Supplementary Material for: Left and Right Ventricular Strain Mechanics in Fetal Tachyarrhythmia

Background: Assessment of myocardial function in fetuses with supraventricular tachyarrhythmia is challenging. Speckle tracking echocardiography (STE) is a newer sensitive method to assess ventricular systolic function. We sought to assess left (LV) and right (RV) ventricular myocardial strain mechanics in fetuses with tachyarrhythmia and hypothesized that strain mechanics are impaired in this patient population even after conversion to sinus rhythm.

Methods: This was a single-center retrospective review. LV and RV strain parameters were assessed
using STE in tachyarrhythmia and after conversion to sinus rhythm and compared to gestational age (GA) matched control fetuses in sinus rhythm.

Results: 18 fetuses with tachyarrhythmia and 18 controls were analyzed at median GA 31 weeks (range 28 to 34 weeks). LV Global Longitudinal Strain (GLS) [-4.5% (-5.2, -1.9) vs. -11.2% ( 14.6, -9.9); p-value 0.0001], Strain Rate [-0.8% (-1.5, -0.6) vs. -1.7% (-2.5, -1.2); p-value 0.007), and Global Longitudinal Velocity (GLV) [0.7 cm/s (0.5, 1.3) vs. 1.8 cm/s (0.9, 2.1); p-value 0.003] were reduced in tachyarrhythmia and improved with sinus rhythm but remained abnormal compared to controls. RV GLS [-6.3% (-8.5, -5.1) vs. -13.6% (-15.3, -10.6); p-value < 0.0001), Strain Rate [-1.3% ( 1.7, -0.9) vs. -2.1% (-2.5, 1.4); p-value 0.0103), and GLV [1.2 cm/s (0.8, 1.7) vs. 1.9 cm/s (1.2, 2.7); p-value 0.026)] were low in tachyarrhythmia and improved with sinus rhythm but remained lower than in controls. Regional strain was decreased in all LV and RV segments in tachyarrhythmia.

Conclusions: Fetuses in tachyarrhythmia had reduced measures of myocardial deformation that improved with sinus rhythm but remained low compared to matched controls. Future studies are needed to explore the utility of STE for serial monitoring of fetuses in tachyarrhythmia and to assess response to therapy.