Key result
Dobutamine stress degrades agreement between volumetric and phase-contrast MR flow measurements in repaired tetralogy of Fallot.
Why the study?
The agreement between volumetric and phase contrast flow cardiac MR parameters for assessing cardiovascular function in repaired tetralogy of Fallot with chronic pulmonary regurgitation at rest and under dobutamine stress was unclear.
Cross-Sectional (n=18)
Method agreement under dobutamine stress needs validation in r-TOF; leaves open whether volumetric and flow assessments are interchangeable.
PURPOSE: To evaluate the MR agreement of cardiac function parameters between volumetric (cine SSFP) and phase contrast flow (PC-flow) assessment in patients with repaired tetralogy of Fallot (r-TOF) and chronic pulmonary regurgitation (PR) at rest and under dobutamine stress (DS-MR). MATERIALS AND METHODS: We studied 18 patients with r-TOF and severe chronic PR (34 ± 12.7 years, PR fraction([flow]) 44 ± 15%) by cardiac MR at rest, 10 and 20 μg/kg/min of dobutamine. We compared analogous functional parameters by volumetry and PC-flow: (i) Systemic output [left ventricle stroke volume (LV(SV)) versus aortic forward flow (AO(FF))], (ii) Pulmonary output [right ventricle stroke volume (RV(SV)) versus pulmonary forward flow (PA(FF))], (iii) PR volume [(RV(SV)-LV(SV)) versus pulmonary backward flow (PA(BF))], (iv) PR fraction [(RV(SV)-LV(SV)/RV(SV)) versus (PA(BF)/PA(FF))]. RESULTS: We found excellent Bland-Altman agreement (mean difference ± limits of agreement, mL/beat/m(2)) at rest for both the systemic (-0.8 ± 5.7) and pulmonary strokes volumes (-0.1 ± 7.6), which slightly deteriorates during DS-MR. The PR volume showed acceptable agreement at rest (-3.6 ± 15.1), but also further deteriorated during stress (5.4 ± 24). In contrast, the PR fraction showed poor agreement equally at rest (-5.6 ± 22.8) and DS-MR (3.2 ± 19.2). CONCLUSION: In r-TOF with chronic PR, analogous functional parameters should not be used interchangeably between volumetric and PC-flow assessment during DS-MR evaluation.
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Valverde et al. (2011) conducted a cross-sectional in Repaired tetralogy of Fallot with severe chronic pulmonary regurgitation (n=18). Volumetric (cine SSFP) MR assessment vs. Phase contrast flow (PC-flow) MR assessment was evaluated on Agreement of cardiac function parameters (systemic output, pulmonary output, PR volume, and PR fraction) between volumetry and PC-flow. In patients with repaired tetralogy of Fallot, agreement between volumetric and phase contrast flow MR for functional parameters like PR volume deteriorated during dobutamine stress.
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