Coronary Embolism in STEMI Is Rare but Warrants a Unique Approach

Fewer than five out of every hundred people who present with STEMI have coronary embolism as the root cause of their event, with subsequently dismal outcomes, according to new observational data from a single center.

“Our study reminds us that atherosclerotic [disease] is not the only STEMI cause, and our findings may help less experienced operators to understand the objectives of an individualized approach in this setting,” lead author Batric Popovic, MD, PhD (CHU Brabois, Vandœuvre-lès-Nancy, France), told TCTMD.

“Long-term outcomes of [STEMI] patients secondary to coronary artery embolism are often [worse] and largely influenced by the underlying cause of the embolic event,” he said via email. Identifying these causes is important, Popovic explained, because this raises the possibility of using “effective therapies that otherwise may not have been considered and that may affect prognosis.”

Certain characteristics, such as a known intracardiac tumor, autoimmune disease, or potential hypercoagulable state, are red flags of an unconventional STEMI, Popovic said, adding, “In our opinion, angiography without evident atherosclerotic disease and/or concomitant multisite [coronary embolism] especially should alert the operators.”

The precise cause of the embolism will inform patient management both acutely and over time, he explained. “An overaggressive reperfusion strategy such as angioplasty with stenting should be avoided [and] a minimalistic approach [is] preferred,” Popovic advised, adding that in some cases mechanical thromboaspiration could be used as a histopathological diagnostic tool. “Common reperfusion strategies may be not useful and even deleterious, as in the case of unrecognized coronary septic emboli leading to subsequent coronary septic aneurysm formation.”

While coronary embolism is indeed a rare reason for STEMI, “interventionalists certainly know about it,” commented Ajay J. Kirtane, MD (NewYork-Presbyterian/Columbia University Medical Center, New York, NY). “There are certain characteristic features typically on the angiogram that are clues to the occurrence of that phenomenon, and also other clinical parameters based on patient presentation that would heighten one’s suspicion for this diagnosis.”

What’s most useful about the current report is that it describes the frequency of these events and gels with what would be expected in clinical practice, Kirtane said to TCTMD.

A-fib Often Responsible

Popovic and colleagues’ findings were published online January 8, 2018, ahead of print in Circulation: Cardiovascular Interventions. Their report involved 1,232 consecutive patients who presented to their center with de novo STEMI between 2006 and 2015. Of these, 53 patients (4.3%) were identified as having coronary embolism, including 12 whose embolisms were seen in multiple coronary sites and nine with other extracoronary localization.

Compared with patients who had a standard STEMI, those whose events arose from coronary embolism were less likely to be smokers and tended to have lower body mass index. Other cardiovascular risk factors were similar in the two groups.

Both cardiac and systemic diseases were identified as the underlying causes of coronary embolism; the most common were atrial fibrillation (28.3%), malignancy (15.1%), dilated cardiomyopathy (9.4%), endocarditis (7.5%), systemic autoimmune disease or antiphospholipid syndrome (7.5%), and intracardiac tumor (5.7%). Diagnosis was based on optical coherence tomography or intravascular ultrasound, as well as by histopathological analysis and testing for the presence of prothrombotic factors.

Treatment strategies varied by the presence of coronary embolism. Patients with embolism were much less likely to undergo primary angioplasty with stenting (45.3% vs 95.5%; P < 0.001), but were more likely to receive manual thrombectomy without angioplasty (15.0% vs 0.6%; P < 0.001), guidewire insertion (9.5% vs 3.0%; P = 0.011), or antithrombotic drugs alone (30.2% vs 0.8%; P < 0.001). This group had lower ST-segment resolution after MI and worse postprocedural TIMI flow grade.

Long-term oral anticoagulation was given to 21 patients at discharge.

At 1 year, all-cause mortality was higher in patients with versus without coronary embolism (15.2% vs 6.2%; P = 0.011). During a median follow-up of 45.1 months, 11 of the 53 coronary-embolism patients (20.8%) died. Most of the deaths were related to a cardiovascular cause, with sepsis and neoplasia responsible for the others.

Referring to coronary embolism as a “formidable challenge,” the investigators suggest that “prospective studies evaluating this rare etiopathogenesis of myocardial infarction including a systemic diagnostic approach and an individualized therapeutic approach are warranted.”