Myocardial infarction with non-obstructive coronary arteries: A comprehensive review and future research directions

Table 1 Myocardial infarction with non-obstructive coronary arteries classification, management overview, prevalence and suggested therapy

Mechanism	Diagnosis	Prevalence in coronary syndromes	Therapy
Epicardial causes
Coronary artery disease	IVUS/OCT, FFR/iFR	5%-20% of MI	Antiplatelet therapy, statins, ACEi/ARB, beta-blockers
Coronary dissection	IVUS/OCT	25% of MI in women under 50 yr of age	Beta-blocker and simple antiplatelet therapy
Coronary artery spasm	Intracoronary nitrates, intracoronary Ach or ergonovine test by experienced teams	3%–95% of MI depending on the registry	Calcium antagonists, nitrates
Microvascular causes
Microvascular coronary spasm	Objective evidence of ischaemia (ECG, LV wall motion abnormalities, PET). Impaired microvascular function (CFR, intracoronary Ach test, abnormal CMR, slow coronary flow)	As high as 25% depending on the registry	Beta-blockers and nitrates, calcium antagonist, possibly ranolazine
Takotsubo syndrome	Ventriculography, echocardiography, troponin, B-natriuretic peptide, CMR	1%-3% of general STEMI, 5%-6% women with STEMI, concomitant CAD 10%-29%	Heart failure treatment, mechanical support in cardiogenic shock
Myocarditis	CMR, EMB, viral serologies, high c-reactive protein	33% of MINOCA when determined by CMR	Heart failure treatment if complication, autoimmune therapy in autoimmune forms
Coronary embolism	History of potential thromboembolic sources, thrombophilia screen, TTE, TOE, bubble contrast echography	2.9% MI	Antiplatelet therapy, anticoagulation, transcatheter closure or surgical repair

MINOCA: Myocardial infarction with non-obstructive coronary arteries; MI: Myocardial infarction; CAD: Coronary artery disease; IVUS: Intravascular ultrasound; OCT: Optical coherence tomography; CMR: Cardiac magnetic resonance; STEMI: ST segment elevation myocardial infarction; PET: Positron emission tomography; FFR: Fractional flow reserve; ECG: Electrocardiogram; iFR: Instantaneous wave-free ratio; EMB: Endomyocardial biopsies; ACEi: Angiotensin-converting-enzyme inhibitors.

Table 2 International takotsubo syndrome diagnostic criteria

Diagnostic criteria
Left ventricular dysfunction usually extending beyond a single coronary territory.
Sometimes triggered by emotional, physical or combined stress.
Acute neurologic disorders, including pheochromocytoma, may become triggers.
New ECG abnormalities. Rare cases can present with without ECG shifts.
Moderate troponin elevation. Usually, significantly high brain natriuretic peptide.
Can have concomitant CAD.
No evidence of infectious myocarditis usually excluded by CMR.
Mostly present in postmenopausal women.

CAD: Coronary artery disease; CMR: Cardiac magnetic resonance; ECG: Electrocardiogram.

Table 3 International takotsubo syndrome diagnostic score

Criteria	Points	Diagnosis probability
Female sex	25 points	≤ 70 points
Emotional stress	24 points
		Low/intermediate
Physical stress	13 points
		TTS probability
No ST-segment depression	12 points
Psychiatric disorders	11 points	> 70 points
Neurologic disorders	9 points
		High TTS probability
QTc prolongation	6 points

TTS: Takotsubo syndrome.

Table 4 European Society of Cardiology 2013 Myocarditis Task Force definition of clinically suspected myocarditis

Presence of ≥ 1 clinical presentation and ≥ 1 diagnostic criteria:
Clinical presentation:
Acute coronary-like syndrome
New onset or worsening unexplained heart failure
Chronic unexpected heart failure over 3 mo duration
Life-threatening unexplained conditions (including arrhythmias, aborted sudden death, cardiogenic shock)
Diagnostic criteria:
ECG/Holter/stress test shifts: Any degree atrioventricular block or bundle branch block, ST/T or Q wave changes, sinus arrest, cardiac arrest rhythms, low voltage, frequent premature beat or supraventricular tachycardia
Elevated cardiac troponins
Functional and structural abnormalities on cardiac imaging
Oedema and/or late gadolinium enhancement of myocarditis pattern in CMR

CMR: Cardiac magnetic resonance; ECG: Electrocardiogram.