QRS duration and mechanical dyssynchrony correlations with right ventricular function after fontan procedure

In studies of adult patients, increased QRS duration and mechanical dyssynchrony have been associated with decreased ventricular function. The aim of this study was to test the hypothesis that similar findings would be present in a population of patients with hypoplastic left heart syndrome (HLHS) after the Fontan procedure.

A retrospective cross-sectional study was conducted. All patients with HLHS after the Fontan procedure were eligible. QRS duration was measured using 12-lead electrocardiography. Echocardiographic measurements of mechanical dyssynchrony included Doppler tissue imaging (DTI) QRS to onset of s' wave difference between the left ventricle and the right ventricle, time to peak strain, time to peak systolic strain rate (SRs), the standard deviation of time to peak strain rate (modified Yu strain), and the standard deviation of time to peak SRs (modified Yu SRs). Right ventricular (RV) functional measurements included DTI s' wave, DTI RV myocardial performance index, global strain, global SRs, and RV fractional area change. Pearson's correlations were performed between the variables.

Thirty-one echocardiographic studies were performed on 26 patients. The median age was 5.3 years (range, 2.5-15.4 years). QRS duration was correlated significantly with global SRs (r = 0.42). Time to peak SRs was correlated significantly with DTI s' wave (r = -0.48) and global SRs (r = 0.37). Modified Yu SRs was correlated significantly with global strain (r = 0.35) and RV fractional area change (r = -0.35).

Both QRS duration and mechanical dyssynchrony were correlated with RV function, albeit weakly. The clinical significance of these findings is intriguing, but only larger studies will determine if these measurements are reliable in guiding treatment options for this complex patient population.