Abstract 16190: Myocardial Deformation as Provided by CMR Based Feature Tracking is Related to Exercise Capacity and Outcome in Patients with Repaired Tetralogy of Fallot
Background: Parameters of myocardial deformation have been suggested to be superior to conventional measures of ventricular function in pts. with repaired tetralogy of Fallot (rToF). We assessed biventricular myocardial function using CMR cine-based feature tracking (FT) in a large cohort of rToF pts. to study its relation to clinical parameters and outcome.
Methods and Results: Pts. with rToF undergoing standardized CMR imaging were recruited as part of a nationwide, prospective study between 2005 and 2008. In addition to conventional parameters of ventricular volumes and function, myocardial deformation was assessed by CMR based FT (TomTec, Unterschleissheim, Germany). FT analysis was performed for the left (LV) and right ventricle (RV), providing longitudinal (LS), circumferential (CS) and radial global strain (RS). Cardiopulmonary exercise data at the time of CMR were available in 95% of pts. A composite endpoint of death, successful cardiopulmonary resuscitation, documented ventricular tachycardia (VT) or ICD implantation was employed. Overall, 343 patients (56% male, age 17.5±8.3 yrs., pulmonary regurgitant fraction 27±19%, RVEDVI 121±33 ml/m², RV EF 50±9%, LV EF 57±9%) were included. A moderate correlation was found between parameters of myocardial deformation and LV or RV EF (r-value 0.32-0.40, for CS and LS, p<0.0001 for all). LV LS and RS correlated to %-predicted peak oxygen uptake (p<0.01), while LV and RV CS were related to the risk of symptomatic deterioration (>1 NYHA class) during follow-up (OR 0.91 and 0.80, p=0.048 and 0.002, respectively) on logistic regression analysis. During a median follow-up time of 4.9 (IQR 3.3-5.4) yrs., 11 adverse events occurred (including 3 deaths and 2 successful resuscitations). On bivariate Cox analysis LV CS emerged as the strongest predictor of outcome (HR 0.82, p=0.0008), independently of QRS-duration, LV and RV EF, RVEDVI, RVESVI, NYHA class and peak oxygen uptake.
Conclusions: Myocardial dysfunction on FT-CMR relates to exercise intolerance and clinical deterioration in patients with rToF. LV circumferential global strain emerged as the strongest predictor of adverse outcome and should, thus, be considered as a useful adjunct to established risk markers, especially in younger rToF pts.
- © 2012 by American Heart Association, Inc.