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
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
“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
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
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.”
Cohen declared relationships with Edwards Lifesciences, Medtronic, and Boston
Pibarot disclosed receiving research grants from Edwards Lifesciences and support from
the Canadian Institutes of Health Research and the Heart & Stroke Foundation of
Web reported research grants and consulting for Edwards Lifesciences.
Journal of the American College of Cardiology
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: