Myocardial Infarction with Non-Obstructive Coronary Arteries: To Stent or Not to Stent? That is the Question.

Myocardial infarction with nonobstructive coronary arteries (MINOCA) in the context of acute ST elevation myocardial infarction (STEMI) is a challenging situation with no clear guidelines. In the absence of a consensus, optical coherence tomography (OCT) provides a better well-informed decision whether to stent or not. Herein, we report a case of MINOCA that underwent stenting of the proximal left anterior descending artery in the setting of extensive anterior wall STEMI in view of high-risk clinical presentation and OCT features of a ruptured plaque. Copyright:

INTRODUCTION

MINOCA is defined as an acute myocardial infarction with nonobstructive coronary arteries on invasive coronary angiogram (i.e., no coronary stenosis >50% in any infarct-related artery) in the absence of a specific cause for acute presentation.[1] Numerous phrases are used to describe patients presenting with ACS and normal or near-normal coronary artery, such as MINOCA, MI in normal coronary artery, ischemia and no obstructive coronary artery disease, troponin-positive nonobstructive coronary artery disease, and ACS with normal or near-normal coronary arteries.[2]

Pasupathy et al. revealed that the prevalence of MINOCA in patients presenting with ACS is 6%. The percentage is higher in young patients, females, nonwhite patients, and patients presenting with non-ST elevation myocardial infarction (STEMI).[3] The “Variation in recovery: Role of gender on outcomes of young AMI patients study’’ revealed that women are five times more likely to have MINOCA than men. It is usually associated with unconventional risk factors such as prior drug use, hypercoagulable syndrome, venous thromboembolism, and autoimmune disorders, rather than traditional risk factors such as hyperlipidemia, hypertension, and diabetes mellitus.[4]

Here, we present a case of MINOCA that underwent stenting of proximal left anterior descending (LAD) in the setting of extensive anterior wall STEMI in view of high-risk clinical presentation and optical coherence tomography (OCT) features of a ruptured plaque.

CASE PRESENTATION

A 35-year-old Bahraini gentleman, smoker with no other known risk factors, was transferred to our cardiac center for rescue percutaneous coronary intervention (PCI) of failed lysis acute anterior wall STEMI [Figure 1a and b]. Emergency coronary angiogram revealed haziness at the proximal LAD [Figure 2a] and otherwise no significant obstructive disease. OCT pullback was performed to study the morphological characteristics of the atheromatous plaque, pathogenesis of ACS, and risk stratification of MINOCA and to have an informed decision whether to deploy a stent or defer stenting.

Figure 1

(a) ST elevation myocardial infarction diagnosis at nonpercutaneous coronary intervention centre. (b) ECG at 60 min postfibrinolysis with ongoing chest pain, suggestive of failed lysis

Figure 2

(a) Emergency coronary angiogram revealed haziness at the proximal left anterior descending. (b) Optical coherence tomography revealed plaque rupture at the proximal left anterior descending (5 o’clock) as culprit lesion with disruption of a thin fibrous cap that overlies a necrotic core and large cavity formation

OCT revealed plaque rupture at the proximal LAD with disruption of a thin fibrous cap that overlies a necrotic core with large cavity formation [Figure 2b], causing the thrombogenic contents of the necrotic core to come into contact with the bloodstream and, hence, significantly increase the risk of thrombus formation. In view of unstable, vulnerable plaque at the proximal LAD that carries a high risk of undergoing acute thrombosis and abrupt vessel occlusion, the consensus decision was not to take chances. Thus, we stented the proximal LAD with Xience Sierra 4.0 mm × 24 mm drug-eluting stent with excellent final angiographic result [Figure 3a], which was confirmed by OCT [Figure 3b]. The patient had an uneventful hospital stay thereafter.

Figure 3

(a) Excellent final angiographic result (b) optical coherence tomography showed good stent apposition and stabilization of the thrombotic plaque (white arrow) by compression and axial redistribution away from the center. This modification of plaque geometry is crucial to seal the intimal tear and enhance healing

DISCUSSION

The management of MINOCA depends on the underlying mechanism. Once the underlying cause is established, the working diagnosis of MINOCA should be discarded, and appropriate treatment related to the underlying condition should be initiated. In a catheterization laboratory, ventriculography can be performed to rule out takotsubo cardiomyopathy. Re-evaluation of patients through their medical history, physical examination, and lab assessment should be performed to exclude various causes of type 2 MI, pulmonary embolism, and nonischemic causes of myocyte injury such as myocarditis.[5] Spontaneous coronary artery dissection is one of the most important diagnoses to be excluded as these patients also do not present with traditional risk factors.[56]

A raptured plaque may not be visible on conventional angiography. Hence, it is important that advanced intracoronary imaging techniques are employed to establish the characteristics of coronary disruption. The preferred mode of imaging is OCT as it provides accurate detection of plaque rupture and differentiates it from plaque erosion and calcified nodule.[7]

MINOCA patients with plaque erosion or calcified nodule should be treated with cardioprotective therapies such as antiplatelet, beta-blockers, ACE inhibitors, and lipid-lowering therapies. However, the finding of plaque rupture on OCT was associated with major adverse cardiac events with more than 2% risk of recurrent myocardial infarction or death up to 12 months. Hence, in patients with plaque rupture, PCI is the recommended strategy as the pathology is distinct, and the probability of major adverse events is much higher compared with plaque erosion and calcified nodule.[89]

CONCLUSION

Identification of plaque characteristics has potential therapeutic implications, and hence, intravascular imaging during coronary angiography of MINOCA is imperative and highly recommended.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his/her consent for images and other clinical information to be reported in the journal. The patient understands that his/her name and initials will not be published and due efforts will be made to conceal his/her identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.