By Jeffrey Zimmet, MD, PhD

Associate Professor of Medicine, University of California, San Francisco; Director, Cardiac Catheterization Laboratory, San Francisco VA Medical Center

SYNOPSIS: This large series of post-transcatheter aortic valve replacement patients with ST-elevation myocardial infarction demonstrates elevated rates of percutaneous coronary intervention failure and high short- and intermediate-term mortality rates.

SOURCE: Faroux L, Lhermusier T, Vincent F, et al. ST-segment elevation myocardial infarction following transcatheter aortic valve replacement. J Am Coll Cardiol 2021;77:2187-2199.

ST-elevation myocardial infarction (STEMI) in patients who have undergone transcatheter aortic valve replacement (TAVR) is a relatively uncommon but morbid event. Previous studies have shown an incidence of < 0.5%. However, with this low frequency comes an outsized risk of death and major adverse cardiac events. Faroux et al sought to describe the characteristics of and outcomes in these patients. In their multicenter, international study of 42,252 TAVR recipients, 118 patients were identified who experienced STEMI after TAVR. Subjects who experienced ST elevation during the TAVR procedure itself were excluded.

For comparison, STEMI patients who were treated with primary percutaneous coronary intervention (PCI) at five high-volume centers within 15 days of each post-TAVR STEMI case were identified, yielding a total of 439 patients for a control group. Among the identified patients with STEMI after TAVR, all had undergone pre-TAVR coronary angiography. Eighty-two patients had a history of coronary disease, while 77 patients had obstructive CAD identified at cardiac catheterization before TAVR. Of these, 50 had multivessel disease. Chronic total occlusions and vessels < 2 mm were managed medically. Local heart teams made decisions regarding pre-TAVR PCI. PCI was performed before TAVR in 46 patients, while 70 patients were considered to have achieved complete revascularization.

Although the median time between TAVR and STEMI was 255 days, more than one-third of MIs occurred in the first month after TAVR. A mechanism other than plaque rupture was thought to be involved in 17.6% of post-TAVR patients vs. just 4.3% in the non-TAVR control group. Specifically, definite or possible coronary embolism were listed as the cause of post-TAVR STEMI in 14 patients, with most of these occurring soon after TAVR (10 occurred the same day as the TAVR procedure, one the following day). Two cases of coronary embolism were thought to be secondary to prosthetic aortic valve endocarditis.

Procedural complexity was higher among TAVR compared with non-TAVR patients, with 47.1% performed from the femoral approach (vs. 9.6% for the controls). TAVR patients logged longer door-to-balloon times, longer procedure times, and used higher contrast volumes. The presence of a self-expanding TAVR valve vs. a balloon-expandable one was associated with longer fluoroscopy time, a higher frequency of nonselective injections, and a significant percentage of cases where two or more guiding catheters were tried to complete the procedure. PCI failure occurred in 16.5% of post-TAVR patients vs. only 3.9% of controls. In particular, four patients presenting with inferior STEMI could not be revascularized because of failure to selectively engage the right coronary artery, despite the use of multiple guiding catheters. Notably, 15 patients were managed medically (without intervention), and nine of these died in the hospital.

Post-TAVR patients presenting with STEMI were quite sick overall, and clinical outcomes were correspondingly poor. Forty-seven percent showed signs of congestive heart failure on admission, 18% experienced clinical shock, and 11% presented with cardiac arrest. The in-hospital mortality rate was just over 25%, while 42% died at a median follow-up of seven months. The authors concluded STEMI in post-TAVR patients is linked to higher procedural complexity, longer door-to-balloon times, and higher rates of PCI failure vs. non-TAVR patients. Additionally, they noted rates of short-term mortality and major complications are correspondingly higher.

COMMENTARY

Although infrequent, STEMI following TAVR is highly morbid, often presenting with heart failure or shock, and leads to high rates of in-hospital and short-term mortality. This largest-to-date series of such patients demonstrates a significant percentage of MI cases involved mechanisms other than atherothrombosis. Interestingly, some cases were assessed as embolic in nature, and presented early after the TAVR procedure. Although the coronary anatomical features (bifurcation lesions, ostial lesions, calcification) were not significantly different from non-TAVR controls, the technical features of coronary intervention in post-TAVR patients means procedural complexity is high. Especially with self-expanding valves (mainly the CoreValve family of prostheses), difficulties with coronary engagement after TAVR leads to higher rates of PCI failure vs. the general case. This at least in part translates to worse outcomes. Do these results carry implications for pre-TAVR coronary angiography and revascularization? On this score, it is notable that no cases of post-TAVR STEMI involved a significant stenosis that had been left unrevascularized, while two cases of stent thrombosis were recorded. Thus, pre-TAVR coronary revascularization should not be undertaken to prevent downstream STEMI. On the other hand, leaving significant and symptomatic coronary stenoses to be treated after TAVR may lead to difficulty with intervention, sincecannulation of the coronaries may be challenging in a subset of patients. Going forward, the focus of pre-TAVR coronary assessment will remain identifying those patients whose coronary disease is so profound as to affect the safety of the TAVR procedure and revascularizing those whose coronary disease is likely to be symptomatic independent of the aortic stenosis.