Clinical Investigation
Valvular Heart Disease
Impact of Valvuloarterial Impedance on 2-Year Outcome of Patients Undergoing Transcatheter Aortic Valve Implantation

https://doi.org/10.1016/j.echo.2013.04.003Get rights and content

Background

Elderly patients with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI) often have increased calcification and fibrosis of the aorta. Indices that account for the severity of valvular obstruction and systemic vascular impedance may better assess total left ventricular afterload. The aims of the present study were to evaluate changes in valvuloarterial impedance (Zva), systemic arterial compliance, and systemic vascular resistance after TAVI and to investigate the prognostic value of these parameters.

Methods

A total of 116 patients (49% men; mean age, 81 ± 8 years) with symptomatic severe aortic stenosis underwent TAVI. Zva, systemic arterial compliance, and systemic vascular resistance were measured at baseline and 1 and 12 months after TAVI. The primary end point was all-cause mortality.

Results

After TAVI, there was a significant reduction in Zva (from 5.40 ± 1.52 mm Hg/mL/m2 at baseline to 4.13 ± 1.17 mm Hg/mL/m2 at 1 month and 4.35 ± 1.38 mm Hg/mL/m2 at 1 year, P < .001). Systemic arterial compliance (from 0.57 ± 0.27 to 0.57 ± 0.28 and 0.53 ± 0.27 mL/m2/mm Hg, P = .408) and systemic vascular resistance (from 1,938 ± 669 to 1,856 ± 888 and 1,871 ± 767, dyne·s·cm−5, P = .697) did not change significantly over time. During a median follow-up period of 25 months, survival rates of patients with baseline Zva ≥ 5 mm Hg/mL/m2 were lower compared with those with Zva < 5 mm Hg/mL/m2 (82% vs 91%, respectively, log-rank P = .04). On multivariate Cox proportional-hazards analysis, baseline Zva was independently associated with all-cause mortality (hazard ratio, 1.48; 95% confidence interval, 1.05–2.07; P = .025).

Conclusions

In patients undergoing TAVI, there is a significant postprocedural reduction in Zva, but there is no reduction in systemic arterial compliance or vascular resistance. Baseline Zva is an independent predictor of overall mortality at 2-year follow-up.

Section snippets

Patient Population

A total of 116 patients with severe symptomatic aortic stenosis (aortic valve area [AVA] < 1.0 cm2 or transaortic mean pressure gradient ≥ 40 mm Hg) who underwent TAVI at two centers (84 patients at Leiden University Medical Center, Leiden, The Netherlands; 32 patients at the Québec Heart and Lung Institute, Department of Medicine, Laval University, Québec, Canada) were included in the present study. Patients who underwent transcatheter valve-in-valve procedures or in whom baseline Zva could

Patient Characteristics

A total of 116 patients with severe symptomatic aortic stenosis (mean age, 81 ± 8 years; 49% men) were evaluated. All patients underwent successful TAVI using a transfemoral (n = 48 [41%]) or transapical (n = 68 [59%]) approach. Thirty-five patients (30%) received 23-mm valve prostheses, and 81 (70%) received 26-mm valves. Clinical and procedural characteristics are outlined in Table 1.

Changes in Aortic Valve Hemodynamics and Global LV Load after TAVI

During the first postoperative month, seven patients (6%) died, and three additional patients died within the

Discussion

The present study showed that TAVI leads to improved valvular hemodynamics, with significant reductions in systolic pressure gradients and increase in AVA, and significant reduction in LV global pressure overload, as measured by Zva. In contrast, systemic arterial compliance and systemic vascular resistance did not change significantly after TAVI. Baseline Zva was independently associated with late outcomes (all-cause mortality) after TAVI.

Conclusions

In patients undergoing TAVI, there is a significant postprocedural reduction in Zva but not in systemic arterial compliance or vascular resistance. High baseline Zva is an independent predictor of increased all-cause mortality at 2-year follow-up. Further studies are needed to identify the role of the routine measurement of Zva for the identification of patients who have a high likelihood to benefit from TAVI.

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      There is a strong association between the presence of aortic stenosis and reduced arterial compliance as both are a manifestation of the degenerative atherosclerotic process common in advanced age [1]. One mechanism by which patients may remain symptomatic is that despite a reduction in the valvular gradient after the procedure, excess LV afterload remains due to ongoing arterial stiffness [7,8]. Therefore, the symptom complex in these patients is likely due to a combination of exposure of the LV to both the valvular load caused by the aortic transvalvular gradient and the arterial load caused by reduced systemic arterial compliance.

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    The Department of Cardiology receives unrestricted research grants from Biotronik (Berlin, Germany), Boston Scientific (Natick, Massachusetts), GE Healthcare (Buckinghamshire, United Kingdom), Medtronic (Minneapolis, Minnesota) and St. Jude Medical (St. Paul, Minnesota). Dr. Delgado received consulting fees from Medtronic and St. Jude Medical. Dr. Katsanos received a grant from the Hellenic Cardiovascular Society.

    Dr. Michael Picard is the guest editor for this paper.

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