TAVR in Intermediate-Risk Patients: A Review of the PARTNER 2 Trial and its Future Implications.

Following publication of the results of the PARTNER trial, the American College of Cardiology/American Heart Association recognized the success of transcatheter aortic valve replacement (TAVR) by incorporating it as a feasible option in high-surgical risk patients, and recommending it as the standard of care for patients at prohibitive risk of surgery. Although this was recognized as a major success in the field of percutaneous valve replacement, surgical aortic valve replacement (SAVR) continued to be realized as the procedure of choice for low and intermediate surgical risk patients. Meanwhile, observational studies - predominantly from Europe - showed encouraging results for TAVR in lower-risk populations. With a lack of any large randomized controlled clinical trial, however, the advantages of TAVR continued to be limited to only a minority of patients with severe, symptomatic aortic stenosis.Between December 2011 and November 2013, the PARTNER 2 investigators enrolled a total of 2,032 intermediate-risk patients with severe symptomatic aortic stenosis at 57 centers in the United States and Canada. Patients were randomized 1:1 to undergo either TAVR or SAVR. The primary end point was death and neurological events after two years.The study results showed similar rates for death and neurological events in the TAVR and SAVR groups. The TAVR group was found to have a larger valve area and a lower incidence of acute kidney injury, bleeding events, and atrial fibrillation. Conversely, the SAVR group experienced fewer vascular complications and lower rates of paravalvular regurgitation.The results of the PARTNER 2 trial are reviewed, and its implications for the future discussed.