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Low-flow severe aortic stenosis boosts mortality risk following TAVR
Low-flow severe aortic stenosis, which is estimated to be present in 5% to 10% of all patients with severe aortic stenosis, was associated with increased mortality at 1 year after transcatheter aortic valve replacement, according to a secondary analysis of the PARTNER trial.
Researchers evaluated 984 participants of the randomized clinical trial and continued-access registry. The mean age of the cohort was 84 years, 59% were men and the mean Society of Thoracic Surgeons score was 11.4%. Patients included in the substudy analysis had evaluable echocardiographic data and low-flow severe aortic stenosis (left ventricular stroke volume index 35 mL/m2) at baseline.
After TAVR, patients were classified by LV stroke volume index status at discharge: severe low flow (mean, 23.1 mL/m2), moderate low flow (31.7 mL/m2) or normal flow (43.1 mL/m2). Patients were additionally classified as having classic low-flow aortic stenosis (ejection fraction < 50%) or paradoxical low-flow aortic stenosis ( 50%) and grouped by tertiles of discharge LV stroke volume index for a separate analysis.
The primary endpoint of the secondary analysis — all-cause mortality at 1 year — was 26.5% among the severe-low-flow group, 20.1% among the moderate-low-flow group and 19.6% among the normal-flow group (P = .045 for comparison). Patients with severe low flow had the highest mortality rate compared with the normal-flow group (HR = 1.45; 95% CI, 1.05-2.01), the moderate-low-flow group (HR = 1.37; 95% CI, 0.99-1.89) and the normal-flow and moderate-low-flow groups combined (HR = 1.41; 95% CI, 1.07-1.86).
CV mortality at 1 year was also increased in the severe-low-flow group (11.4%) compared with the moderate-low-flow (7.9%) and normal flow (6%) groups.
Mortality at 1 year was not significantly different between patients who had a 20% increase in LV stroke volume index between baseline and discharge vs. those who did not.
At 6 months, patients with moderate low flow and normal flow exhibited normalized mean LV stroke volume index (35.9 mL/m2 and 38.8 mL/m2, respectively), but this value remained low in patients with severe low flow at both 6 months (31.4 mL/m2) and 1 year (33 mL/m2; P < .001 for all groups), according to the results.
In other results, patients with classic low-flow aortic stenosis (43.1%) had a similar timeline for improvement in flow compared with patients with paradoxical low-flow aortic stenosis (56.8%). While there was no significant difference in survival among the three LV stroke volume index groups with classic low-flow aortic stenosis, patients who achieved normal flow after TAVR had increased survival. Among patients with paradoxical low-flow aortic stenosis, those with severe low flow had the highest rate of mortality at 1 year (24.7%).
Independent predictors of 1-year mortality in this secondary analysis included effective orifice area index (HR = 1.87; 95% CI, 1.09-3.19), moderate/severe mitral regurgitation at discharge (HR = 1.65; 95% CI, 1.21-2.26), sex (HR = 1.59; 95% CI, 1.18-2.13), atrial fibrillation (HR = 1.41; 95% CI, 1.06-1.87), STS score (HR = 1.03; 95% CI, 1.01-1.06) and mean transvalvular gradient before TAVR (HR = 0.98; 95% CI, 0.87-0.99).
“Many of the differences observed within this subset of patients stem from preexisting cardiac disease and its interaction with aortic stenosis,” the researchers wrote. “Although flow improved in most patients by 6 months after TAVR, severe low flow at discharge persisted in up to one-third of the patients and was independently associated with higher 1-year mortality rates. The identification of remedial causes of persistent low flow after TAVR may represent an opportunity to improve the outcome of these patients.” – by Jennifer Byrne
Disclosure: The PARTNER trial was funded by Edwards Lifesciences. Many researchers report financial ties with Edwards Lifesciences and other device companies. Please see the full study for a list of the researchers’ relevant financial disclosures.