How we can adjust for high heart rates in patients with mitral stenosis, to accurately estimate the degree of stenosis for a patient who is tachycardic at the time of image acquisition?
In patients with mitral stenosis, high heart rates increase the measured mean mitral valve gradient.
Starting with the 2020 valve guidelines, I honed in on this sentence: "Doppler echocardiography mean transvalvular gradients always should be reported with heart rate because a high heart rate will result in overestimation of stenosis severity." Following that primary reference took me to a 1994 Dr. Nishimura-as-first-author publication (it occurs to me that some of you may not have even been born in 1994 which means I am ancient 🙃) entitled Accurate measurement of the transmitral gradient in patients with mitral stenosis: A simultaneous catheterization and Doppler echocardiographic study which I've attached for your review. I was pretty excited to read this because (a) Dr. Nishimura is amazing and (b) I like reviewing landmark papers - we don't do that so much anymore.
Sadly, I did not find anything about how fast heart rates lead to gradient overestimations, nor any data that would allow me to deduce some sort of a conversion factor. It was a good reminder to me to actually look at the cited references!
That said, it was still cool to see the study that formed the basis for how we assess mitral stenosis today. Apparently until this point in time, cardiologists were using wedge pressure as a surrogate for LA pressure to determine LA-LV gradients in patients with mitral stenosis (the idea being to avoid an unnecessary transeptal puncture). This paper showed that wedge pressures, even when corrected for the time it takes to cross the pulmonary circulation, consistently overestimated true gradients, while echo-measured mean mitral valve gradients were much more accurate.
Wedge pressures (r = 0.77):
Figure 3.
Echo-measured mean mitral valve gradients (r = 0.97):
Figure 5.
I found a recent JACC CV Imaging paper that created and validated an equation to address this exact concern.
EQUATIONS -
For men, projected transmitral gradient = transmitral gradient - 0.07 (HR - 70) - 0.03 (SV - 97).
For women, projected transmitral gradient = transmitral gradient - 0.08 (HR - 72) - 0.04 (SV - 84).
Figure 1. Comparison of MVA Measurement and Relationship Between Heart Rate or Stroke Volume and TMG
In my experience, this equation isn't prime time, but my interest has been piqued and I may utilize it next time I'm making a decision in clinic. Here's a helpful image, and the paper is attached.
Kato N, Pislaru SV, Padang R, et al. A Novel Assessment Using Projected Transmitral Gradient Improves Diagnostic Yield of Doppler Hemodynamics in Rheumatic and Calcific Mitral Stenosis. JACC: Cardiovascular Imaging. 2021;14(3):559-570. doi:https://doi.org/10.1016/j.jcmg.2020.12.013
Nishimura RA, Rihal CS, Tajik A, Holmes DR. Accurate measurement of the transmitral gradient in patients with mitral stenosis: A simultaneous catheterization and Doppler echocardiographic study. 1994;24(1):152-158. doi:https://doi.org/10.1016/0735-1097(94)90556-8
Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2021;143(5). doi:https://doi.org/10.1161/cir.0000000000000923
