Abstract 429: Prediction of Ventricular Arrhythmias by Mechanical Dispersion in Patients After Myocardial Infarction
Background Left ventricular ejection fraction (EF) is insufficient in selecting patients for ICD therapy after MI. Electrical dispersion in infarcted myocardium facilitates malignant arrhythmia. Myocardial strain by echocardiography can quantify detailed regional and global myocardial function. We hypothesized that electrical abnormalities in patients after MI will lead to LV mechanical dispersion which can be measured as regional heterogeneity of contraction by myocardial strain.
Methods We included 104 patients post MI, 45 meeting primary and 59 meeting secondary ICD prevention criteria. Strain measurements were assessed by echocardiography. Contraction duration was measured as the time from ECG Q to maximum LV shortening by strain. Standard deviation (SD) of contraction duration in a 16 LV segment model was calculated as a parameter of mechanical dispersion.
Results After 3.4±2.6 years follow up, 53 had no and 51 patients had one or more recorded arrhythmias requiring appropriate ICD therapy. Mechanical dispersion was more pronounced in patients with recurrent arrhythmias during follow up compared to those without (90±31ms vs. 57±14ms, p<0.001). By Cox regression analysis, mechanical dispersion >90ms was a strong and independent predictor of arrhythmias (HR 3.7, 95%CI 2.1– 6.6, p<0.001). Kaplan Meier analysis showed more arrhythmic events in patients with mechanical dispersion>90ms (Log rank p<0.001) (Figure⇓). EF did not discriminate those with follow up arrhythmias from those without (36±10% vs. 35±11%, p = 0.59.
Conclusions Mechanical dispersion predicted ventricular arrhythmias in post MI patients independently of EF.