Impaired left ventricular myocardial mechanics and their relation to pulmonary regurgitation, right ventricular enlargement and exercise capacity in asymptomatic children after repair of tetralogy of Fallot.
BACKGROUND
Left ventricular (LV) dysfunction is common in adults late after repair of tetralogy of Fallot (TOF). The early detection of myocardial dysfunction may be important, but LV myocardial strain and dyssynchrony are not well studied in children with TOF. The objective of this study was to investigate LV strain and dyssynchrony in asymptomatic children and adolescents after contemporary repair of TOF. The hypothesis was that impaired LV myocardial mechanics are related to pulmonary regurgitation, right ventricular (RV) enlargement, and exercise capacity.


METHODS
Children and adolescents were prospectively studied after TOF repair. LV regional strain and dyssynchrony were assessed using two-dimensional speckle-tracking echocardiography. Ventricular volumes, ejection fraction, and pulmonary regurgitation were assessed using magnetic resonance imaging. Exercise capacity was determined using metabolic exercise testing.


RESULTS
One hundred twenty-four subjects (53 patients with TOF and 71 controls) were studied. Regional circumferential (e.g., basal lateral wall, -15.0 ± 7.0% vs -19.0 ± 7.0%, P = .02) and radial (e.g., basal posterior wall, 32.0 ± 18.0% vs 48.0 ± 21.0%, P < .001) LV strain and longitudinal septal strain (-18.5 ± 3.5% vs -20.2 ± 2.8%, P = .01) were significantly reduced in patients with TOF compared with controls. LV mechanical dyssynchrony indices were not significantly different between groups (e.g., standard deviation of time to peak circumferential strain, 52.5 ± 40.4 vs 50.5 ± 27.1 msec, P = .81). Higher pulmonary regurgitation volume and larger RV end-diastolic volume were associated with decreased LV radial strain (P = .09). There was no association between LV longitudinal, radial, or circumferential dyssynchrony and indexed pulmonary regurgitation flow volume, RV end-diastolic volume, or RV ejection fraction.


CONCLUSIONS
LV circumferential and radial strain are significantly reduced in children and adolescents after TOF repair and are associated with pulmonary regurgitation and RV dilatation. Resting LV mechanical dyssynchrony does not appear to contribute to early impaired LV strain in this population.
Labatt Family Heart Centre, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada.
Fernanda P
FP
Fernandes
Cedric
C
Manlhiot
Susan L
SL
Roche
Lars
L
Grosse-Wortmann
Cameron
C
Slorach
Brian W
BW
McCrindle
Luc
L
Mertens
Paul F
PF
Kantor
Mark K
MK
Friedberg
D000293:Adolescent; D000367:Age Factors; D000704:Analysis of Variance; D006348:Cardiac Surgical Procedures / Q000009:adverse effects / Q000379:methods; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004452:Echocardiography / Q000379:methods; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017380:Hypertrophy, Right Ventricular / Q000000981:diagnostic imaging* / Q000209:etiology; D007090:Image Interpretation, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology; D011446:Prospective Studies; D011665:Pulmonary Valve Insufficiency / Q000000981:diagnostic imaging* / Q000209:etiology; D012016:Reference Values; D018570:Risk Assessment; D012720:Severity of Illness Index; D013318:Stroke Volume; D013771:Tetralogy of Fallot / Q000150:complications* / Q000503:physiopathology / Q000601:surgery; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology