Meta-analysis: Disease Prevalence, Number of TAVR Candidates Growing

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Close to 300,000 elderly patients are currently candidates for transcatheter aortic valve replacement (TAVR). That population stands to grow as approximately 27,000 new patients become eligible for the procedure each year, according to a meta-analysis scheduled to be published online May 28, 2013, ahead of print in the Journal of the American College of Cardiology.

A. Pieter Kappetein, MD, PhD, of Erasmus University Medical Center (Rotterdam, The Netherlands), and colleagues compiled data on 9,723 patients aged 75 years and older from 7 population-based studies. Each study used echocardiography to diagnose aortic stenosis, though definitions of the condition and its severity varied.

Large Estimates of US, European TAVR Patients

The combined prevalence of aortic stenosis ranged from 2.6% to 22.8% in 6 studies, with a pooled prevalence of 12.4% (95% CI 6.6%-18.2%). Severe aortic stenosis was reported in 5 studies and ranged from 1.2% to 6.1%, with a pooled prevalence of 3.4% (95% CI 1.1%-5.7%).

Among patients with severe aortic stenosis, 75.6% (95% CI 65.8%-85.4%) were symptomatic and 40.5% (95% CI 35.8%-45.1%) were not surgically treated. The pooled percentage of patients referred for TAVR who actually received a transcatheter valve was 28.7% (95% CI 22.8%-34.6%), amounting to 40.3% in Europe and 24.4% in the United States. The authors estimate that 12.3% of patients with severe aortic stenosis at prohibitive surgical risk are candidates for TAVR.

Additional modeling estimated there to be nearly 300,000 high- or prohibitive-risk elderly patients with symptomatic severe aortic stenosis—candidates for TAVR—in the United States (102,558; 95% CI 43,612-187,002) and Europe (189,836; 95% CI 80,281-347,372). Based on the number of patients reaching the age of 75 in 2011, the researchers calculated that there would be an annual growth of 17,712 (95% CI 7,590-32,691) new TAVR candidates in Europe and 9,189 (95% CI 3,898-16,682) in the United States.

‘Substantial’ Burden of Disease

“Our estimates of the prevalence demonstrate that the overall burden of disease due to [aortic stenosis] in the general elderly population is substantial,” Dr. Kappetein and colleagues write. “Population demographics clearly show that Western populations are ageing, thereby further increasing the impact of [aortic stenosis]...These data suggest that the treatment of [aortic stenosis] in the elderly will have an increasing impact on public health and health care resource consumption in the future.”

If the prevalence estimates are correct, the “large number of TAVR candidates has clinical, economic, and social implications,” they continue. Assuming an index admission cost of $72,000—a number derived from the PARTNER trial—the authors calculated that treatment of all candidates would cost $13.7 billion in Europe and $7.2 billion in the United States.

Approach Estimates with Caution

However, in an accompanying editorial, Alec Vahanian, MD, Bernard Iung, MD, and Dominique Himbert, MD, all of Bichat Hospital (Paris, France), highlight several flaws in the meta-analysis. First, they question the number of patients with symptomatic aortic stenosis.

“There could be caveats in this estimation, because in the elderly population it could be difficult to establish that the symptoms are related to [aortic stenosis] and not to comorbidities,” they write. “In addition, many patients who claim to be asymptomatic are in fact symptomatic when exercise testing is performed.”

Dr. Vahanian and colleagues caution that the authors’ estimation that as many as 40% of patients with severe disease were not treated surgically might be too high. “The studies quoted are heterogeneous as regards the period of time covered, the evaluation of the degree of stenosis, and symptoms which may result in marked differences in the percentages of patients who were not referred to surgery,” they explain.

Another point of contention concerns the estimate that among patients not treated surgically, nearly 30% received TAVR. The editorial takes issue with defining all of these patients as true candidates, “because the decision for [TAVR] requires a careful individual evaluation of each patient in this population by a Heart Team.”

Yet Dr. Vahanian and colleagues acknowledge that the meta-analysis contributes important information. As the field “moves forward,” they conclude, “we need actual figures and must perform contemporary prospective observational studies in order to accurately assess the number of possible candidates to [TAVR].”

Sources:

1. Osnabrugge RLJ, Mylotte D, Head SJ, et al. Aortic stenosis in the elderly: Disease prevalence and number of candidates for transcatheter aortic valve replacement. A meta-analysis and modeling study. J Am Coll Cardiol. 2013;Epub ahead of print.
2. Vahanian A, Iung B, Himbert D. TAVI, a treatment we are going to need! J Am Coll Cardiol. 2013;Epub ahead of print.

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