Strain imaging potentially useful in detecting right ventricular dysfunction
Strain imaging is an alternative, noninvasive method suitable for detecting right ventricular (RV) dysfunction in repaired Tetralogy of Fallot (TOF) patients, though not a replacement for cardiac magnetic resonance imaging (MRI), according to a study presented at the ASEAN Federation of Cardiology Congress (AFCC) 2016 held in Yangon, Myanmar.
“RV function has been shown to be a major determinant of clinical outcome in congenital heart disease patients,” said Dr Lorielyn Mandigma from the Golden Gate General Hospital in Batangas, the Philippines, who presented the findings. “Accurate assessment of RV function might be important for the optimal timing of RV outflow revalvulation, especially because [RV ejection fraction (RVEF)] is now being used as one of the criteria influencing the timing of pulmonary valve replacement.”
However, according to Mandigma, measurement of RV function is not always easy to perform, and MRI remains the gold standard and reference method to evaluate volume and ventricular function.
To determine the accuracy and cut-off values of RV strain imaging parameters that would detect RV dysfunction, Mandigma and colleagues conducted a prospective, cross-sectional study involving 22 patients (mean age 16.7 years) from the Philippine Heart Centre between August 2015 and January 2016. Patients underwent cardiac MRI and two-dimensional strain imaging on the same day.
Results of the study showed that cut-off values of -16.25 percent for the RV free wall (RVFW) mid-segment strain and -20.66 percent of the global longitudinal strain enabled detection of RV dysfunction, defined in this study as cardiac MRI-derived RVEF <50 percent.
The cut-off values for RV dysfunction detection were both sensitive at 83.33 percent and specific at 100 percent, said Mandigma. The findings also validated the correlation between the global and regional RV strain [the extent of regional shortening and thickening] and strain rate [rate at which deformation takes place] with cardiac MRI-derived RVEF, she said.
Nonetheless, Mandigma cautioned that RV strain imaging is not yet a surrogate for cardiac MRI in determining RVEF, but the utilization of RV strain imaging can complement the current echocardiographic assessment of repaired TOF patients as well as accurately predict the presence of RV dysfunction.