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In high-surgical-risk patients with severe aortic stenosis who survived to 3 years after transcatheter aortic valve replacement (TAVR) with the CoreValve prosthesis, improvements in hemodynamics and symptoms were largely maintained, according to a study published online June 9, 2014, ahead of print in the American Journal of Cardiology. However, clinically meaningful aortic regurgitation occurred in about 1 in 7 patients and worsened in many over the study period.

Early Hemodynamic Improvement Fades Over 3 Years

Aortic valve area increased from a baseline of 0.7 ± 0.1 cm² to 1.8 ± 0.2 cm² immediately after TAVR (P < .001). However, by 3 years the improvements had fallen off to 1.5 ± 0.4 cm²;P < .001), with an annual approximate decrease of 0.1 cm². Restenosis occurred in 2 patients.

Immediately after TAVR, echocardiography identified aortic valve regurgitation in 88 patients (66 with mild regurgitation, 19 with moderate, and 2 with severe). Over 3 years, the condition worsened in 20 patients and improved in 9.

Thirty-day all-cause mortality (primary endpoint) was 10%. By 1 year, the rate had increased to 25%, and both all-cause and cardiovascular mortality rose steadily between years 1 and 3. Also, before TAVR, 95% of patients were in NYHA functional class III or IV. At 1 year, only one-third were in those functional classes, although the dramatic improvement declined somewhat over the next 2 years (table 1).

Table 1. Outcomes From 1 to 3 Years

On univariate analysis, aortic regurgitation was identified as a risk factor for:

• All-cause mortality (HR 2.27; 95% CI 1.65-3.13; P < .001)
• Cardiovascular mortality (HR 2.53; 95% CI 1.7-3.75; P < .001).

Two patients developed prosthesis-related endocarditis more than 1 year after implantation and died due to septic multi-organ failure. Overall, 7 patients (1.5% per year) developed a clinically relevant issue with the prosthesis.

Poor Results Due to Early Nature of Study  

The “relatively high” long-term mortality rate could be explained by the limited worldwide experience with TAVR at the time the study began as well as the prevalence of patient comorbidities and high mean EuroSCORE, the authors say. Nonetheless, they point out, the results are similar to those of comparable studies.

In a telephone interview with TCTMD, Jeffrey J. Popma, MD, of Beth Israel Deaconess Hospital (Boston, MA), called the results “amazingly good for the time period,” but he said advances in TAVR with CoreValve since the initiation of the study have improved outcomes.

For example, he explained, “there has been a clear evolution [in use of] cardiac CT to size the valves rather than echocardiography.” Moreover, he noted, “the paravalvular regurgitation rates [in the study] are a little high compared with what we’re used to in contemporary practice” due to better valve selection. He added that regurgitation and mortality should continue to decrease with better implantation techniques as well.

Improvements in patient selection over time have reduced poor long-term outcomes with all transcatheter valves, Dr. Popma noted, adding that the appropriate patients for TAVR are those “who [are] not surgical candidates but [have] an otherwise good prognosis.”

Comorbidity Driving Poor Outcomes?

In a telephone interview with TCTMD, David H. Adams, MD, of Mount Sinai Medical Center (New York, NY), largely agreed with Dr. Popma's assessment of the reasons for the poor midterm outcomes. Compared with the US CoreValve Pivotal trial, for which Drs. Popma and Adams were co-principal investigators, "there were many more patients who had residual aortic insufficiency," he said. "[The current study also] had many more patients that were [NYHA] class III and IV after TAVR,... and 17% had at baseline severe mitral valve regurgitation," which was an exclusion criterion in the pivotal trials in the US, and could partially explain the high 3-year mortality outcomes, he explained.

Though 3-year data are not yet available for the pivotal trial, "their short-term outcomes don't match our contemporary ones," Dr. Adams observed, suggesting that as a rule-of-thumb, their longer-term outcomes may not be representative of current practice either.

Durability of CoreValve Needs Long-term Research  

Dr. Gotzmann and colleagues point out that the slow [annual] decrease in aortic valve area in CoreValve within 3 years warrants further research. Anita Asgar, MD, of the Institut de Cardiologie de Montreal (Montreal, Canada), told TCTMD in an email that this phenomenon is not concerning “in this particular population, but as with all [TAVR] technology we require long-term follow-up to understand the durability of these valves, in particular, prior to widespread use in lower-risk patient subgroups.”

Dr. Asgar noted “some concern over the higher rates of [permanent] pacemaker implantation following CoreValve use, but it is doubtful that this will be a major impediment.” She added that although the “self-expanding technology is different to use for those familiar with balloon-expandable technology, the learning curve is only approximately 10 to 15 cases.”

 Source: 
Gotzmann M, Czauderna A, Hehnen T, et al. Three-year outcomes after transcatheter aortic valve implantation with the CoreValve prosthesis. Am J Cardiol. 2014;Epub ahead of print.

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