Impact of afterload on the assessment of severity of aortic stenosis

Background: Aortic stenosis (AS) is increasingly diagnosed in current aging society. Chocardiography is the most important tool in the assessment of AS and its severity. However, load-ependency of Doppler measurement could affect the accuracy of AS severity assessment. We tried to evaluate the impact of afterload on the assessment of AS severity by modifcation of afterload using pneumatic compression (Pcom). Methods: Forty patients diagnosed as moderate or severe AS [effective orifice area of aortic valve (EOA_av) by continuity equation of < 1.5 cm²] were consecutively enrolled. Patients with severely uncontrolled hypertension, severe left ventricular (LV) dysfunction, and other signifcant valve disease were excluded. Comprehensive echocardiography was performed at baseline to assess AS severity. Then, pneumatic compression of the lower extremities by 100 mmHg was applied to increase LV afterload. After 3 minutes, echocardiography was repeated to assess AS severity. Results: Mean blood pressure was signifcantly increased under Pcom (p < 0.001), while heart rate remained unchanged. Peak aortic valve velocity (V_max) was slightly, but signifcantly decreased under Pcom (p = 0.03). However, Doppler velocity index and EOAav by continuity equation were not affected by Pcom. Conclusion: AS severity assessment by echocardiography was not dependent on the change of LV afterload imposed by Pcom. AV V_max was slightly decreased with LV afterload increment, but these changes were too small to alter treatment plan of AS patients. EOA_av and Doppler velocity index are more stable parameters for AS severity assessment.