1Universitätsklinikum Frankfurt Med. Klinik III - Kardiologie, Angiologie Frankfurt am Main, Deutschland; 2Universitätsklinikum Frankfurt Klinik für Thorax-, Herz- und Thorakale Gefäßchirurgie Frankfurt am Main, Deutschland; 3Klinikverbund Südwest - Klinikum Sindelfingen-Böblingen GmbH Medizinische Klinik II, Kardiologie Sindelfingen, Deutschland
Introduction
Transthoracic echocardiography is the gold standard modality for diagnosis and evaluation of aortic stenosis (AS). Cardiac catheterization provides a direct pressure measurement but can generate different results. This study’s aim was to compare invasive with echocardiographic measurement in patients with aortic stenosis undergoing transcatheter aortic valve implantation (TAVI).
Methods
We compared echocardiography-derived and invasively measured transvalvular gradients of 220 patients with severe AS who received transfemoral TAVI at our institution. Patients were divided into groups according to mean gradients (pmean) and stroke volume index (SVI): normal-flow high-gradient AS (aortic valve area (AVA) <1.0cm2, pmean > 40 mmHg), low flow low gradient AS (AVA <1.0cm2, pmean <40 mmHg), SVI < 35 ml/m2 and SVI > 35 ml/m2. Invasive gradients were derived by simultaneous measurements with one pigtail catheter placed in the aorta and one pigtail catheter placed in die left ventricle after retrograde passage of the aortic valve.
Results
For the overall cohort echocardiographic measurement revealed higher mean and maximal gradients than invasive measurement (41.2 vs 37.0 mmHg, p=0.01 and 64.27 vs 43.64 mmHg, p<0.001). In patients with low flow low gradient AS, normal flow high gradient AS or low SVI (< 35 ml/m2) mean gradient was significantly lower invasively measured (22.8 vs. 26.3mmHg, p=0.022; 41.3 vs. 45.8mmHg, p=0.011 and 34.8 vs. 41.3 mmHg, p= 0.014 respectively). In contrast, the mean gradients in the normal-flow group with preserved SVI (> 35 ml/m2) did not differ statistically (39.1 vs. 40.5mmHg, p= 0.615).
Conclusions
Invasively measured and echocardiography-derived transvalvular mean gradients correlate poor in the setting of aortic stenosis. Only in patients with preserved SVI (>35ml/m2) both modalities generated comparable mean aortic valve gradients. Further research is needed to evaluate the clinical implications of this finding.