While incidence of adverse event rates remain low following transcatheter aortic valve replacement (TAVR), especially among experienced operators, researchers are looking to drive them down further through a greater understanding of how certain patient characteristics, procedural approach or even which device can impact outcomes.
Lessons from PARTNER
To avoid adverse events with TAVR, clinicians must first recognize that complications do occur. “While the PARTNER trial showed us that TAVR had a remarkable impact on survival in patients with high-operative risk with severely symptomatic aortic stenosis compared with medical therapy, there were also some important complications with the procedure,” says Prateek J. Khatri, MD, of the University of Toronto’s Institute for Clinical Evaluative Sciences, and Schulich Heart Centre, Sunnybrook Health Sciences Centre.
|Learning Curve & Survival: Kaplan-Meier survival in the first 25 vs. last 50 patients treated with transcatheter aortic valve replacement.
Source: Elizabeth A. Magnuson, PhD
The prospective, randomized, controlled trial has revealed a great deal about this patient population, especially when assessing both cohort B—patients with severe aortic stenosis (AS) who were deemed inoperable—and cohort A—patients with severe AS who were deemed high-risk for surgery.
In late 2012, Philippe Généreux, MD, of Columbia University Medical Center/New York-Presbyterian Hospital in New York City, and colleagues combined both cohorts to identify incidence, predictors and impact of vascular complications (VCs) after transfemoral TAVR, using the first-generation Sapien valves, via a 22- or 24-Fr sheath (Edwards Lifesciences) (J Am Coll Cardiol 2012;60:1043-1052).
The researchers included 419 patients (177 from cohort B and 242 from cohort A) from PARTNER. Overall, 15.3 percent had major VCs and 11.9 percent had minor VCs within 30 days of the procedure. Among patients with major VCs, vascular dissection (62.8 percent), perforation (31.3 percent) and access-site hematoma (22.9 percent) were the most frequent modes of presentation. Major VCs, not minor VCs, were associated with significantly higher 30-day rates of major bleeding, transfusions and renal failure requiring dialysis, and with a significantly higher rate of 30-day and one-year mortality. Major VC and renal disease at baseline were identified as independent predictors of one-year mortality.
In distinguishing between the two cohorts, the researchers found that VCs were more frequent and less well tolerated in the cohort B population, while in the cohort A population, the rate of VCs decreased in frequency and had less impact on mortality, explains Généreux. This finding is in spite of the fact that the larger device was typically used in cohort A.
“This is an important distinction because people often associate TAVR with higher rates of vascular complications, because the findings from cohort B were released and scrutinized first,” he says. Of course, because the cohort A patients are slightly less sick, this finding would be expected.
Also, the study authors found that the only identifiable independent predictor of major VC was female gender. “This is probably due to several factors; one being a smaller vessel size, but women also may have more fragile vessels,” says Généreux.
“An intrinsic increased vulnerability to peri-procedural complication during and early after an invasive procedure may be present in women,” the study authors wrote. “Exact mechanisms for this finding remain elusive and warrant further investigation.”
However, longer term, TAVR is still found to be beneficial for women. While this analysis of PARTNER demonstrated that although the female sex is a strong predictor of peri-procedural vascular complications, the female sex also was associated with a reduction in all-cause mortality at one year.
While not identified as independent predictors of adverse events, diabetes and small vessel size showed a trend toward experiencing vascular complications.
Lessons from practice
“In clinical trials, we look at individual endpoints as independent entities, such as stroke or death; however, in practice, things are a little more complicated,” says Stephan Windecker, MD, head of interventional cardiology at the Swiss Cardiovascular Center Bern. “In clinical reality, one adverse event may trigger another one, as many events are interrrelated.”
To get an assessment of how these patients fare in real-life clinical