Annular tilt as a screening test for right ventricular enlargement in patients with tetralogy of fallot.

BACKGROUND

Right ventricular end-diastolic volume (RVEDV) greater than 150 mL/m² is a risk factor for sudden death in patients with tetralogy of Fallot (TOF) after repair. Because of its anterior placement and abnormal geometry, two-dimensional echocardiography is limited to a qualitative assessment of RVEDV. Cardiac magnetic resonance imaging (CMRI) and computed tomography angiography (CTA) are the accepted standards for quantifying RVEDV. This study evaluated the ability of a novel echocardiographic measure, the right ventricular annular tilt (RVAT), to identify patients with increased RVEDV.

METHODS

All patients with repaired TOF with an echocardiogram and CMRI or CTA were included in this retrospective study. The RVAT was determined by measuring the angle of the tricuspid valve plane relative to the mitral valve plane at end-diastole in the apical 4-chamber view in study (n = 38) and age-matched control (n = 74) patients. The RVEDV measurements were obtained by CMRI (n = 32) or CTA (n = 6). The study and control patients' ages were no different (11.3 and 11.8 years, P = .73).

RESULTS

The study group RVAT was significantly higher than the control group RVAT (17.4 vs. 0.1 degrees; P < .0001). RVAT values greater than 20 degrees had a mean RVEDV of 166 ± 60 mL/m², whereas RVAT less than 20 degrees had a mean RVEDV of 122 ± 25 mL/m² (P = .0370). Receiver operating characteristic analysis demonstrated an RVAT of 17.9 degrees as the cutoff for predicting a RVEDV of greater than 150 mL/m² with a sensitivity of 75% and specificity of 73% (area under the curve = 0.76; confidence interval, 0.56-0.96; P = .0063). Intraclass correlation analysis demonstrated minimal interobserver and intraobserver variability when measuring RVAT (0.99 and 0.92).

CONCLUSION

An RVAT less than 20 degrees is associated with an RVEDV less than 150 mL/m². RVAT is a useful echocardiographic technique for detecting increased RVEDV in patients with TOF and may help discern which patients should undergo RVEDV quantification by CMRI or CTA.