Purpose or Case Report: Cardiac magnetic resonance imaging (CMR) is commonly used in evaluation of patients with repaired Tetralogy of Fallot (TOF). Impaired peak strain by echocardiography in TOF has been associated with adverse clinical outcome. Assessment of myocardial deformation (strain) using novel CMR software may provide prognostic information in TOF. Because of ventricular interaction, abnormal left ventricle (LV) mechanics are seen in echocardiography speckle tracking. We aimed to determine correlates of right (RV) and LV function using LV diastolic filling analysis in patients with repaired TOF.
Methods & Materials: Retrospective analysis of 61 CMR studies in patients (14±5 years) with repaired TOF was performed. RV and LV volumes and ejection fraction (EF) were recorded from the clinical reports. LV peak strain and strain rates were measured in 4-chamber and mid short axis cine views using in-house developed CMR software that utilizes a semi-automatic feature tracking program. The resulting strain curves were analyzed for filling patterns, and compared to RV and LV volumes and ejection fraction, and also to those of 42 normal patients and volunteers (11±5) years using the unpaired t test. Peak strain, early (E) and atrial (A) phase diastolic filling rates were also measured.
Results: Three abnormal diastolic LV filling patterns were observed in 14 patients with repaired TOF, compared with 1 normal patient (P<0.002). Abnormal patterns were as follows: largest filling wave during atrial phase (2), early phase wave split with two substantial early waves of similar size and a discernible atrial phase wave( 5), and a sizable mid-diastolic phase filling wave midway between the E and A waves (7). The normal pattern was large E and small A waves. Patients with cardiac cycles less than 500 msec (3 TOF and 3 normals) were excluded from analysis as only one filling wave that occupied most of diastole. The repaired TOF patients with abnormal diastolic LV filling had lower RV (p 0.02) and LV EF (p 0.02) than normal diastolic filling TOF or normal children. ( Table 1) RV or LV volumes, and peak strain rates were not significantly different between the abnormal diastolic LV filling TOF patients and their TOF counterparts. All TOF patients had higher RV volumes, lower RV and LVEF, and RV/LV peak strain rate than the normal patients.
Conclusions: Abnormal diastolic filling of the LV is detectable on routine cine CMR and is associated with lower systolic LV/ RV function in repaired TOF patients.