Combining Frailty Index With Existing Risk Models Improves Mortality Prediction in TAVR

Adding frailty assessment to conventional risk scores improves the ability to predict 1-year mortality after TAVR, with the odds of death increasing alongside worsening degrees of frailty, according to new data.

While previous efforts have hinted that determining frailty prior to TAVR can improve risk stratification independent of standard scores, now investigators are taking it one step further by showing that the frailty component accounted for 58.2% of the predictive information when added to EuroSCORE and 77.6% of the predictive information when added to the Society of Thoracic Surgeons (STS) score.

“Even though further research is needed, we emphasize that frailty should already now be part of every pre-TAVR clinical evaluation, as it may improve clinical decision-making,” write researchers led by Andreas W. Schoenenberger, MD (Bern University Hospital, Switzerland), in a paper published online ahead of the February 26, 2018, issue of JACC: Cardiovascular Interventions.

Since there is no “gold standard” for measuring frailty, the researchers used their own index, based on assessment of cognition, mobility, nutrition, and instrumental and basic activities of daily living. The study included 330 consecutive TAVR patients, all of whom were 70 years of age or older and were evaluated between 2009 and 2013.

In an accompanying editorial, Lars Søndergaard, MD, DMSc (Copenhagen University Hospital, Denmark), and colleagues say adding frailty to “an algorithm for risk stratification of patients undergoing TAVR would be a much-needed tool that could aid clinical recommendations and also provide information of potential reversible risk factors that could guide in-hospital stay and postprocedural management to a better outcome for the patient.”

Philippe Généreux, MD (Morristown Medical Center, NJ), who was not involved in the study, commented that improving accuracy of TAVR assessments is a timely and ongoing concern since EuroSCORE and STS were both created for surgery patients, not TAVR.

“It’s not surprising that frailty would trump everything in terms of mortality prediction,” he said in an interview with TCTMD. “But within frail patients you also need to stratify by a more granular assessment of cardiac dysfunction.”

Differentiating Levels of Frailty

In the single-center study, logistic EuroSCORE and STS score were calculated for each patient then followed by a geriatric baseline examination that included Mini-Mental State Exam (MMSE) for cognitive function, Timed Up and Go (TUG) test for gait function, Mini Nutritional Assessment (MNA) for nutritional status, basic activities of daily living (BADL), and instrumental activities of daily living (IADL). The frailty index was scored on a scale of 0 to 7. One-third of the study population had cognitive impairment, and nearly one-third had mobility impairment

At 1 year the mortality rate was 0.18 (95% CI 0.13-0.23) for the entire cohort. Mortality was lowest in patients on the lowest end of the frailty scale and steadily increased with increasing frailty score. Among those with a score of 0, for example, mortality risk at 1 year was 0.04 (95% CI 0.01-0.27), while for those with a score of 7 it was 3.94 (95% CI 1.27-12.2).

In the two highest frailty score categories, mortality at 1 year exceeded 50%. Although some research suggests that frailty occurring as a result of severe aortic stenosis can be reversed with valve replacement, Schoenenberger and colleagues say the high mortality rates among the frailest frail suggest “there might be a level of frailty, which is irreversible.”

In addition to providing more predictive information to the EuroSCORE and the STS score than either tool alone, sensitivity analysis showed that the frailty index enhanced mortality prediction even when known risk factors such as anemia, A-fib, and LVEF < 35% were added to the conventional risk scores. Among the individual components of the frailty index, the TUG test for gait function was the strongest independent predictor of 1-year mortality.

Frail, but Not Always Futile

While the editorialists agree that frailty should be considered by every heart team when assessing individual TAVR risk, they say more research is needed to refine frailty scores and their association with TAVR. They also note that the study used the older logistic EuroSCORE no longer recommended for use in clinical practice, rather than the newer EuroSCORE II, which incorporates mobility criteria and instrumental activities of daily living. The study also is limited by its single-center design and by advances in operator experience, TAVR devices, and lowered complication rates in the years since the cohort was assessed.

Nevertheless, Søndergaard and colleagues say the results are important “and should increase the interest of combining frailty with conventional algorithms.”

To TCTMD, Généreux said while objective measures of frailty are useful, they may not always be needed, since a certain level of frailty is often obvious and agreed upon by heart teams. But of paramount importance, he added, is that frailty not be equated with futility and that efforts continue to tease out which patients along the spectrum of frailty will benefit from TAVR.

“It’s very difficult to predict who will bounce back . . . but this is where cardiac function is important to factor into those decisions,” he said. “For moderately or even very frail patients, TAVR may be an option. Sometimes we want to improve quality of life. This is why it’s important to have a very good discussion with the family and primary caregiver about expectations.”