Right Ventricular Strain in Patients With Ductal-Dependent Tetralogy of Fallot

Abstract

Background: Right ventricular (RV) dysfunction is an independent predictor of poor outcomes in patients with tetralogy of Fallot (TOF), and global longitudinal strain (GLS) is a well-validated echocardiographic technique to measure RV function. Although trends in RV GLS have been examined in patients with TOF, they have not been studied specifically in those with ductal-dependent TOF, a group in which there is not a clear consensus on the best surgical strategy. The aim of this study was to assess the midterm trajectory of RV GLS in patients with ductal-dependent TOF, drivers of this trajectory, and differences in RV GLS between repair strategies.

Methods: This was a retrospective two-center cohort study of patients with ductal-dependent TOF who underwent repair. Ductal dependence was defined as being initiated on prostaglandin therapy and/or undergoing surgical intervention on or before 30 days of life. RV GLS was measured on echocardiography preoperatively, early after complete repair, and at 1 and 2 years of age. RV GLS was trended over time and compared between surgical strategies and with control subjects. Mixed-effects linear regression models were used to evaluate the factors associated with changes in RV GLS over time.

Results: Forty-four patients with ductal-dependent TOF were included in the study, of whom 33 (75%) underwent primary complete repair and 11 (25%) underwent staged repair. Complete TOF repair was performed at a median of 7 days in the primary-repair group and 178 days in the staged-repair group. RV GLS improved over time from post-complete repair echocardiography through 2 years of age (-17.4% [interquartile range, -15.5% to -18.9%] vs -21.5% [interquartile range, -18.0% to -23.3%], P < .001). However, compared with age-matched control subjects, patients had worse RV GLS at all time points. There was no difference in RV GLS between the staged and primary complete repair groups at 2-year follow-up. Shorter intensive care unit length of stay after complete repair was independently associated with improvement in RV GLS over time. Strain improved by 0.07% (95% CI, 0.01 to 0.12) for each fewer day in the intensive care unit (P = .03).

Conclusions: RV GLS improves over time among patients with ductal-dependent TOF, though it is consistently reduced compared with control subjects, suggesting an altered deformation pattern in patients with ductal-dependent TOF. There was no difference in RV GLS between the primary- and staged-repair groups at midterm follow-up, suggesting that repair strategy is not a risk factor for worse RV strain in the mid postoperative period. A shorter complete-repair intensive care unit length of stay is associated with an improved trajectory of RV GLS.

Keywords: Ductal dependent; Right ventricle; Strain; Tetralogy of Fallot.

Figure 1-

Identification and Exclusion of Patients

Figure 2-. Right Ventricular Global Longitudinal Strain in Subjects and Controls.

Right Ventricular Global Longitudinal Strain (RV GLS) was better in controls compared to subjects at all time points.

Figure 3-. Median Right Ventricular Global Longitudinal Strain Over Time

There was no difference in Right Ventricular Global Longitudinal Strain (RV GLS) between the pre-operative and post-complete repair timepoints. P-values comparing RV GLS between the pre-operative and post-complete repair timepoints to the 1 year and two year timepoints are shown.

Figure 4-. Right Ventricular Global Longitudinal Strain in Staged Repair and Primary

Repair Subjects Over Time There was no difference in Right Ventricular Global Longitudinal Strain (RV GLS) between those who underwent staged or primary repair at the pre-operative, 1 year and 2 year time points. Those who underwent staged repair had better RV GLS at the post-complete repair timepoint.

Figure 5-. Median Right Ventricular Fractional Area Change Over Time

Right ventricular fractional area change (RV FAC) was normal at the pre-repair, 1 year and 2 year timepoints, but was lower at the post-complete repaired timepoint compared to all other timepoints P-values comparing RV FAC between the pre-operative and post-complete repair timepoints to the other timepoints are shown.