The transcatheter aortic valve replacement (TAVR) procedure replaces a narrow aortic valve that obstructs normal blood flow with a catheter. Three years ago an estimated 300,000 TAVRs had been performed. That number has climbed dramatically since and will continue with the recent FDA approval for expansion of TAVR procedures to even low-risk patients with severe aortic stenosis. However, there are several concerns regarding TAVR and the risk of acute coronary syndrome (ACS), or blood flow obstruction, following the procedure.
Using a data sample of 142,000 Medicare patients, a team of Internal Medicine researchers mostly in the Division of Cardiovascular Medicine, revealed a low incidence rate of ACS following TAVR. The study also suggested that the use of invasive management in cases of ACS post-TAVR, is associated with better outcomes. Amgad Mentias, MD; Mary Vaughan-Sarrazin, PhD; Phillip Horwitz, MD; James D. Rossen, MD; and Sidakpal Panaich, MD, published their study in the Journal of the American College of Cardiology: Cardiovascular Intervention.
TAVR valves are implanted near the openings of coronary arteries, which within six months of procedure, can cause obstruction in blood flow or ACS. Additionally, thrombi or blood clots can form on the valve leaflets. In the case of thrombosis, embolization or the lodging of a blood clot in the artery can block the blood flow.
“TAVR patients have high prevalence of preexisting coronary artery disease, and the implanted valve poses some difficulties in accessing the coronary arteries for future interventions in case of an emergency such as a heart attack,” Mentias said.
The study also compares the outcomes based on the different types of ACS. These types include ST-segment elevation myocardial infarction (STEMI) and non-ST segment elevation myocardial infarction (NSTEMI), both types of heart attack that happen when blood supply to the heart is disrupted, and unstable angina, chest pain that could lead to a heart attack.
Only 5% of patients studied were admitted with ACS a median of 297 days after the TAVR procedure. Of those ACS admissions, 48% occurred within the first 6 months after the TAVR procedure, and the most common type of ACS was NSTEMI. Among patients with NSTEMI, which is lower risk, invasive modes of treatment such as coronary angiogram, balloon angioplasty, and bare metal or drug eluting stents, were associated with lower mortality.
Patients with the higher risk STEMI were associated with higher rates of 30-day and 1-year mortality than NSTEMI, with one third of patients dying within 30 days. This is also much higher than STEMI rates in a non-TAVR setting. Additionally, the team identified precursors for ACS which included coronary artery disease, prior revascularization, diabetes, valve-in-TAVR, and acute kidney injury.
The University of Iowa team collaborated with researchers from the Iowa City VA Medical Center, the Heart and Vascular Institute at Cleveland Clinical Foundation, the Cardiovascular Institute at Warren Alpert Medical School at Brown University, the Division of Cardiovascular Medicine at University of Texas Medical Branch, the Valve Science Center at Minneapolis Heart Institute Foundation, and the Division of Cardiology at Baylor College of Medicine.