myocardium was independently associated with reduced LV ejection fraction, after adjusting for age, gender, infarct size, and comorbidity (β = -0.34, P = 0.03).

CONCLUSION

In chronic MI, the severity of LV systolic dysfunction after MI is independently associated with native T₁ in the remote myocardium. Diffuse myocardial fibrosis in the remote myocardium may play an important pathophysiological role of post-MI LV dysfunction.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1073-1081.

Long-Term Prognostic Value of Late Gadolinium-Enhanced Magnetic Resonance Imaging in Patients With and Without Left Ventricular Dysfunction Undergoing Coronary Artery Bypass Grafting

The value of late gadolinium-enhanced (LGE) magnetic resonance imaging (MRI) for the prediction of functional recovery after surgical revascularization has been previously established. However, the impact of LGE-MRI on the long-term prognosis after coronary artery bypass grafting (CABG) remains incompletely understood. Therefore, we aimed to evaluate the long-term prognostic value of LGE-MRI, based on the presence or absence of left ventricular (LV) dysfunction, in patients with coronary artery disease undergoing CABG. One hundred forty-six consecutive patients underwent cine- and LGE-MRI before CABG. Adverse cardiac events included cardiac death, nonfatal myocardial infarction, heart failure, and unstable angina. A 3-year landmark analysis of the primary end point was also performed for patients surviving beyond 3 years after CABG. During a median follow-up of 9.4 years, 44 patients (30%) experienced adverse cardiac events. Although a LV ejection fraction <50% was associated only with adverse cardiac events at 3 years after CABG, LGE was associated with a worse outcome both at and beyond 3 years after CABG. In the overall study population, LGE presence (adjusted hazard ratio [HR] 2.58; p = 0.027), score (adjusted HR 1.06; p <0.001), and extent (adjusted HR 1.08; p <0.001) were independent predictors of adverse cardiac events. Moreover, in both the LV ejection fraction <50% and ≥50% groups, the LGE extent was an independent predictor of adverse cardiac events. In conclusion, our qualitative and quantitative analyses of LGE-MRI provide long-term prognostic information after surgical revascularization. The LGE extent was a strong predictor of adverse cardiac events, independent of the LV function.

The Role of Cardiovascular Magnetic Resonance Imaging in Heart Failure

Cardiovascular imaging is key for the assessment of patients with heart failure. Today, cardiovascular magnetic resonance imaging plays an established role in the assessment of patients with suspected and confirmed heart failure syndromes, in particular identifying aetiology. Its role in informing prognosis and guiding decisions around therapy are evolving. Key strengths include its accuracy; reproducibility; unrestricted field of view; lack of radiation; multiple abilities to characterise myocardial tissue, thrombus and scar; as well as unparalleled assessment of left and right ventricular volumes. T2* has an established role in the assessment and follow-up of iron overload cardiomyopathy and a role for T1 in specific therapies for cardiac amyloid and Anderson-Fabry disease is emerging.

T(Rho) and magnetization transfer and INvErsion recovery (TRAMINER)-prepared imaging: A novel contrast-enhanced flow-independent dark-blood technique for the evaluation of myocardial late gadolinium enhancement in patients with myocardial infarction

PURPOSE

To evaluate a new dark-blood late gadolinium enhancement (LGE) technique called "T(Rho) And Magnetization transfer and INvErsion Recovery" (TRAMINER) for the ability to detect myocardial LGE versus standard "bright-blood" inversion recovery (SIR) imaging.

MATERIALS AND METHODS

This Institutional Review Board (IRB)-approved, Health Insurance Portability and Accountability Act (HIPAA)-compliant prospective study included 40 patients (62 ± 14 years [mean ± standard deviation (SD)], 29 males) with suspected myocardial infarction (MI) referred for the assessment of myocardial viability. The patients underwent a 1.5T cardiac magnetic resonance imaging (MRI) including postcontrast SIR and TRAMINER acquisitions. Normalized images were evaluated by two readers. Subjective (3-point Likert scale) and objective image qualities were compared using Mann-Whitney U-test and paired t-test, respectively. Interobserver agreement, LGE detection rate, and level of certainty were compared using Cohen's kappa, Wilcoxon-test, and Mann-Whitney U-test, respectively. Results are reported as mean ± SD or mean [95% confidence interval].

RESULTS

Overall, image quality was rated similar between TRAMINER and SIR; however, TRAMINER performed better on a visual assessment of the ability to differentiate LGE from blood (Likert scale: 3.0 [3.0-3.0] vs. 2.0 [1.7-2.2], P < 0.0001). TRAMINER provided significantly higher signal intensity range (69.8 ± 10.2 vs. 9.6 ± 7.6, P < 0.0001) and a 4-fold higher signal intensity ratio (4.2 ± 1.9 vs. 1.1 ± 0.1, P < 0.0001) between LGE and blood signals. TRAMINER detected more patients (19/40 vs. 17/40) and segments (91/649 vs. 79/649) with LGE with higher level of certainty (2.9 [2.8-3.0] vs. 2.7 [2.5-2.8], P = 0.0185). Interobserver agreement was good to excellent for LGE detection.

CONCLUSION

TRAMINER provides better contrast between LGE and blood and consequently may have increased ability to discriminate thin subendocardial and papillary muscle enhancement from the blood signal, which can have an indistinct appearance using SIR.

LEVEL OF EVIDENCE

2 J. MAGN. RESON. IMAGING 2017;45:1429-1437.

Impact of Stress Cardiac Magnetic Resonance Imaging on Clinical Care

Given the rising costs of imaging, there is increasing pressure to provide evidence for direct additive impact on clinical care. Appropriate use criteria (AUC) were developed to optimize test-patient selection and are increasingly used by payers to assess reimbursement. However, these criteria were created by expert consensus with limited systematic validation. The aims of this study were therefore to determine (1) rates of active clinical change resulting from stress cardiovascular magnetic resonance (CMR) imaging and (2) whether the AUC can predict these changes. We prospectively enrolled 350 consecutive outpatients referred for stress CMR. Categories of "active changes in clinical care" due to stress CMR were predefined. Appropriateness was classified according to the 2013 AUC. Multivariate logistic regression analysis was used to identify factors independently associated with active change. Overall, stress CMR led to an active change in clinical care in about 70% of patients. Rates of change in clinical care did not vary significantly across AUC categories (p = 0.767). In a multivariate model adjusting for clinical variables and AUC, only ischemia (odds ratio [OR] 6.896, 95% CI 2.637 to 18.032, p <0.001), known coronary artery disease (OR 0.300, 95% CI 0.161 to 0.559, p <0.001), and age (OR 0.977, 95% CI 0.954 to 1.000, p = 0.050) independently predicted significant clinical change. In conclusion, stress CMR made a significant impact on clinical management, resulting in active change in clinical care in about 70% of patients. AUC categories were not an independent predictor of clinical change. Clinical change was independently associated with the presence of ischemia, absence of known coronary artery disease, and younger age.

Scar quantification by cardiovascular magnetic resonance as an independent predictor of long-term survival in patients with ischemic heart failure treated by coronary artery bypass graft surgery

BACKGROUND

Scar burden by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) is associated with functional recovery after coronary artery bypass surgery (CABG). There is limited data on long-term mortality after CABG based on left ventricular (LV) scar burden.

METHODS

Patients who underwent LGE CMR between January 2003 and February 2010 within 1 month prior to CABG were included. A standard 16 segment model was used for scar quantification. A score of 1 for no scar, 2 for ≤ 50 % and 3 for > 50 % transmurality was assigned for each segment. LV scar score (LVSS) defined as the sum of segment scores divided by 16. All-cause mortality was ascertained by social security death index.

RESULTS

One hundred ninety-six patients met the inclusion criteria. 185 CMR studies were available. History of prior MI was present in 64 % and prior CABG in 5.4 % of patients. Scar was present in 72 % of patients and median LVEF was 38 %. Over a median follow up of 8.3 years, there were 64 deaths (34.6 %). There was no statistically significant difference in mortality between Scar and No-scar groups (37 % versus 29 %). In the group with scar, a lower scar burden (defined either < 4 segments with scar or based on LVSS) was independently associated with increased survival.

CONCLUSION

In patients undergoing surgical revascularization, scar burden is negatively associated with survival in patients with scar. However, there is no difference in survival based on presence or absence of scar alone. CMR prior to CABG adds additional prognostic information.

Predictors and Prognostic Impact of Progressive Ischemic Mitral Regurgitation in Patients With Advanced Ischemic Cardiomyopathy

Background—

Ischemic mitral regurgitation (IMR) is associated with poor outcomes. It is unknown what factors contribute to progression of IMR and how progressive IMR affects outcomes. We sought to determine imaging predictors of IMR progression and to determine if progressive IMR is an independent predictor of survival in patients with advanced ischemic cardiomyopathy.

Methods and Results—

Consecutive advanced ischemic cardiomyopathy patients who underwent cardiac magnetic resonance and echocardiograms at baseline with echocardiographic follow-up were studied. Cardiac magnetic resonance was used to assess left ventricular volumes, infarct size, and mitral valve geometry. The effective regurgitant orifice area (EROA) was calculated from the proximal isovelocity surface area by echocardiography. Repeated measures mixed effects and Cox proportional hazards regression models were built to identify predictors of IMR progression and survival. We evaluated 336 patients (age, 62±11 years) over a median follow-up time of 54 months: 154 patients were subsequently revascularized, and 182 patients were medically treated. Ninety-eight patients (29%) demonstrated an increase in EROA values of ≥0.1 cm 2 . There were 87 adverse events (death or transplant). On multivariable analysis, infarct size ( P <0.001), progression in IMR ( P =0.008), age ( P =0.003), and baseline EROA ( P =0.010) were independently associated with adverse events. Independent predictors of IMR progression were as follows: baseline EROA ( P <0.001), left ventricular end–systolic volume index ( P =0.014), and total scar ( P =0.036).

Conclusions—

IMR frequently increases in severity, and progression is independently associated with adverse left ventricular remodeling and infarct size, as assessed by cardiac magnetic resonance. Furthermore, IMR progression is a powerful independent predictor of adverse events, even after controlling for the severity of IMR at baseline.

IGF-1 degradation by mouse mast cell protease 4 promotes cell death and adverse cardiac remodeling days after a myocardial infarction

Heart disease is a leading cause of death in adults. Here, we show that a few days after coronary artery ligation and reperfusion, the ischemia-injured heart elaborates the cardioprotective polypeptide, insulin-like growth factor-1 (IGF-1), which activates IGF-1 receptor prosurvival signaling and improves cardiac left ventricular systolic function. However, this signaling is antagonized by the chymase, mouse mast cell protease 4 (MMCP-4), which degrades IGF-1. We found that deletion of the gene encoding MMCP-4 (Mcpt4), markedly reduced late, but not early, infarct size by suppressing IGF-1 degradation and, consequently, diminished cardiac dysfunction and adverse structural remodeling. Our findings represent the first demonstration to our knowledge of tissue IGF-1 regulation through proteolytic degradation and suggest that chymase inhibition may be a viable therapeutic approach to enhance late cardioprotection in postischemic heart disease.

Prediction of Outcomes in Patients with Chronic Ischemic Cardiomyopathy by Layer-Specific Strain Echocardiography: A Proof of Concept

BACKGROUND

Cardiac magnetic resonance imaging (CMR) has been established as a powerful tool for predicting mortality. However, its application is limited by availability and various contraindications. The aim of this study was to evaluate the predictive value of layer-specific myocardial deformation analysis as assessed by strain echocardiography for cardiac events in patients with chronic ischemic left ventricular dysfunction in comparison with CMR.

METHODS

Three hundred ninety patients (mean age, 63 ± 4 years; 69% men; mean left ventricular ejection fraction [LVEF], 41 ± 7%) with chronic ischemic cardiomyopathy were prospectively enrolled and underwent strain echocardiography and CMR within 3 ± 1 days. LVEF, wall motion score index, and circumferential strain (CS), longitudinal strain, and radial strain for total wall thickness and for three myocardial layers (endocardial, midmyocardial, and epicardial) were determined by echocardiography. The extent of total myocardial scar (TMS) was determined by CMR. Follow-up was obtained for a mean of 4.9 ± 2.2 years. Cardiac events were defined as readmission for worsening of heart failure, ventricular arrhythmias, or death of any cause. The incremental value of LVEF, strain parameters, and TMS to relevant clinical variables was determined in nested Cox models.

RESULTS

There were 133 cardiac events (34%). Baseline clinical data associated with outcomes were age (hazard ratio [HR], 1.27; P = .04), diabetes mellitus (HR, 1.52; P = .001), and renal insufficiency (HR, 1.77; P = .001) by multivariate analysis. The addition of LVEF, global and endocardial strain parameters, and TMS increased the predictive power, but endocardial CS (HR, 1.52; P < .01) caused the greatest increment in model power (χ(2) = 39.2, P < .001). Endocardial CS < -20% was found to be the optimal predictor of prognosis.

CONCLUSIONS

Endocardial CS is a powerful predictor of cardiac events and appears to be a better parameter than LVEF, TMS by CMR, and other strain variables by echocardiography.

Comparison of Low-Dose Higher-Relaxivity and Standard-Dose Lower-Relaxivity Contrast Media for Delayed-Enhancement MRI: A Blinded Randomized Crossover Study

OBJECTIVE

The gadolinium-based MRI contrast agent gadobenate dimeglumine has nearly twice the MR relaxivity of gadopentetate dimeglumine at 1.5 T. The purpose of this study was to determine whether a lower dose (0.1 mmol/kg) of gadobenate dimeglumine can be used to obtain delayed-enhancement MR images comparable to those obtained with a standard dose (0.2 mmol/kg) of gadopentetate dimeglumine.

SUBJECTS AND METHODS

In this blinded randomized crossover study, 20 patients with known myocardial infarction underwent two separate delayed-enhancement MRI examinations after receiving 0.1 mmol/kg gadobenate dimeglumine and 0.2 mmol/kg gadopentetate dimeglumine (random administration). The conspicuity of lesion enhancement 5, 10, and 20 minutes after contrast administration was quantified as relative enhancement ratio (RER).

RESULTS

With either gadolinium-based contrast agent, damaged myocardium had higher signal intensity than normal remote myocardium (RER > 4) on delayed-enhancement MR images, and the blood RER declined over time after contrast administration. The blood RER was not significantly higher for gadobenate dimeglumine than for gadopentetate dimeglumine at 5 and 10 minutes. Nevertheless, there was a larger reduction in blood RER for gadobenate dimeglumine than for gadopentetate dimeglumine between 5 and 10 minutes and between 10 and 20 minutes. The volumes of enhancement were similar for gadobenate dimeglumine (13.6 ± 8.8 cm(3)) and gadopentetate dimeglumine (13.5 ± 8.9 cm(3)) (p = 0.98). The mean difference in Bland-Altman analysis for delayed-enhancement volume between the agents was 0.1 cm(3).

CONCLUSION

Qualitatively and quantitatively, delayed-enhancement MR images of ischemic myocardium obtained with 0.1 mmol/kg gadobenate dimeglumine are comparable to those obtained with 0.2 mmol/kg gadopentetate dimeglumine 5, 10, and 20 minutes after contrast administration.

Relationship between Myocardial Extracellular Space Expansion Estimated with Post-Contrast T1 Mapping MRI and Left Ventricular Remodeling and Neurohormonal Activation in Patients with Dilated Cardiomyopathy

OBJECTIVE

Post-contrast T1 values are closely related to the degree of myocardial extracellular space expansion. We determined the relationship between post-contrast T1 values and left ventricular (LV) diastolic function, LV remodeling, and neurohormonal activation in patients with dilated cardiomyopathy (DCM).

MATERIALS AND METHODS

Fifty-nine patients with DCM (mean age, 55 ± 15 years; 41 males and 18 females) who underwent both 1.5T magnetic resonance imaging and echocardiography were enrolled. The post-contrast 10-minute T1 value was generated from inversion time scout images obtained using the Look-Locker inversion recovery sequence and a curve-fitting algorithm. The T1 sample volume was obtained from three interventricular septal points, and the mean T1 value was used for analysis. The N-Terminal pro-B-type natriuretic peptide (NT-proBNP) level was measured in 40 patients.

RESULTS

The mean LV ejection fraction was 24 ± 9% and the post-T1 value was 254.5 ± 46.4 ms. The post-contrast T1 value was significantly correlated with systolic longitudinal septal velocity (s'), peak late diastolic velocity of the mitral annulus (a'), the diastolic elastance index (Ed, [E/e']/stroke volume), LV mass/volume ratio, LV end-diastolic wall stress, and LV end-systolic wall stress. In a multivariate analysis without NT-proBNP, T1 values were independently correlated with Ed (β = -0.351, p = 0.016) and the LV mass/volume ratio (β = 0.495, p = 0.001). When NT-proBNP was used in the analysis, NT-proBNP was independently correlated with the T1 values (β = -0.339, p = 0.017).

CONCLUSION

Post-contrast T1 is closely related to LV remodeling, diastolic function, and neurohormonal activation in patients with DCM.

Sudden cardiac death risk stratification

Arrhythmic sudden cardiac death (SCD) may be caused by ventricular tachycardia/fibrillation or pulseless electric activity/asystole. Effective risk stratification to identify patients at risk of arrhythmic SCD is essential for targeting our healthcare and research resources to tackle this important public health issue. Although our understanding of SCD because of pulseless electric activity/asystole is growing, the overwhelming majority of research in risk stratification has focused on SCD-ventricular tachycardia/ventricular fibrillation. This review focuses on existing and novel risk stratification tools for SCD-ventricular tachycardia/ventricular fibrillation. For patients with left ventricular dysfunction or myocardial infarction, advances in imaging, measures of cardiac autonomic function, and measures of repolarization have shown considerable promise in refining risk. Yet the majority of SCD-ventricular tachycardia/ventricular fibrillation occurs in patients without known cardiac disease. Biomarkers and novel imaging techniques may provide further risk stratification in the general population beyond traditional risk stratification for coronary artery disease alone. Despite these advances, significant challenges in risk stratification remain that must be overcome before a meaningful impact on SCD can be realized.

Mapping the future of cardiac MR imaging: case-based review of T1 and T2 mapping techniques

Cardiac magnetic resonance (MR) imaging has grown over the past several decades into a validated, noninvasive diagnostic imaging tool with a pivotal role in cardiac morphologic and functional assessment and tissue characterization. With traditional cardiac MR imaging sequences, assessment of various pathologic conditions ranging from ischemic and nonischemic cardiomyopathy to cardiac involvement in systemic diseases (eg, amyloidosis and sarcoidosis) is possible; however, these sequences are most useful in focal myocardial disease, and image interpretation relies on subjective qualitative analysis of signal intensity. Newer T1 and T2 myocardial mapping techniques offer a quantitative assessment of the myocardium (by using T1 and T2 relaxation times), which can be helpful in focal disease, and demonstrate special utility in the evaluation of diffuse myocardial disease (eg, edema and fibrosis). Altered T1 and T2 relaxation times in disease states can be compared with published ranges of normal relaxation times in healthy patients. In conjunction with traditional cardiac MR imaging sequences, T1 and T2 mapping can limit the interpatient and interstudy variability that are common with qualitative analysis and may provide clinical markers for long-term follow-up.

Current clinical applications of cardiovascular magnetic resonance imaging

Cardiovascular magnetic resonance (CMR) imaging is unsurpassed in the evaluation of myocardial anatomy, function and mass. Myocardial perfusion pre- and post-stress, as well as late enhancement is increasingly used in the work-up for ischaemic heart disease, especially in establishing the presence of myocardial viability. Late enhancement patterns can contribute substantially to the diagnosis of myocarditis and various cardiomyopathies as well as infiltrative diseases and tumours. With their high incidence of cardiovascular disease, patients on the African continent could potentially benefit enormously from the proper utilisation of this exciting, continually evolving and versatile technique, via thorough didactic and clinical training as well as interdisciplinary co-operation.

Clinical Significance of Late Enhancement and Regional Wall Remodeling Assessed by 3T Magnetic Resonance Imaging

BACKGROUND

Clinical follow-up studies comparing left ventricular (LV) function and late gadolinium enhancement (LGE) by high-field 3T cardiac magnetic resonance (CMR) are of general interest due to the increased use of 3T scanners. In this study, the occurrence of LGE and LV regional wall remodeling (RWR) was assessed by 3T CMR in patients undergoing coronary angiography for suspected stable coronary artery disease (CAD).

MATERIALS AND METHODS

Analysis of myocardial viability by LGE was performed at the segmental level. LVRWR was identified by a significant reduction (≥50%) of the wall thickness. Major adverse cardiovascular events (MACE) were registered during a median follow-up time of 58 (45-62) months.

RESULTS

Of the 87 patients (59 ± 9 years; 13 women) enrolled, nonviable myocardium was detected in 35 (40%) and significant CAD in 69 (79%). Nonviable myocardium was correlated to angiographic significant stenosis or occlusion. LVRWR was significantly related to a higher number of nonviable segments compared to those without LVRWR: ie, 6.0 ± 3.2 segments versus 2.6 ± 1.3; P < 0.001. In the nonviable group, LVEF was significantly reduced (P < 0.001) compared to the viable group: ie, 50 ± 16% versus 61 ± 8%, and LVEF was significantly correlated to the number of nonviable segments (r = -0.66, P < 0.001). The number of nonviable segments by LGE was significantly associated with MACE by an odds ratio of 1.25 (95% CI, 1.05-1.49; P = 0.013).

CONCLUSION

The presence of nonviable myocardium as detected by LGE at 3T CMR is associated with angiographically significant CAD, and is associated with the development of LVRWR and reduced LVEF. Assessing the extent of nonviable myocardium by both LGE and LVRWR at the segmental level may therefore contribute to individualized risk stratification and treatment strategies.

Intramyocardial bone marrow mononuclear cell transplantation in ischemic heart failure: Long-term follow-up

BACKGROUND

Long-term results regarding treatment of chronic ischemic heart failure with bone marrow mononuclear cells (BMMCs) have been few. We received encouraging results at the 1-year follow-up of patients treated with combined coronary artery bypass grafting (CABG) and BMMCs, so we decided to extend the follow-up.

METHODS

The study patients had received injections of BMMCs or vehicle into the myocardial infarction border area during CABG in a randomized and double-blind manner. We could contact 36 of the 39 patients recruited for the original study. Pre-operatively and after an extended follow-up period, we performed magnetic resonance imaging, measured pro-B-type amino-terminal natriuretic peptide, reviewed patient records from the follow-up period, and determined current quality of life with the Medical Outcomes Study Short-Form 36 (SF-36) Health Survey.

RESULTS

The median follow-up time was 60.7 months (interquartile range [IQR], 45.1-72.6 months). No statistically significant difference was detected in change of pro-B-type amino-terminal natriuretic peptide values or in quality of life between groups. The median change in left ventricular ejection fraction was 4.9% (IQR, -2.1% to 12.3%) for controls and 3.9% (IQR, -5.2% to 10.2%) for the BMMC group (p = 0.647). Wall thickening in injected segments increased by a median of 17% (IQR, -5% to 30%) for controls and 15% (IQR, -12% to 19%) for BMMC patients (p = 0.434). Scar size in injected segments increased by a median of 2% (IQR, -7% to 19%) for controls but diminished for BMMC patients, with a median change of -17% (IQR, -30% to -6%; p = 0.011).

CONCLUSIONS

In the treatment of chronic ischemic heart failure, combining intramyocardial BMMC therapy with CABG fails to affect cardiac function but can sustainably reduce scar size, even in the long-term.

Clinical decision making with myocardial perfusion imaging in patients with known or suspected coronary artery disease

Myocardial perfusion imaging (MPI) to diagnose coronary artery disease (CAD) is best performed in patients with intermediate pretest likelihood of disease; unfortunately, pretest likelihood is often overestimated, resulting in the inappropriate use of perfusion imaging. A good functional capacity often predicts low risk, and MPI for diagnosing CAD should be reserved for individuals with poor exercise capacity, abnormal resting electrocardiography, or an intermediate or high probability of CAD. With respect to anatomy-based testing, coronary CT angiography has a good negative predictive value, but stenosis severity correlates poorly with ischemia. Therefore decision making with respect to revascularization may be limited when a purely noninvasive anatomical test is used. Regarding perfusion imaging, the diagnostic accuracies of SPECT, PET, and cardiac magnetic resonance are similar, though fewer studies are available with cardiac magnetic resonance. PET coronary flow reserve may offer a negative predictive value sufficiently high to exclude severe CAD such that patients with mild to moderate reversible perfusion defects can forego invasive angiography. In addition, combined anatomical and perfusion-based imaging may eventually offer a definitive evaluation for diagnosing CAD, even in higher risk patients. Any remarkable findings on single-photon emission computed tomography and PET MPI studies are valuable for prognostication. Furthermore, assessment of myocardial blood flow with PET is particularly powerful for prognostication as it reflects the end result of many processes that lead to atherosclerosis. Decision making with respect to revascularization is limited for cardiac MRI and PET MPI. In contrast, retrospective radionuclide studies have identified an ischemic threshold, but randomized trials are needed. In patients with at least moderately reduced left ventricular systolic function, viable myocardium as assessed by PET or MRI, appears to identify patients who benefit from revascularization, but well-executed randomized trials are lacking.

Diagnosis and management of ischemic cardiomyopathy: Role of cardiovascular magnetic resonance imaging

Coronary artery disease (CAD) represents an important cause of mortality. Cardiovascular magnetic resonance (CMR) imaging evolved as an imaging modality that allows the assessment of myocardial function, perfusion, contractile reserve and extent of fibrosis in a single comprehensive exam. This review highlights the role of CMR in the differential diagnosis of acute chest pain by detecting the location of obstructive CAD or necrosis and identifying other conditions like stress cardiomyopathy or myocarditis that can present with acute chest pain. Besides, it underlines the prognostic implication of perfusion abnormalities in the setting of acute chest pain. Furthermore, the review addresses the role of CMR to detect significant CAD in patients with stable CAD. It elucidates the accuracy and clinical utility of CMR with respect to other imaging modalities like single-photon emission computed tomography and positron emission tomography. Besides, the prognostic value of CMR stress testing is discussed. Additionally, it summarizes the available CMR techniques to assess myocardial viability and describes algorithm to identify those patient who might profit from revascularization those who should be treated medically. Finally, future promising imaging techniques that will provide further insights into the fundamental disease processes in ischemic cardiomyopathy are discussed.

The prognostic impact of myocardial late gadolinium enhancement

Cardiovascular magnetic resonance using late gadolinium enhancement (LGE) provides a unique opportunity to assess myocardial tissue in vivo. LGE enables tissue characterization in ischemic and nonischemic cardiomyopathies and other cardiac diseases. LGE is associated with adverse clinical outcomes across a range of different cardiac conditions and may improve risk stratification for death, sudden cardiac death, or serious adverse events beyond traditional prognostic markers. Generally, matching data for the prognostic impact of LGE are frequently reached in cardiac disorders. In other diseases, only a limited number of trials are available, but it is anticipated that the prognostic impact of delayed enhancement will become evident. The development and validation of new cardiovascular magnetic resonance methods for diffuse myocardial fibrosis measurements would even improve the prognostic impact of LGE. The evaluation of diffuse myocardial fibrosis has a great potential in large-scale diseases, including their initial phases, with the possibility to identify patients at risk for subsequent development of clinical heart failure, to assess repeatedly the stage and progression of cardiac diseases, and to monitor the effect of treatment.

Established and emerging cardiovascular magnetic resonance techniques for the assessment of stable coronary heart disease and acute coronary syndromes

Coronary heart disease (CHD) is a leading cause of death and disability worldwide. International guidelines recommend cardiovascular magnetic resonance (CMR) as an investigative option in those presenting with chest pain to inform diagnosis, risk stratify and determine the need for revascularization. CMR offers a unique method to assess global and regional cardiac function, myocardial perfusion, myocardial viability, tissue characterisation and proximal coronary anatomy all within a single study. This results in high diagnostic accuracy for the detection of significant coronary stenoses and an established role in the management of both stable CHD and acute coronary syndromes (ACS). The growing evidence base for the prognostic value of CMR, emerging advances in acquisition techniques, improvements in hardware and the completion of current major multi-centre clinical CMR trials will further raise its prominence in international guidelines and routine cardiological practice. This article will focus on the rapidly evolving role of the multi-parametric CMR examination in the assessment of patients with stable and unstable CHD.

The angiopoietin/TIE receptor system: Focusing its role for ischemia-reperfusion injury

Ischemia and reperfusion (I/R) are of fatal consequence for the affected organs, as they provoke a profound inflammatory reaction. This thoroughly destroys cells and tissues, inducing functional failure or even complete loss of organ function. Since I/R is primarily a vascular problem, the interaction between the endothelium and the surrounding environment is of great significance. The angiopoietins (ANG) and the TIE receptors are key players for the vascular homeostasis. This review summarizes biochemical and cellular mechanisms leading to I/R injury. After a brief introduction to the ANG/TIE system, a comprehensive overview of its role for the development of I/R syndrome is given. Finally, current therapeutic approaches to mitigate the consequences of I/R by modulating ANG/TIE signaling are reviewed in detail.

Reference values for healthy human myocardium using a T1 mapping methodology: results from the International T1 Multicenter cardiovascular magnetic resonance study

BACKGROUND

T1 mapping is a robust and highly reproducible application to quantify myocardial relaxation of longitudinal magnetisation. Available T1 mapping methods are presently site and vendor specific, with variable accuracy and precision of T1 values between the systems and sequences. We assessed the transferability of a T1 mapping method and determined the reference values of healthy human myocardium in a multicenter setting.

METHODS

Healthy subjects (n=102; mean age 41 years (range 17-83), male, n=53 (52%)), with no previous medical history, and normotensive low risk subjects (n=113) referred for clinical cardiovascular magnetic resonance (CMR) were examined. Further inclusion criteria for all were absence of regular medication and subsequently normal findings of routine CMR. All subjects underwent T1 mapping using a uniform imaging set-up (modified Look- Locker inversion recovery, MOLLI, using scheme 3(3)3(3)5)) on 1.5 Tesla (T) and 3 T Philips scanners. Native T1-maps were acquired in a single midventricular short axis slice and repeated 20 minutes following gadobutrol. Reference values were obtained for native T1 and gadolinium-based partition coefficients, λ and extracellular volume fraction (ECV) in a core lab using standardized postprocessing.

RESULTS

In healthy controls, mean native T1 values were 950±21 msec at 1.5 T and 1052±23 at 3 T. λ and ECV values were 0.44±0.06 and 0.25±0.04 at 1.5 T, and 0.44±0.07 and 0.26±0.04 at 3 T, respectively. There were no significant differences between healthy controls and low risk subjects in routine CMR parameters and T1 values. The entire cohort showed no correlation between age, gender and native T1. Cross-center comparisons of mean values showed no significant difference for any of the T1 indices at any field strength. There were considerable regional differences in segmental T1 values. λ and ECV were found to be dose dependent. There was excellent inter- and intraobserver reproducibility for measurement of native septal T1.

CONCLUSION

We show transferability for a unifying T1 mapping methodology in a multicenter setting. We provide reference ranges for T1 values in healthy human myocardium, which can be applied across participating sites.

Free-breathing combined three-dimensional phase sensitive late gadolinium enhancement and T1 mapping for myocardial tissue characterization

PURPOSE

To develop a novel MR sequence for combined three-dimensional (3D) phase-sensitive (PS) late gadolinium enhancement (LGE) and T1 mapping to allow for simultaneous assessment of focal and diffuse myocardial fibrosis.

METHODS

In the proposed sequence, four 3D imaging volumes are acquired with different T1 weightings using a combined saturation and inversion preparation, after administration of a gadolinium contrast agent. One image is acquired fully sampled with the inversion time selected to null the healthy myocardial signal (the LGE image). The other three images are three-fold under-sampled and reconstructed using compressed sensing. An acquisition scheme with two interleaved imaging cycles and joint navigator-gating of those cycles ensures spatial registration of the imaging volumes. T1 maps are generated using all four imaging volumes. The signal-polarity in the LGE image is restored using supplementary information from the T1 fit to generate PS-LGE images. The accuracy of the proposed method was assessed with respect to a inversion-recovery spin-echo sequence. In vivo T1 maps and LGE images were acquired with the proposed sequence and quantitatively compared with 2D multislice Modified Look-Locker inversion recovery (MOLLI) T1 maps. Exemplary images in a patient with focal scar were compared with conventional LGE imaging.

RESULTS

The deviation of the proposed method and the spin-echo reference was < 11 ms in phantom for T1 times between 250 and 600 ms, regardless of the inversion time selected in the LGE image. There was no significant difference in the in vivo T1 times of the proposed sequence and the 2D MOLLI technique (myocardium: 292 ± 75 ms versus 310 ± 49 ms, blood-pools: 191 ± 75 ms versus 182.0 ± 33). The LGE images showed proper nulling of the healthy myocardium in all subjects and clear depiction of scar in the patient.

CONCLUSION

The proposed sequence enables simultaneous acquisition of 3D PS-LGE images and spatially registered 3D T1 maps in a single scan.

Infarct tissue heterogeneity by contrast-enhanced magnetic resonance imaging is a novel predictor of mortality in patients with chronic coronary artery disease and left ventricular dysfunction

BACKGROUND

Strategies for prevention of sudden cardiac death focus on severe left ventricular (LV) dysfunction, although most sudden cardiac death postmyocardial infarction occurs in patients with mild/moderate LV dysfunction. We tested the hypothesis that infarct heterogeneity by cardiac magnetic resonance is associated with mortality beyond LV ejection fraction (LVEF) in patients with coronary artery disease and LV dysfunction. In addition, we examined the association between infarct heterogeneity and mortality in those with LVEF >35%.

METHODS AND RESULTS

We studied 301 patients with coronary artery disease and LV dysfunction referred for cardiac magnetic resonance. We quantified total infarct mass, infarct core mass, and peri-infarct zone (PIZ) normalized for total infarct mass (%PIZ) using signal-intensity criteria of >2 SDs, >3 SDs, and 2- to -3 SDs above remote myocardium, respectively. Mean LVEF was 41 ± 14%. After 3.9 years median follow-up, 66 (22%) patients died (13 sudden cardiac death; 33 with LVEF >35%). In patients with LVEF >35%, below-median %PIZ carried an annual death rate of 2.8% versus 12% in patients with above-median %PIZ (P<0.001). In a multivariable model, %PIZ maintained strong association with mortality adjusted to patient age, LVEF, right ventricular ejection fraction, prolonged QT interval, and total infarct size and resulted in improve risk reclassification 0.492 (95% confidence interval, 0.183-0.817).

CONCLUSIONS

Cardiac magnetic resonance infarct heterogeneity has a strong association with mortality independent of LVEF in patients with coronary artery disease and LV dysfunction, particularly in patients with mild or moderate LV dysfunction. Further studies incorporating cardiac magnetic resonance in clinical decision making for defibrillator therapy are warranted.

Prognostic value of myocardial ischemia and necrosis in depressed left ventricular function: a multicenter stress cardiac magnetic resonance registry

INTRODUCTION AND OBJECTIVES

The incremental prognostic value of inducible myocardial ischemia over necrosis derived by stress cardiac magnetic resonance in depressed left ventricular function is unknown. We determined the prognostic value of necrosis and ischemia in patients with depressed left ventricular function referred for dipyridamole stress perfusion magnetic resonance.

METHODS

In a multicenter registry using stress magnetic resonance, the presence (≥ 2 segments) of late enhancement and perfusion defects and their association with major events (cardiac death and nonfatal infarction) was determined.

RESULTS

In 391 patients, perfusion defect or late enhancement were present in 224 (57%) and 237 (61%). During follow-up (median, 96 weeks), 47 major events (12%) occurred: 25 cardiac deaths and 22 myocardial infarctions. Patients with major events displayed a larger extent of perfusion defects (6 segments vs 3 segments; P <.001) but not late enhancement (5 segments vs 3 segments; P =.1). Major event rate was significantly higher in the presence of perfusion defects (17% vs 5%; P =.0005) but not of late enhancement (14% vs 9%; P =.1). Patients were categorized into 4 groups: absence of perfusion defect and absence of late enhancement (n = 124), presence of late enhancement and absence of perfusion defect (n = 43), presence of perfusion defect and presence of late enhancement (n = 195), absence of late enhancement and presence of perfusion defect (n = 29). Event rate was 5%, 7%, 16%, and 24%, respectively (P for trend = .003). In a multivariate regression model, only perfusion defect (hazard ratio = 2.86; 95% confidence interval, 1.37-5.95]; P = .002) but not late enhancement (hazard ratio = 1.70; 95% confidence interval, 0.90-3.22; P =.105) predicted events.

CONCLUSIONS

In depressed left ventricular function, the presence of inducible ischemia is the strongest predictor of major events.

Imaging techniques in the evaluation of post-infarction function and scar

Imaging techniques are essential in the clinical evaluation of patients with a myocardial infarction. They are of value for both initial assessment of the ischemic injury and for detection of the subgroup of patients at higher risk of developing cardiovascular events during follow-up. Echocardiography remains the technique of choice for the initial evaluation, owing to its bedside capability to determine strong predictors, such as ventricular volumes, global and regional systolic function, and valvular regurgitation. New techniques for evaluating ventricular mechanics, mainly assessment of ventricular deformation, are revealing important aspects of post-infarction ventricular adaptation. The main alternative to echocardiography is cardiac magnetic resonance imaging. This technique is highly accurate for determining ventricular volumes and ventricular function and has the additional advantage of being able to characterize the myocardium and demonstrate changes associated with the ischemic insult such as necrosis/fibrosis, edema, microvascular obstruction, and intramyocardial hemorrhage. These features not only allow detection and quantification of the infarct size, but also reveal additional characteristics of the scar tissue with prognostic value.

Infarct characterization and quantification by delayed enhancement cardiac magnetic resonance imaging is a powerful independent and incremental predictor of mortality in patients with advanced ischemic cardiomyopathy

BACKGROUND

Infarct heterogeneity has been shown to be independently associated with adverse outcomes in previous smaller studies. However, it is unknown whether infarct characterization is an independent predictor of all-cause mortality in patients with advanced ischemic cardiomyopathy, after adjusting for clinical risk factors, severity of ischemic mitral regurgitation, incomplete revascularization, and device therapy.

METHODS AND RESULTS

A total of 362 patients with ischemic cardiomyopathy (left ventricular dysfunction with >70% stenosis in ≥1 epicardial coronary artery) underwent delayed hyperenhancement-magnetic resonance imaging and coronary angiography between 2002 and 2006. Total myocardial scar and peri-infarct (PI) area were measured using various threshold techniques. Multivariate survival analysis (primary end point of all-cause mortality) was conducted. One hundred fifty-seven deaths occurred during a mean 5.4-year follow-up (mean left ventricular ejection fraction, 23±9%; mean end-systolic volume index, 113±48 mL; mean total myocardial scar %, 25.5±16.0%; mean PI%, 5.7±2.9%). PI% (β=2.07; P<0.001) was an independent predictor of survival, independent of age, end-systolic volume, sex, mitral regurgitation, diabetes mellitus, dyslipidemia, coronary artery disease severity, implantable cardioverter defibrillator, and incomplete revascularization. PI% using 2 to 3 SD technique yielded the highest incremental prognostic power (χ(2) score 149).

CONCLUSIONS

In advanced ischemic cardiomyopathy, PI% is a powerful independent and incremental predictor of all-cause mortality. Infarct heterogeneity offers substantial further risk stratification when compared with quantification of total myocardial scar % alone even after adjusting for clinical risk factors, end-systolic volume index, mitral regurgitation, incomplete revascularization, and implantable cardioverter defibrillator implantation.