Two clinical trials recently presented at the American College of Cardiology (ACC 2016) meeting evaluated the role of TAVR in intermediate-risk populations: 

A study by Leon et al. in NEJM evaluated 2032 intermediate-risk patients with severe aortic stenosis from 57 centers, who underwent either TAVR or surgical aortic valve replacement (ClinicalTrials.gov number, NCT01314313).(1) In the TAVR group, 76.3% of the patients were included in the transfemoral-access cohort and 23.7% in the transthoracic-access cohort. The primary end point was death from any cause or disabling stroke at 2 years. 

The rate of death from any cause or disabling stroke was similar in the TAVR group and the surgery group (P=0.001 for non-inferiority). At 2 years, the Kaplan–Meier event rates were 19.3% in the TAVR group and 21.1% in the surgery group (hazard ratio in the TAVR group, 0.89; 95% confidence interval [CI], 0.73 to 1.09; P=0.25). In the transfemoral-access cohort, TAVR resulted in a lower rate of death or disabling stroke than surgery (hazard ratio, 0.79; 95% CI, 0.62 to 1.00; P=0.05), whereas in the transthoracic-access cohort, outcomes were similar in the two groups. TAVR resulted in larger aortic-valve areas than did surgery and also resulted in lower rates of acute kidney injury, severe bleeding, and new-onset atrial fibrillation; surgery resulted in fewer major vascular complications and less paravalvular aortic regurgitation.

The study was funded by Edwards Lifesciences.

Data from the SAPIEN 3 observational study recently published in The Lancet evaluated 1077 intermediate-risk patients at 51 sites in the USA and Canada, who were assigned to receive TAVR with the SAPIEN 3 valve [952 [88%] via transfemoral access) between Feb 17, 2014, and Sept 3, 2014. (2) In this population the authors assessed all-cause mortality and incidence of strokes, re-intervention, and aortic valve regurgitation at 1 year after implantation. 1 year outcomes in this population were compared with those for intermediate-risk patients treated with surgical valve replacement in the PARTNER 2A trial between Dec 23, 2011, and Nov 6, 2013, using a prespecified propensity score analysis to account for between-trial differences in baseline characteristics. The primary endpoint was the composite of death from any cause, all strokes, and incidence of moderate or severe aortic regurgitation.

At 1 year follow-up of the SAPIEN 3 observational study, 79 of 1077 patients who initiated the TAVR procedure had died (all-cause mortality 7·4%; 6·5% in the transfemoral access subgroup), and disabling strokes had occurred in 24 (2%), aortic valve re-intervention in six (1%), and moderate or severe paravalvular regurgitation in 13 (2%). In the propensity-score analysis 963 patients treated with SAPIEN 3 TAVR and 747 with surgical valve replacement were included. For the primary composite endpoint of mortality, strokes, and moderate or severe aortic regurgitation, TAVR was both non-inferior (pooled weighted proportion difference of −9·2%; 90% CI −12·4 to −6; p<0·0001) and superior (−9·2%, 95% CI −13·0 to −5·4; p<0·0001) to surgical valve replacement.

A recent meta-analysis summarized clinical trials and observational studies including intermediate risk patients. (3) Only studies with matching patient populations by propensity scores or randomization were included and clinical outcomes between TAVR and surgical aortic valve replacement (SAVR) were compared.

Analysis of the TAVR and SAVR cohorts revealed no significant differences in the outcomes of 30-day [OR (95% CI): 0.85 (0.57, 1.26)] or 1-year mortality [OR (95% CI): 0.96 (0.75, 1.23)]. A trend towards benefit with TAVR was noted in terms of neurological events and myocardial infarction (MI) without statistical significance. A statistically significant decrease in risk of post-procedural acute renal failure in the TAVR group [OR (95% CI): 0.52 (0.27, 0.99)] was observed, but so was a significantly higher rate of pacemaker implantations for the TAVR group [OR (95% CI): 6.51 (3.23, 13.12)].

The authors conclude that in intermediate risk patients undergoing aortic valve replacement, the risk of mortality, neurological outcomes, and MI do not appear to be significantly different between TAVR and SAVR. However, there appears to be a significant reduction in risk of acute renal failure at the expense of an increased risk of requiring a permanent pacemaker in low and intermediate risk patients undergoing TAVR compared to SAVR.

References: 

1.Martin B. Leon, Craig R. Smith, Michael J. Mack, et al. for the PARTNER 2 Investigators. Transcatheter or Surgical Aortic-Valve Replacement in Intermediate-Risk Patients. NEJM 2016: April 2, 2016 DOI: 10.1056/NEJMoa1514616

2.Vinod H Thourani, Susheel Kodali, Raj R Makkar, et al. Transcatheter aortic valve replacement versus surgical valve replacement in intermediate-risk patients: a propensity score analysis. Lancet, 2016 DOI: https://dx.doi.org/10.1016/S0140-6736(16)30073-3

3.Sameer Arora, Jacob A. Misenheimer, Wesley Jones, et al. Transcatheter versus surgical aortic valve replacement in intermediate risk patients: a meta-analysis. Cardiovascular Diagnosis and Therapy. https://cdt.amegroups.com/article/view/9681