Methodologic issues in clinical evaluation of stenosis severity in adults undergoing aortic or mitral balloon valvuloplasty

Abstract

Although both catheterization and Doppler measures of valvular stenosis severity have been validated, each has specific advantages and limitations, particularly in the setting of balloon valvuloplasty. Invasive valve area and mean pressure gradient recorded immediately before and after aortic (n = 589) or mitral (n = 608) catheter balloon valvuloplasty were compared with Doppler valve area and mean pressure gradient recorded <30 days before and 24 to 72 hours after the procedure. For aortic stenosis, Doppler valve area ranged from 0.1 to 1.4 cm 2 before and 0.2 to 2.3 cm 2 after catheter balloon valvuloplasty. Doppler and invasive aortic valve areas differed by ≤0.5 cm 2 in 99% and by <0.2 cm 2 in 92% of patients. Linear correlation was higher before versus after catheter balloon valvuloplasty, for both valve area (r = 0.49 vs r = 0.35, p = 0.01) and mean pressure gradient (r = 0.64 vs r = 0.50, p = 0.01). Group mean invasive valve area was slightly smaller before (0.50 vs 0.59 cm 2, p < 0.0001) but was not different after (0.80 vs 0.78 cm 2, p = 0.16) catheter balloon valvuloplasty. Variables affecting the valve area differences were cardiac output, aortic regurgitation, heart rate and blood pressure. Mean pressure gradient differences were related to echo quality, blood pressure and mitral regurgitation. For mitral stenosis, 2-dimensional echocardiographic valve area ranged from 0.4 to 2.8 cm 2 before and 0.7 to 3.8 cm 2 after catheter balloon valvuloplasty. Two-dimensional echocardiography and invasive mitral valve areas differed by ≤0.5 cm 2 in 96% and by <0.2 cm 2 in 81% of cases. Linear correlation was not different before versus after catheter balloon valvuloplasty for two-dimensional echocardiographic valve area (r = 0.40 vs 0.36), pressure halftime valve area (r = 0.31 vs 0.32) or mean pressure gradient (r = 0.55 vs r = 0.46). Group mean 2-dimensional echocardiography and pressure halftime valve areas were larger than invasive valve areas before (1.09 vs 1.02 cm 2, p = 0.001) and smaller after (1.71 vs 2.02 cm 2, p < 0.0001) catheter balloon valvuloplasty. Important variables affecting the differences were mitral regurgitation, interatrial shunt, cardiac output and heart rate. Nonsimultaneous studies, differing volume flow measurements, and the underlying accuracy of each technique largely account for discrepancies between these methods. The clinical use of each will depend on its ability to predict long-term patient outcome.