An Alternative Method to Calculate Simplified Projected Aortic Valve Area at Normal Flow Rate

BACKGROUND: Simplified projected aortic valve area (EOA(proj)) is a valuable echocardiographic parameter in the evaluation of low flow low gradient aortic stenosis (LFLG AS). Its widespread use in clinical practice is hampered by the laborious process of flow rate (Q) calculation. OBJETIVE: This study proposes a less burdensome, alternative method of Q calculation to be incorporated in the original formula of EOA(proj) and measures the agreement between the new proposed method of EOA(proj) calculation and the original one. METHODS: Retrospective observational single-institution study that included all consecutive patients with classic LFLG AS that showed a Q variation with dobutamine infusion ≥ |15|% by both calculation methods. RESULTS: Twenty-two consecutive patients with classical LFLG AS who underwent dobutamine stress echocardiography were included. Nine patients showed a Q variation with dobutamine infusion calculated by both classical and alternative methods ≥ |15|% and were selected for further statistical analysis. Using the Bland-Altman method to assess agreement we found a systematic bias of 0,037 cm(2) (95% CI 0,004 - 0,066), meaning that on average the new method overestimates the EOA(proj) in 0,037 cm(2) compared to the original method. The 95% limits of agreement are narrow (from -0,04 cm(2) to 0,12 cm(2)), meaning that for 95% of individuals, EOA(proj) calculated by the new method would be between 0,04 cm(2) less to 0,12 cm(2) more than the EOA(proj) calculated by the original equation. CONCLUSION: The bias and 95% limits of agreement of the new method are narrow and not clinically relevant, supporting the potential interchangeability of the two methods of EOA(proj) calculation. As the new method requires less additional measurements, it would be easier to implement in clinical practice, promoting an increase in the use of EOA(proj).