A narrative review of electrocardiogram manifestation of myocardial infarction with non-obstructive coronary arteries (MINOCA)

Introduction

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is an acute coronary syndrome (ACS) characterized by the absence of significant obstructive coronary artery lesions (defined as a lesion equal to or more than 50% stenosis) (1,2). As many as 10% of patients presenting with classical signs and symptoms of ACS do not exhibit significant obstructive coronary artery disease (CAD) (1). Thus, this subset of patients is categorized as having MINOCA (1). A diagnosis of MINOCA requires: (I) the presence of ACS symptoms, such as chest pain, shortness of breath, palpitations, nausea or vomiting; electrocardiogram (ECG) manifestations and potentially increased troponin levels; (II) the absence of significant artery obstruction in coronary angiography; and (III) no other apparent cause for the clinical presentation at the time of angiography (1,3). Under all circumstances, further tests such as cardiac magnetic resonance imaging (MRI) and angiography are imperative to determine the underlying cause and either confirm or rule out MINOCA and an ECG may add further value to the diagnosis process (1).

Specific ECG findings have the potential to inform clinical management and should be integrated into the diagnosis of MINOCA. However, in routine practice, there is often a failure to identify distinctive ECG patterns for this syndrome. This might be due to the various causes of MINOCA, such as spontaneous coronary artery dissection (SCAD), coronary artery vasospasm and coronary microvascular dysfunction (CMD), which all present with non-specific ECG features. Thus, this manuscript aims to identify ECG manifestations of MINOCA and will discuss the diagnostic value of the ECG in patients with the syndrome. We present this article in accordance with the Narrative Review reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1688/rc).

Methods

An electronic, narrative review of published data was conducted (Table 1). PubMed, EMBASE and MEDLINE databases were used. The selection of articles of interest was made according to the following criteria: (I) publications issued from January 2015 to June 2025; (II) case series, case reports, systematic reviews, and pronouncements of professional associations and scientific societies; (III) English language; and (IV) papers referring to the ECG pattern of MINOCA. Studies were excluded if the full text was not accessible.

The keywords used were chosen according to MESH terminology: “Electrocardiography”, “ECG”, “EKG”, “Myocardial Infarction with Non-Obstructive Coronary Arteries”, “Myocardial Infarction Without Obstructive Coronary Arteries”, “MINOCA” “Myocardial Infarction”, “MI”, “ST-segment elevation”, “ST-segment depression”, “T-wave inversions” and “QTc interval”. The research was conducted independently by three investigators (A.R., S.G., A.B.). First, relevance based on title and abstract was determined. Selected publications were further reviewed for relevance using the full text. Any disagreements were resolved by consensus. A secondary search was conducted by reviewing the reference lists of included papers. Additionally, data from two individual case reports from Kingston Health Sciences Center were also collected, separate from the literature search.

Case reports

Two ECG patterns of patients with MINOCA are depicted in Figures 1,2. Case 1 is a 40-year-old female with no known cardiovascular risk factors. This patient presented with atypical chest pain and was found to have an elevated high-sensitivity troponin level of 480 ng/L. The 12-lead ECG revealed normal sinus rhythm alongside T-wave inversions in the inferolateral leads (Figure 1A). These dynamic repolarization changes were consistent with myocardial ischemia and, in the absence of obstructive coronary disease on angiography, raised clinical suspicion for a non-obstructive ischemic process such as MINOCA. Coronary angiography revealed normal epicardial coronary arteries with preserved left ventricular (LV) systolic function on the ventriculogram (Figure 1B). Case 2 is a 56-year-old female with a significant history of obstructive sleep apnea, who presented with typical chest pain and was found to have an elevated high-sensitivity troponin level of 3,295 ng/L. The ECG showed normal sinus rhythm, LV hypertrophy with left LV strain and T-wave flattening and inversions in the inferior leads (Figure 2A). The presence of ischemic-appearing ST-T abnormalities despite angiographically normal coronary arteries further supported a diagnosis of MINOCA, emphasizing the diagnostic value of ECG in identifying myocardial ischemia of non-obstructive origin. Coronary angiography revealed highly tortuous arteries without evidence of coronary artery vasospasm or SCAD. Systolic function was normal on the ventriculogram (Figure 2B). In both cases, the patients presented with elevated troponin levels indicating myocardial injury but without evidence of obstructive CAD (4).

Figure 1 A 40-year-old female with no known cardiovascular risk factors presented to the hospital with thirty minutes of atypical chest pain. High-sensitivity troponin rose to 480 ng/L. (A) A 12-lead ECG obtained in the emergency room demonstrated normal sinus rhythm with T-wave inversions in leads II, III, AVF, V4, V5, and V6. (B) Coronary angiography revealed normal epicardial coronary arteries and preserved LV systolic function. LAO projection of the right coronary artery is notable. AVF, augmented voltage foot lead; ECG, electrocardiogram; LAO, left anterior oblique; LV, left ventricle.

Figure 2 A 56-year-old female with a medical history significant for obstructive sleep apnea presented to the hospital with typical chest pain and high-sensitivity troponin of 3,295 ng/L. (A) A 12-lead ECG at admission demonstrated normal sinus rhythm with LV hypertrophy, signs of LV strain, and T-wave flattening and inversions in the inferior leads. (B) Coronary angiography performed during the episode revealed highly tortuous arteries but no features of spasm or spontaneous coronary artery dissection. The left ventriculogram showed normal systolic function. RAO projection of the right coronary artery is notable. ECG, electrocardiogram; LV, left ventricle (or left ventricular); RAO, right anterior oblique.

Results

From a total of 17 references obtained in the initial literature search, 8 studies have been considered for this narrative review: 3 case reports, 1 retrospective, 1 prospective, 1 observational, 1 systematic review and 1 cross-sectional study (Table 2).

Table 2 summarizes the major ECG findings from the selected studies (5-12). Among MINOCA cases, only a minority (5–10.5%) exhibit ST-segment elevations on the ECG (5,6,8-10,12). MINOCA patients often present with other ECG findings, including ST-segment depression in 15.0% of cases, T-wave inversions in 45.0% of cases, 12.8% T-wave abnormalities, and prolonged QTc intervals in 28.0% of cases (8-10). Additional ECG findings associated with MINOCA include pathological Q waves, reduced R-wave height, widened QRS complex, and left bundle branch block (8). It is also important to note that approximately 35.0% of MINOCA cases may present with a normal initial ECG (8).

ST-segment changes

ST-segment elevation often represents an acute myocardial infarction (MI), where an ECG can localize the site of ischemia. An ST-segment elevation is characterized at the J point in two adjacent leads, with a threshold of 0.1 mV and more in all leads except for V2 and V3. For leads V2–V3, the threshold is higher, set at 0.2 mV and more in men over 40 years old, 0.25 mV and more in men under 40 years old, or 0.15 mV and more in women (13).

Compared to patients with ST-segment elevation myocardial infarction (STEMI) and obstructive coronary arteries, patients with STEMI with non-obstructive coronary arteries (STE-MINOCA) tend to be younger, more often female and have fewer cardiovascular risk factors (12). Furthermore, STE-MINOCA patients tend to have lower peak troponin levels, relatively preserved LV function and higher ejection fraction when compared to STEMI-obstruction (12). Lower peak troponin levels found in STE-MINOCA compared to STEMI-obstruction suggest that there may be less myocardial damage in the scenario of MINOCA (5).

Furthermore, it was also found that STE-MINOCA results in worse outcomes such as mortality, heart failure and major cardiovascular events (MACE), compared to non-ST-segment elevation MI with non-obstructive coronary arteries (NSTE-MINOCA) (14).

T-wave abnormalities

A tall, broad-based, “hyperacute” T-wave is often an early sign of coronary obstruction and is associated with ST-segment elevation on the ECG of patients with ACS (15). Due to the lack of significant coronary artery obstruction in MINOCA, the ECG is unlikely to present with “hyperacute” T-waves (16). In MINOCA, the ECG findings may present differently, with T-wave inversions appearing in up to 45% of MINOCA cases (8). These changes vary from the “hyperacute” T-waves associated with coronary obstruction in ACS, which often manifest with acute occlusions in the coronary arteries (17).

Prolonged QTc intervals

The QT interval presented on the ECG reveals the duration of the ventricular action potential, which depends on the closing and opening of ion channels in the myocyte and the positive potassium ions causing repolarization (18). Prolonged QTc interval results from the prolongation of action potential due to excess potassium ions intracellularly, possibly due to disturbances in the ion channels (18). In men, QTc is considered prolonged if it is greater than 440 ms and in women if it is greater than 460 ms (18). Prolonged QTc intervals have been found in about 28% of cases of MINOCA in women (8), which may indicate underlying abnormalities in ventricular repolarization. This ECG finding can be a marker of electrical instability and could be associated with specific pathophysiological mechanisms of MINOCA, such as coronary artery vasospasm and CMD.

Pathological Q waves

Pathological Q waves typically reveal clinical evidence of MI by forming in the absence of electrical activity. They are described as a negative deflection that comes before an R wave and are wider and deeper than normal Q waves. Pathological Q-wave may be present in two or more contiguous leads when diagnosing MINOCA (19). A classic Q-wave has a duration of ≥40 ms and/or a depth ≥25% of the R-wave in the same lead or the presence of a Q-wave equivalent (20).

Discussion

This review acknowledges the heterogeneity of ECG characteristics among patients presenting with MINOCA. While the presence of ST-segment elevation is mentioned as a minority occurrence, most cases exhibit other ECG features. ECG findings in MINOCA exhibit variations among cases and the ECG findings alone may not definitively distinguish MINOCA from ACS resulting from obstruction of the epicardial vessels. Therefore, the diagnosis of MINOCA requires the incorporation of clinical and ECG characteristics.

MINOCA itself is a heterogenous syndrome, caused by several pathophysiologic mechanisms (2). Recognizing the diverse ECG presentations of MINOCA is important to avoid misdiagnosis, delayed treatment, and inappropriate management strategies. Longitudinal studies to track the ECG changes in MINOCA patients over time can provide insights into the prognostic significance of different ECG patterns and associated clinical outcomes. This exploration can help determine ECG features that may be predictive of future cardiovascular events or recurrence of MINOCA, helping to guide risk stratification and treatment plans. For example, ST-segment elevation at presentation is associated with a higher risk of all-cause mortality in MINOCA patients (21). Considering this, patients presenting with ST-segment elevation might be more aggressively monitored for potential complications and undergo more diagnostic testing to understand and treat the underlying disorder (22,23).

The varied ECG manifestations in MINOCA patients also highlight a significant gap in knowledge that future research should address. Investigations should focus on why there are heterogeneous ECG manifestations and aim to identify possible subtypes of MINOCA based on distinct ECG patterns (24). Differing ECG patterns may align with the subtypes of MINOCA and its underlying pathophysiological mechanisms such as SCAD, coronary artery vasospasm, and CMD. Each of these causes of MINOCA may present with unique ECG features that may assist in making the underlying diagnosis. For instance, the ECG findings for SCAD commonly present with STEMI or non-STEMI; however, in some cases, patients have presented with normal ECGs (35%), non-specific ST abnormalities (30%) (25). A few of the common ECG findings during coronary artery vasospasm include symmetrical peaked T-waves, ST-segment elevation or depression, increased height and width of the R wave and a negative T-wave (26). The ECG changes for coronary artery vasospasm may resolve once the spasm resolves, resulting in a normal ECG (26). The ECG of CMD may characteristically present with ST-T-wave abnormalities or no significant ECG findings (27). Considering the various possible presentations and underlying aetiologies, MINOCA is unlikely to present with one unified ECG. Recognizing the diverse ECG presentations of MINOCA is important to accelerate the appropriate management according to the underlying cause and reduce over- and under-treatment.

Moreover, investigations should also focus on the correlation between specific patient characteristics, such as age, gender, or comorbidities, and specific ECG manifestations of MINOCA. This could further contribute to individualized diagnostic and clinical management approaches, as certain ECG patterns may be associated with a higher risk for adverse cardiovascular events. By integrating patient-specific factors into risk assessment models based on ECG findings, clinicians can develop personalized risk profiles and implement appropriate monitoring strategies and therapeutic interventions tailored to each patient’s risk profile.

Interestingly, while obstructive ACS predominantly affects young and middle-aged males, MINOCA disproportionately affects younger females more, suggesting that sex and hormones may play a role in the underlying etiology of MINOCA (1). To understand the reason for these differences, further research about why there is a higher prevalence of MINOCA in young women should also be done to better understand female risk and develop specific preventive, diagnostic, and treatment strategies (5).

Due to incomplete diagnostic criteria and variable presentation, it is challenging to distinguish MINOCA from non-ischemic conditions that may also present without obstructive coronary arteries, such as Takotsubo syndrome and myocarditis, which must be part of the differential diagnosis (28). It is crucial to rule out these conditions through a comprehensive evaluation that incorporates the ECG alongside clinical and imaging evaluation. For instance, a key difference between the clinical appearance of MONICA and Takotsubo syndrome is that Takotsubo syndrome often presents in postmenopausal females, whereas MINOCA primarily affects younger females (28). Distinguishing MINOCA and Takotsubo syndrome solely based on ECG findings can be challenging, as both may exhibit similar ECG changes (28). While certain ECG patterns and clinical features may still provide clues to differentiate between the two conditions, a conclusive differentiation requires a comprehensive evaluation that must include diagnostic imaging. By definitively assessing for MINOCA mimickers, such as Takotsubo syndrome, an accurate diagnosis can be made.

Proper diagnosis of MINOCA would allow healthcare providers to implement precision management strategies based on the underlying etiology of the condition (29). As a result, patient health outcomes may be improved (29). More frequent, accurate diagnosis of MINOCA would also contribute to the broader understanding of MINOCA, including its etiology, risk factors, prognosis, and management strategies, which is essential for ongoing research and improvements in patient care.

To illustrate the clinical implications of these findings, Case 1 and Case 2 can be considered. In both cases, the coronary angiograms did not reveal significant coronary artery blockages, which is indicative of MINOCA. The ECG findings in both cases include T-wave abnormalities, with Case 2 also demonstrating signs of LV hypertrophy and strain. MINOCA is considered a potential diagnosis when there is evidence of MI, such as chest pain and elevated cardiac biomarkers, but a lack of obstructive coronary arteries (19). The absence of significant coronary artery obstruction on the angiography suggests that the myocardial injury may be related to factors other than traditional atherosclerotic plaque rupture (5). Risk factors and medical history, including obstructive sleep apnea in Case 2, should be considered in the overall clinical evaluation (5).

Furthermore, it would be important to validate the findings of this literature review through a large-scale study to ensure the generalizability of the ECG patterns found. Further external verification of the ECG manifestations in diverse groups of patients can strengthen the evidence base and reliability of the findings. Addressing these future research directions can help contribute to filling the identified gap in knowledge and further advancements and understanding of the management of MINOCA.

Limitations

The existing literature on MINOCA is limited by sample size and diversity, which limits the generalizability of the findings to broader patient populations. Another limitation is that there is a lack of widespread availability for comprehensive testing, resulting in inconsistencies in reporting and analysis and making it challenging to draw definitive conclusions about the diagnostic value of ECG in MINOCA (30). Inaccurate MINOCA diagnosis may be due to the challenge of definitively diagnosing and ruling out alternative conditions, such as myocarditis, which require the use of MRI (31). Access to MRIs, however, is restricted to countries in upper-middle to high-income groups (32). Without this, we might misdiagnose a patient as having MINOCA when they have myocarditis. There also may be undocumented or underreported cases of MINOCA with unique ECG manifestations that were not captured in this review, highlighting the need for prospective studies and larger-scale clinical trials. Furthermore, the selection of articles was made according to clear criteria, disagreements were resolved by consensus, and three investigators took part in choosing the articles. However, the potential for selection bias still exists due to the non-systematic approach used.

Conclusions

This non-systematic review shows that there is no isolated ECG manifestation of MINOCA. The diagnosis of MINOCA requires the incorporation of clinical, electrocardiographic, and imaging findings characteristics.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the Narrative Review reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1688/rc

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1688/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1688/coif). A.B. serves as an unpaid editorial board member of Journal of Thoracic Disease from November 2025 to December 2027. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All clinical procedures described in this study were performed in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patients for the publication of this article and accompanying images.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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