Diagnostic and Prognostic Use of Myocardial Strain in Patients with Acute Myocardial Infarction

Hjerteultralyd som markør for funksjon og prognose ved akutt hjerteinfarkt Lege og forsker Benthe Sjøli har vist at bruk av hjerteultralyd før utskrivelse av pasienter som har gjennomgått hjerteinfarkt, er en god markør på infarktstørrelse, hjertets pumpefunksjon og prognose. Graden av hjertemuskelskade etter gjennomgått hjerteinfarkt er viktig for å gi diagnostisk og prognostisk informasjon hos disse pasientene. Ved å tidlig identifisere pasienter med stor risiko, kan videre valg av behandling optimaliseres. Hjerteultralyd er en lett tilgjengelig, skånsom og billig undersøkelsesmetode. I dag brukes ejeksjons fraksjon (EF) som et mål på venstre hovedkammers pumpefunksjon. Denne metoden er svært undersøkeravhengig og har stor variabilitet. Sjøli og medarbeidere har vist at bruk av nyere ultralydteknikker har mindre variabilitet og dermed flere fordeler sammenlignet med EF til å evaluere infarktstørrelse og funksjon hos pasienter med akutt hjerteinfarkt. Ved å måle deformering av hjertemuskelveggen (strain) viser dette et godt samsvar med infarktstørrelse målt ved MR. I tillegg er denne metoden bedre til å tidlig forutsi hendelser etter gjennomgått hjerteinfarkt. Avhandlingen ”Diagnostic and prognostic use of myocardial strain in patients with acute myocardial infarction” utgår fra Universitetet i Oslo og har vært et samarbeid mellom Sørlandet Sykehus, Arendal og Oslo Universitetssykehus, Rikshospitalet. Funnene i avhandlingen viser at en ny hjerteultralyd markør kan gi bedre vurdering av hjerteinfarktstørrelse, hjertets pumpefunksjon og prognose ved bruk før utskrivelse etter hjerteinfarkt

Global longitudinal strain is a more reproducible measure of left ventricular function than ejection fraction regardless of echocardiographic training

Background: Left ventricular ejection fraction (LVEF) is an established method for evaluation of left ventricular (LV)systolic function. Global longitudinal strain (GLS) by speckle tracking echocardiography seems to be an important additive method for evaluation of LV function with improved reproducibility compared with LVEF. Our aim was to compare reproducibility of GLS and LVEF between an expert and trainee both as echocardiographic examiner and analyst. Methods: Forty-seven patients with recent Acute Coronary Syndrome (ACS) underwent echocardiographic examination by both an expert echocardiographer and a trainee. Both echocardiographers, blinded for clinical data and each other’s findings, performed image analysis for evaluation of intra- and inter- observer variability. GLS was measured using speckle tracking echocardiography. LVEF was calculated by Simpson’s biplane method. Results: The trainee measured a GLS of−19.4% (±3.5%) and expert−18.7% (±3.2%) with an Intra class correlation coefficient (ICC) of 0.89 (0.74–0.95). LVEF by trainee was 50.3% (±8.2%) and by expert 53.6% (±8.6%), ICC coefficient was 0.63 (0.32–0.80). For GLS the systematic difference was 0.21% (−4.58–2.64) vs. 4.08% (−20.78–12.62) for LVEF. Conclusion: GLS is a more reproducible method for evaluation of LV function than LVEF regardless of echocardiographic training

Strain echocardiography improves prediction of arrhythmic events in ischemic and non-ischemic dilated cardiomyopathy

Background Recent evidence suggests that an implantable cardioverter defibrillator (ICD) in non-ischemic cardiomyopathy (NICM) may not offer mortality benefit. We aimed to investigate if etiology of heart failure and strain echocardiography can improve risk stratification of life threatening ventricular arrhythmia (VA) in heart failure patients. Methods This prospective multi-center follow-up study consecutively included NICM and ischemic cardiomyopathy (ICM) patients with left ventricular ejection fraction (LVEF) <40%. We assessed LVEF, global longitudinal strain (GLS) and mechanical dispersion (MD) by echocardiography. Ventricular arrhythmia was defined as sustained ventricular tachycardia, sudden cardiac death or appropriate shock from an ICD. Results We included 290 patients (67 ± 13 years old, 74% males, 207(71%) ICM). During 22 ± 12 months follow up, VA occurred in 32(11%) patients. MD and GLS were both markers of VA in patients with ICM and NICM, whereas LVEF was not (p = 0.14). MD independently predicted VA (HR: 1.19; 95% CI 1.08–1.32, p = 0.001), with excellent arrhythmia free survival in patients with MD 70 ms had highest VA incidence with an event rate of 16%/year. Conclusion Patients with NICM and normal MD had low arrhythmic event rate, comparable to the general population. Patients with ICM and MD >70 ms had the highest risk of VA. Combining heart failure etiology and strain echocardiography may classify heart failure patients in low, intermediate and high risk of VA and thereby aid ICD decision strategies

Strain Echocardiography Improves Risk Prediction of Ventricular Arrhythmias After Myocardial Infarction

ObjectivesThe aim of this study was to test the hypothesis that strain echocardiography might improve arrhythmic risk stratification in patients after myocardial infarction (MI).BackgroundPrediction 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.MethodsIn 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.ResultsVentricular 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%).ConclusionsMechanical 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