Strain echocardiography improves risk prediction of ventricular arrhythmias after myocardial infarction
Kristina H Haugaa1, Bjørnar L Grenne, Christian H Eek
1Department of Cardiology, Institute for Surgical Research and Center for Cardiological Innovation, Oslo University Hospital, Rikshospitalet Oslo, Norway.
Insights
Strain echocardiography, measuring mechanical dispersion and global strain, can improve risk stratification for ventricular arrhythmias after myocardial infarction (MI). This technique may help identify patients, especially those with preserved ejection fraction, who could benefit from implantable cardioverter-defibrillator therapy.
Area of Science:
- Cardiology
- Echocardiography
- Cardiac Electrophysiology
Background:
- Predicting ventricular arrhythmias post-myocardial infarction (MI) is clinically significant.
- Left ventricular ejection fraction (LVEF) is the primary criterion for implantable cardioverter-defibrillator (ICD) selection, but its predictive power is limited.
Purpose of the Study:
- To evaluate if strain echocardiography can enhance arrhythmic risk stratification in post-MI patients.
- To investigate the role of mechanical dispersion and global strain in predicting ventricular arrhythmias.
Main Methods:
- A prospective, multicenter study included 569 patients >40 days post-MI.
- Global strain and mechanical dispersion (a measure of contraction heterogeneity) were assessed using echocardiography.
- Patients were followed for a median of 30 months for arrhythmic events (sustained ventricular tachycardia or sudden death).
Main Results:
- Fifteen patients (3%) experienced arrhythmic events.
- Patients with arrhythmias had reduced global strain and increased mechanical dispersion compared to those without.
- Mechanical dispersion independently predicted arrhythmic events and was a significant marker in patients with non-ST-segment elevation MI and LVEF >35%, unlike LVEF itself.
Conclusions:
- Mechanical dispersion, assessed by strain echocardiography, is an independent predictor of arrhythmic events post-MI, irrespective of LVEF.
- Combining mechanical dispersion and global strain may improve the identification of patients suitable for ICD therapy, particularly those with LVEF >35%.
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.
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