Comparison of Regional Versus Global Assessment of Left Ventricular Function in Patients with Left Ventricular Dysfunction, Heart Failure, or Both After Myocardial Infarction: The Valsartan in Acute Myocardial Infarction Echocardiographic Study

Incremental prognostic value of speckle tracking echocardiography and early follow-up echo assessment in predicting left ventricular recovery after reperfusion for ST-segment elevation myocardial infarction (STEMI)

PURPOSE

Up to 50% of patients do not achieve significant left ventricular ejection fraction (LVEF) recovery after primary percutaneous intervention (PPCI) for STEMI. We aimed to identify the echocardiographic predictors for LVEF recovery and assess the value of early follow-up echocardiography (Echo) in risk assessment of post-myocardial infarction (MI) patients.

METHODS

One hundred one STEMI patients undergoing PPCI were enrolled provided EF below 50%. Baseline echocardiography assessed LVEF, volumes, wall motion score index (WMSI), global longitudinal strain (GLS), global circumferential strain (GCS), and E/e'. Follow-up echocardiography after 6 weeks reassessed left ventricular volumes, LVEF and GLS.GCS was not assessed at follow up. Patients were classified into recovery and non-recovery groups. Predictors of LVEF recovery and major adverse cardiovascular events (MACE) at 6 months were analysed.

RESULTS

The mean change of EF was 8.04 ± 3.32% in group I versus -.39 ± 5.09 % in group II (p < .001). Recovered patients had better baseline GLS, baseline GCS, E/e', and follow-up GLS. Multivariate regression analysis revealed E/e', GCS, and follow-up GLS after 6 weeks to be strong independent predictors for LVEF recovery. Composite MACE was considerably higher in group II (32.7% vs. 4.1%, p < .001) mainly driven by higher heart failure hospitalisation Multivariate regression analysis revealed baseline GLS, E/e', and ejection fraction (EF) percentage recovery as strong independent predictors for MACE.

CONCLUSIONS

Multiparametric echocardiographic approach incorporating LVEF, strain parameters, and diastolic function could allow early optimal risk stratification after STEMI treated with PPCI. Follow-up GLS and LVEF percentage change are the strongest predictors for early LV recovery and long term clinical outcome, respectively.

Value of myocardial deformation parameters for detecting significant coronary artery disease

Introduction: The study aimed to evaluate the diagnostic value of global and regional myocardial deformation parameters derived from two-dimensional speckle-tracking echocardiography to detect functionally significant coronary artery stenosis.

Methods: Dobutamine stress echocardiography and cardiac magnetic resonance myocardial perfusion imaging (CMR-MPI) were performed on 145 patients with a moderate and high probability of coronary artery disease (CAD) and LVEF≥55%. Significant CAD was defined as>50% stenosis of the left main stem,>70% stenosis in a major coronary vessel, or in the presence of intermediate stenosis (50-69%) validated as hemodynamically significant by CMRMPI. Patients were divided in two groups: non-pathological (48.3%) vs pathological (51.7%), according to CAG and CMR-MPI results. Afterwards, off-line speckle-tracking analysis was performed to analyse myocardial deformation parameters.

Results: There were no differences in myocardial deformation parameters at rest between groups, except global longitudinal strain (GLS) and global radial strain (GRS) were significantly lower in the CAD (+) group: -21.3±2.2 vs.-16.3±2.3 (P<0.001) and 39.7±23.2 vs. 24.5±15.8 (P<0.001). GLS and regional longitudinal strain rate (SR) had the highest diagnostic value at high dobutamine dose with AUC of 0.902 and 0.878, respectively. At early recovery, GLS was also found to be the best myocardial deformation parameter with a sensitivity of 78%, specificity 67%, AUC 0.824.

Conclusion: Global and regional myocardial deformation parameters are highly sensitive and specific in detecting functionally significant CAD. The combination of deformation parameters and WMA provides an incremental diagnostic value for patients with a moderate and high probability of CAD, especially the combination with regional longitudinal SR.

Transmural difference in myocardial damage assessed by layer-specific strain analysis in patients with ST elevation myocardial infarction

We performed layer-specific strain analysis with speckle-tracking echocardiography to investigate the transmural difference of myocardial damage as the predicting factor for the viability of damaged myocardium in patients with ST segment elevation myocardial infarction (STEMI). We analysed patients with acute STEMI who had undergone primary percutaneous coronary intervention and echocardiography within 24 h from the intervention and 2 months after the event. Segmental strains of the left ventricular (LV) endocardium, myocardium, epicardium, and strain gradient (SG) between the endocardium and epicardium were evaluated. In 34 patients, 112 akinetic/dyskinetic and 94 hypokinetic segments were observed among 612 segments of the LV at baseline, and 65 akinetic/dyskinetic segments had viability. In our study, layer-specific strains were gradually deteriorated by their wall motion. SG was augmented in the hypokinetic segments where inhomogeneous wall motion impairment was progressed. SG in the akinetic/dyskinetic segments was different between the viable and non-viable myocardium and was maintained in viable segments. We therefore believe that significantly reduced SG is indicative of irreversible transmural damage in the acute stage of STEMI and can be suitably used as a parameter for predicting myocardial viability.

Predictors of segmental myocardial functional recovery in patients after an acute ST-Elevation myocardial infarction

Objective

We hypothesized that Displacement Encoding with Stimulated Echoes (DENSE) and feature-tracking derived circumferential strain would provide incremental prognostic value over the extent of infarction for recovery of segmental myocardial function.

Methods

Two hundred and sixty-one patients (mean age 59 years, 73% male) underwent MRI 2 days post-ST elevation myocardial infarction (STEMI) and 241 (92%) underwent repeat imaging 6 months later.

The MRI protocol included cine, 2D-cine DENSE, T2 mapping and late enhancement.

Wall motion scoring was assessed by 2-blinded observers and adjudicated by a third. (WMS: 1=normal, 2=hypokinetic, 3=akinetic, 4=dyskinetic). WMS improvement was defined as a decrease in WMS ≥ 1, and normalization where WMS = 1 on follow-up. Segmental circumferential strain was derived utilizing DENSE and feature-tracking.

A generalized linear mixed model with random effect of subject was constructed and used to account for repeated sampling when investigating predictors of segmental myocardial improvement or normalization

Results

At baseline and follow-up, 1416 segments had evaluable data for all parameters. Circumferential strain by DENSE (p < 0.001) and feature-tracking (p < 0.001), extent of oedema (p < 0.001), infarct size (p < 0.001), and microvascular obstruction (p < 0.001) were associates of both improvement and normalization of WMS. Circumferential strain provided incremental predictive value even after accounting for infarct size, extent of oedema and microvascular obstruction, for segmental improvement (DENSE: odds ratio, 95% confidence intervals: 1.08 per −1% peak strain, 1.05–1.12, p < 0.001, feature-tracking: odds ratio, 95% confidence intervals: 1.05 per −1% peak strain, 1.03–1.07, p < 0.001) and segmental normalization (DENSE: 1.08 per −1% peak strain, 1.04–1.12, p < 0.001, feature-tracking: 1.06 per −1% peak strain, 1.04–1.08, p < 0.001).

Conclusions

Circumferential strain provides incremental prognostic value over segmental infarct size in patients post STEMI for predicting segmental improvement or normalization by wall-motion scoring.

Use of two-dimensional speckle tracking echocardiography to predict cardiac events: Comparison of patients with acute myocardial infarction and chronic coronary artery disease

BACKGROUND

Two-dimensional speckle strain (2D STE) echocardiography can aid in the prognosis of acute myocardial infarction (AMI) and chronic coronary artery disease (CAD).

HYPOTHESIS

Differences occur in the prediction of cardiac events using 2D STE in AMI vs CAD patients.

METHODS

In this prospective study, 94 patients with a first AMI and successful revascularization, and 137 patients with stable CAD after complete revascularization were included. In all patients, we performed echocardiography and myocardial deformation analysis for layer-specific global circumferential strain (GCS) and longitudinal strain. Receiver operating characteristic (ROC) curve analysis was used to predict the presence of a cardiac event using strain values and baseline characteristics in different regression models.

RESULTS

Patients were followed for 3.6 ± 0.8 years. Strain parameters in AMI and CAD patients were significantly different with respect to the occurrence of a cardiac event. Frequency of diabetes and hypertension was associated with the presence of a cardiac event in CAD patients. Furthermore, in CAD patients, ROC analysis demonstrated that the addition of endocardial GCS to baseline characteristics and ejection fraction to a regression model significantly improved the prediction of cardiac events (area under curve = 0.86, cutoff value: 20%, sensitivity: 79%, specificity: 84%). In contrast, the addition of strain parameters in AMI patients did not increase the prediction power for cardiac events.

CONCLUSIONS

Global strain parameters by 2D STE may be useful for the prediction of cardiac events in patients with CAD but add no supplemental information to baseline characteristic and ejection fraction in patients with AMI.

Left Ventricular Systolic Function Assessed by Global Longitudinal Strain is Impaired in Atrial Fibrillation Compared to Sinus Rhythm

Background

Atrial fibrillation (AF) is the most common aberrant cardiac arrhythmia. Many AF patients present with symptoms of dyspnea and fatigue, but have normal left ventricular ejection fraction (LVEF).

Purpose

To determine the reproducibility of measurements of global longitudinal strain (GLS) and strain rate in patients with AF and examine if the arrhythmia is associated with abnormal LV strain and strain rate independent of age, sex, heart rate, LVEF and LV mass. We hypothesized that AF independently reduces ventricular systolic performance.

Methods

The study was conducted as a retrospective analysis of images from 150 randomly selected patients with AF compared to an equal number of subjects with sinus rhythm (SR) matched for age, sex, heart rate, LVEF and LV mass. Half of the patients had normal LVEF (LVEF > 50%) and half had reduced LVEF (LVEF < 50%). GLS and strain rate were measured in each group, as were quantitative LV volumes and standard systolic and diastolic parameters. Results: GLS was significantly impaired in patients with AF compared to subjects with SR, both in the overall population (-12.25 ± 4.1% vs. -16.13 ± 4.7%, p<0.0001), in patients with normal LVEF (-14.41 ± 3.9% vs. -19.42 ± 3.1%, p<0.0001) and in patients with reduced LVEF (-10.10 ± 3.1% vs. -12.85 ± 3.5%, p<0.0001).Linear regression and Bland Altman analyses demonstrated good intraobserver and interobserver agreement for measurements of GLS and strain rate parameters even in patients with AF.

Regional Longitudinal Myocardial Deformation Provides Incremental Prognostic Information in Patients with ST-Segment Elevation Myocardial Infarction

Background

Global longitudinal systolic strain (GLS) has recently been demonstrated to be a superior prognosticator to conventional echocardiographic measures in patients after myocardial infarction (MI). The aim of this study was to evaluate the prognostic value of regional longitudinal myocardial deformation in comparison to GLS, conventional echocardiography and clinical information.

Method

In total 391 patients were admitted with ST-Segment elevation myocardial infarction (STEMI), treated with primary percutaneous coronary intervention and subsequently examined by echocardiography. All patients were examined by tissue Doppler imaging (TDI) and two-dimensional strain echocardiography (2DSE).

Results

During a median-follow-up of 5.3 (IQR 2.5–6.1) years the primary endpoint (death, heart failure or a new MI) was reached by 145 (38.9%) patients. After adjustment for significant confounders (including conventional echocardiographic parameters) and culprit lesion, reduced longitudinal performance in the anterior septal and inferior myocardial regions (but not GLS) remained independent predictors of the combined outcome. Furthermore, inferior myocardial longitudinal deformation provided incremental prognostic information to clinical and conventional echocardiographic information (Harrell's c-statistics: 0.63 vs. 0.67, p = 0.032). In addition, impaired longitudinal deformation outside the culprit lesion perfusion region was significantly associated with an adverse outcome (p<0.05 for all deformation parameters).

Conclusion

Regional longitudinal myocardial deformation measures, regardless if determined by TDI or 2DSE, are superior prognosticators to GLS. In addition, impaired longitudinal deformation in the inferior myocardial segment provides prognostic information over and above clinical and conventional echocardiographic risk factors. Furthermore, impaired longitudinal deformation outside the culprit lesion perfusion region seems to be a paramount marker of adverse outcome.

Echocardiographic Predictors for Left Ventricular Remodeling after Acute ST Elevation Myocardial Infarction with Low Risk Group: Speckle Tracking Analysis

BACKGROUND

We sought to assess echocardiographic predictors of left ventricular (LV) adverse remodeling after successfully reperfused acute ST elevation myocardial infarction (STEMI). LV remodeling is commonly found in STEMI patients and it may suggest adverse outcome in acute myocardial infarction. We sought to identify whether 2D strain and torsion be independent parameters for prediction of LV adverse remodeling.

METHODS

We investigated 208 patients with low-risk STEMI patients who had follow up echocardiography at 6 or more months. After clinical assessments, all patients received revascularization according to current guideline. LV remodeling was defined as > 20% increase in end-diastolic volume (EDV) at follow up.

RESULTS

During the follow-up (11.9 ± 5.3 months), 53 patients (25.5%) showed LV remodeling. In univariate analysis, EDV, end-systolic volume, deceleration time (DT), CK-MB, and global longitudinal strain (GLS) were associated with LV remodeling. In multivariate analysis, EDV [hazard ratio (HR): 0.922, 95% confidence interval (CI): 0.897-0.948, p< 0.001],

GLS (HR

0.842, 95% CI: 0.728-0.974, p = 0.020), DT (HR: 0.989, 95% CI: 0.980-0.998, p = 0.023) and CK-MB (HR: 1.003, 95% CI: 1.000-1.005, p = 0.033) independently predicted LV remodeling. However, global circumferential strain, net twist, and twist or untwist rate were not associated with remodeling.

CONCLUSION

Of various parameters of speckle strain, only GLS predicted adverse remodeling in STEMI patients.

Identification of High-Risk Patients with Non-ST Segment Elevation Myocardial Infarction using Strain Doppler Echocardiography: Correlation with Cardiac Magnetic Resonance Imaging

Assessment of left ventricular (LV) function is important for decision-making and risk stratification in patients with acute coronary syndrome. Many patients with non-ST segment elevation myocardial infarction (NSTEMI) have substantial infarction, but these patients often do not reveal clinical signs of instability, and they rarely fulfill criteria for acute revascularization therapy.

AIM

This study evaluated the potential of strain Doppler echocardiography analysis for the assessment of LV infarct size when compared with standard two-dimensional echo and cardiac magnetic resonance (CMR) data.

METHODS

Thirty patients with NSTEMI were examined using echocardiography after hospitalization for 1.8 ± 1.1 days for the assessment of left ventricular ejection fraction, wall motion score index (WMSI), and LV global longitudinal strain (GLS). Infarct size was assessed using delayed enhancement CMR 6.97 ± 3.2 days after admission as a percentage of total myocardial volume.

RESULTS

GLS was performed in 30 patients, and 82.9% of the LV segments were accepted for GLS analysis. Comparisons between patients with a complete set of GLS and standard echo, GLS and CMR were performed. The linear relationship demonstrated moderately strong and significant associations between GLS and ejection fraction (EF) as determined using standard echo (r = 0.452, P = 0.012), WMSI (r = 0.462, P = 0.010), and the gold standard CMR-determined EF (r = 0.57, P < 0.001). Receiver operating characteristic curves were used to analyze the ability of GLS to evaluate infarct size. GLS was the best predictor of infarct size in a multivariate linear regression analysis (β = 1.51, P = 0.027). WMSI >1.125 and a GLS cutoff value of -11.29% identified patients with substantial infarction (≥12% of total myocardial volume measured using CMR) with accuracies of 76.7% and 80%, respectively. However, GLS remained the only independent predictor in a multivariate logistic regression analysis to identify an infarct size ≥12%.

CONCLUSION

GLS is a good predictor of infarct size in NSTEMI, and it may serve as a tool in conjunction with risk stratification scores for the selection of high-risk NSTEMI patients.

Non-Invasive Evaluation of Heart Function with Four-Dimensional Echocardiography

Background

The aim of this study is to assess the accuracy and feasibility of left ventricular systolic function determined by four-dimensional echocardiography (4DE).

Methods

Latex balloons were sewn into the left ventricle (LV) of 20 freshly harvested pig hearts which were then passively driven by a pulsatile pump apparatus. Global longitudinal strain (GLS), global circumferential strain (GCS), global area strain (GAS) and left ventricular ejection fraction (LVEF) derived from 4DEand two-dimensional echocardiography (2DE)-derived LVEF were quantified at different stroke volumes (SV) 30–70 ml and correlated with sonomicrometry data.

Results

In all comparisons, GLS, GCS, GAS, 2DE-LVEF, and 4DE-LVEF demonstrated strong correlations with sonomicrometry data (r = 0.77, r = 0.89, r = 0.79, r = 0.93, r = 0.96, all P <0.001). Bland-Altman analyses showed slight overestimations of echo-derived GLS, GCS, 2DE-LVEF and 3DE-LVEF over sonomicrometry values (bias = 2.88, bias = 3.99, bias = 3.37, bias = 2.78, respectively). Furthermore, there is better agreement between GCS, 4D LVEF and sonomicrometry values compared with GLS and 2D LVEF.

Conclusion

Four-dimensional echocardiography accurately assesses LV function. GCS derived by 4DE is a potential alternative parameter to quantify LV systolic function.

Material stiffness parameters as potential predictors of presence of left ventricle myocardial infarction: 3D echo-based computational modeling study

Background

Ventricle material properties are difficult to obtain under in vivo conditions and are not readily available in the current literature. It is also desirable to have an initial determination if a patient had an infarction based on echo data before more expensive examinations are recommended. A noninvasive echo-based modeling approach and a predictive method were introduced to determine left ventricle material parameters and differentiate patients with recent myocardial infarction (MI) from those without.

Methods

Echo data were obtained from 10 patients, 5 with MI (Infarct Group) and 5 without (Non-Infarcted Group). Echo-based patient-specific computational left ventricle (LV) models were constructed to quantify LV material properties. All patients were treated equally in the modeling process without using MI information. Systolic and diastolic material parameter values in the Mooney-Rivlin models were adjusted to match echo volume data. The equivalent Young’s modulus (YM) values were obtained for each material stress–strain curve by linear fitting for easy comparison. Predictive logistic regression analysis was used to identify the best parameters for infract prediction.

Results

The LV end-systole material stiffness (ES-YM_f) was the best single predictor among the 12 individual parameters with an area under the receiver operating characteristic (ROC) curve of 0.9841. LV wall thickness (WT), material stiffness in fiber direction at end-systole (ES-YM_f) and material stiffness variation (∆YM_f) had positive correlations with LV ejection fraction with correlation coefficients r = 0.8125, 0.9495 and 0.9619, respectively. The best combination of parameters WT + ∆YM_f was the best over-all predictor with an area under the ROC curve of 0.9951.

Conclusion

Computational modeling and material stiffness parameters may be used as a potential tool to suggest if a patient had infarction based on echo data. Large-scale clinical studies are needed to validate these preliminary findings.

Infarcted Left Ventricles Have Stiffer Material Properties and Lower Stiffness Variation: Three-Dimensional Echo-Based Modeling to Quantify In Vivo Ventricle Material Properties

Methods to quantify ventricle material properties noninvasively using in vivo data are of great important in clinical applications. An ultrasound echo-based computational modeling approach was proposed to quantify left ventricle (LV) material properties, curvature, and stress/strain conditions and find differences between normal LV and LV with infarct. Echo image data were acquired from five patients with myocardial infarction (I-Group) and five healthy volunteers as control (H-Group). Finite element models were constructed to obtain ventricle stress and strain conditions. Material stiffening and softening were used to model ventricle active contraction and relaxation. Systolic and diastolic material parameter values were obtained by adjusting the models to match echo volume data. Young's modulus (YM) value was obtained for each material stress-strain curve for easy comparison. LV wall thickness, circumferential and longitudinal curvatures (C- and L-curvature), material parameter values, and stress/strain values were recorded for analysis. Using the mean value of H-Group as the base value, at end-diastole, I-Group mean YM value for the fiber direction stress-strain curve was 54% stiffer than that of H-Group (136.24 kPa versus 88.68 kPa). At end-systole, the mean YM values from the two groups were similar (175.84 kPa versus 200.2 kPa). More interestingly, H-Group end-systole mean YM was 126% higher that its end-diastole value, while I-Group end-systole mean YM was only 29% higher that its end-diastole value. This indicated that H-Group had much greater systole-diastole material stiffness variations. At beginning-of-ejection (BE), LV ejection fraction (LVEF) showed positive correlation with C-curvature, stress, and strain, and negative correlation with LV volume, respectively. At beginning-of-filling (BF), LVEF showed positive correlation with C-curvature and strain, but negative correlation with stress and LV volume, respectively. Using averaged values of two groups at BE, I-Group stress, strain, and wall thickness were 32%, 29%, and 18% lower (thinner), respectively, compared to those of H-Group. L-curvature from I-Group was 61% higher than that from H-Group. Difference in C-curvature between the two groups was not statistically significant. Our results indicated that our modeling approach has the potential to determine in vivo ventricle material properties, which in turn could lead to methods to infer presence of infarct from LV contractibility and material stiffness variations. Quantitative differences in LV volume, curvatures, stress, strain, and wall thickness between the two groups were provided.

Left ventricular ejection fraction assessment by non-cardiologists from transverse views using a simplified wall motion score index

For the non-cardiologist emergency physician and intensivist, performing an accurate estimation of left ventricular ejection fraction (LVEF) is essential for the management of critically ill patients, such as patients presenting with shock, severe respiratory distress or chest pain. Our objective was to develop a semi-quantitative method to improve visual LVEF evaluation. A group of 12 sets of transthoracic echocardiograms with LVEF in the range of 18–64% were interpreted by 17 experienced observers (PRO) and 103 untrained observers or novices (NOV), without previous training in echocardiography. They were asked to assess LVEF by two different methods: i) visual estimation (VIS) by analysing the three classical left ventricle (LV) short-axis views (basal, midventricular and apical short-axis LV section) and ii) semi-quantitative evaluation (base, mid and apex (BMA)) of the same three short-axis views. The results for each of these two methods for both groups (PRO and NOV) were compared with LVEF obtained by radionuclide angiography. The semi-quantitative method (BMA) improved estimation of LVEF by PRO for moderate LV dysfunction (LVEF 30–49%) and normal LVEF. The visual estimate was better for lower LVEF (<30%). In the NOV group, the semi-quantitative method was better than than the visual one in the normal group and in half of the subjects in the moderate LV dysfunction (LVEF 30–49%) group. The visual estimate was better for the lower LVEF (ejection fraction <30%) group. In conclusion, semi-quantitative evaluation of LVEF gives an overall better assessment than VIS for PRO and untrained observers.

Association between left ventricular global longitudinal strain and adverse left ventricular dilatation after ST-segment-elevation myocardial infarction

BACKGROUND

Myocardial infarct size is a major determinant of left ventricular (LV) remodeling after ST-segment-elevation myocardial infarction. We evaluated whether LV global longitudinal strain (GLS), proposed as a novel marker of infarct size, is associated with 3- and 6-month LV dilatation after ST-segment-elevation myocardial infarction.

METHODS AND RESULTS

In the first ST-segment-elevation myocardial infarction patients treated with primary percutaneous coronary intervention, baseline LVGLS was measured with 2-dimensional speckle-tracking echocardiography. Patients were dichotomized according to median value. The independent relationship between GLS groups and LV end-diastolic volume at 3 and 6 months (adjusted for clinical and echocardiographic variables) was assessed. The final study population comprised 1041 patients (60±12 years; 76% men). Median LVGLS was -15.0%. Patients with baseline LVGLS>-15.0% exhibited greater LV dilatation at 3 and 6 months compared with patients with GLS≤-15.0% (LV end-diastolic volume 123±44 versus 106±36 mL and 121±43 versus 102±34 mL, respectively; global group-time interaction P<0.001). This association retained the same statistical significance after adjustment for various relevant demographic, clinical, and echocardiographic characteristics. Further, net reclassification improvement index demonstrated significant incremental value of LVGLS for prediction of LV end-diastolic volume increase (0.14 [95% confidence interval, 0.00034-0.29]; P=0.04).

CONCLUSIONS

LVGLS before discharge after ST-segment-elevation myocardial infarction is independently associated with LV dilatation at follow-up.

Automatic classification of left ventricular regional wall motion abnormalities in echocardiography images using nonrigid image registration

Identification and classification of left ventricular (LV) regional wall motion (RWM) abnormalities on echocardiograms has fundamental clinical importance for various cardiovascular disease assessments especially in ischemia. In clinical practice, this evaluation is still performed visually which is highly dependent on training and experience of the echocardiographers and therefore suffers from significant interobserver and intraobserver variability. This paper presents a new automatic technique, based on nonrigid image registration for classifying the RWM of LV in a three-point scale. In this algorithm, we register all images of one cycle of heart to a reference image (end-diastolic image) using a hierarchical parametric model. This model is based on an affine transformation for modeling the global LV motion and a B-spline free-form deformation transformation for modeling the local LV deformation. We consider image registration as a multiresolution optimization problem. Finally, a new regional quantitative index based on resultant parameters of the hierarchical transformation model is proposed for classifying RWM in a three-point scale. The results obtained by our method are quantitatively evaluated to those obtained by two experienced echocardiographers visually as gold standard on ten healthy volunteers and 14 patients (two apical views) and resulted in an absolute agreement of 83 % and a relative agreement of 99 %. Therefore, this diagnostic system can be used as a useful tool as well as reference visual assessment to classify RWM abnormalities in clinical evaluation.

Global left ventricular longitudinal systolic strain for early risk assessment in patients with acute myocardial infarction treated with primary percutaneous intervention

BACKGROUND

Left ventricular systolic function is a key determinant of outcome after ST-segment elevation myocardial infarction (STEMI). The aim of this study was to study speckle-tracking global longitudinal strain (GLS) for early risk evaluation in STEMI and compare it with left ventricular ejection fraction (LVEF), wall motion score index (WMSI), and end-systolic volume index (ESVI).

METHODS

Five-hundred seventy-six patients underwent echocardiography ≤24 hours after primary percutaneous coronary intervention for STEMI. The end point was the composite of death, hospitalization with reinfarction, congestive heart failure, or stroke. Associations with outcome were assessed by multivariate Cox regression with adjustment for clinical parameters. Hazard ratios (HRs) for events within the first year are reported per absolute percentage GLS increase.

RESULTS

During a median follow-up period of 24 months, 162 patients experienced at least one event. GLS was associated with the composite end point (adjusted HR, 1.20; 95% confidence interval [CI], 1.12-1.29) and also when controlling for LVEF (adjusted HR, 1.17; 95% CI, 1.07-1.29) and ESVI (adjusted HR, 1.18; 95% CI, 1.08-1.28). Although WMSI was significantly associated with outcome beyond any association accounted for by GLS, a borderline significant association was found after controlling for WMSI (adjusted HR for GLS, 1.10; 95% CI, 1.00-1.21). When GLS or WMSI was known, there was no significant association between LVEF or ESVI and outcome.

CONCLUSIONS

In a large population of patients with STEMI, GLS and WMSI were comparable and both superior for early risk assessment compared with volume-based left ventricular function indicators such as LVEF and ESVI. Compared with WMSI, the advantage of GLS is the provision of a semiautomated quantitative measure.

Exenatide reduces reperfusion injury in patients with ST-segment elevation myocardial infarction

AIMS

Exenatide, a glucagon-like-peptide-1 analogue, increases myocardial salvage in experimental settings with coronary occlusion and subsequent reperfusion. We evaluated the cardioprotective effect of exenatide at the time of reperfusion in patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (pPCI).

METHODS AND RESULTS

A total of 172 patients with STEMI and Thrombolysis in Myocardial Infarction flow 0/1 were randomly assigned to exenatide or placebo (saline) intravenously. Study treatment was commenced 15 min before intervention and maintained for 6 h after the procedure. The primary endpoint was salvage index calculated from myocardial area at risk (AAR), measured in the acute phase, and final infarct size measured 90 ± 21 days after pPCI by cardiac magnetic resonance (CMR). In 105 patients evaluated with CMR, a significantly larger salvage index was found in the exenatide group than in the placebo group (0.71 ± 0.13 vs. 0.62 ± 0.16; P= 0.003). Infarct size in relation to AAR was also smaller in the exenatide group (0.30 ± 0.15 vs. 0.39 ± 0.15; P= 0.003). In a regression analysis, there was a significant correlation between the infarct size and the AAR for both treatment groups and an analysis of covariance showed that datapoints in the exenatide group lay significantly lower than for the placebo group (P= 0.011). There was a trend towards smaller absolute infarct size in the exenatide group (13 ± 9 vs. 17 ± 14 g; P= 0.11). No difference was observed in left ventricular function or 30-day clinical events. No adverse effects of exenatide were observed.

CONCLUSION

In patients with STEMI undergoing pPCI, administration of exenatide at the time of reperfusion increases myocardial salvage.

Three-dimensional speckle tracking echocardiography for automatic assessment of global and regional left ventricular function based on area strain

OBJECTIVE

We evaluated the ability of a novel automatic index based on area strain to reliably quantify global and regional left ventricular (LV) function and accurately identify wall motion (WM) abnormalities using three-dimensional speckle tracking echocardiography.

METHODS

A total of 140 consecutive patients underwent two- and three-dimensional echocardiography. Segmental WM assessment by area strain was compared with visual assessment of two-dimensional images by two experienced echocardiographers. For global LV function assessment, area strain was validated against LV ejection fraction (EF) and wall motion score index (WMSI). Observer reliability was assessed in all patients, whereas test-retest reliability was evaluated in a subgroup of 50 randomly selected patients. Normal reference values of area strain were determined in 56 healthy subjects.

RESULTS

Agreement of WM scores between area strain and visual assessment was found in 94% of normal, 55% of hypokinetic, and 91% of akinetic segments (κ-coefficient 0.88). Sensitivity, specificity, and accuracy of area strain to distinguish abnormal segments from normal segments were 91%, 96%, and 94%, respectively. In regard to global LV function assessment, area strain was highly correlated with EF and WMSI (r = 0.91 and 0.88, respectively). Observer and test-retest reliability of area strain for quantitative assessment of global and regional LV function were good to excellent (all intraclass correlation coefficients ≥0.77). Intraobserver and interobserver reliability of semiquantitative segmental WM analysis by area strain (κ-coefficients 0.87 and 0.73) were comparable to visual assessment by experienced echocardiographers (0.85 and 0.69, respectively).

CONCLUSION

Area strain represents a promising novel automatic index that may provide an accurate and reproducible alternative to current echocardiographic standards for quantitative assessment of global and regional LV function. Area strain seems to adequately identify regional wall motion abnormalities compared with the clinical standard of visual assessment by experienced echocardiographers.

Longitudinal and circumferential strain rate, left ventricular remodeling, and prognosis after myocardial infarction

OBJECTIVES

We sought to investigate the clinical prognostic value of longitudinal and circumferential strain (S) and strain rate (SR) in patients after high-risk myocardial infarction (MI).

BACKGROUND

Left ventricular (LV) contractile performance after MI is an important predictor of long-term outcome. Tissue deformation imaging might more closely reflect myocardial contractility than traditional measures of systolic functions.

METHODS

The VALIANT (Valsartan in Acute Myocardial Infarction Trial) Echo study enrolled 603 patients with LV dysfunction, heart failure, or both 5 days after MI. We measured global peak longitudinal S and systolic SR (SRs) from apical 4- and 2-chamber views and global circumferential S and SRs from parasternal short-axis view with speckle tracking software (Velocity Vector Imaging, Siemens, Inc., Mountain View, California). We related global S and SRs to LV remodeling at 20-month follow-up and to clinical outcomes.

RESULTS

Both longitudinal (mean: -5.1 ± 1.6 100/ms) and circumferential SRs (mean: -8.0 ± 2.8 100/ms) were predictive of death or hospital stay for heart failure (hazard ratio: 2.4, 95% confidence interval [CI]: 2.0 to 3.1, p < 0.001; hazard ratio: 1.3, 95% CI: 1.2 to 1.4, p < 0.001, respectively) after adjustment for clinical covariates by Cox proportional hazards, and longitudinal SRs further improved in predicting 18-month survivor on a model based on clinical and standard echocardiographic measures (increase in area under the receiver-operator characteristic curve: 0.13, p = 0.009). With multivariable logistic regression, circumferential SRs, but not longitudinal SRs, was strongly predictive of remodeling (odds ratio: 1.3, 95% CI: 1.1 to 1.4, p < 0.001).

CONCLUSIONS

Both longitudinal and circumferential SRs were independent predictors of outcomes after MI, whereas only circumferential SRs was predictive of remodeling, suggesting that preserved circumferential function might serve to restrain ventricular enlargement after MI.

Cardiac imaging after myocardial infarction

After myocardial infarction, optimal clinical management depends critically on cardiac imaging. Remodelling and heart failure, presence of inducible ischaemia, presence of dysfunctional viable myocardium, future risk of adverse events including risk of ventricular arrhythmias, need for anticoagulation, and other questions should be addressed by cardiac imaging. Strengths and weaknesses, recent developments, choice, and timing of the different non-invasive techniques are reviewed for this frequent clinical scenario.

Global longitudinal strain by speckle tracking for infarct size estimation

AIMS

To assess the utility of speckle tracking global longitudinal systolic strain (GLS) compared with traditional echocardiographic indices including left ventricular ejection fraction (LVEF), wall motion score index (WMSI), and end-systolic volume index (ESVI), in estimating the infarct size (IS) following a ST-elevation myocardial infarction (STEMI).

METHODS AND RESULTS

The study includes 227 patients with STEMI and day 1 and day 30 echocardiograms, and myocardial perfusion imaging (MPI) only at day 30 to assess IS. IS was modelled by linear regression with echocardiographic parameters using MPI as reference. Resulting echocardiographic IS estimates were compared by ratios of standard deviations of model residuals (RSD). To estimate the resultant day 30 IS 1 day after a STEMI, GLS was more precise than LVEF (RSD: 0.91, P = 0.014) and ESVI (RSD: 0.88, P = 0.002), and comparable with WMSI (RSD 0.99, P = 0.86). To estimate IS from a day 30 echocardiogram, GLS was comparable with LVEF (RSD: 0.98, P = 0.68) and ESVI (RSD: 1.04, P = 0.40), but WMSI was more precise (RSD: 0.89, P = 0.006). Multiple linear regression revealed that on day 1 after STEMI, GLS significantly complemented the standard parameters separately (P-values all models <0.001) or combined [multivariable model: GLS (P = 0.001), WMSI (P = 0.03), LVEF (P = 0.40)]. On day 30, GLS significantly complemented LVEF and ESVI, but when WMSI was in the model, GLS's association with IS was not significant.

CONCLUSION

On day 1 after revascularization for STEMI, GLS contains additional information about final IS compared with standard echocardiographic systolic function indices. Studies are needed to clarify whether this has prognostic implications.

Systolic time intervals as simple echocardiographic parameters of left ventricular systolic performance: correlation with ejection fraction and longitudinal two-dimensional strain

AIMS

Conventionally, the evaluation of left ventricular (LV) systolic function is based on ejection fraction assessment, which may be supplemented by other echocardiographic techniques, such as tissue Doppler imaging, 3D evaluation, and speckle tracking strains. However, these imaging modalities have a high technicity and are time-consuming, while being associated with reproducibility limitations. In this context, the usefulness of simpler measurements such as systolic time intervals (STI) by pulsed Doppler echocardiography must be emphasized.

METHODS AND RESULTS

In this multicentre study, left ventricular ejection fraction (LVEF), dP/dt(max), LV stroke volume, myocardial longitudinal deformation, aortic pre-ejectional period (PEP, ms), and left ventricular ejection time (LVET, ms) were prospectively investigated and compared in 134 consecutive heart failure (HF) patients and 43 control subjects. Feasibility of STI measurements was 100%. Intra-observer reproducibility was 98% for PEP, 96% for LVET, 87% for LVEF, and 93% for global longitudinal strain (GLS). By subgroup analyses, with increasingly altered LVEF or GLS, PEP significantly increased, whereas significantly LVET decreased, resulting in a significantly increased PEP/LVET ratio (P < 0.001). In the HF patients group, a correlation between LVEF and PEP/LVET was found, with r = 0.55 (y = -0.0083x + 0.75, P < 0.001). Based on receiver operating curve analyses, the area under the curve was 0.91 for PEP/LVET > 0.43, which allowed us to detect LVEF < 35% with a sensitivity of 87%, and a specificity of 84%.

CONCLUSION

STI can be easily and accurately measured in clinical practice, and may be used for detecting alterations in LV systolic function. Moreover, this method is likely to have potential applications in the management of HF patients.

Mechanical dyssynchrony after myocardial infarction in patients with left ventricular dysfunction, heart failure, or both

BACKGROUND

Mechanical dyssynchrony is considered an independent predictor for adverse cardiovascular outcomes in patients with heart failure. However, its importance as a risk factor after myocardial infarction is not well defined.

METHODS AND RESULTS

We examined the influence of mechanical dyssynchrony on outcome in patients with left ventricular dysfunction, heart failure, or both after myocardial infarction who were enrolled in the Valsartan in Acute Myocardial Infarction (VALIANT) echocardiography study. B-mode speckle tracking with velocity vector imaging was used to assess ventricular synchrony in 381 patients who had image quality sufficient for analysis. Time to regional peak velocity and time to strain rate were measured among 12 left ventricular segments from the apical 4- and 2- chamber views, and the SDs between all 12 segments were used as a measure of dyssynchrony. The relationships between the SD of time to regional peak velocity and strain rate and clinical outcome of death or heart failure were assessed. In a multivariate Cox model adjusted for clinical and echocardiographic variables, the SD of time to peak velocity (hazard ratio per 10 ms, 1.10; 95% confidence interval, 1.02 to 1.18; P=0.010) and the SD of time to strain rate (hazard ratio per 10 ms, 1.16; 95% confidence interval, 1.06 to 1.27; P=0.001) were independent predictors of death or heart failure.

CONCLUSIONS

Left ventricular dyssynchrony is independently associated with increased risk of death or heart failure after myocardial infarction, suggesting that contractile pattern may play a role in post-myocardial infarction prognosis.

Cardioprotective effects of ischemic postconditioning in patients treated with primary percutaneous coronary intervention, evaluated by magnetic resonance

BACKGROUND

Postconditioning has been suggested to reduce myocardial damage during primary percutaneous coronary intervention (PPCI) in patients with ST-segment-elevation myocardial infarction. However, because clinical experience is limited, we examined the cardioprotective effects of postconditioning, using cardiac MRI in patients treated with PPCI.

METHODS AND RESULTS

One hundred eighteen patients with ST-segment-elevation myocardial infarction referred for PPCI were randomly assigned to have either conventional PPCI or PPCI with postconditioning. Postconditioning was performed immediately after obtained reperfusion with 4 balloon occlusions, each lasting 30 seconds, followed by 30 seconds of reperfusion. The primary end point was myocardial salvage after 3 months as judged by delayed enhancement cardiac MRI. We found a 19% relative reduction of infarct size in the postconditioning group (51+/-16% of total area at risk versus 63+/-17%, P<0.01), corresponding to a 31% increase in salvage ratio. The number of patients developing heart failure was significantly fewer in the postconditioning group (27% versus 46%, P=0.048). No significant evidence of interaction between the impact of postconditioning and the location of the culprit lesion or size of the myocardium at risk was detected (P=0.21 and P=0.71).

CONCLUSIONS

Mechanical postconditioning reduces infarct size in patients with ST-segment-elevation myocardial infarction treated with PPCI. The impact of mechanical postconditioning seems to be independent of the size of myocardium at risk.

CLINICAL TRIAL REGISTRATION- URL

http://www.clinicaltrials.gov. Unique Identifier: NCT00507156.

A New Tool for Automatic Assessment of Segmental Wall Motion Based on Longitudinal 2D Strain

Background— Identification and quantification of segmental left ventricular wall motion abnormalities on echocardiograms is of paramount clinical importance but is still performed by a subjective visual method. We constructed an automatic tool for assessment of wall motion based on longitudinal strain.

Methods and Results— Echocardiograms of 105 patients (3 apical views) were blindly analyzed by 12 experienced readers. Visual segmental scores (VSS) and peak systolic longitudinal strain were assigned to each of 18 segments per patient. Ranges of peak systolic longitudinal strain that best fit VSS (by receiver operating characteristic analysis) were used to generate automatic segmental scores (ASS). Comparisons of ASS and VSS were performed on 1952 analyzable segments. There was agreement of wall motion scores between both methods in 89.6% of normal, 39.5% of hypokinetic, and 69.4% of akinetic segments. Correlation between methods was r =0.63 ( P <0.0001). Interobserver and intraobserver reliability using interclass correlation for scoring segmental wall motion into 3 scores by ASS was 0.82 and 0.83 and by VSS 0.70 and 0.69, respectively. Compared with VSS (majority rule), ASS had a sensitivity, specificity, and accuracy of 87%, 85%, and 86%, respectively. ASS and VSS had similar success rates for correct identification of wall motion abnormalities in territories supplied by culprit arteries. VSS had greater specificity and positive predictive values, whereas ASS had higher sensitivity and negative predictive values for identifying the culprit artery.

Conclusions— Automatic quantification of wall motion on echocardiograms by this tool performs as well as visual analysis by experienced echocardiographers, with a greater reliability and similar agreement to angiographic findings.

Are ejection fraction measurements by echocardiography and left ventriculography equivalent?

BACKGROUND

Left ventricular ejection fraction (EF) is an important parameter in the diagnosis and treatment of patients with coronary heart disease. Previous studies comparing echocardiography and contrast left ventriculography (CVG) for the measurement of EF have shown considerable variation in results, yet, in clinical practice, EF measurements are used interchangeably. The purpose of this study was to assess the concordance between echocardiography and CVG for the determination of EF in routine clinical practice and to identify factors associated with variation in test results.

METHODS

We reviewed the medical records of 5,385 patients hospitalized for acute myocardial infarction between 1997 and 2005 as part of a community-based surveillance project. Of these, 741 patients had EF measurements recorded by both echocardiography and CVG during hospitalization.

RESULTS

While good correlation (r = 0.73) and no systematic bias were noted between the measurement of EF by echocardiogram compared to CVG, there was wide variation between the 2 methods for any given patient. In approximately one third of patients with acute myocardial infarction, the measurement of EF by echocardiography and CVG differed by >10 points, while in approximately 1 in 20 patients, EF measurements by echocardiography and CVG differed by >20 points. The number of days between tests to measure EF, level of EF, temporal order of EF testing, and patient-related factors made only a minor contribution to the variation in test results.

CONCLUSIONS

Our results demonstrate that, in routine clinical practice, EF determinations obtained by echocardiography and CVG may vary widely, with potentially important clinical implications.

Left ventricular function and heart failure in myocardial infarction: impact of the new definition in the community

OBJECTIVES

The aim of this study is to evaluate ventricular function and the occurrence of heart failure (HF) among persons with myocardial infarction (MI) meeting only troponin criteria compared to persons meeting creatine kinase and its MB fraction (CK-MB) criteria.

BACKGROUND

The 2000 American College of Cardiology/European Society of Cardiology MI definition enabled identification of MIs meeting only troponin-based criteria. Data on ventricular function and HF among these are lacking.

METHODS

Between November 2002 and May 2006, we prospectively identified 835 persons with MI in the community using standardized criteria including cardiac pain, electrocardiogram, and biomarkers. Troponin and CK-MB were prospectively measured in all; each patient was classified according to the criteria met.

RESULTS

We performed echocardiograms (median of 1 day post-MI) in 482 patients (age 68+/-15 years; 45% women); 363 patients met CK-MB criteria, whereas 119 met only troponin criteria. The latter had lower wall motion score index (1.3+/-0.4 vs 1.5+/-0.5 for CK-MB; P<.01). Diastolic dysfunction was similar in both groups. After 1 year of follow up, 142 patients developed post-MI HF. Patients meeting only troponin criteria had a lower risk of HF after adjustment for age, sex, comorbidity (hazard ratio 0.56, 95% confidence interval 0.37-0.85, P<.01), which persisted after further adjustments for systolic or diastolic function.

CONCLUSIONS

In the community, the prospective application of the new MI definition identifies patients meeting only troponin criteria with better systolic function than cases meeting CK-MB criteria. Such MIs have a lower risk of subsequent HF. These findings are important for risk stratification in clinical practice.

Evaluation of acute coronary syndromes by cardiac magnetic resonance imaging

The use of cardiovascular magnetic resonance (CMR) imaging for the evaluation of patients with acute chest pain and acute coronary syndromes has great potential. The strength of CMR relies on its ability to provide information on anatomy, physiology, and function in a single scanning session in a noninvasive manner without the need for iodinated contrast, radiation, or the need to undergo invasive procedures. Specifically, with regard to imaging patients with acute chest pain and/or myocardial infarction (MI), CMR has the ability to qualitatively and quantitatively evaluate global and regional right and left ventricular systolic functions, myocardial edema, myocardial perfusion, and myocardial infarct size and transmurality/viability. This review will focus on CMR imaging for the following applications: (1) imaging for the evaluation of ventricular function and infarct size in patients with acute chest pain and/or acute MI, (2) for triage and prognosis of patients presenting to the emergency department with acute chest pain, (3) for evaluating patients after sustaining an acute MI, and (4) for stem cell research.