MINOCA, Takotsubo syndrome and spontaneous coronary artery

• Myocardial infarction with nonobstructive coronary arteries (MINOCA) means myocardial injury meeting the criteria for infarction with less than 50% stenosis in every major epicardial artery. It is a working diagnosis, not a final one, because several different mechanisms can produce it. ^[1]
• Takotsubo syndrome (TTS) is a transient, usually reversible left ventricular systolic dysfunction that looks like an acute coronary syndrome. It is seen in about 1 to 2% of patients presenting with suspected acute coronary syndrome or ST-segment elevation, and more than 90% of cases occur in postmenopausal women. ^[4]
• Spontaneous coronary artery dissection (SCAD) is an epicardial dissection not caused by atherosclerosis or trauma: an intramural haematoma compresses the true lumen. It is found in 1 to 4% of all acute coronary syndromes and may cause up to 35% of myocardial infarctions in women aged 50 or under. ^[3]
• The three conditions share chest pain, troponin elevation and electrocardiogram changes, which is why a patient with unobstructed coronaries still needs a careful search for SCAD, vasospasm, microvascular dysfunction, thromboembolism and TTS.
• For MINOCA, SCAD and typical TTS alike, conservative management with close monitoring is preferred first, with invasive treatment reserved for high-risk features such as ongoing ischaemia, haemodynamic instability or left main disease. ^{[1] [3] [4]}

By the end of this page you should be able to:

1. Define MINOCA, Takotsubo syndrome and SCAD, and state why MINOCA is a working diagnosis.
2. Estimate how common each condition is and describe the typical patient.
3. Explain the mechanisms by which SCAD and TTS produce myocardial injury, and why plaque disruption also matters in MINOCA.
4. Interpret a coronary angiogram showing no obstructive disease, and know when intravascular imaging, echocardiography and cardiac magnetic resonance (CMR) are needed.
5. Use the diagnostic concepts of MINOCA (criteria, angiography, CMR reclassification) and TTS (Mayo Clinic, Heart Failure Association/ESC, InterTAK) to reach a mechanism-based diagnosis.
6. Plan initial management for MINOCA, stable SCAD and TTS, including when to avoid percutaneous coronary intervention (PCI).
7. Recognise complications of TTS (left ventricular outflow tract obstruction, thrombus, shock) and of SCAD (recurrence, propagation), and know what follow-up is required.
8. Adapt investigations and treatment to pregnancy, women across the lifespan, older adults and low-resource settings.

MINOCA is therefore a clinical syndrome and a working diagnosis. A patient with troponin elevation and unobstructed coronary arteries can have coronary plaque disruption, epicardial vasospasm, coronary microvascular dysfunction, coronary thromboembolism or SCAD as the underlying cause, as well as non-ischaemic mimics such as myocarditis or TTS. ^{[1] [5]} The task after the angiogram is to find which of these is responsible, not to stop there.

Classical TTS shows apical ballooning of the left ventricle, but mid-ventricular, basal, focal and biventricular forms are now well described. Triggers are emotional or physical stress of many kinds, from grief and intense anger to sepsis, surgery, subarachnoid haemorrhage and phaeochromocytoma. ^{[2] [4]}

For teaching, these three can be thought of as three different ways to reach the same presenting pattern: chest pain, electrocardiogram (ECG) change and troponin rise. MINOCA is defined by the angiographic result, TTS by a characteristic pattern of ventricular dysfunction, and SCAD by a structural arterial lesion.

MINOCA accounts for approximately 5 to 15% of all acute myocardial infarctions, with pooled estimates around 6%. Patients are younger than those with infarction due to obstructive disease, women make up more than half of cases, and higher prevalence has been reported in Black, Maori, Pacific Islander and Hispanic populations. ^[1]

SCAD is identified in 1 to 4% of all acute coronary syndromes. It occurs overwhelmingly in women, may account for up to 35% of myocardial infarctions in women aged 50 years or younger, and is the most common cause of pregnancy-related myocardial infarction (43% of cases). Mean age at presentation is 44 to 53 years, and patients typically have few traditional cardiovascular risk factors, but a high prevalence of fibromuscular dysplasia and other arteriopathies. ^{[3] [4]}

TTS is found in 1 to 2% of patients presenting with suspected acute coronary syndrome or ST-segment elevation myocardial infarction. Over 90% of patients are postmenopausal women, with mean ages of roughly 65 to 75 years across series (about 67 to 70 years in the international Takotsubo consensus), although SCAD and TTS overlap substantially in age distribution. ^{[4] [7]} Emotional or physical triggers are identified in roughly 65 to 70% of cases; no trigger is found in 30 to 35%. ^[4]

Once thought benign, MINOCA carries significant long-term risk: an annual mortality of approximately 2%, with increased risks of recurrent infarction, heart failure and stroke. In one systematic review, suspected MINOCA had a 12-month all-cause mortality of 3.4% and a major adverse cardiovascular event (MACE) rate of 9.6%. TTS is also not benign: the International Takotsubo Registry reported serious in-hospital complications in 21.8% of patients and about 5% in-hospital mortality. ^{[1] [4]}

MINOCA has atherosclerotic and non-atherosclerotic causes. Mechanisms include coronary plaque disruption with thrombus, plaque erosion, calcified nodules, epicardial vasospasm, coronary microvascular dysfunction, coronary thromboembolism and SCAD; TTS and myocarditis can masquerade as it. Emerging data suggest that women are more often affected by microvascular dysfunction and SCAD, while men are more likely to have thromboembolic or atherosclerotic causes. Postmenopausal status is over-represented. ^[1]

SCAD risk factors are more often hormonal, structural and stress-related than atherosclerotic: female sex (often premenopausal), pregnancy and the peripartum period, physical triggers such as intense or isometric exercise and Valsalva manoeuvres, emotional stress, fibromuscular dysplasia and other arteriopathies, connective tissue disorders, migraine and, in smaller series, inflammatory or autoimmune disease. Emotional stress precedes roughly one quarter of events in large registries and up to about 40% in single-centre series; physical stress accounts for roughly 24% to 30%; no trigger is found in the rest. ^{[3] [4]}

TTS risk factors are female sex and older age, an emotional or physical stressor, and comorbidity. Physical and neurological triggers (subarachnoid haemorrhage, stroke, seizures, sepsis, respiratory failure, major surgery, malignancy, endocrine crises such as phaeochromocytoma) are common and carry a worse prognosis than emotionally triggered disease. ^{[2] [4]}

In SCAD, the problem is mechanical obstruction inside the wall, not the lumen: an intramural haematoma forms and compresses the true lumen. Two mechanisms have been proposed. The first is an intimal tear that lets blood enter a false lumen; the second is spontaneous haemorrhage from the vasa vasorum within the vessel wall. Either way the result is reduced perfusion and infarction, and angiographically this can look like a smooth diffuse stenosis (type 2 SCAD) rather than an obvious flap, which is why it is so easily missed. ^{[3] [4]}

In TTS, excess catecholamine signalling produces myocardial and microvascular stunning. The effects include microvascular dysfunction, neurogenic injury and autonomic dysregulation, producing transient dysfunction that often extends beyond a single coronary territory. This is why wall motion in TTS does not match one artery's distribution and why the electrocardiogram changes are diffuse. ^[2]

About 20% of people with TTS develop left ventricular outflow tract (LVOT) obstruction during systole, and right ventricular involvement, mitral regurgitation, LV thrombus or cardiogenic shock can follow. ^[2]

For MINOCA generally, plaque rupture or erosion can create thrombus that dissolves or is not large enough to be haemodynamically obstructive. Vasospasm may come and go. Microvascular dysfunction limits flow at the level of the arterioles. Thromboembolism may travel from a distant source. These are all testable once the patient is safe. ^[1]

All three present with acute coronary syndrome-like features. Chest pain is common in SCAD (about 96% in reported series) and TTS (about 75%). TTS often adds dyspnoea (about 47%). ST-segment elevation is seen in roughly 26 to 49% of SCAD and in about 44% of TTS. Troponin is almost always elevated, although in TTS the rise is often modest compared with the extent of ventricular dysfunction, while natriuretic peptides (BNP or NT-proBNP) are frequently markedly raised. ECG changes in SCAD are territory-specific, confined to the leads of the affected artery. TTS produces more diffuse change, often with four phases of ECG evolution, progressively deep and diffuse T-wave inversion and QT prolongation that can exceed 500 milliseconds. ^{[3] [4]}

A clue to TTS is the mismatch between a modest troponin rise and a large wall motion abnormality. A clue to SCAD is a young woman with few risk factors, a history of pregnancy, migraine, fibromuscular dysplasia or intense physical or emotional stress. ^{[3] [4]}

Examine for complications: in TTS look for signs of heart failure, hypotension, new murmurs (mitral regurgitation or LVOT obstruction), and arrhythmia. In SCAD, look for ongoing ischaemia, heart failure or arrhythmia. ^[2]

The working problem is "chest pain with troponin rise". The coronary angiogram then divides the causes.

Beyond these, the important mimics of the presentation are atherosclerotic acute coronary syndrome, myocarditis, coronary vasospasm, coronary microvascular angina, coronary embolism, pulmonary embolism, aortic dissection, hypertrophic cardiomyopathy with dynamic obstruction and sepsis-related or critical-illness cardiomyopathy. CMR is the test that best separates myocarditis and TTS from infarction. ^{[1] [2] [4]}

The acute work-up is the same as for any suspected acute coronary syndrome. ECG and high-sensitivity troponin establish the diagnosis of myocardial infarction, while angiography assesses obstruction.

Coronary angiography. In MINOCA the key definition is stenosis under 50% in all major epicardial arteries. ^[1] In SCAD the diagnosis is often missed at this step, especially with type 2 (diffuse smooth narrowing) or distal disease, because attention is drawn to the most obvious lesion and to apical ballooning if TTS coexists. Review the images meticulously, including distal segments, after the case is stable. ^{[3] [4]}

Intracoronary imaging (optical coherence tomography, OCT, or intravascular ultrasound, IVUS). These are the next step when angiography is inconclusive, particularly with suspected type 2 or type 3 SCAD. OCT gives near-histological wall detail; IVUS gives greater penetration and may suit larger proximal vessels. They are also the tools that show plaque rupture, erosion, intramural haematoma or SCAD that is invisible on angiography, and they guide mechanism-based treatment. The 2023 ESC acute coronary syndrome guidelines also recommend OCT or IVUS when the angiographic diagnosis is ambiguous. ^{[5] [4]}

Echocardiography. Transthoracic echocardiography is first-line in all three conditions. In TTS it shows the wall motion phenotype (apical, mid-ventricular, basal, focal or biventricular), which usually extends beyond one coronary territory, plus complications: LVOT obstruction, mitral regurgitation, right ventricular involvement, LV thrombus. Speckle-tracking strain may help distinguish TTS from infarction by showing preserved myocardial viability in segments that look akinetic. ^[2]

Cardiac magnetic resonance (CMR). CMR is the non-invasive reference test for separating true ischaemic injury from mimics such as myocarditis and TTS, and in suspected MINOCA it reclassifies the working diagnosis in up to two-thirds of cases. It shows myocardial oedema and late gadolinium enhancement (LGE) patterns: in infarction (including SCAD-related infarction) LGE is subendocardial to transmural in a coronary territory; in TTS, classically there is diffuse oedema with little or no LGE, although LGE can be seen in up to 40% acutely; myocarditis shows non-ischaemic LGE. CMR performed 7 to 14 days after the event has a diagnostic yield of about 84%. ^{[1] [5] [4]}

Coronary CT angiography. A non-invasive option for lower-risk patients and a tool that can exclude epicardial disease; it may also evaluate LV function and thrombus. It is not the first test in high-risk acute coronary syndrome and does not exclude SCAD, especially type 2 disease. ^[3]

Functional testing. Acetylcholine and adenosine testing can reveal epicardial or microvascular vasospasm and microvascular dysfunction when these are the suspected mechanism of MINOCA. ^[5]

Biomarkers. Troponin and ECG are required to diagnose infarction. In TTS, troponin is usually elevated but modest, and natriuretic peptides are disproportionately high. In suspected phaeochromocytoma-induced TTS, plasma or urinary metanephrines and imaging of the adrenal glands are needed. ^[2]

MINOCA should be treated as a working diagnosis. The steps are: (1) confirm infarction by the Fourth Universal Definition; (2) exclude obstructive disease on angiography (under 50% stenosis); (3) exclude non-ischaemic causes such as myocarditis and TTS; (4) find the mechanism using clinical context, angiography, intravascular imaging, echocardiography, CMR and functional testing. ^[1]

TTS criteria have evolved from the restrictive Mayo Clinic definition to the broader Heart Failure Association/ESC and InterTAK frameworks. Important evolution: the older Mayo rules required no obstructive coronary artery disease and excluded phaeochromocytoma, which misses cases with coexistent CAD, secondary triggers, atypical phenotypes and right ventricular involvement. The contemporary view accepts coexistence with coronary artery disease: the question is whether the coronary lesion explains the full extent and distribution of the wall motion abnormality. ^[2]

For estimating probability before definitive imaging, the InterTAK Diagnostic Score uses seven clinical variables (female sex, triggers, ECG findings, psychiatric or neurological disorders and QT prolongation) and gives an early estimate. It is not a replacement for urgent coronary assessment when acute coronary syndrome is likely, and in combined SCAD-TTS its variables are present in both conditions and do not separate them. ^{[2] [4]}

For management and prognosis, the InterTAK Prognostic Score is a practical tool that combines clinical, ECG, biomarker and left ventricular functional variables associated with adverse in-hospital outcomes. It was derived from registry populations and estimates mortality risk rather than diagnosing subtype; it should complement, not replace, judgement. ^[2]

A combined SCAD-TTS picture deserves specific thought. SCAD type 2 can be overlooked when attention has already shifted to apical ballooning. Features that should prompt a second, careful look at the distal coronary anatomy include territory-specific changes outside the expected pattern of TTS, a wall motion abnormality that seems partly arterial, and any angiographic smooth diffuse narrowing. Diffuse T-wave inversion with QT prolongation above 500 milliseconds extending beyond the dissected territory suggests superimposed TTS. Conversely, when SCAD is confirmed, a wall motion pattern much wider than the dissected artery's territory suggests concurrent TTS. ^[4]

Acute stabilisation. All patients are initially managed as an acute coronary syndrome until a culprit lesion is excluded. Once SCAD is recognised, the approach changes: conservative management is generally preferred in stable patients without ongoing ischaemia, and PCI for SCAD has much lower technical success and higher complication rates than PCI for atherosclerotic disease (one SCAD registry reported PCI success in 34.7% of attempted cases, with in-hospital MACE of 29.3% with PCI versus 2.8% with conservative management). ^{[3] [4]}

For patients with unobstructive disease after angiography, secure the mechanism before committing to prolonged treatment. Treat the acute presentation as for acute coronary syndrome, including anti-ischaemic therapy where indicated, then tailor.

MINOCA. There is no single protocol, because the mechanisms differ. Antiplatelet and statin therapy, blood pressure and lipid control, and secondary prevention are reasonable when plaque disruption or an atherosclerotic component is possible, but treatment should follow the identified mechanism: calcium-channel blockade or nitrates for vasospasm, and short- or long-term anticoagulation when thromboembolism is proven or strongly suspected. ^{[1] [5]}

SCAD. Conservative therapy is generally the preferred strategy in clinically stable patients without objective evidence of ongoing ischaemia; it has generally been associated with favourable outcomes, and is additionally appropriate for occluded distal vessels not amenable to PCI. Angiographic healing occurs in roughly 70% to 97% of patients over the following weeks to months, with about 90% healed by four weeks in many series, which makes stenting biologically unnecessary and mechanically hazardous in stable cases. Reserve PCI for high-risk features: ongoing ischaemia with reduced flow, haemodynamic instability or cardiogenic shock, left main dissection, or life-threatening ventricular arrhythmias. Coronary artery bypass grafting is reserved for left main or extensive proximal multivessel dissection, or failed or unresolvable PCI; long-term graft patency is poor because healing of the native vessel competes with graft flow. A minimum of 48 hours in hospital, and often 3 to 5 days, is reasonable because of the risk of early dissection extension. ^{[3] [4]}

Medical therapy after SCAD should be cautious. Antiplatelet therapy is usually a single antiplatelet agent; prolonged dual antiplatelet therapy is generally not required without stents. Routine statin therapy is not recommended unless there is another guideline indication, because of conflicting data on recurrent SCAD. Beta-blockers, ACE inhibitors or ARBs and antianginals are used according to symptoms and ventricular function, and antianginal agents (nitrates, calcium-channel blockers, ranolazine) are most useful for post-SCAD chest pain. ^[3]

TTS. Management is supportive: treat heart failure, arrhythmia and thromboembolic risk. Anticoagulation should be considered when there is major left ventricular dysfunction, apical akinesia or visible thrombus, because of LV thrombus formation and systemic embolisation. ^[2]

The cardiogenic shock strategy depends on the mechanism. In LVOT obstruction, catecholamine inotropes, aggressive diuresis and vasodilators can worsen haemodynamics: use cautious beta-blockade, optimise volume and avoid vasodilators. In shock without LVOT obstruction, mechanical circulatory support can be considered in selected patients. ^[2]

In phaeochromocytoma-induced TTS, diagnose and treat the catecholamine-secreting tumour; avoid beta-blockers until adequate alpha-blockade, because unopposed alpha stimulation can worsen hypertension. ^[2]

Drug exposure deserves extra care. In women with, or at risk of, these conditions, the balance of anticoagulation differs in pregnancy, and late postmenopausal hormone therapy has not been shown to protect the heart and adds thrombotic risk; combined hormonal contraception adds thrombotic risk in predisposed patients. ^[6]

• SCAD: myocardial infarction, heart failure, arrhythmia, dissection propagation and recurrence; pregnancy-associated SCAD is associated with more extensive dissection and more haemodynamic complications. ^{[3] [4]}
• TTS: heart failure, cardiogenic shock, LVOT obstruction in about 20% of cases, mitral regurgitation, right ventricular involvement, ventricular arrhythmias, LV thrombus and systemic embolisation. ^[2]
• TTS recovery is usually over days to weeks, but can be delayed; an inflamed course (residual C-reactive protein above 19 mg per L at discharge) predicts impaired recovery and higher long-term cardiac mortality or heart failure hospitalisation. ^[2]
• MINOCA: recurrent infarction, heart failure, stroke and, at 12 months, overall mortality around 3.4% in suspected cases. ^[1]

MINOCA should not be dismissed as benign. Annual mortality is approximately 2%, recurrent infarction, heart failure and stroke are increased, and a 12-month MACE rate of about 9.6% has been reported in suspected cases. Older individuals and women carry a higher risk of heart failure and long-term events, and peak troponin correlates with adverse outcomes. ^[1]

SCAD has a lower in-hospital mortality than feared, but recurrence and major adverse events are not negligible, and pregnancy-associated disease is more aggressive. Long-term vascular assessment (screening for fibromuscular dysplasia and other arteriopathies) matters because extracoronary disease is common. ^[3]

TTS usually resolves within days to weeks, but it causes real in-hospital risk (serious complications in about 21.8% of patients in a large registry) and on-going cardiac risk after discharge. Physical and neurological triggers, male sex, severe left ventricular dysfunction, right ventricular involvement, shock, mitral regurgitation, LVOT obstruction and markers of inflammation and myocardial stretch predict worse outcomes. ^{[2] [4]}

• Screen all SCAD patients for fibromuscular dysplasia and other extracoronary arteriopathies. ^[3]
• After SCAD, assess recurrence risk, residual symptoms (chest pain after SCAD is common and often non-ischaemic) and emotional health; cardiac rehabilitation is appropriate and specifically under-utilised in women. ^{[3] [6]}
• After TTS, follow recovery with echocardiography; CMR at follow-up confirms resolution and reclassifies uncertain cases. ^[2]
• After MINOCA, find the mechanism, then treat secondary prevention accordingly; advanced imaging often changes management. ^{[1] [5]}

Pregnancy and the postpartum period. SCAD is the leading cause of pregnancy-related myocardial infarction (about 43%). Most pregnancy-associated SCAD occurs within the first 4 weeks after delivery, but it has been reported at almost any stage. It is associated with more extensive dissection, more shock and arrhythmia despite occurring in women with few traditional risk factors, so a multidisciplinary cardio-obstetrics team is essential. Management follows the same principles as non-pregnancy SCAD, with drug choices adjusted for fetal and lactation considerations. Women with established cardiovascular disease need pre-conception counselling. ^{[3] [6]}

Women across the lifespan. Girls and younger women increasingly have risk factors that matter (congenital disease, autoimmune disease, stimulant use). Pregnancy-related complications (gestational hypertension, pre-eclampsia, gestational diabetes) are long-term cardiovascular risk signals, and fertility treatment and hormonal exposures need informed discussion. Women are under-represented in trial evidence, which is why management here is largely extrapolated rather than protocolised. ^[6]

Older adults. Age changes risk: MINOCA risk of heart failure is higher in older women. In apparently stable older patients coronary CT can be a reasonable non-invasive route to exclude disease, with invasive testing reserved for higher-risk presentations. ^[1]

Immunocompromised. No disease-specific immunosuppression guidance is supported by the material available for these conditions; manage cardiovascular risk factors and the underlying condition.

• A high-sensitivity troponin and an ECG are enough to suspect infarction. The angiographic definition cannot be confirmed where catheterisation is unavailable, so these patients should be managed as acute coronary syndrome with risk-based stratification and transfer when feasible. ^[1]
• Echocardiography is the practical pivot: a wall motion abnormality beyond one coronary territory, or right ventricular involvement, should raise TTS.
• Team awareness of SCAD is disproportionately important where angiography exists at all, because a smooth diffuse narrowing in a young woman must not be dismissed as mild disease. ^[3]
• CMR and intracoronary imaging may be unavailable; rely on careful angiography, echo, history and follow-up recovery.
• Conservative management is the default everywhere these conditions are recognised.

• MINOCA is myocardial infarction with less than 50% stenosis in all major arteries, and it is a working diagnosis that requires a search for the cause: plaque disruption, vasospasm, microvascular dysfunction, thromboembolism or SCAD, as well as non-ischaemic mimics.
• MINOCA is not benign: roughly 5 to 15% of infarctions, about 2% annual mortality, higher long-term heart failure and stroke risk.
• TTS is transient, usually reversible ventricular dysfunction, often postmenopausal, trigger-related, with a characteristic wall motion pattern extending beyond one coronary territory, modest troponin and high natriuretic peptides.
• TTS criteria have widened from the restrictive Mayo Clinic definition to the Heart Failure Association/ESC and InterTAK frameworks; coexisting coronary disease does not automatically exclude TTS.
• SCAD is non-atherosclerotic epicardial dissection from intramural haematoma; 1 to 4% of acute coronary syndromes, overwhelmingly women, up to 35% of MI in women 50 or younger, leading cause of pregnancy-related MI.
• Type 2 SCAD is a diffuse smooth narrowing and is often missed; distal segments and intravascular imaging matter.
• Conservative management is first-line for stable SCAD and supportive for TTS; PCI for SCAD has low success and high complications.
• Suspect pregnancy-associated SCAD early, and beware LVOT obstruction in TTS (about 20%).
• CMR reclassifies suspected MINOCA in up to two-thirds of cases and shows infarction versus stunning versus myocarditis.
• Every patient in this group needs follow-up imaging and, for SCAD, screening for fibromuscular dysplasia and arteriopathy.

Plain-text related topics (no direct links from this page): acute coronary syndromes and ST-elevation myocardial infarction, myocarditis, pericarditis, heart failure, acute aortic syndromes, pregnancy-associated thrombosis, fibromuscular dysplasia and systemic arteriopathies, hypertension emergencies, phaeochromocytoma, QT prolongation and torsades de pointes, cardiac magnetic resonance, intracoronary imaging and optical coherence tomography, pregnancy in cardiovascular disease, guidelines for low-resource cardiology, sex differences in cardiovascular disease.