Prognostic implications of left ventricular regional function heterogeneity assessed with two-dimensional speckle tracking in patients with ST-segment elevation myocardial infarction and depressed left ventricular ejection fraction

Strain Imaging and Ventricular Arrhythmia

Ventricular arrhythmia is one of the main causes of sudden cardiac death. Hence, identifying patients at risk of ventricular arrhythmias and sudden cardiac death is important but can be challenging. The indication for an implantable cardioverter defibrillator as a primary preventive strategy relies on the left ventricular ejection fraction as a measure of systolic function. However, ejection fraction is flawed by technical constraints and is an indirect measure of systolic function. There has, therefore, been an incentive to identify other markers to optimize the risk prediction of malignant arrhythmias to select proper candidates who could benefit from an implantable cardioverter defibrillator. Speckle-tracking echocardiography allows for a detailed assessment of cardiac mechanics, and strain imaging has repeatedly been shown to be a sensitive technique to identify systolic dysfunction unrecognized by ejection fraction. Several strain measures, including global longitudinal strain, regional strain, and mechanical dispersion, have consequently been proposed as potential markers of ventricular arrhythmias. In this review, we will provide an overview of the potential use of different strain measures in the context of ventricular arrhythmias.

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.

Prediction for Improvement and Remodeling in First-Onset Myocardial Infarction by Speckle Tracking Echocardiography: Is Global or Regional Selection Better?

Cardiac function improvement and chamber remodeling after the onset of acute myocardial infarction (AMI) is crucial as it is closely related to the outcomes of patients. We sought to investigate the predictive value of left ventricular (LV) global and region of interest (ROI) assessment for prognosis of AMI patients by speckle tracking echocardiography (STE). We prospectively enrolled 81 first-onset AMI patients for baseline and 6-mo follow-up analysis. The echocardiography-derived parameters were compared in receiver operator characteristics (ROC) analysis for prediction of LV remodeling (LVR) (a minimum 20% increase of LV end-diastolic volume) and cardiac function improvement (a minimum 5% increase of LV ejection fraction). The ROI strain was selected by wall motion score index (WMSI) scores ≥2. The time of whole analysis process was recorded. Cut-off values of -9.92% for global circumferential strain (CS) and -5.53% for ROI CS predicted LVR. Cut-off values of -10.40% for global longitudinal strain (LS) and -5.33% for ROI LS predicted cardiac function improvement. Areas under curves of global and ROI parameters were comparable in ROC analysis (p > 0.05, all). The time of global analysis was less than the time of ROI analysis (p < 0.05) and the reproducibility of global analysis was slightly better than the ROI analysis. Our results demonstrated that STE was valuable for the prediction of LVR and cardiac function improvement after AMI. Compared with ROI parameters, global parameters were more integral and efficient as predictive factors with high predictive power, less analysis time and better reproducibility.

Relationships of left ventricular strain and strain rate to wall stress and their afterload dependency

Whether and how left ventricular (LV) strain and strain rate correlate with wall stress is not known. Furthermore, it is not determined whether strain or strain rate is less dependent on the afterload. In 41 healthy young adults, LV global peak strain and systolic peak strain rate in the longitudinal direction (LS and LSR, respectively) and circumferential direction (CS and CSR, respectively) were measured layer-specifically using speckle tracking echocardiography (STE) before and during a handgrip exercise. Among all the points before and during the exercise, all the STE parameters significantly correlated linearly with wall stress (LS: r = -0.53, p < 0.01, LSR: r = -0.28, p < 0.05, CS in the inner layer: r = -0.72, p < 0.01, CSR in the inner layer: r = -0.47, p < 0.01). Strain more strongly correlated with wall stress than strain rate (r = -0.53 for LS vs. r = -0.28 for LSR, p < 0.05; r = -0.72 for CS vs. r = -0.47 for CSR in the inner layer, p < 0.05), whereas the interobserver variability was similar between strain and strain rate (longitudinal 6.2 vs. 5.2 %, inner circumferential 4.8 vs. 4.7 %, mid-circumferential 7.9 vs. 6.9 %, outer circumferential 10.4 vs. 9.7 %), indicating that the differences in correlation coefficients reflect those in afterload dependency. It was thus concluded that LV strain and strain rate linearly and inversely correlated with wall stress in the longitudinal and circumferential directions, and strain more strongly depended on afterload than did strain rate. Myocardial shortening should be evaluated based on the relationships between these parameters and wall stress.