Page 163 - The role of advanced echocardiography in patients with ischemic heart disease - Rachid Abou
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of LV scaring.20 However, it remains unclear which scar characteristics are prognostic in the prediction of ventricular arrhythmias. Some studies have shown that the extent of the infarct core scar is most predictive of events, while other studies have showed that the border zone (grey zone) is more important.4,19,21-24 Some of this variability may be attributed to different populations (acute STEMI vs chronic ischemic heart disease ) and different definitions for quantifying LV scar. Furthermore, the presence or reactive fibrosis, measured with native T1 mapping techniques has been associated with the occurrence of ventricular arrhythmias. Chen et al 25 showed in 130 patients (71 with ischemic heart failure), that for every 10-ms increment in non-contrast T1 (native) value, the risk of appropriate ICD therapy or documented sustained ventricular arrhythmia increased by 10% (HR 1.10; CI 1.04-1.16). Therefore, new non-invasive parameters may further aid in early recognition of patients at risk of adverse outcomes.
Recently LV MD by 2D STE has appeared as a relative novel parameter in the risk stratification of various cardiac diseases. It is hypothesized that the extent of tissue heterogeneity causes heterogeneous electrical conduction, which is associated with ventricular arrhythmias and mortality in various cardiac diseases.5-8,26-30
A previous study by Leong et al 31, demonstrated that LV MD was independently
associated with the occurrence of ventricular arrhythmias in 206 patients with ischemic 8 heart disease. Interestingly, Leong et al demonstrated that a higher total percentage
of LGE as evaluated by CMR was associated with prolonged LV MD, indicating a larger
burden of LV fibrosis.31 These findings were corroborated by a recent study measuring
LV MD with feature tracking CMR.7 In 130 STEMI patients after first STEMI evaluated
with feature tracking CMR and LGE CMR, Muser et al 156 showed a correlation between myocardial infarct size and LV MD (r=0.50, p<0.001).
Left ventricular mechanical dispersion and clinical implications
LV dyssynchrony can be observed in patients after myocardial infarction and has been associated with myocardial infarct size and poor outcome.32.33 Although current guidelines still include the use of LVEF as the main functional parameter to manage patients after STEMI, 2D STE has been shown to be of incremental value over LVEF in this group of patients.5,6,34
Of 988 patients post-myocardial infarction, Ersbøll et al 26 reported the occurrence of ventricular arrhythmias or sudden cardiac death in 34 patients. Patients presenting with ventricular arrhythmias or sudden cardiac death showed more prolonged LV MD than patients who were free of those events (70.7 ± 29.7ms vs. 56.1 ± 15.3ms).26
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