• Study: Aortic Valve Gradient Key to TAVR Outcomes LVEF, on the other hand, not so much

    A reduced aortic valve gradient — not left ventricular ejection fraction (LVEF) — may

    be telling of poor outcomes after transcatheter aortic valve replacement (TAVR), a study

    found.

    Low gradients (less than 40 mm Hg) were associated with a higher 1-year mortality rate

    (hazard ratio [HR] 1.21, 95% CI 1.11-1.32) and more cases of heart failure (HR 1.52,

    95% CI 1.36-1.69), according to David J. Cohen, MD, MSc, of Saint Luke’s Mid

    America Heart Institute in Kansas City, Mo., and colleagues.

    According to the study, published online in the Journal of the American College of

    Cardiology, left ventricular dysfunction was not associated with either outcome on

    multivariable analysis.

    “From a practical perspective, our findings suggest that the presence of low aortic valve

    gradient (<40 mm Hg) may identify a cohort of aortic stenosis patients who derive less

    long-term benefit from TAVR. Nevertheless, it is important to recognize that neither left

    ventricular dysfunction nor low aortic valve gradient identifies a group of patients with

    sufficiently poor outcomes to preclude consideration for TAVR in the absence of other

    indicators of poor prognosis,” the authors emphasized.

    A low gradient apparently doesn’t preclude the options of surgery or medical therapy

    either, according to Philippe Pibarot, DVM, PhD, of Laval University in Quebec City,

    and John Webb, MD, of St. Paul’s Hospital in Vancouver, Canada.

    “Although the results of this study confirm that patients with low gradient and/or low

    LVEF have worse outcomes following TAVR, they do not permit the establishment of

    whether these patients would have better or worse outcomes with conservative

    management or with surgical aortic valve replacement [SAVR],” they wrote in an

    accompanying editorial.

    Nonetheless, the duo noted that “several nonrandomized studies as well as post hoc

    analyses of the PARTNER trial have demonstrated that patients with severe aortic

    stenosis and low LVEF, low-flow, and/or low-gradient aortic stenosis have higher

    mortality following TAVR or SAVR. However, in these studies, the outcome of these

    patients was even worse with conservative management.”

    Cohen’s investigation included data from 11,292 patients in the TVT Registry whose

    records were linked to Centers for Medicare & Medicaid Services files.

    Low gradients and poor LVEF were not uncommon in TAVR recipients (comprising

    34.4% and 32.8% of the population, respectively).

    In unadjusted analysis, patients with increasing LV dysfunction had longer lengths of

    stay (6 days for LVEF>50% versus 7 days for LVEF 30-50% versus 7 days for

    LVEF<30%). Also predictive of a longer length of stay was low aortic valve gradient (7

    days versus 6 days for higher AVG, P<0.001). Poor gradients were additionally

    associated with more in-hospital death (5.6% versus 4.7%, P=0.035) and a new

    requirement for dialysis (2.3% versus 1.5%, P=0.005).

    “Low aortic valve gradient may be an indication of reduced flow, which is often related

    to intrinsic myocyte dysfunction,” Cohen and colleagues suggested.

    The authors noted that the TVT Registry did not collect data on contractile reserve and

    other important variables for their investigation. In addition, it was not possible to

    calculate transvalvular flow. The site-reported echocardiography and hemodynamic data

    lacked adjudication as well, the researchers acknowledged, leaving room for subjective

    interpretation in each case.

    On top of that, “the TVT registry did not capture the flow and dobutamine stress

    echocardiography data, which limit the ability to perform more refined analyses,

    particularly with regards to resting flow and flow reserve,” Pibarot and Webb added.

    Yet they still maintained that “patients with low LVEF/low flow/low gradient often have

    more vulnerable LV function, and any additional myocardial impairment related to the

    procedure may compromise their outcome.”

    “For that reason, it may also be preferable to use a transfemoral, transaxillary, or

    transaortic approach rather than a transapical approach when performing TAVR in these

    patients.”

    Pibarot and Webb concluded: “Information about gradient, aortic valve area, flow, and

    LVEF is available from the routine Doppler echocardiographic examination and should

    be systematically integrated in the risk stratification process of patients with aortic

    stenosis being considered for aortic valve replacement.”

    Disclosures

    Cohen declared relationships with Edwards Lifesciences, Medtronic, and Boston

    Scientific.

    Pibarot disclosed receiving research grants from Edwards Lifesciences and support from

    the Canadian Institutes of Health Research and the Heart & Stroke Foundation of

    Quebec.

    Web reported research grants and consulting for Edwards Lifesciences.

    Source:

    Journal of the American College of Cardiology

    http://content.onlinejacc.org/journal.aspx

    Pibarot P, et al “The complex interaction between left ventricular ejection fraction, flow,

    and gradient in patients undergoing TAVR” J Am Coll Cardiol 2016; DOI:

    10.1016/j.jacc.2016.02.072.

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