Expanding indications for TAVR: The preferred procedure in intermediate-risk patients?
ABSTRACT
Transcatheter aortic valve replacement (TAVR) has steadily replaced surgical aortic valve replacement (SAVR) in symptomatic patients with severe aortic stenosis, primarily those at high risk for surgical complications. As TAVR use increases, spurred by technological advances in valve design and patient preferences for the less-invasive procedure, studies have provided data supporting the efficacy and safety of TAVR. Recently, TAVR has expanded to intermediate-risk patients, increasing the potential patient population. Although emerging evidence supports its use in lower-risk patients, some adverse events may limit its adoption in a wider patient population. These include stroke, paravalvular leak, valve durability, valve thrombosis, and need for pacemaker replacement. Ongoing clinical trials are expected to provide answers.
KEY POINTS
- TAVR has become the preferred alternative to SAVR in inoperable and high-risk patients.
- The US Food and Drug Administration has approved TAVR with open-heart surgery.
- Initial outcomes support expanding TAVR to intermediate-risk patients, including mortality and stroke data, but concerns exist related to valve durability, valve thrombosis, and rates of permanent pacemaker implantation.
IS TAVR APPROPRIATE FOR INTERMEDIATE-RISK PATIENTS?
Although there are ample data supporting the use of TAVR in intermediate-risk patients, SAVR remains the most effective option in certain clinical situations:
- Younger patients who will need valve replacement later in life
- Bicuspid valves with eccentric bulky calcification
- Aortopathy (aortic disease above the valve)
- Small calcified roots
- Severe calcification of left ventricular outflow tract
- Low-lying coronary arteries (typically, ≤ 6 mm from the aortic annulus)
- Severe septal bulging
- Severe mitral regurgitation and/or tricuspid regurgitation
- Conduction system disease that puts the patient at high risk for pacemaker implantation
- Valve replacement in valves with a diameter 20 mm or smaller.
Nevertheless, outcomes seem to support TAVR in intermediate-risk patients. At the Heart Hospital Baylor Plano, 30-day outcomes with the Sapien 3 valve have shown all-cause mortality of 1.1% and all-stroke mortality of 2.6% (1.0% for disabling stroke). Large registries of the Sapien 3 valve have reported similar outcomes at 30 days: mortality 1%, disabling stroke 2%, major vascular complications 2%, and moderate to severe paravalvular leak 2%.15
Overall, the rates of major vascular complications and of life-threatening bleeding are 2%, and the need for new pacemakers is 4%. Results from several trials support TAVR as an alternative to surgery in intermediate-risk patients. In patients who are candidates for transfemoral access, TAVR may provide additional clinical advantages. However, questions about long-term durability and new requirements for pacemakers are issues for TAVR use in intermediate- and low-risk patients. More data are needed to answer these questions.
At the Heart Hospital Baylor Plano, the number of TAVR procedures from 2012 to 2015 increased from 49 cases to 215, while the number of SAVR procedures remained constant (166 in 2012 and 162 in 2015). During that time, outcomes improved dramatically: in-hospital mortality rates dropped from 2% to 0% and 30-day mortality dropped from 3% to 0%. There have been 227 consecutive SAVR patients with no in-hospital or 30-day mortality and 261 consecutive TAVR patients with no mortality.
These results support initiating clinical trials of TAVR in low-risk patients. In 2016, the FDA approved TAVR valves for 2 clinical trials in patients with aortic stenosis who are at low risk of surgical mortality. These large clinical trials, each with about 1,200 patients, are expected to provide data that will help determine whether TAVR is a safe and effective option for low-risk patients.
