QRS Duration and Mechanical Dyssynchrony Correlations with Right Ventricular Function after Fontan Procedure Janaki Gokhale, MD, Nazia Husain, MD, MPH, Lisa Nicholson, PhD, Karen M. Texter, MD, Ali N. Zaidi, MD, and Clifford L. Cua, MD, Columbus, Ohio Background: 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. Methods: A retrospective cross-sectional study was conducted. All patients with HLHS after the Fontan pro- cedure 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 0 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 0 wave, DTI RV myocardial performance index, global strain, global SRs, and RV fractional area change. Pearson’s correlations were performed between the variables. Results: 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 0 wave (r = 0.48) and global SRs (r = 0.37). Modified Yu SRs was cor- related significantly with global strain (r = 0.35) and RV fractional area change (r = 0.35). Conclusions: 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. (J Am Soc Echo- cardiogr 2012;-:---.) Keywords: Hypoplastic left heart syndrome, Fontan, Strain, Dyssynchrony, Echocardiography Because of surgical and medical advances, life expectancy is increasing for patients with hypoplastic left heart syndrome (HLHS). A major is- sue these patients face as they age is progressive heart failure, with a re- ported incidence as high as 40%. 1,2 One treatment that has been established to improve morbidity and mortality in the adult heart failure population is cardiac resynchronization therapy (CRT). 3,4 One criterion used to determine if CRT is an appropriate treatment option is QRS duration. 5,6 Various mechanical dyssynchrony measurements, measured via echocardiographic techniques, have also been used to determine if patients would respond to CRT, but results have been mixed. 7-9 CRT has been used in the congenital heart population for heart fail- ure as well, but indications are usually determined on a case-by-case basis. 10-12 Increased QRS duration in patients with HLHS compared with historical controls with normal hearts has been previously noted. 13 In addition, increased mechanical dyssynchrony via echocar- diographic evaluation has been documented in patients with single right ventricles. 14-18 The relationship of QRS duration and mechanical dyssynchrony to right ventricular (RV) function, however, has not been clearly defined in patients with single RV physiology. We hypothesized that QRS duration and mechanical dyssynchrony measurements in patients with HLHS after the Fontan procedure would correlate with measurements of ventricular function, similar to findings in adult studies. METHODS The institutional review board approved this cross-sectional, retro- spective study. All patients with HLHS who had undergone the Fontan procedure were included. Patients also needed to have adequate echocardiographic images with frame rates of 60 to 110 frames/sec performed obtained using a Vivid I or Vivid 7 machine (GE Healthcare, Wauwatosa, WI). An electrocardiogram obtained within 3 months of the echocardiogram was also required. The offline From The Heart Center, Nationwide Children’s Hospital, Columbus, Ohio. Reprint requests: Janaki Gokhale, MD, The Heart Center, Nationwide Children’s Hospital, 700 Children’s Drive, Columbus, OH 43205 (E-mail: janakig@gmail.com). 0894-7317/$36.00 Copyright 2012 by the American Society of Echocardiography. http://dx.doi.org/10.1016/j.echo.2012.10.018 1