Objectives The aim of this study was to test the hypothesis that strain echocardiography might improve arrhythmic risk stratification in patients after myocardial infarction (MI). Background ...Prediction of ventricular arrhythmias after MI is challenging. Left ventricular ejection fraction (LVEF) <35% is the main parameter for selecting patients for implantable cardioverter-defibrillator therapy. Methods In this prospective, multicenter study, 569 patients >40 days after acute MI were included, 268 of whom had ST-segment elevation MIs and 301 non–ST-segment elevation MIs. By echocardiography, global strain was assessed as average peak longitudinal systolic strain from 16 left ventricular segments. Time from the electrocardiographic R-wave to peak negative strain was assessed in each segment. Mechanical dispersion was defined as the standard deviation from these 16 time intervals, reflecting contraction heterogeneity. Results Ventricular arrhythmias, defined as sustained ventricular tachycardia or sudden death during a median 30 months (interquartile range: 18 months) of follow-up, occurred in 15 patients (3%). LVEFs were reduced (48 ± 17% vs. 55 ± 11%, p < 0.01), global strain was markedly reduced (−14.8 ± 4.7% vs. −18.2 ± 3.7%, p = 0.001), and mechanical dispersion was increased (63 ± 25 ms vs. 42 ± 17 ms, p < 0.001) in patients with arrhythmias compared with those without. Mechanical dispersion was an independent predictor of arrhythmic events (per 10-ms increase, hazard ratio: 1.7; 95% confidence interval: 1.2 to 2.5; p < 0.01). Mechanical dispersion and global strain were markers of arrhythmias in patients with non–ST-segment elevation MIs (p < 0.05 for both) and in those with LVEFs >35% (p < 0.05 for both), whereas LVEF was not (p = 0.33). A combination of mechanical dispersion and global strain showed the best positive predictive value for arrhythmic events (21%; 95% confidence interval: 6% to 46%). Conclusions Mechanical dispersion by strain echocardiography predicted arrhythmic events independently of LVEF in this prospective, multicenter study of patients after MI. A combination of mechanical dispersion and global strain may improve the selection of patients after MI for implantable cardioverter-defibrillator therapy, particularly in patients with LVEFs >35% who did not fulfill current implantable cardioverter-defibrillator indications.
Many patients with suspected non-ST-segment elevation acute coronary syndrome (NSTE-ACS) do not have significant coronary artery disease. The current diagnostic approach of repeated ...electrocardiography and cardiac biomarker assessment requires observation for >6 to 12 hours. This strategy places a heavy burden on hospital facilities. The objective of this study was to investigate whether myocardial strain assessment by echocardiography could exclude significant coronary artery stenosis in patients presenting with suspected NSTE-ACS.
Sixty-four patients presenting to the emergency department with suspected NSTE-ACS without known coronary artery disease, inconclusive electrocardiographic findings, and normal cardiac biomarkers at arrival were enrolled. Twelve-lead electrocardiography, troponin T assay, and echocardiography were performed at arrival, and all patients underwent coronary angiography. Significant coronary stenosis was defined as >50% luminal narrowing. Global myocardial peak systolic longitudinal strain was measured using speckle-tracking echocardiography. Left ventricular ejection fraction and wall motion score index were calculated.
No significant stenosis in any coronary artery was found in 35 patients (55%). Global peak systolic longitudinal strain was superior to conventional echocardiographic parameters in distinguishing patients with and without significant coronary artery stenosis (area under the curve, 0.87). Sensitivity and specificity were calculated as 0.93 and 0.78, respectively, and positive predictive value and negative predictive value as 0.74 and 0.92, respectively. Feasibility of the strain measurements was excellent, with 97% of segments analyzed.
Myocardial strain by echocardiography may facilitate the exclusion of significant coronary artery stenosis among patients presenting with suspected NSTE-ACS with inconclusive electrocardiographic findings and normal cardiac biomarkers.
Early Prediction of Infarct Size by Strain Doppler Echocardiography After Coronary Reperfusion Trond Vartdal, Harald Brunvand, Eirik Pettersen, Hans-Jørgen Smith, Erik Lyseggen, Thomas Helle-Valle, ...Helge Skulstad, Halfdan Ihlen, Thor Edvardsen The objective of this study was to investigate whether strain by Doppler performed immediately after revascularization by percutaneous coronary intervention could predict the extent of myocardial scar. We examined 30 individuals with acute anterior myocardial infarction. Strain in all left ventricular segments was averaged to obtain a global value. A good correlation was found between strain and total infarct size. In addition, infarct size was estimated by the most common cardiac markers. Strain exceeded the other markers in predicting the infarct size. Furthermore, strain predicted the transmural extent of infarction in each segment. Global strain may be an important clinical tool for risk stratification after myocardial infarction.
Diagnostic Capability and Reproducibility of Strain by Doppler and by Speckle Tracking in Patients With Acute Myocardial Infarction Benthe Sjøli, Stein Ørn, Bjørnar Grenne, Halfdan Ihlen, Thor ...Edvardsen, Harald Brunvand In this validation of strain by Doppler and speckle tracking, a 16-segment model of the left ventricle (LV) was used to compare peak systolic, end systolic and peak negative strain against the corresponding myocardial segments measured by contrast-enhanced cardiac magnetic resonance. In tests obtained after acute ST-elevation myocardial infarction (STEMI) treated with thrombolysis, circumferential strain provided a better separation between the different levels of infarct transmurality than did longitudinal strain. LV global longitudinal strain (averaged over 16 segments) correlated well with myocardial infarct size, with peak systolic speckle strain as the preferred method.
Early prediction of infarct size directs therapy in patients with acute myocardial infarction (AMI). Global strain by echocardiography describes myocardial deformation and correlates with infarct ...size. However, peak strain measures deformation at a single time point, whereas ischemia and necrosis influence deformation throughout the heart cycle. It was hypothesized that the measurement of myocardial deformation throughout the heart cycle by mean strain is a more comprehensive expression of myocardial deformation. The aim of this study was to assess the ability of mean strain to predict infarct size and to identify large infarctions at admission and after revascularization in patients with AMI.
Seventy-six patients with AMI were included. Echocardiographic measurements were performed at admission and after revascularization. Myocardial strain was calculated using speckle-tracking echocardiography. Infarct size was measured using contrast-enhanced magnetic resonance imaging ≥3 months after revascularization.
There were significant correlations between infarct size and longitudinal global mean strain, longitudinal global strain, and left ventricular ejection fraction (P < .0001), both at admission and after revascularization. The correlations improved after revascularization. Longitudinal global mean strain had the best correlation with infarct size and the best ability to discriminate between different infarct size categories. At admission, a cutoff value of -7.6 had 89% sensitivity, 88% specificity, and an area under the receiver operating characteristic curve of 0.92 for the identification of large infarctions. Prediction of infarct size improved for all parameters after revascularization.
Longitudinal global mean strain provides improved early prediction of infarct size in patients with AMI compared with longitudinal global strain and left ventricular ejection fraction.
Increasing infarct mass is associated with impaired prognosis in chronic ischemic heart disease. Global strain by echocardiographic assessment relates closely to infarct mass assessed by delayed ...enhancement magnetic resonance imaging but requires deformation analysis in a 16-segment model of the left ventricular. Mitral annular (MA) displacement reflects longitudinal left ventricular deformation and could provide similar information.
Global longitudinal strain and MA displacement by Doppler tissue imaging were assessed in 61 patients 9 months after first myocardial infarctions and compared with global myocardial infarct mass assessed using contrast-enhanced magnetic resonance imaging.
Both indices significantly separated medium-sized infarcts from small or large infarcts (P < .05) and correlated significantly with global infarct mass (P < .01 for both). There was a good correlation between global strain and MA displacement (r = 0.65, P < .01). The sensitivities and specificities to identify myocardial infarcts differed only slightly among the indices, but global longitudinal strain tended to be the best.
Longitudinal deformation by global strain or MA displacement correlated well with myocardial infarct mass and could discriminate between different extents of myocardial infarctions. Global longitudinal strain tended to be better, especially for the identification of the smallest infarcts.
The aim was to compare left ventricular ejection fraction (LVEF) and left ventricular (LV) global strain by speckle tracking as predictors of final infarct size.
LV global strain and LVEF by ...echocardiography were assessed in the acute phase and after revascularization in 39 patients with ST-elevation myocardial infarction treated with thrombolysis.
After revascularization, global strain and LVEF correlated well with infarct size measured by contrast-enhanced cardiac magnetic resonance. A cutoff value of -15.0% for global strain had a sensitivity of 90% and a specificity of 86% to identify myocardial infarcts larger than 20%. Interobserver variability, expressed by intraclass correlation coefficients, for global strain and LVEF was 0.91 and 0.72, respectively.
LV global strain is a more precise diagnostic predictor of large infarcts compared with LVEF and is more reproducible. Global strain measured after revascularization demonstrates advantages over LVEF in the evaluation of LV injury in patients with ST-elevation myocardial infarction.
The optimal timing of coronary angiography in patients with non–ST elevation (NSTE) acute coronary syndromes (ACS) is debated. American Heart Association and American College of Cardiology guidelines ...recommend an early invasive strategy <12 to 48 hours after the onset of symptoms. The objective of the present study was to determine possible changes in myocardial function in patients with NSTE ACS awaiting coronary angiography. One hundred two patients with suspected NSTE ACS were enrolled, including 56 with NSTE myocardial infarctions (NSTEMIs), 23 with unstable angina pectoris, and 23 with noncoronary chest pain. Global and regional myocardial function was measured as longitudinal and circumferential strain using speckle-tracking echocardiography. Measurements were performed at admission and immediately before coronary angiography (30 ± 16 hours after admission). In patients with NSTEMIs, there was deterioration in longitudinal global strain from −16.1 ± 2.6% at admission to −15.0 ± 2.6% before coronary angiography (p <0.001). This was due to deterioration in longitudinal strain in the territory supplied by the infarct-related artery from −14.2 ± 4.2% to −12.0 ± 4.1% (p <0.001). Patients with NSTEMIs due to acute coronary occlusion underwent prominent worsening in longitudinal and circumferential strains (−15.7 ± 2.9% to −13.9 ± 3.0%, p = 0.001, and −16.7 ± 4.0% to −15.0 ± 3.9%, p = 0.01, respectively) compared to patients with NSTEMIs without occlusions. There were no changes in strain in patients with unstable angina pectoris or noncoronary chest pain. In patients with NSTEMIs without acute coronary occlusions, myocardial function improved after revascularization, whereas patients with acute occlusions demonstrated no improvement. In conclusion, myocardial function deteriorates in patients with NSTEMIs awaiting coronary angiography. Patients with acute coronary occlusions have the most prominent deterioration, and this subgroup shows no recovery of function after revascularization.
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