Impact of residual right ventricular outflow tract obstruction on biventricular strain and synchrony in patients after repair of tetralogy of Fallot: a cardiac magnetic resonance feature tracking study.
OBJECTIVE
Residual right ventricular outflow tract (RVOT) obstruction (RVOTO) is considered beneficial in patients after repair of tetralogy of Fallot (TOF) although underlying mechanisms are unknown. We sought to elucidate differences in myocardial strain and dyssynchrony parameters in patients after TOF repair with and without residual RVOTO using cardiovascular magnetic resonance (CMR) feature-tracking (CMR-FT) analysis.


METHODS
Fifty-four patients (mean age 16.4 ± 8.4 years) were assessed by CMR 14.2 ± 7.3 years after repair of TOF. Residual RVOTO on echocardiography was defined as a peak systolic RVOT gradient >25 mmHg and was present in 27 patients (no RVOTO in n = 27 patients). Right ventricular (RV) and left ventricular (LV) strain measurements were performed using CMR-FT software.


RESULTS
The two groups were well matched for age at CMR scan, time and type of surgical repair. There was no difference in the degree of pulmonary regurgitation (PR) and RV end-diastolic volume. Patients with RVOTO showed significant higher RV circumferential strain (CS) (P = 0.02) and RV radial strain (RS) (P = 0.02) values, whereas RV longitudinal strain (LS) did not differ between the two groups (P = 0.39). The degree of RVOTO showed a significant correlation with RV-CS (r = 0.37; P = 0.006) and RV-RS (r = 0.30; P = 0.03) while RV-LS was unrelated to RVOTO (r = 0.06; P = 0.68). Significant relationships between RV and LV strain parameters were only found in the RVOTO group. Interventricular dyssynchrony was significantly higher in the group without RVOTO (P = 0.03) while LV-LS (P = 0.03) and LV intraventricular synchrony (P = 0.05) were impaired in the RVOTO group.


CONCLUSIONS
In patients after TOF repair, residual RVOTO seems to preserve RV strain and results in stronger RV-LV interactions and less interventricular dyssynchrony and may therefore possess an early protective effect on RV remodelling. However, the potential negative impact of residual pulmonary stenosis on LV strain and intraventricular synchrony needs further investigation.
Pediatric Heart Centre, University Children's Hospital, Giessen, Germany heiner.latus@googlemail.com.
Heiner
H
Latus
Pediatric Heart Centre, University Children's Hospital, Giessen, Germany.
Pauline
P
Hachmann
Pediatric Heart Centre, University Children's Hospital, Giessen, Germany.
Kerstin
K
Gummel
Pediatric Heart Centre, University Children's Hospital, Giessen, Germany.
Markus
M
Khalil
Pediatric Heart Centre, University Children's Hospital, Giessen, Germany.
Can
C
Yerebakan
Pediatric Heart Centre, University Children's Hospital, Giessen, Germany.
Juergen
J
Bauer
Pediatric Heart Centre, University Children's Hospital, Giessen, Germany.
Dietmar
D
Schranz
Pediatric Heart Centre, University Children's Hospital, Giessen, Germany.
Christian
C
Apitz
D000293:Adolescent; D004452:Echocardiography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011665:Pulmonary Valve Insufficiency / Q000209:etiology / Q000503:physiopathology; D013771:Tetralogy of Fallot / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome; D018497:Ventricular Dysfunction, Right / Q000209:etiology / Q000503:physiopathology; D014694:Ventricular Outflow Obstruction / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*
CMR feature tracking; Residual pulmonary stenosis; Tetralogy of Fallot