Patient Selection Trends Younger, Less High Risk for Transcatheter Valve Therapy

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Over 3 years, patient selection for transcatheter aortic valve replacement (TAVR) has shifted toward those with a lower risk profile while the procedure has remained just as safe in terms of mortality, according to results published online December 21, 2011, ahead of print in the Journal of the American College of Cardiology.

For the single-center, observational study, a research team led by Nicolo Piazza, MD, PhD, of the German Heart Center (Munich, Germany), reviewed data from 420 patients with severe aortic stenosis who underwent TAVR at their institution between June 2007 and June 2010. After dividing the cohort into quartiles according to enrollment date (Q1 through 4), the investigators examined the changes in patients’ baseline characteristics over time and the impact of TAVR on survival by quartile.

Marked Change Over 3 Years

Compared with patients undergoing TAVR during Q1, those in Q4 had lower logistic EuroScores (17.8 ± 12% vs. 25.4 ± 16%) and Society of Thoracic Surgeons (STS) scores (4.8 ± 2.6% vs. 7.1 ± 5.4%; P < 0.001 for both). Furthermore, use of the CoreValve system (Medtronic, Minneapolis, MN) decreased from 86.7% in Q1 to 59.4% in Q4 (P < 0.001), while use of the Edwards Sapien device (Edwards Lifescienes, Irvine, CA) increased accordingly from 13.3% in Q1 to 40.6% in Q4 (P < 0.001). There also was a corresponding 36% decrease in the proportion of cases performed transfemorally (from 85% to 49%; P < 0.001), a 30% reduction in the use of general anesthesia (from 100% to 69%), and a decline in contrast use (from 156 ± 69 mL to 104 ± 41 mL; P < 0.001) between Q1 and Q4.

Baseline characteristics associated with increased 30-day mortality were:

• Age (HR 1.01; 95% CI 1.04-1.17; P = 0.001)
• STS predicted risk of mortality (HR 1.06; 95% CI 1.002-1.12; P = 0.043)
• Stroke/TIA (HR 3.06; 95% CI 1.20-7.80; P = 0.019)

Predictors of 6-month mortality varied somewhat:

• STS predicted risk of mortality (HR 1.09; 95% CI 1.03-1.12; P < 0.001)
• Stroke/TIA (HR 3.41; 95% CI 1.70-6.70; P < 0.001)
• Previous aortic valve surgery (HR 3.29; 95% CI 1.03-10.51; P = 0.04)
• Log NT-proBNP (HR 1.64; 95% CI 1.04-2.58; P = 0.03)

Between Q1 and Q4, there was a strong trend for a threefold decrease in the risk of 30-day mortality and a twofold decrease in the risk of 6-month mortality (the combined primary endpoint). However, after adjustment for baseline differences, the improvement was not significant (table 1).

Table 1. Thirty-Day and 6-Month Mortality: First vs. Fourth Quartile

 
In addition, no differences were seen for these endpoints between patients undergoing transfemoral or transapical TAVR (HR for 30-day mortality: 1.07; 95% CI 0.54-2.11; P = 0.83; HR for 6-month mortality: 1.13; 95% CI 0.71-1.80; P = 0.60).

Over 6-month follow-up, rates of stroke/TIA and need for permanent pacemaker were similar for the earliest and latest quartiles of patients, while the incidence of vascular complications (total and femoral only) decreased over time (table 2).

Table 2. Secondary Outcomes at 6 Months

 
In a telephone interview with TCTMD, Philippe Pibarot, DVM, PhD, of Laval University (Quebec City, Canada), sketched the evolution and future direction of TAVR in regard to patient eligibility.

“We started at the worst end of the spectrum in terms of risk profile. The most recent patients are clearly younger and have better STS scores that would probably not have been included in the initial experience,” he said. “And both the short- and intermediate-term mortality have improved in parallel.”

Despite the fact that lower baseline risk would be expected to improve survival contributions to the patient profile trend by growing operator expertise and marked improvements in device design cannot be discounted, Dr. Pibarot said. However, it is difficult to dissect out the relative importance of patient, device, and procedure-related factors, he added.

Recent Mortality Lower than Predicted

“We expected that TAVR would be superior to surgery and provide the greatest benefit in high-risk patients,” Dr. Pibarot noted. “But with this paper, the observed mortality in the fourth quartile patients was actually lower than what was predicted by their STS scores, as opposed to what we’ve seen with higher-risk patients. That’s good news.”

Another important finding is that as patients’ baseline risk decreased, so did stroke incidence—even more than mortality, Dr. Pibarot observed. “Initially we thought that most strokes occurred during the procedure. But then we realized that a large number occur [later],” he said. “This may be a signal that they are driven by the baseline risk profile. If stroke incidence decreases to 1%, as it does in the most recent patients in this study, that compares favorably with surgery and makes TAVR a valid alternative.”

Although the study focuses on changes in surgical risk scores, like the authors, Dr. Pibarot stressed that clinical judgment should take precedence in assessing eligibility of patients for TAVR. With experience, TAVR experts have learned that some risk factors, such as frailty, COPD, and cognitive function, carry more weight than others, he said, cautioning that this more targeted assessment cuts both ways: Some patients with a high surgical risk score may be deemed acceptable candidates, while others with lower scores may not.

Advancing with Due Caution

“The evolution of TAVR toward [treatment of] intermediate and potentially lower risk patients is inevitable,” Dr. Pibarot asserted. “The questions are how much time it will take and how to move appropriately. This paper provides a robust argument in favor of doing randomized trials in this intermediate-risk population,” as in the ongoing European SURTAVI trial.

Nonetheless, the TAVR field should be cautious about lowering the bar, Dr. Pibarot commented. “Before moving toward lower risk younger patients, we definitely need more data on the durability of [percutaneous] valves,” he said. “We would like them to last at least 15 years, but we don’t have the follow-up. And we don’t want a large number of patients coming back [for repeat replacements].” Paravalvular leakage—which may not be a major issue in elderly patients with short life expectancy—remains an important limitation of the current technology. “We have to be careful about moving to younger patients, especially since surgery performs very well in this population,” he concluded.

 

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Source:
Lange R, Bleiziffer S, Mazzitelli D, et al. Improvements in transcatheter aortic valve implantation outcomes in lower surgical risk patients: A glimpse into the future. J Am Coll Cardiol. 2011;Epub ahead of print.

 

 

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