title: Strain echocardiography improves risk prediction of ventricular arrhythmias after myocardial infarction.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Cardiology, Institute for Surgical Research and Center for Cardiological Innovation, Oslo University Hospital, Rikshospitalet Oslo, Norway.
authors.forename: Kristina H
authors.initials: KH
authors.lastname: Haugaa
authors.forename: Bjørnar L
authors.initials: BL
authors.lastname: Grenne
authors.forename: Christian H
authors.initials: CH
authors.lastname: Eek
authors.forename: Mads
authors.initials: M
authors.lastname: Ersbøll
authors.forename: Nana
authors.initials: N
authors.lastname: Valeur
authors.forename: Jesper H
authors.initials: JH
authors.lastname: Svendsen
authors.forename: Anca
authors.initials: A
authors.lastname: Florian
authors.forename: Benthe
authors.initials: B
authors.lastname: Sjøli
authors.forename: Harald
authors.initials: H
authors.lastname: Brunvand
authors.forename: Lars
authors.initials: L
authors.lastname: Køber
authors.forename: Jens-Uwe
authors.initials: JU
authors.lastname: Voigt
authors.forename: Walter
authors.initials: W
authors.lastname: Desmet
authors.forename: Otto A
authors.initials: OA
authors.lastname: Smiseth
authors.forename: Thor
authors.initials: T
authors.lastname: Edvardsen
mesh_terms: D000368:Aged; D016757:Death, Sudden, Cardiac / Q000209:etiology* / Q000517:prevention & control; D017147:Defibrillators, Implantable; D004452:Echocardiography / Q000379:methods*; D004554:Electric Countershock / Q000295:instrumentation; D004562:Electrocardiography; D005060:Europe; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000150:complications / Q000000981:diagnostic imaging* / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D018579:Patient Selection; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D013318:Stroke Volume; D017180:Tachycardia, Ventricular / Q000209:etiology* / Q000401:mortality / Q000503:physiopathology / Q000517:prevention & control; D013997:Time Factors; D016277:Ventricular Function, Left
keywords: GLS; ICD; LV; LVEDV; LVEF; LVESV; MI; NSTEMI; PPV; PSSI; SCD; global longitudinal strain; implantable cardioverter-defibrillator; left ventricular; left ventricular ejection fraction; left ventricular end-diastolic volume; left ventricular end-systolic volume; myocardial infarction; non–ST-segment elevation myocardial infarction; positive predictive value; post-systolic strain index; risk assessment; strain echocardiography; sudden cardiac death; ventricular arrhythmias