Unmasking coronary embolism: rare non-atherosclerotic causes of acute coronary syndrome in the young: case series

Abstract

Background

Coronary embolism is an uncommon, non-atherosclerotic cause of acute coronary syndrome (ACS) and is frequently under-recognized. We describe three rare presentations of coronary embolism causing ACS in young patients.

Cases summary

Case 1: A 23-year-old male developed inferior wall myocardial infarction due to septic coronary embolism complicated by basal inferior submitral aneurysm and mitral valve infective endocarditis with anterior mitral leaflet perforation. He underwent mitral valve replacement and aneurysm repair.

Case 2: A 35-year-old male presented with acute inferior wall myocardial infarction secondary to tumour embolism from left atrial myxoma and underwent mass excision, mitral annuloplasty, and coronary artery bypass grafting.

Case 3: A 38-year-old female with non–ST elevation myocardial infarction and severe mitral stenosis demonstrated probable coronary embolism without atrial fibrillation or left atrial appendage thrombus and was managed with anticoagulation and planned percutaneous transmitral commissurotomy.

Discussion

The aetiology and source for coronary embolism in majority of the non-atherosclerotic ACS patients become clear from past symptoms in history and cardiovascular imaging. The treatment in most cases of coronary embolism depends on the site of obstruction, i.e. distal branch vessel vs. proximal vessel obstruction and also the nature of suspected embolic material. Aspiration thrombectomy and anticoagulation remains the mainstay in majority of thromboembolic lesions, whereas non-thrombotic lesions need to be managed on an individualized approach.

Conclusion

Coronary embolism should be considered among the differential diagnoses of myocardial infarction with non-obstructive coronary arteries and ACS in young patients without significant atherosclerotic disease, particularly when an embolic substrate is identifiable.

Learning points.

• Consider coronary embolism in acute coronary syndrome (ACS) patients without significant atherosclerotic risk factors, especially when a potential embolic source is present.

• A comprehensive imaging strategy is crucial for differentiating coronary embolism from other causes of myocardial infarction with non-obstructive coronary arteries and ACS.

• Management of coronary embolism should be individualized according to the underlying aetiology, coronary anatomy, and clinical status.

Introduction

Coronary artery embolism accounts for 2.9% of de novo acute myocardial infarction cases, and the diagnosis relies on clinical suspicion supported by angiographic findings and Shibata criteria. In most scenarios, the underlying causes include atrial fibrillation (AF), bioprosthetic valve thrombosis, and cardiomyopathies with intraventricular thrombosis. The following three cases demonstrate how infective endocarditis, atrial myxoma, and rheumatic heart disease can present with acute coronary syndrome (ACS) and emphasize the diagnostic challenges and treatment strategies.

Summary figure

Case 1

A 23-year-old male with no comorbidities presented with New York Heart Association class III dyspnoea for 2 months. He was initially treated elsewhere for presumed pneumonia with antibiotics for 1 month. He subsequently presented to our hospital with worsening breathlessness and chest pain for 3 weeks. On examination, blood pressure was 100/60 mmHg, pulse rate was 116 beats/min, respiratory rate was 24/min, and SpO₂ was 88% on room air. A pansystolic murmur was heard at the mitral area with bibasal crepitations. Electrocardiogram (ECG) was suggestive of evolved inferior wall myocardial infarction (IWMI) (Figure 1A). Transthoracic echocardiogram (TTE) showed regional wall motion abnormality (RWMA) in the mid, basal inferior, and posterior segments; a basal inferior submitral aneurysm (5 cm) with a wide neck (Figure 1B); severe mitral regurgitation; and left ventricular ejection fraction (EF) of 46% (see Supplementary material online, Videos S1 and S2).

Figure 1.

(A) Electrocardiogram showing ST-segment elevation with T-wave inversions in II, III, and aVF leads, suggestive of evolved inferior wall myocardial infarction with normal sinus rhythm. (B) Transthoracic echocardiogram apical 2-chamber (A2C) view showing large basal inferior wall aneurysm of size 5 mm with wide neck in submitral location. (C) Transoesophageal echocardiogram mid-oesophageal 2-chamber view at 85° colour Doppler across the mitral valve showing large infero-basal submitral aneurysm with vegetation over anterior mitral leaflet with severe eccentric mitral regurgitation with 2 jets. (D) Three-dimensional transoesophageal echocardiogram showing anterior mitral leaflet perforation of size 1.3 × 0.4 cm. (E) Coronary angiogram in right anterior oblique caudal view showing normal left coronary system with distal thrombolysis in myocardial infarction 3 flow. (F) Coronary angiogram in left anterior oblique view showing mid right coronary artery occlusion with filling defect, distal thrombolysis in myocardial infarction 0 flow.

Erythrocyte sedimentation rate, C-reactive protein, and white blood cell counts were elevated; troponin was negative. Transoesophageal echocardiogram (TEE) demonstrated a large basal inferior submitral aneurysm with a wide neck, an anterior mitral leaflet (AML) tear measuring 1.3 × 0.4 cm with vegetation on it, and severe eccentric mitral regurgitation (two jets) (Figure 1C and D, Supplementary material online, Video S3). Blood cultures were negative. Coronary angiography (CAG) revealed normal left coronary arteries with total occlusion of the mid right coronary artery (RCA) without retrograde filling (Figure 1E and F, Supplementary material online, Videos S4 and S5). Cardiac magnetic resonance imaging confirmed a wide-necked basal-to-mid inferior submitral aneurysm measuring 56 × 31 mm with moderate systolic dysfunction (EF 40%) and transmural late gadolinium enhancement in the RCA territory, suggesting non-viable myocardium (see Supplementary material online, Video S6 and S7). Septic embolization of vegetation to the RCA was considered the likely mechanism, given a normal left coronary system and absence of atherosclerotic risk factors. After 4 weeks of antibiotics, the patient underwent successful mitral valve replacement (24 mm St Jude) with submitral aneurysm repair, was discharged on anticoagulation and guideline directed medical therapy for heart failure, and remained well at 1-year follow-up.

Case 2

A 35-year-old male with no comorbidities presented with chest pain of 4-h duration, without palpitations and breathlessness. On examination, blood pressure was 100/60 mmHg and heart rate was 75 beats/min. Auscultation revealed normal S1 and S2. ECG showed ST elevation in inferior leads, consistent with acute IWMI (Figure 2A). TTE performed prior to primary percutaneous coronary intervention showed dilated left-sided chambers, inferior wall hypokinesia with EF of 40%–45%, and a large 4.6 × 3.3 cm pedunculated left atrial mass attached to the interatrial septum (Figure 2B, Supplementary material online, Video S8), prolapsing across the mitral valve with severe eccentric mitral regurgitation (Figure 2C, Supplementary material online, Video S9), moderate tricuspid regurgitation, and pulmonary hypertension.

Figure 2.

(A) Electrocardiogram showing ST-segment elevation in inferior leads, suggestive of acute inferior wall myocardial infarction with normal sinus rhythm. (B) Transthoracic echocardiogram apical 4-chamber (A4C) view showing large 4.6 × 3.3 cm pedunculated left atrial mass attached to the interatrial septum and freely mobile across the mitral valve. (C) Transthoracic echocardiogram apical 4-chamber (A4C) view with colour Doppler showing large left atrial mass with severe mitral regurgitation. (D) Transthoracic echocardiogram continuous wave Doppler across the mitral valve showing no significant transmitral gradient. (E, F) coronary angiogram showing normal proximal right coronary artery with mid right coronary artery total cutoff (2E) with no antegrade flow, distal RCA is filling through retrograde collaterals from left anterior descending artery (2F). (G) A 5 × 4 cm surgically excised left atrial myxoma.

CAG demonstrated a normal left coronary system and mid-RCA occlusion with retrograde filling via collaterals from left anterior descending artery (Figure 2E and F, Supplementary material online, Videos S10 and S11). Given adequate collateral flow and haemodynamic stability, the patient was managed conservatively with anticoagulation and antiplatelets for 3 days. On day 4, he underwent surgery. Intraoperative findings revealed a large 5 × 4 cm pedunculated left atrial mass attached to the interatrial septum, dilated mitral and tricuspid annuli with severe mitral and tricuspid regurgitation. He underwent left atrial mass excision (Figure 2G), and mitral (32-mm ring) and tricuspid valve (28-mm ring) annuloplasty, and, in view of persistent RCA occlusion, coronary artery bypass graft to RCA was done. Histopathology confirmed benign myxoma. Although histopathological confirmation of coronary tumour embolization was unavailable, the presentation of acute RCA occlusion with normal left coronaries and a large mobile left atrial myxoma strongly supported an embolic mechanism as the most likely cause. Post-procedure, he was discharged on anticoagulation and antiplatelet. At 1-month follow-up, echocardiography showed improved EF with no mitral/tricuspid regurgitation. He remained well at 1-year follow-up.

Case 3

A 38-year-old female with no comorbidities presented with chest pain of 2-h duration. She was afebrile with pulse rate 88 bpm and blood pressure 120/70 mmHg. Auscultation revealed a loud S1 and a faint mid-diastolic murmur at the apex. ECG showed 0.5 mm ST depression in V5, V6, I, and aVL (Figure 3A). Troponin-I was positive. She was diagnosed with non-ST elevation myocardial infarction and started on anticoagulation, antiplatelets, and statins. TTE revealed rheumatic heart disease with severe mitral stenosis (mitral valve orifice area: 0.6 cm²), mild mitral regurgitation, dilated left atrium with size 54 mm (Figure 3B) with a volume index of 60.5 mL/m², mild pulmonary hypertension (pulmonary artery systolic pressure: 40 mmHg), and no visible thrombus.

Figure 3.

(A) Electrocardiogram at presentation showing sinus rhythm with heart rate of 60 bpm, and 0.5 mm ST segment depression in lateral leads. (B) Transthoracic echocardiogram in parasternal long-axis view showing dilated left atrium with measurement of 5.4 cm. (C–E) Coronary angiogram in anteroposterior caudal and left anterior oblique cranial views, respectively, in (C) and (D), with distal major obtuse marginal branch showing filling defect with distal thrombolysis in myocardial infarction 1 flow; and (E) zoomed-in view of distal obtuse marginal showing filling defect in anteroposterior caudal view. (F) Transoesophageal echocardiogram images confirming no left atrial appendage thrombus in mid-oesophageal view at 135°. (G) Three-dimensional transoesophageal echocardiogram showing mitral valve apparatus as seen from left atrium, showing commissural fusion of both lateral and medial commissures and fish mouth-like opening of mitral valve orifice with a mitral valve orifice area of 0.6 cm², suggestive of critical mitral stenosis.

CAG showed occlusion of the distal obtuse marginal artery (Figure 3C–E, Supplementary material online, Video S12). Given the absence of coronary atherosclerosis and the presence of severe mitral stenosis with dilated left atrium and distal coronary artery occlusion, coronary embolism was considered the likely cause of ACS. TEE was done to look for left atrial appendage (LAA) clots. TEE confirmed severe mitral stenosis with dilated left atrium and reduced LAA inflow velocities and grade 1 spontaneous echo contrast but showed no LAA clot (Figure 3F and G, Supplementary material online, Video S13). Holter monitoring for 3 days showed no AF. Given the presence of severe mitral stenosis, dilated left atrium with markedly reduced LAA velocities suggestive of impaired LAA function, and suspected embolic presentation, long-term anticoagulation was considered after multidisciplinary team discussion. The patient was discharged on oral anticoagulation, beta-blockers, penicillin prophylaxis and antiplatelets were discontinued in view of suspected embolic mechanism. She was advised percutaneous transmitral commissurotomy after 4 weeks of anticoagulation.

Discussion

Myocardial infarction in the absence of significant atherosclerotic disease on angiogram points towards the diagnosis of myocardial infarction with non-obstructive coronary arteries (MINOCA). A variety of causes present as MINOCA and can include coronary plaque disruption, vasospasm, coronary embolism, spontaneous coronary artery dissection, and coronary microvascular dysfunction.¹ Treatment in MINOCA is individualized based on underlying aetiology. Intravascular imaging and cardiac magnetic resonance help in identifying aetiology of MINOCA in many cases; optical coherence tomography (OCT) especially helps differentiate plaque disruption with thrombosis from coronary embolism.¹

When to suspect coronary embolism?

Coronary embolism (CE) is a rare, non-atherosclerotic cause for myocardial infarction. The estimated incidence of CE is 2%–5% among patients presenting with de novo acute myocardial infarction.^2,3 The causes are multifactorial, but AF remains the most common cause of coronary embolism.² Diagnosis of CE is suspected whenever atherosclerosis is absent on angiogram, there is an identifiable source for cardiac embolus, and especially if there is evidence of other systemic embolism; the exception here is to identify primary thrombotic/hypercoagulable disorders.

The sources of embolus in ACS have been classified into three categories²:

1. Direct CE secondary to thrombus originating from the LAA, left ventricle, the aortic or mitral valves, pulmonary veins, or aorta. Direct CE may also result from endocarditis and more rarely from cardiac tumours.

2. Second type is paradoxical coronary embolism occurs when emboli from the systemic veins and right heart gain access to left heart via a patent foramen ovale, atrial septal defect or pulmonary arteriovenous fistulae.

3. Third type is iatrogenic coronary emboli that occurs during coronary interventions or aortic valve replacements.

In 2015, Shibata et al.³ proposed major and minor criteria to aid in the diagnosis of CE (Table 1). Two or more major criteria, one major criterion and two or more minor criteria, or all three minor criteria make a definitive diagnosis of coronary embolism, and a probable diagnosis would be made if one major and one minor criterion or two minor criteria are present.³

Table 1.

Criteria for the diagnosis of coronary embolism

Major criteria	Minor criteria
a) Angiographic evidence of coronary embolism and thrombosis without atherosclerotic component	a) Stenosis <25% on coronary angiography, except in the culprit lesion
b) Concomitant coronary embolization: multiple vessels in the same coronary territory or multiple vessels of the coronary tree	b) Evidence of an embolic source by multimodal imaging
c) Concomitant systemic embolism without evidence of intracavitary thrombus attributed to acute myocardial infarction	c) Presence of embolic risk factors such as atrial fibrillation, dilated cardiomyopathy, rheumatic valve disease, presence of valve prosthesis, patent foramen ovale, atrial septal defects, infective endocarditis, or hypercoagulable state

Two or more major criteria, one major and more than two minor criteria, or all three minor criteria make a definitive diagnosis of coronary embolism, and a probable diagnosis would be made if one major and one minor criterion or two minor criteria are present.

Source: Shibata et al.³

Given the absence of intracoronary imaging or histopathological confirmation, the diagnosis of coronary embolism in the current series was based on clinical presentation, angiographic appearance, identifiable embolic substrate, and application of Shibata criteria (Table 2).

Table 2.

Application of Shibata criteria

Case	Major criteria	Minor criteria	Diagnostic category
Case 1	a) Angiographic evidence of right coronary artery occlusion without underlying atherosclerosis	a) Normal left coronary system b) Identifiable embolic source (infective endocarditis vegetation), young age, no risk factors	Definite coronary embolism
Case 2	a) Angiographic evidence of right coronary artery occlusion without underlying atherosclerosis	a) Normal left coronary system b) Left atrial myxoma as embolic source, absence of risk factors	Definite coronary embolism
Case 3	a) Distal coronary occlusion without atherosclerosis	a) Normal left anterior descending and right coronary artery b) Severe rheumatic mitral stenosis with low left atrial appendage velocities, no risk factors	Probable-definite coronary embolism

Different embolic sources and role of multi-modality imaging in diagnosis

Infective endocarditis can cause myocardial infarction by 2 mechanisms: First by septic emboli of the vegetation itself and second by coronary compression by an enlarging aortic root abscess.⁴ Intracoronary septic emboli from infective endocarditis occurs mostly to the left circulation due to favourable anatomy and angulation of its origin compared to right coronary system, which is angled significantly.⁴ TTE/TEE remains the mainstay in imaging of mobile vegetations on valves or other intracardiac structures or aortic root abscess. Cardiac computed tomography and nuclear imaging have complementary role in prosthetic valve endocarditis diagnosis and perioperative planning.

Atrial myxomas are mostly benign tumours. Majority of the symptoms are related to mitral valve obstruction by the tumour per se, and patients can present with dyspnoea, fatigue, syncope, and palpitations due to increased incidence of AF. Atrial myxomas can be a significant source of embolism; one-third of patients have embolic events.⁵ Echocardiogram remains the first-line imaging modality for myxomas, while cardiac computed tomography/magnetic resonance imaging may be recommended in selected patients for surgical planning or tissue characterization.

Rheumatic heart disease is a major cause of systemic embolism. This increased risk is due to left atrial enlargement and dysfunction subsequent to mitral valve disease (mitral stenosis or regurgitation or both), which also increases the incidence of AF in these patients.⁶ Systemic embolism occurs in as much as 10%–20% of cases, and the most common clinical presentation is with ischaemic strokes due to cerebral emboli; exact incidence of coronary emboli has not been estimated or studied. The risk of embolic events correlates directly with the left atrial size and the patient's age.⁷ Approximately 20% of patients with mitral stenosis and embolic events are in sinus rhythm.⁷ So the absence of AF at presentation does not rule out cardioembolic source of systemic embolism.

Management of coronary embolism

Management of CE lacks any standardized guidelines largely due to the heterogeneity of aetiological causes and also due to underdiagnosis and overall rare incidence. Management largely depends on embolus location, haemodynamic effect on distal flow, and residual disease after thrombectomy. Consensus-based literature supports percutaneous intervention, such as aspiration thrombectomy or balloon angioplasty with stenting, as first-line treatment though aspiration thrombectomy was associated with increased risk of stroke.^2,8 A review of 147 patients with CE by Lacey et al. showed that thrombectomy was employed in 47.6% of patients, balloon angioplasty in 29.9%, half of whom underwent stent placement, thrombolysis in 14.9%, and surgical intervention, either for coronary embolism or an underlying valvopathy, in 20.4%.⁸

Thrombus aspiration is recommended for high thrombus burden affecting distal flow [thrombolysis in myocardial infarction (TIMI) ≤ 2].^2,8 Primary stenting may be considered after thrombectomy if residual thrombus causes distal TIMI flow of <2. A minimalistic revascularization strategy aiming for TIMI 3 flow, without stenting, when feasible, is preferred.

Anticoagulation is the mainstay of medical management in CE^8,9 and that alone would be recommended in patients where catheter aspiration may not be feasible for far-distal thrombi or small non-obstructive thrombi visualized on angiogram with distal TIMI 3 flow. When a mitral stenosis patient is in sinus rhythm, ESC guidelines recommend the use of oral anticoagulation when TEE shows spontaneous echo-contrast or an enlarged left atrium (M-mode diameter > 50 mm/volume index > 60 mL/m²).¹⁰

CE from intracardiac tumours may be treated with catheter aspirations and balloon dilations to establish antegrade flow; but most times, surgical extirpation is the only curative treatment possibility and is coupled with excellent results.⁵

In case 1, RCA territory was non-viable, hence the revascularization was not advised during surgery.

In case 2, in view of persistent RCA occlusion and acute presentation, coronary artery bypass graft to RCA was done during the mass excision.

In case 3, the patient had rheumatic heart disease with a dilated left atrium (diameter: 54 mm; volume index: 60.5 mL/m²). Thus, the patient was put on anticoagulation.

Table 3 provides a visual summary of the presenting complaints, diagnostic findings, embolic sources, management, and outcomes of the cases included in this series.

Table 3.

Case summary

S. No.	Age, years	Presenting complaints	Investigations	Management	Outcome and follow-up
1	23	NYHA class III/IV breathlessness and chest pain of 2-month duration	ECG: Evolved IWMI Echocardiogram (TTE and TEE): RWMA in RCA territory, AML perforation with vegetation, severe mitral regurgitation, large basal inferior aneurysm, and EF of 45% CAG: mid-RCA occlusion CMR: large inferior submitral aneurysm with non-viable RCA territory	Intravenous antibiotics. Surgery: mitral valve replacement + submitral aneurysm repair	Stable at 12-month follow-up
2	35	Chest pain of 4-h duration	ECG: acute IWMI Echocardiogram: RWMA in RCA territory, large mobile left atrial mass, severe mitral regurgitation, and EF of 40%–45% CAG: mid-RCA occlusion with retrograde filling through collaterals	Anticoagulation and antiplatelets, followed by surgery: left atrial myxoma excision, mitral and tricuspid valve annuloplasty with coronary artery bypass grafting to the RCA	Stable at 12-month follow-up
3	38	Chest pain of 2-h duration	Troponin-positive echocardiogram (TTE and TEE): rheumatic heart disease, severe mitral stenosis, moderate aortic regurgitation, no evidence of clot. CAG: distal major obtuse marginal branch occlusion Holter: no evidence of AF	Anticoagulation, beta-blockers, and penicillin prophylaxis Advised PTMC	Stable at 6-month follow-up

AML, anterior mitral leaflet; CAG, coronary angiogram; CMR, cardiac magnetic resonance; EF, ejection fraction; IWMI, inferior wall myocardial infarction; PTMC, percutaneous transmitral commissurotomy; RWMA, regional wall motion abnormality; RCA, right coronary artery; TTE, transthoracic echocardiogram; TEE, transoesophageal echocardiogram.

Limitation

A major limitation of this series is the absence of intracoronary imaging (OCT/intravascular ultrasound), which limited definitive exclusion of plaque rupture, plaque erosion, spontaneous coronary artery dissection, or in situ thrombosis. Consequently, the diagnosis of coronary embolism remained based on clinical, angiographic, and multimodality imaging findings.

Conclusion

Coronary embolism should be considered among the differential diagnoses of MINOCA and ACS in young patients without significant atherosclerotic disease, particularly when an embolic substrate is identifiable. Multimodality imaging and careful diagnostic evaluation are essential to improve diagnostic confidence and guide individualized management.

Lead author biography

Dr. Gopidi Aparanji is an interventional cardiologist in the Department of Cardiology at KIMS-Sunshine Hospitals, Hyderabad, India. She was graduated from Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bangalore, India. Her clinical and research interests include complex coronary interventions, coronary imaging, and structural heart interventions.

Supplementary material

Supplementary material is available at European Heart Journal – Case Reports online.

Author contributions

Gopidi Aparanji (Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Validation, Visualization, Writing—original draft, Writing—review & editing [lead]), Tency Joshu Thomas (Data curation, Formal analysis, Methodology, Supervision, Writing—original draft, Writing—review & editing [equal]), Nagaraja Moorthy (Data curation, Investigation, Methodology, Supervision, Visualization, Writing—review & editing [supporting]), Sunil Roy (Data curation, Formal analysis, Investigation, Supervision, Writing—review & editing [supporting]), Talakola Naveen (Data curation, Formal analysis, Methodology, Supervision, Writing—original draft, Writing—review & editing [supporting]), Manidipa Majumdar (Formal analysis, Methodology, Supervision, Validation, Writing—review & editing [supporting]), Gunasekaran Surendhar (Formal analysis, Methodology, Visualization, Writing—review & editing [supporting]), and Disha R Shetty (Formal analysis, Investigation, Supervision, Writing—review & editing [supporting])

Patient consent: Informed consent was obtained from the patients for the publication of case series.

Consent for publication: The authors confirm that written consent for submission and publication of this case series including images and associated text has been obtained from the patients, in line with COPE guidance.

Funding

None declared.

Data availability

The supporting data including images and video files relating to the cases can be made available by the primary and corresponding authors on request.