Ventricular Dyssynchrony is Associated with Worse Left Ventricular Ejection Fraction Trajectories in Severe Decompensated Systolic Heart Failure

IntroductionIncreased QRS duration (QRSd) and left ventricular dyssynchrony are associated with worse outcomes in heart failure (HF). The implication of QRSd on left ventricular ejection fraction (LVEF) trajectories among patients with severe decompensated systolic HF is unclear.MethodsPatients hospitalized with HF between 2014-2018 with an LVEF ≤ 35% and at least two echocardiograms with LVEF assessments were included. Patients received guideline-directed medical and device therapies. Survival was assessed for up to 4 years after the index admission. LVEF trajectory was defined as the difference between the lowest LVEF and the highest LVEF, multiplied by -1 if the lowest LVEF was more recent than the highest LVEF. Linear regression was used to evaluate the association between LVEF trajectory and QRSd, and logistic regression was used to assess survival based on QRSd and LVEF trajectory.ResultsAmong 1,674 patients (65.3 ± 14.2 years, 35.9 % female), 39% had QRSD > 120 ms. The lowest LVEF was 26.7% ± 9.7%, the highest LVEF was 45.5% ± 14.5%, and the LVEF trajectory had a median of 5% with an interquartile range of -10% to +25%. The frequency of QRSd less than 120 ms, 120-149 ms, and greater than or equal to 150 ms were 60.5%, 20.5%, and 19.5% respectively. Increasing QRSd was associated with more negative LVEF trajectories (r = -0.24, p < 0.0001). Median LVEF trajectories (panel A) and mortality rates (panel B) in the three QRS duration groups are shown in the Figure (p<0.0001 for both comparisons). Although LVEF trajectory and QRSd had a moderate correlation, both were still independently associated with survival in a multivariable logistic regression model (OR 1.08 per 10 ms for QRSd, 95% CI 1.04-1.12, p < 0.0001; OR 0.92 per 5% LVEF trajectory units, 95% CI 0.90-0.95, p < 0.0001).ConclusionsIncreasing QRS duration in HF is associated with worsening LVEF trajectories and increased mortality despite contemporary guideline-directed medical and device therapy. The effect of QRS duration on survival appears to be mediated both by its impact on LVEF trajectory and mechanisms independent of the LVEF trajectory.