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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 , of Saint Luke's Mid America Heart Institute in Kansas City, Mo., and colleagues.

According to the study, published online in the , 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 , of Laval University in Quebec City, and , 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 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."