Determinants of Left Ventricular Dysfunction and Remodeling in Patients with Corrected Tetralogy of Fallot (ToF)

Aims: The main clinical focus after ToF repair is directed to the right ventricle (RV) and the pulmonary valve. Left ventricular (LV) dysfunction and remodeling has received much less attention, though some studies indicate, that RV volume or pressure overload may in the long term significantly contribute to left heart failure. Therefore, the aim of this study was to characterize left-sided cardiac function and remodeling after ToF repair, including changes of LV geometry and myocardial tissue structure.

Methods: LV, RV, and left atrial (LA) function and myocardial extracellular volume (ECV) a marker of interstitial fibrosis, were measured with cardiac magnetic resonance imaging (CMR) in 103 asymptomatic ToF patients, (median: 16.3 years; range: 1.6–55), after corrective surgery, and 63 age-matched controls.

Results: Compared with healthy controls, ToF patients had a lower LV ejection fraction (EF) (52.2 ± 8.0% vs. 59.0 ± 5.4%; p = 0.001), a lower LV mass index (45.5 ± 12.5 vs. 49.6 ± 9.2 g/m² BSA; p = 0.003) and a lower LV mass-to-volume ratio (0.58 ± 0.13 vs. 0.65 ± 0.13; p < 0.01) indicating eccentric LV geometry. 42% of the ToF patients showed systolic dysfunction (LV EF < 50%). RV mass-to-volume ratio was the best predictor for LV systolic dysfunction and lower LV mass-to-volume ratio. LA passive emptying volume and LA total EF (parameters for LV diastolic dysfunction) were lower in ToF (56 + 7 vs. 50+9%; p < 0.01). LV ECV was increased in ToF (0.32 ± 0.05 vs. 0.26 ± 0.01; p < 0.001), particularly in females (p = 0.017). A higher ECV, a lower resting LV function and a lower LV mass index were associated with subnormal peak oxygen consumption (< 3rd percentile) during cardio-pulmonary exercise testing (p < 0.05).

Conclusion: In asymptomatic ToF patients at a median of 14 years after repair, we found a high proportion of LV systolic and diastolic dysfunction, a reduced LV mass index and adverse LV remodeling. LV systolic dysfunction was associated with an eccentric RV geometry. The clinical significance was reflected by subnormal peak oxygen consumption, and suggests that monitoring of LV status is important for long-term prognosis.

No conflict of interest has been declared by the author(s).