Left ventricular dyssynergy and dispersion as determinant factors of fatal ventricular arrhythmias in patients with mildly reduced ejection fraction

Aims: Current guidelines recommend implantation of prophylactic implantable cardioverter-defibrillators (ICD) in patients with left ventricular (LV) ejection fraction (EF) <35%. We explored the prognostic factors of fatal ventricular arrhythmias for heart failure (HF) patients with LVEF ≥35%.

Methods and results: We retrospectively studied 72 patients with LVEF of 52 ± 12% (all ≥35%) who had undergone ICD implantation. Heterogeneity of LV regional myocardial contraction was defined as standard deviation of peak strain (dyssynergy index) and time-to-peak strain (dispersion index) from 18 LV segments determined by speckle tracking. Fatal ventricular arrhythmias with appropriate ICD therapy occurred in 34 patients (47%) during a median follow-up of 17 months. Receiver operating characteristic curve analysis identified dispersion index ≥101 ms and dyssynergy index ≥6.1% as predictors of fatal ventricular arrhythmias (P = 0.004 and P = 0.0001, respectively). In addition, the combination of dispersion index ≥101 ms and dyssynergy index ≥6.1% was the most predictive of fatal ventricular arrhythmias with a sensitivity of 77%, specificity of 79%, and area under the curve of 0.795 (P < 0.0001). A sequential Cox model based on clinical and conventional echocardiographic variables including age, gender, HF aetiology, and LVEF (χ(2) = 4.8) was improved, but not statistically significant (χ(2) = 4.9; P = 0.82), by addition of global longitudinal strain, whereas improvement by the addition of the dispersion index (χ(2) = 8.9; P = 0.04) and further improvement by the addition of the dyssynergy index (χ(2) = 20.2; P < 0.005).

Conclusion: Combined assessment of LV dyssynergy and dispersion can enhance predictive capability for fatal ventricular arrhythmias in patients with LVEF ≥35% and may have potential for better management of such patients.