OBJECTIVES: Transthoracic echocardiography is the current standard for assessing aortic regurgitation (AR). Â AR severity can also be evaluated by flow measurement in the ascending aorta using cardiac magnetic resonance (CMR); however, the optimal site for flow measurement and the regurgitant fraction (RF) severity grading criteria that best compares with the transthoracic echocardiographic assessment of AR are not clear. Â The present study aimed to determine the optimal site and RF grading criteria for AR severity using phase-contrast flow measurements and CMR.
METHODS: A prospective observational study was performed of 107 consecutive patients who were undergoing CMR of the thoracic aorta. Â Using CMR, the AR severity and aortic dimensions were measured at 3 levels in the aorta (the sinotubular junction, mid-ascending aorta, and distal ascending aorta).
RESULTS: The results were compared to the transthoracic echocardiographic grade of AR severity using multiple qualitative and quantitative criteria (grade 0, none; I+, mild; II+, mild to moderate; III+, moderate to severe; and IV+, severe). Â The mean RF values were significantly greater at the sinotubular junction than at the distal ascending aorta (13 Â± 13.3% vs 9.4 Â± 12.6%, respectively; p <0.001). Â The RF values that best defined AR severity using phase-contrast CMR were as follows: grade 0 to I+, <8%; grade II+, 8% to 19%; grade III+, 20 to 29%; and grade IV+, 30%) at the sinotubular or mid-ascending aorta.
CONCLUSIONS: In conclusion, the quantitative RF values of AR severity using phase-contrast flow are best assessed in the proximal ascending aorta and differ from recognized quantitative echocardiographic criteria.