Physiological basis in the assessment of myocardial mechanics using speckle-tracking echocardiography 2D. Part II

[Clinical Capabilities and Limitations in the Use of Modern Technologies in Echocardiography]

Transthoracic echocardiography is the most frequently used method for detection of impaired contractility of the left ventricle. In most cases, assessment of contractility is carried out visually "by eye", what increases its subjectivity, is operator-dependent in nature and requires a high level of clinical training and experience of the researcher. Currently in the arsenal of a specialist in echocardiography for quantification of left ventricular contractility sometimes is used tissue Doppler echocardiography, however, this method requires special settings of the image (high frame rate, the allocation of zones of interest), depends on the scanning angle and on operator qualification, has high intra - and inter-operator variability, and significantly increases the duration of the study. Therefore, this method has not received wide clinical application. In the 2000s years an innovative technique of speckle tracking emerged, which, unlike tissue Doppler echocardiography is efficient, does not burden a researcher with time costs, has a low intra - and inter- operator variability, does not depend on scan angle. In recent years, this technology is actively implemented in clinical practice for detection of subclinical impairment of the functional state of the myocardium in different diseases and syndromes: arterial hypertension, ischemic heart disease, valvular defects, and congenital heart disease, heart failure, cardiomyopathy of different etiology.

Prognostic importance of mechanical dyssynchrony in predicting heart failure development after ST-segment elevation myocardial infarction

The aim of this study is to assess the prognostic value of mechanical dyssynchrony defined as the standard deviation of the time to peak longitudinal strain (SD T2P LS) in predicting the development of heart failure (HF) after an ST-segment elevation myocardial infarction (STEMI). Three hundred and seventy-three patients were admitted with STEMI and treated with primary percutaneous coronary intervention. Left ventricular (LV) mechanical dyssynchrony was examined through speckle tracking echocardiography and defined as SD T2P LS. The association with the outcome of HF hospitalization was assessed using Cox proportional hazard models. During a median follow-up of 5.12 years, 144 patients (38.6%) were admitted due to HF. Worse dyssynchrony was associated with the outcome in unadjusted and multivariable analysis (multivariable hazard ratio 1.05, 95% confidence interval 1.00-1.10, p-value 0.039, per 10 ms increase), but not after further adjustment for LV ejection fraction (LVEF), E/e' and global longitudinal strain (GLS) (hazard ratio 1.01, 95% confidence interval 1.00-1.07, p-value 0.71, per 10 ms increase), nor in a model only adjusting for GLS (hazard ratio 1.01, 95% confidence interval 1.00-1.06, p-value 0.61, per 10 ms increase). These findings were reproduced in a competing risk analysis treating all-cause mortality as a competing risk. LV mechanical dyssynchrony, as assessed by SD T2P LS is not an independent predictor of post-STEMI HF development and mechanical dyssynchrony does not provide independent prognostic information regarding HF when GLS is known.