Low Aortic Valve Gradient Associated With Higher Mortality and Recurrent Heart Failure

Low aortic valve gradient (AVG), but not left ventricular (LV) dysfunction, was associated with higher mortality rates and recurrent heart failure in patients undergoing transcatheter aortic valve replacement (TAVR), according to findings published in the Journal of the American College of Cardiology.

Researchers sought to assess the impact of LV ejection fraction (LVEF) and AVG on clinical outcomes, and to confirm whether the effect of AVG is modified by LVEF.

LV dysfunction has been associated with an increased risk of poor periprocedural outcomes in patients with severe aortic stenosis who undergo surgical aortic valve replacement (SAVR). For patients considered either inoperable or too high-risk for surgery, TAVR has worked as an alternative treatment. It also has demonstrated improvements in survival and quality of life compared with medical therapy alone, and has improved similar intermediate-term survival compared with SAVR.

Researchers collected data from patients in the Transcatheter Valve Therapies Registry (n=11 292), including 1-year mortality and recurrent heart failure rates. LV dysfunction and AVG levels varied from <30% vs 30% to 50% vs >50% and <40 mm Hg vs ≥40 mm Hg, respectively. Across the LVEF strata, the median LVEF was 23%, 42%, and 60%. In addition, patients with severe LV dysfunction and mild/moderate dysfunction had significantly lower median AVG compared with those with preserved LV function (37 mm Hg vs 41 mm Hg vs 45 mm Hg; P<.001).

With respect to comorbidites, patients with severe LV dysfunction and mild/moderate dysfunction had significantly higher Society of Thoracic Surgeons mortality risk scores when compared with patients with preserved LVEF (9.7% vs 8.0% vs 6.6%; P<.001). Median AVG was 32 mm Hg in the “low AVG group” and 49 mm Hg in the “high AVG group” (P<.001), and those patients with low AVG had significantly lower median LVEFs (55% vs 60%; P<.001).

In terms of in-hospital outcomes, LV dysfunction was associated with increased lengths of stay (median days: 7 days vs 7 days vs 6 days; P<.001) and a trend toward higher mortality (6.4% vs 5.4% vs 4.7%%; P=.069). Patients with low AVG also tended to have worse in-hospital outcomes, including higher mortality rates, and longer lengths of stay (5.6% vs 4.7%; P=.035 and 7 days vs 6 days; P<.001, respectively).

At 1 year, severe LV dysfunction was associated with higher mortality rates (29.3% vs 25.5% vs 21.9%; P<.001) and recurrent heart failure rates (19.3% vs 17.2% vs 12.8%; P<.001). Patients with low AVG had higher mortality rates at 1 year (27.1% vs 21.5%; P<.001) and heart failure hospitalizations (19.2% vs 11.9%; P<.001) compared with patients with high AVG.

However, only AVG was independently associated with 1-year mortality, after adjustment for baseline clinical factors (adjusted hazard ratio [HR]: 1.21; 95% confidence interval [CI]: 1.11-1.32; P<.001) and recurrent heart failure (adjusted HR: 1.52; 95% CI: 1.36-1.69; P<.001).

In addition, there were no associations between baseline LVEF or AVG values and stroke or MI rates at 1 year.

Overall, patients with preserved LV function and high AVG had the most favorable outcomes at 1 year, with a 23.6% mortality rate and 11.2% compared with patients who had severe LV dysfunction and low AVG (33.1% rate of mortality and 23.6% rate of heart failure).

“This study both confirms and extends the results of previous research regarding the benefits of both SAVR and TAVR in patients with severe AS [aortic stenosis],” researchers wrote. “From a practical perspective, our findings suggest that the presence of low AVG (<40 mm Hg) may identify a cohort of AS patients who derive less long-term benefit from TAVR.”

However, they cautioned, “it is important to recognize that neither LV dysfunction nor low AVG identifies a group of patients with sufficiently poor outcomes to preclude consideration for TAVR in the absence of other indicators of poor prognosis.”

Further investigation of factors responsible for the interactions among transvalvular flow, AVG, LVEF, and clinical outcomes may offer useful prognostic guidance for patients undergoing TAVR.

Reference

Baron SJ, Arnold SV, Herrmann HC, et al. Impact of ejection fraction and aortic valve gradient on outcomes of transcatheter aortic valve replacement. J Am Coll Cardiol. 2016;67(20):2349-2358. doi: 10.1016/j.jacc.2016.03.514.