Letter by Dumesnil and Pibarot Regarding Article, “Systemic Hypertension in Low-Gradient Severe Aortic Stenosis With Preserved Ejection Fraction”
To the Editor:
We read with interest the recent article by Eleid et al.1 This study, which reports the effects of nitroprusside administration in 18 patients with low-gradient severe aortic stenosis and preserved ejection fraction, provides added evidence that hypertension importantly affects hemodynamics in such patients and that treatment thereof should be beneficial. The accompanying editorial is supportive and presents an algorithm indicating that hypertension should indeed be an important consideration when evaluating therapeutic options. In this context, however, the following should also be emphasized2: (1) Reduced systemic arterial compliance is very frequent in elderly patients with aortic stenosis and is the main mechanism responsible for hypertension. (2) Reduced compliance acts as a second obstruction in series and may thus add significantly to global left ventricular load, expressed in terms of valvuloarterial impedance (Zva), to the extent that Zva may be as elevated in patients with moderate aortic stenosis and reduced compliance more than in patients with severe stenosis and normal compliance. (3) Blood pressure levels may nonetheless be pseudonormalized in patients with reduced compliance owing to a concomitant decrease in stroke volume; hence, in our original series,2 hypertension was present in 92% of patients with moderate stenosis and reduced compliance, but in only 58% of patients with severe stenosis and reduced compliance, owing to a phenomenon of pseudonormalization. (4) Prognosis has been shown in multivariable analysis to be more significantly related to the increase in global hemodynamic load (ie, Zva)3 or the reduction in systemic arterial compliance4 than to blood pressure levels per se. Hence, it should be re-emphasized that therapeutic decision making in these patients should not be based solely on blood pressure measurements but rather on a comprehensive evaluation of vascular dynamics including measurements of systemic arterial compliance, vascular resistance, and Zva.5 As recently emphasized,4 failure to measure compliance makes it impossible to distinguish between the following 3 possibilities when recording a normal blood pressure level: (1) normal vascular dynamics, (2) successfully treated hypertension, and (3) pseudonormalized hypertension attributable to a concomitant decrease in cardiac output. Also, pseudonormalization of blood pressure is not unique to aortic stenosis but may be found in other categories of patients where it also corresponds to significantly abnormal vascular dynamics.4 Finally, it is interesting to note that group 2 (patients with low-gradient aortic stenosis and reduced ejection fraction) of Eleid et al1 had resting blood pressure levels that were relatively normal and clearly lower than in group 1. Nonetheless, their vascular dynamics and left ventricular end-diastolic pressures were as abnormal as in group 1 and similarly improved by treatment (the lower P values are likely attributable to a smaller number of patients (n=6 versus 18). Hence, we would submit that the consideration of therapeutic options in patients with aortic stenosis and abnormal vascular dynamics should be based on a comprehensive evaluation including measurements of systemic arterial compliance, vascular resistance, and Zva rather than on blood pressure measurements alone.
Jean G. Dumesnil, MD
Philippe Pibarot, DVM, PhD
Institut Universitaire de Cardiologie et de Pneumologie de
Québec/Québec Heart & Lung Institute
Department of Medicine
- © 2014 American Heart Association, Inc.