Treatment Delays May Undermine TAVR Efficacy

Download this article's Factoid (PDF & PPT for Gold Subscribers)


Once patients are accepted for transcatheter aortic valve replacement (TAVR), the longer they wait to undergo the procedure, the greater their risk of dying either preprocedurally or within 1 year, according to a study published online March 13, 2014, ahead of print in the Canadian Journal of Cardiology. In particular, waiting longer than 60 days translates to loss of equivalence to surgery in high-risk patients.

According to the authors, tracking delays and establishing benchmarks for waiting times could help reduce complications before the procedure and improve longer-term outcomes.

 

Methods

Investigators led by Harindra C. Wijeysundera, MD, PhD, of Sunnybrook Health Sciences Centre (Toronto, Canada), used mathematical modeling to simulate mortality risks over 7 wait times ranging from 10 to 180 days after completion of diagnostic workup and acceptance for the procedure and at 1 year from the starting point. Data were derived from the pivotal PARTNER trials of the Sapien balloon-expandable valve (Edwards Lifesciences; Irvine, CA).

Two patient groups, modeled on the PARTNER A and B populations, were analyzed:

  • High-risk surgical candidates (PARTNER A) had a mean age of 84.1 years and 57% were male. Mean Society of Thoracic Surgeons (STS) risk score was 11.8 in the TAVR group and 11.7 in the surgical group. In keeping with contemporary practice, the surgical wait time was fixed at a mean of 15.6 days for all scenarios.
 
  • Inoperable patients (PARTNER B) had a mean age of 83.1 years and about 45% were male. Mean STS score was 11.2 in the TAVR arm and 12.1 in the medical-therapy arm.
 


The daily risk of dying before TAVR as well as the mortality risk over the year after acceptance for the procedure increased progressively with longer wait times, showing a 27% difference in daily risk between the shortest and longest wait times for inoperable patients and a 20% difference for high-risk patients. In contrast, wait times and mortality risks were considered relatively stable for control patients receiving medical therapy or surgery, respectively (tables 1 and 2).

Table 1. Inoperable Patients: Estimated Mortality by Wait Time for TAVRa

 

 

During Wait

At 1 Year

10 Days

1.9%

31.5%

60 Days

10.7%

34.6%

180 Days

28.9%

41.4%

a For medical therapy patients, 1-year mortality ranged from 49.7% to 49.9% for all wait times.

Table 2. High-Risk Patients: Estimated Mortality by Wait Time for TAVRa

 

 

During Wait

At 1 Year

10 Days

2.2%

24.5%

60 Days

8.1%

26.7%

180 Days

22.4%

32.6%

a For surgery patients, the mean fixed wait-time and 1-year mortality rates were 2.5% and 27.0%, respectively.

Sensitivity analyses showed that in the inoperable cohort, the vast majority of TAVR patients (99.2%) had lower death rates than those receiving medical therapy regardless of how long they had to wait for the procedure. On the other hand, among high-risk patients, when the wait time exceeded 60 days, TAVR led to higher 1-year mortality than did surgery. Moreover, at wait times beyond 180 days, the noninferiority of TAVR to surgery demonstrated in PARTNER A was lost in 41% of the scenarios

The authors note that the only study reporting wait times, a multicenter Dutch observation of 358 patients (Nuis RJ, et al. Netherlands Heart J. 2012;20:16-23), showed a median of 71 days (IQR 30-119 days) from TAVR acceptance to the procedure.

An important caveat regarding the current findings, the investigators observe, is that the clock on wait times started only after diagnostic workup was complete. But because TAVR workups are more extensive and typically longer than those for surgery, they caution, the study data may underestimate the adverse impact of delays on TAVR outcomes.

In light of the current findings, Dr. Wijeysundera and colleagues say, wait times should be monitored and these data should be made available in a timely fashion so that cases can be triaged. This is especially important for patients for whom surgery is an option so that a decision can be made on whether high-risk surgery may be preferable to TAVR, they urge, adding that creating benchmarks for appropriate wait times should be a priority.

Complexity of TAVR Workup a Challenge

In an accompanying editorial published online May 15, John G. Webb, MD, and colleagues from St. Paul’s Hospital (Vancouver, Canada), write that the “rapid emergence of [TAVR] as the recommended or preferred therapy for many patients with aortic stenosis is challenging clinicians, administrators, and policy-makers to ensure adherence to evidence-based indications and access to services within safe and appropriate times.”

The editorial highlights the logistical and expertise complexity of case selection. Prior to TAVR, patients must be seen in consultation with a cardiologist and surgeon and typically undergo cardiac catheterization, transthoracic echocardiogram, computed tomography, and functional assessment. Each of these requirements may create potential time delays related to scheduling and availability of specialty services, staging of contrast administration, and burden of patient travel to attend repeated appointments. 

In US, Problem Is Less Capacity Than Efficiency 

In a telephone interview with TCTMD, David J. Cohen, MD, MSc, of Saint Luke’s Mid America Heart Institute (Kansas City, MO), noted that in Canada the number of TAVR centers is limited and indications for the procedure are somewhat less restrictive than in the United States. In contrast, the United States currently has about 300 TAVR centers, he said, “so waiting times are not a big issue once the procedure is scheduled.”

Rather, the greater concern in the United States is the efficiency of the workup—how long it takes for patients to get an initial clinic appointment, undergo all the required studies, and then set a final date.

The real-world trend toward treating lower-risk patients has countervailing effects, Dr. Cohen observed. On the one hand, patients may be less sick and so less likely to die while waiting for TAVR. Though as more and more patients seek the procedure, the pressure increases to improve preprocedural efficiency.

As for stratifying patients to give priority to those at highest risk, Dr. Cohen conceded that “the idea makes sense, but I would have no idea how to do it. You can get some general clinical sense, but the progression of aortic stenosis is very unpredictable.” In fact, very few US patients wait longer than 60 days, Dr. Cohen noted, and when they do, there are usually medical reasons for the delay that would apply to surgery as well.

Overall, Dr. Cohen said, the findings should “help motivate physicians and valve programs to ensure that their wait times are not excessive.” 

 

 


Sources:
1. Wijeysundera HC, Wong WWL, Bennell MC, et al. Impact of wait times on the effectiveness of transcatheter aortic-valve replacement (TAVR) in severe aortic valve disease: a discrete event simulation model. Can J Cardiol. 2014;Epub ahead of print.

2. Lauck S, Stub D, Webb J. Monitoring wait times for transcatheter aortic valve implantation: a need for national benchmarks [editorial]. Can J Cardiol. 2014;Epub ahead of print.

Related Stories:

Disclosures
  • The study was funded in part by a grant from the Heart and Stroke Foundation of Canada.
  • Dr. Wijeysundera reports being supported by a Distinguished Clinician Scientist award from the Heart and Stroke Foundation, Ontario Provincial Office.
  • Dr. Webb makes no statement regarding conflicts of interest.
  • Dr. Cohen reports receiving research grant support from Boston Scientific, Edwards Lifesciences, and Medtronic and consulting for Medtronic.

We Recommend

Comments