Page 21 - The role of advanced echocardiography in patients with ischemic heart disease - Rachid Abou

Identification of LV hypertrophy aetiologies 1 LV GLS may aid in the differentiation of the causes of LV hypertrophy. Certain characteristic patterns are evident: patients with mutation positive sarcomeric hypertrophic cardiomyopathy usually demonstrate regionally impaired LV GLS in the
regions where hypertrophy is most prominent.18 In contrast, cardiac amyloidosis is characterized by relative sparing of the LV apical segments (Figure 3).19
The clinical implications of impaired LV GLS in patients with hypertrophic cardiomyopathy have been demonstrated in several studies.20, 21 LV GLS is usually impaired in these patients, despite having normal LVEFs.21In a systematic review, including 3154 patients with hypertrophic cardiomyopathy, the mean LVEF ranged between 62% and 72% whereas LV GLS was impaired and ranged between -9% and -16.%. The different vendors used to analyse LV GLS could partly explain the relatively wide range of values. However, it is important to note that hypertrophic cardiomyopathy is a very heterogenous disease and that the magnitude of myocyte disarray is probably the main determinant of functional and structural abnormalities whereas replacement fibrosis and microvessel disease, which can also impact on LV GLS, are related to LV mass, sex and local autocrine factors.22 The majority of studies have shown that impaired LV GLS is associated with an increased risk of ventricular arrhythmias, heart failure symptoms and all-cause mortality.21, 23
In cardiac amyloidosis, LV GLS has also shown incremental prognostic value over a current prognostic staging algorithm including cardiac troponin T, N-terminal pro- brain natriuretic peptide and free light chain serum levels.23 Among 150 patients with biopsy-proven light chain amyloidosis and LVEF≥55%, a value of LV GLS ≥-14.8% was associated with a hazard ratio of 2.68 for the occurrence of all-cause mortality.
Coronary artery disease
LV subendocardial muscle fibres are predominantly oriented in a longitudinal direction. Since the subendocardium is most susceptible to ischaemia, it is therefore not surprising that LV GLS is affected by coronary artery disease earlier than LVEF. Speckle tracking echocardiography can be used in patients with coronary artery disease during both rest and stress (exercise or pharmacological).24 Measuring LV GLS from images obtained during stress echocardiography does however, present a number of technical challenges: 1) increased heart rate influences LV GLS values, 2) image quality is often suboptimal and 3) STE cannot be performed in conjunction with contrast agents.
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