Severe Impairment of Left Ventricular Regional Strain in STEMI Patients Is Associated with Post-Infarct Remodeling

Background: Measures of global left ventricular (LV) systolic function have limitations for the prediction of post-infarct LV remodeling (LVR). Therefore, we tested the association between a new measure of regional LV systolic function—the percentage of severely altered strain (%SAS)- and LVR after acute ST-elevation myocardial infarction (STEMI). As a secondary objective, we also evaluated the association between %SAS and clinical events during follow-up. Methods: Of 177 patients undergoing echocardiography within 24 h from primary percutaneous coronary angioplasty, 172 were studied for 3 months, 167 for 12 months, and 10 died. The %SAS was calculated by dividing the number of LV myocardial segments with ≥−5% peak systolic longitudinal strain by the total number of segments. LVR was defined as the increase in end-diastolic volume >20% at its first occurrence compared to baseline. Results: LVR percentage was 10.2% and 15.8% at 3 and 12 months, respectively. Based on univariable analysis, a number of clinical, laboratory, electrocardiographic and echocardiographic variables were associated with LVR. Based on multivariable analysis, %SAS and TnI peak remained associated with LVR (for %SAS 5% increase, OR 1.226, 95% CI 1.098−1.369, p < 0.0005; for TnI peak, OR 1.025, 95% CI 1.004−1.047, p = 0.022). %SAS and LVR were also associated with occurrence of clinical events at a median follow-up of 43 months (HR 1.02, 95% CI 1.0−1.04, p = 0.0165). Conclusions: In patients treated for acute STEMI, acute %SAS is associated with post-infarct LVR. Therefore, we suggest performing such evaluations on a routine basis to identify, as early as possible, STEMI patients at higher risk.

Evaluation of strain averaging area and strain estimation errors in a spheroidal left ventricular model using synthetic image data and speckle tracking

BACKGROUND

In majority of studies on speckle tracking echocardiography (STE) the strain estimates are averaged over large areas of the left ventricle. This may impair the diagnostic capability of the STE in the case of e.g. local changes of the cardiac contractility. This work attempts to evaluate, how far one can reduce the averaging area, without sacrificing the estimation accuracy that could be important from the clinical point of view.

METHODS

Synthetic radio frequency (RF) data of a spheroidal left ventricular (LV) model were generated using FIELD II package and meshes obtained from finite element method (FEM) simulation. The apical two chamber (A2C) view and the mid parasternal short axis view (pSAXM) were simulated. The sector encompassed the entire cross-section (full view) of the LV model or its part (partial view). The wall segments obtained according to the American Heart Association (AHA17) were divided into subsegments of area decreasing down to 3 mm2. Longitudinal, circumferential and radial strain estimates, obtained using a hierarchical block-matching method, were averaged over these subsegments. Estimation accuracy was assessed using several error measures, making most use of the prediction of the maximal relative error of the strain estimate obtained using the FEM derived reference. Three limits of this predicted maximal error were studied, namely 16.7%, 33% and 66%. The smallest averaging area resulting in the strain estimation error below one of these limits was considered the smallest allowable averaging area (SAAA) of the strain estimation.

RESULTS

In all AHA17 segments, using the A2C projection, the SAAA ensuring maximal longitudinal strain estimates error below 33% was below 3 mm2, except for the segment no 17 where it was above 278 mm2. The SAAA ensuring maximal circumferential strain estimates error below 33% depended on the AHA17 segment position within the imaging sector and view type and ranged from below 3-287 mm2. The SAAA ensuring maximal radial strain estimates error below 33% obtained in the pSAXM projection was not less than 287 mm2. The SAAA values obtained using other maximal error limits differ from SAAA values observed for the 33% error limit only in limited number of cases. SAAA decreased when using maximal error limit equal to 66% in these cases. The use of the partial view (narrow sector) resulted in a decrease of the SAAA.

CONCLUSIONS

The SAAA varies strongly between strain components. In a vast part of the LV model wall in the A2C view the longitudinal strain could be estimated using SAAA below 3 mm2, which is smaller than the averaging area currently used in clinic, thus with a higher resolution. The SAAA of the circumferential strain estimation strongly depends on the position of the region of interest and the parameters of the acquisition. The SAAA of the radial strain estimation takes the highest values. The use of a narrow sector could increase diagnostic capabilities of 2D STE.

Current Role of Echocardiography in Cardiac Resynchronization Therapy: from Cardiac Mechanics to Flow Dynamics Analysis

PURPOSE OF REVIEW

The aim of this review is to summarily explain what LV synchrony, coordination, myocardial work, and flow dynamics are, trying to clarify their advantages and limitations in the treatment of heart failure patients undergoing or with implanted cardiac resynchronization therapy (CRT).

RECENT FINDINGS

CRT is an established treatment for patients with heart failure and left ventricular systolic dysfunction. In the current guidelines, CRT implant indications rely only on electrical dyssynchrony, but in the last years, many aspects of cardiac mechanics (including contractile synchrony, coordination, propagation, and myocardial work) and flow dynamics have been studied using echocardiographic techniques to better characterize patients undergoing or with implanted CRT. However, the concepts, limits, and potential applications of all these echocardiographic evaluations are unclear to most clinicians. The use of left ventricular dyssynchrony and discoordination indices may help to identify those significant mechanical alterations whose correction may increase the probability of a favorable CRT response. Assessment of myocardial work and intracardiac flow dynamics may overcome some limitations of the conventional evaluation of cardiac mechanics but more investigations are needed before extensive clinical application.

Left Ventricular Deformation and Vortex Analysis in Heart Failure: From Ultrasound Technique to Current Clinical Application

Heart failure (HF) is a leading cause of cardiovascular morbidity and mortality. However, its symptoms and signs are not specific or can be absent. In this context, transthoracic echocardiography plays a key role in diagnosing the various forms of HF, guiding therapeutic decision making and monitoring response to therapy. Over the last few decades, new ultrasound modalities have been introduced in the field of echocardiography, aiming at better understanding the morpho-functional abnormalities occurring in cardiovascular diseases. However, they are still struggling to enter daily and routine use. In our review article, we turn the spotlight on some of the newest ultrasound technologies; in particular, analysis of myocardial deformation by speckle tracking echocardiography, and intracardiac flow dynamics by color Doppler flow mapping, highlighting their promising applications to HF diagnosis and management. We also focus on the importance of these imaging modalities in the selection of responses to cardiac resynchronization therapy.

Speckle Tracking Echocardiography: Early Predictor of Diagnosis and Prognosis in Coronary Artery Disease

Echocardiography represents a first level technique for the evaluation of coronary artery disease (CAD) which supports clinicians in the diagnostic and prognostic workup of these syndromes. However, visual estimation of wall motion abnormalities sometimes fails in detecting less clear or transient myocardial ischemia and in providing accurate differential diagnosis. Speckle tracking echocardiography (STE) is a widely available noninvasive tool that could easily and quickly provide additive information over basic echocardiography, since it is able to identify subtle myocardial damage and to localize ischemic territories in accordance to the coronary lesions, obtaining a clear visualization with a "polar map" useful for differential diagnosis and management. Therefore, it has increasingly been applied in acute and chronic coronary syndromes using rest and stress echocardiography, showing good results in terms of prediction of CAD, clinical outcome, left ventricular remodeling, presence, and quantification of new/residual ischemia. The aim of this review is to illustrate the current available evidence on STE usefulness for the assessment and follow-up of CAD, discussing the main findings on bidimensional and tridimensional strain parameters and their potential application in clinical practice.

Speckle Tracking Echocardiography in Non-ST-Segment Elevation Acute Coronary Syndromes

Non-ST-segment elevation acute coronary syndromes (NSTE-ACSs) are a group of clinical conditions characterized by acute myocardial ischemia. Conventional echocardiography is generally used to evaluate cardiac function using wall motion analysis and left ventricular ejection fraction but may be insufficient to explore all the complex features of NSTE-ACSs, which may vary substantially from patient to patient in terms of severity of ischemia and extent of involved myocardium. In the last years, speckle tracking echocardiography (STE) has become a widely available technique for the non-invasive assessment of cardiac function and has been repeatedly applied in the setting of NSTE-ACSs. In this review we summarize current evidence about the use of STE in patients with NSTE-ACSs, trying to underline advantages and limitations in comparison with conventional echocardiography for: diagnosis of NSTE-ACS, differential diagnosis, identification of high-risk patients, and prediction of outcome.

Echocardiographic evaluation of cardiac dyssynchrony: Does it still matter?

Cardiac resynchronization therapy (CRT) is an established treatment for patients with heart failure and left ventricular systolic dysfunction. For many years, cardiac mechanical dyssynchrony assessed by echocardiography has been considered as a key evaluation to characterize CRT candidates and predict CRT response. In current guidelines, however, CRT implant indications rely only on electrical dyssynchrony. The aim of this article was to clarify whether and how the evaluation of cardiac mechanical dyssynchrony should be performed today by echocardiography.

Speckle tracking analysis in intensive care unit: A toy or a tool?

The use of conventional echocardiography in the intensive care unit (ICU) is today established to assess left and right ventricular systolic function, for preload determination and procedural guidance. Next step in ICU echocardiography could be the use of novel ultrasound techniques such as strain echocardiography to assist in the management of patients with acute coronary syndrome, heart failure, or pulmonary embolism. This review has gathered the available evidence supporting the incremental value of strain in the diagnostic workup of cardiac diseases treated in ICU.

Prognostic value of global longitudinal strain in heart failure patients treated with cardiac resynchronization therapy

BACKGROUND

Myocardial fibrosis (macroscopic scar or diffuse reactive fibrosis) is one of the determinants of impaired left ventricular (LV) global longitudinal strain (GLS) in heart failure (HF) patients.

OBJECTIVE

The purpose of this study was to evaluate the prognostic value of LV GLS in HF patients treated with cardiac resynchronization therapy (CRT).

METHODS

The study included 829 HF patients (mean age 64.6 ± 10.4 years; 72% men) treated with CRT. Before CRT implantation, LV GLS was assessed using 2-dimensional speckle tracking echocardiography. The primary endpoint was the combination of all-cause mortality, heart transplantation, and LV assist device implantation. The secondary endpoint was the occurrence of ventricular arrhythmias or appropriate implantable defibrillator device therapies.

RESULTS

During follow-up, 332 patients reached the primary endpoint, and 233 presented with the secondary endpoint. Patients were divided according to LV GLS quartiles. Patients with the most impaired LV GLS quartile had a 2-fold higher risk of reaching the combined endpoint compared with patients in the best LV GLS quartile (hazard ratio [HR] 2.088; 95% confidence interval [CI] 1.555-2.804; P <.001). LV GLS was significantly associated with the combined endpoint (HR 1.075; 95% CI 1.020-1.133; P = .007) after adjusting for clinical, electrocardiographic, and echocardiographic characteristics. Although patients in the most impaired LV GLS quartile showed higher event rates for the secondary endpoint compared with the other groups, LV GLS was not independently associated with the secondary endpoint (HR 1.047; 95% CI 0.989-1.107; P = .115).

CONCLUSION

In this large cohort of CRT patients, baseline LV GLS was independently associated with the combined endpoint.

The years 2015-2016 in the European Heart Journal-Cardiovascular Imaging. Part I

The multimodality cardiovascular imaging journal, European Heart Journal-Cardiovascular Imaging, was launched in 2012. It has gained an impressive impact factor of 5.99 during its 5 first years and is now established as the most important cardiovascular imaging journal in Europe. The most important studies from the journal's forth and fifth years will be highlighted in two reports. Part I of the review will focus on studies about myocardial function and risk prediction, myocardial ischaemia, and emerging techniques in cardiovascular imaging, while Part II will focus on valvular heart disease, heart failure, cardiomyopathies, and congenital heart disease.

Standardized unfold mapping: a technique to permit left atrial regional data display and analysis

PURPOSE

Left atrial arrhythmia substrate assessment can involve multiple imaging and electrical modalities, but visual analysis of data on 3D surfaces is time-consuming and suffers from limited reproducibility. Unfold maps (e.g., the left ventricular bull's eye plot) allow 2D visualization, facilitate multimodal data representation, and provide a common reference space for inter-subject comparison. The aim of this work is to develop a method for automatic representation of multimodal information on a left atrial standardized unfold map (LA-SUM).

METHODS

The LA-SUM technique was developed and validated using 18 electroanatomic mapping (EAM) LA geometries before being applied to ten cardiac magnetic resonance/EAM paired geometries. The LA-SUM was defined as an unfold template of an average LA mesh, and registration of clinical data to this mesh facilitated creation of new LA-SUMs by surface parameterization.

RESULTS

The LA-SUM represents 24 LA regions on a flattened surface. Intra-observer variability of LA-SUMs for both EAM and CMR datasets was minimal; root-mean square difference of 0.008 ± 0.010 and 0.007 ± 0.005 ms (local activation time maps), 0.068 ± 0.063 gs (force-time integral maps), and 0.031 ± 0.026 (CMR LGE signal intensity maps). Following validation, LA-SUMs were used for automatic quantification of post-ablation scar formation using CMR imaging, demonstrating a weak but significant relationship between ablation force-time integral and scar coverage (R ² = 0.18, P < 0.0001).

CONCLUSIONS

The proposed LA-SUM displays an integrated unfold map for multimodal information. The method is applicable to any LA surface, including those derived from imaging and EAM systems. The LA-SUM would facilitate standardization of future research studies involving segmental analysis of the LA.

Early Speckle-tracking Echocardiography Predicts Left Ventricle Remodeling after Acute ST-segment Elevation Myocardial Infarction

Background:

Prediction of the left ventricular remodeling (LVR) after ST-segment elevation myocardial infarction (STEMI) in patients treated with effective myocardial reperfusion is challenging.

Methods:

Forty-one consecutive patients (36 males, age 59 ± 10 years) with STEMI who underwent effective (TIMI III) primary coronary angioplasty were enrolled. All patients had an echocardiography and cardiac magnetic resonance (CMR) study within 72 h from revascularization. Three echocardiographic parameters including LV ejection fraction (EF), global longitudinal strain (GLS) and severe altered longitudinal strain (SAS) area by two-dimensional speckle-tracking echocardiography (2D-STE) and 3 CMR indices including LV global function index (LV-GFI), myocardial salvage index (MSI), and microvascular obstruction (MVO) were calculated. LVR was defined as an increase in CMR LV end-diastolic volume (EDV) >15% after 6 months.

Results:

Of 41 patients, 10 (24%) had LVR (LV-EDV from 145.1 ± 29.3 to 185.9 ± 49.8 ml, P < 0.001). A significant correlation with LV-EDV variation was found for baseline SAS area (r = 0.81), LV-GFI (r = −0.56), MVO (r = 0.55), EF (r = −0.42), GLS (r = 0.42), not for MSI (r = −0.25). At the multivariable analysis, a significant correlation remained only for the SAS area. The receiver-operating characteristic curve analysis showed that a baseline SAS area ≥15% predicts LVR with a sensitivity of 80.0% and a specificity of 90.3%.

Conclusions:

The SAS area evaluated by 2D-STE early in acute STEMI is a valuable predictor of LVR after 6 months. Further investigations are needed to verify its value in predicting patient survival.

Cardiac resynchronization therapy guided by multimodality cardiac imaging

AIMS

Up to 30-45% of implanted patients are non-responders to CRT. We evaluated the role of a 'CRT team' using cardiac magnetic resonance (CMR) and longitudinal myocardial strain to identify the target area defined as the most delayed and viable region for LV pacing.

METHODS AND RESULTS

A total of 100 heart failure patients candidates for CRT divided into two groups were enrolled. Group 1 consisted of 50 consecutive patients scheduled for CRT and prospectively included. Group 2 (control) consisted of 50 patients with a CRT device implanted according to standard clinical practice and matched for age, sex, and LVEF with group 1. Patients were evaluated at baseline and at 6-month follow-up. In group 1, patients underwent two-dimensional speckle-tracking assessment of longitudinal myocardial strain and CMR imaging to identify the target area for LV lead pacing. A positive response to CRT was defined as a reduction of ≥15% of the LV end-systolic volume at 6-month follow-up. A total of 39 (78%) patients of group 1 were classified as responders to CRT whilst in group 2, only 28 (56%) were responders (P = 0.019). The 'CRT team' identified as target for LV pacing the lateral area in 30 (60%) patients, and the anterolateral or posterolateral areas in 12 (24%) patients. In 8 (16%) patients, the target was far from the lateral area, in the anterior or posterior areas. The patients with concordant position exhibited the highest positive response (93.1%) to CRT.

CONCLUSIONS

Multimodality cardiac imaging as a guide for CRT implantation is useful to increase response rate.