MINOCA (Myocardial Infarction in the Absence of Obstructive Coronary Artery Disease)

Definition

MINOCA is a working clinical diagnosis applied to patients who meet the criteria for acute myocardial infarction (AMI) but have no obstructive coronary artery disease (stenosis <50% in any major epicardial vessel) on angiography and no clinically overt alternate explanation for the presentation. It should prompt active investigation into the specific underlying mechanism.

Nomenclature changed in 2026. The Fifth Universal Definition redefines MINOCA as "myocardial injury with non-obstructive coronary arteries" and frames it explicitly as a working diagnosis rather than a final one: most such patients turn out to have a non-coronary cardiac cause (myocarditis, Takotsubo, cardiomyopathy) or a non-cardiac cause such as pulmonary embolism, and MI is the final diagnosis in only 22%–27% once CMR is applied. The AHA 2019 framing of MINOCA as an ischaemic diagnosis is therefore superseded for nomenclature, though the diagnostic pathway it defined remains in use; a subsequently confirmed MI is reclassified as primary, secondary or procedure-related. (sources/5thMI-AHA-2026, rating: very high)

Key Concepts

Diagnostic Criteria (AHA 2019)

Three criteria must all be met sources/minoca-aha-2019 (high):

1. AMI per 4th Universal Definition: rise/fall of cTn with ≥1 value >99th percentile + corroborative clinical evidence (symptoms, ischemic ECG changes, new wall motion abnormality, or coronary thrombus)
2. Nonobstructive coronaries: no stenosis ≥50% in any major epicardial vessel (includes normal arteries, <30% irregularities, 30–49% moderate stenosis); FFR >0.80 in borderline lesions retains MINOCA classification
3. No specific alternate diagnosis: excludes sepsis, PE, myocarditis, takotsubo (latter categorised separately per 4th Universal MI Definition)

Epidemiology

• Prevalence 5–6% of angiography-referred AMI patients; range 5–15% across populations sources/minoca-aha-2019 (high)
• Disproportionately affects women (~50% of MINOCA vs ~25% in AMI-CAD; women >2× more likely than men to have MINOCA)
• Younger age: mean 58 years vs 61 years in AMI-CAD
• Higher prevalence in Black, Maori, Pacific, and Hispanic populations
• Lower traditional CAD risk factor burden than AMI-CAD
• SCAD and MINOCA are prevalent causes of MI in pregnancy, accounting for the majority of ischemic events alongside atherosclerosis sources/cv-pregnancy-aha-2020 (high)

Traffic Light Diagnostic Algorithm

Three sequential decision steps sources/minoca-aha-2019 (high):

• Red — exclude overt mimics: clinically obvious nonischemic causes (sepsis, PE, myocarditis) → not MINOCA
• Yellow — exclude subtle mimics: (a) re-review angiogram for overlooked obstructive disease or SCAD; (b) CMRI to exclude myocarditis, takotsubo, cardiomyopathies; (c) intracoronary OCT/IVUS if any angiographic atherosclerosis present
• Green — MINOCA confirmed: working diagnosis established; mechanistic testing in specialized centres (provocative spasm testing, microvascular function testing, thrombophilia panel)
• CMRI strongly recommended but absence of necrosis does not exclude MINOCA (some MINOCA patients have no visible necrosis on CMR)

Six Mechanistic Causes

See concepts/Coronary-Vasospasm and concepts/Coronary-Microvascular-Dysfunction for detailed mechanistic pages.

Medical Management — SWEDEHEART Registry Data

Stratified propensity analysis, n=9,138, mean follow-up 4.1 years sources/minoca-aha-2019 (high):

• Statins: HR 0.77 (95% CI 0.68–0.87) — significant reduction in composite MACE
• ACE inhibitors/ARBs: HR 0.82 (95% CI 0.73–0.93) — significant reduction
• β-blockers: HR 0.86 (95% CI 0.74–1.01) — trend, not significant; contraindicated in coronary vasospasm
• Dual antiplatelet therapy: HR 0.90 (95% CI 0.74–1.08) — no significant benefit
• Secondary prevention medications should be individualised by underlying cause, not applied uniformly as in AMI-CAD
• MINOCA-BAT RCT (n≥3,500): prospective evaluation of ACEi/ARBs ± β-blockers — results awaited at time of 2019 statement

Prognosis

• Better than AMI-CAD but not benign sources/minoca-aha-2019 (high):
  • In-hospital mortality 0.9–1.1% (ACTION-GWTG, meta-analysis)
  • 12-month mortality 4.7% (meta-analysis)
  • 4-year mortality 13.4%; re-MI 7.1%; ischemic stroke 4.3%; HF hospitalization 6.4% (SWEDEHEART)
• ~25% develop angina within 12 months (similar frequency to AMI-CAD)
• VIRGO study: similar 1-month and 1-year mortality rates to AMI-CAD in young patients
• ST-elevation and shock/HF presentation are more strongly predictive of in-hospital death in MINOCA than in AMI-CAD

Contradictions / Open Questions

• Prognosis heterogeneity: VIRGO and Korean Infarct Registry show comparable outcomes to AMI-CAD; most registries suggest better outcomes — population differences (age, sex, cause mix) likely explain discrepancy sources/minoca-aha-2019 (high)
• DAPT uncertainty: SWEDEHEART showed no DAPT benefit in the overall MINOCA cohort, but this analysis did not isolate plaque disruption cases where DAPT is theoretically justified — evidence gap sources/minoca-aha-2019 (high)
• Microvascular dysfunction as cause vs consequence: inducible perfusion defects present in 2/3 of female MINOCA patients on stress CMR, but these occur with any cause of myocardial oedema (including myocarditis) — directionality unresolved sources/minoca-aha-2019 (high)
• FFR threshold: whether all 30–49% stenoses should undergo FFR measurement in MINOCA workup is unresolved; up to 25% of 30–50% stenoses have functionally significant FFR in stable patients sources/minoca-aha-2019 (high)

Connections

• Related to concepts/Coronary-Vasospasm — vasospasm is the most common single cause in provocative testing series
• Related to concepts/Coronary-Microvascular-Dysfunction — overlapping diagnosis; MINOCA is distinct from INOCA (stable ischemia without infarction)
• Related to concepts/Late-Gadolinium-Enhancement — CMR LGE used to confirm necrosis and exclude myocarditis/cardiomyopathy in MINOCA workup
• Related to concepts/Myocardial-Viability — wall motion abnormality pattern on imaging is part of MINOCA AMI diagnostic criteria
• Related to entities/SCAD — SCAD is a key nonatherosclerotic MINOCA cause; especially in women <50 and in pregnancy

Sources

• sources/cv-pregnancy-aha-2020
• sources/minoca-aha-2019