Mechanisms of Infarction in Coronary Arteries with Non-Significant Lesions

Infarctions with non-obstructive coronary artery disease, also known as MINOCA (myocardial infarction with nonobstructive coronary arteries), often present plaque rupture and thrombi associated with the affected myocardial territory. In these patients, optical coherence tomography (OCT) is of great value to identify the “culprit”.

Even though atherosclerosis has been identified as a potential MINOCA mechanism, the association between plaque rupture and myocardial injury has been showed. 

This study recently published in JACC Cardiovasc Imaging prospectively analyzed patients with acute myocardial infarction with non-significant lesions (all <50%) in the angiography that received OCT and MRI with late gadolinium enhancement. The culprit artery was identified by localization in the MRI.

More than half of patients (55%) with MINOCA resulted women, which was expected, and 39% presented with ST elevation. Maximum diameter stenosis resulted 35% and 13% of patients had completely normal angiogram results.

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OCT showed plaque disruption in 24% of patients with thrombi in 18% of patients. 

Half the patients showed an ischemia pattern with late gadolinium enhancement and that was more frequent in patients with plaque rupture vs. no plaque rupture (50% vs. 13%, p=0.053) and in patients with thrombi imaging vs. no thrombi (67% vs. 12%; p=0.014).

When looking at lesions, culprit lesions more often showed plaque rupture by OCT (40% vs. 6%; p=0.02), thrombi (50% vs. 4%; p=0.014) and thin cap fibroatheroma (70% vs. 30%; p=0.03) compared to non-culprit lesions.

Conclusion

Plaque rupture and thrombi are frequent infarction mechanisms in patients with non-significant lesions by angiogram. This fact can be associated to ischemia localization by late gadolinium enhancement on MRI. 

OCT is of great value to identify atherosclerosis etiology in patients with MINOCA. 

Original Title: Mechanisms of Myocardial Infarction in Patients With Nonobstructive Coronary Artery Disease. Results From the Optical Coherence Tomography Study.

Reference: Maksymilian P. Opolski et al. JACC Cardiovasc Imaging. 2019 Nov;12 2210-2221.

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