Which medication is preferred for a patient, considering efficacy, safety, and medical history?

ANOCA vs MINOCA vs INOCA: Definitions and Clinical Distinctions

These are three distinct clinical entities describing different presentations of myocardial ischemia or infarction in the absence of obstructive coronary artery disease, each requiring different diagnostic and therapeutic approaches.

Core Definitions

MINOCA (Myocardial Infarction with Non-Obstructive Coronary Arteries)

• Acute myocardial infarction with angiographically confirmed absence of obstructive coronary disease (typically <50% stenosis in all major epicardial vessels) 1
• Requires evidence of myocardial injury with elevated cardiac biomarkers (troponin) and clinical features consistent with acute MI 1
• Represents approximately 6-8% of all acute MI presentations 1

INOCA (Ischemia with Non-Obstructive Coronary Arteries)

• Chronic stable angina or angina-equivalent symptoms with objective evidence of myocardial ischemia on stress testing 1
• Angiography demonstrates no obstructive coronary disease 1
• Encompasses coronary microvascular dysfunction and/or vasospastic angina as underlying mechanisms 1
• Patients have recurrent symptoms but no acute myocardial necrosis 1

ANOCA (Angina with Non-Obstructive Coronary Arteries)

• Anginal chest pain without objective evidence of ischemia on non-invasive testing 1
• No obstructive disease on angiography 1
• Represents the broadest category, including patients whose symptoms may not have a clear ischemic basis 1

Key Distinguishing Features

Acute vs Chronic Presentation

• MINOCA is acute: Presents as ST-elevation MI (STEMI) or non-ST-elevation MI (NSTEMI) with troponin elevation 1
• INOCA is chronic: Recurrent stable symptoms with positive stress test but normal troponins at baseline 1
• ANOCA is chronic: Symptoms without documented ischemia on testing 1

Biomarker Status

• MINOCA: Elevated troponin required for diagnosis 1
• INOCA: Normal troponin at baseline, but positive ischemia on functional testing 1
• ANOCA: Normal troponin and negative or equivocal stress testing 1

Diagnostic Approach

For MINOCA

• Confirm acute MI criteria with troponin elevation and ECG changes or imaging evidence of new wall motion abnormality 1
• Coronary angiography showing <50% stenosis in all vessels 1
• Exclude alternative diagnoses: myocarditis, takotsubo cardiomyopathy, pulmonary embolism 1
• Consider cardiac MRI to identify myocarditis or infarction pattern 1
• Evaluate for coronary dissection, plaque rupture, or thromboembolism with intravascular imaging if available 1

For INOCA

• Document anginal symptoms with positive stress test (exercise ECG, stress echo, or nuclear imaging showing reversible ischemia) 1
• Angiography demonstrating non-obstructive disease 1
• Invasive coronary function testing is the gold standard: measure coronary flow reserve (CFR <2.0 indicates microvascular dysfunction) and assess for vasospasm with acetylcholine provocation 1

For ANOCA

• Anginal symptoms with negative or non-diagnostic stress testing 1
• Non-obstructive coronary disease on angiography 1
• Consider alternative causes: esophageal disorders, musculoskeletal pain, anxiety 1

Management Differences

MINOCA Treatment

• Antiplatelet therapy: Aspirin 75-325 mg daily plus consider P2Y12 inhibitor (clopidogrel 75 mg daily) for dual antiplatelet therapy, particularly if plaque disruption or thrombosis identified 1
• Statin therapy: High-intensity statin (rosuvastatin 20-40 mg or atorvastatin 40-80 mg daily) regardless of LDL level 1
• ACE inhibitor or ARB: Particularly if LV dysfunction present (start losartan 25-50 mg daily or equivalent) 1, 2
• Beta-blocker: If LV dysfunction or ongoing ischemia (metoprolol succinate 50-200 mg daily) 1
• Address underlying mechanism: anticoagulation if thromboembolism, immunosuppression if myocarditis 1

INOCA Treatment

• Antianginal medications:
  • First-line: Beta-blockers (metoprolol 50-200 mg daily) or calcium channel blockers (amlodipine 5-10 mg daily for microvascular dysfunction; diltiazem or verapamil for vasospasm) 1
  • Second-line: Long-acting nitrates, ranolazine, or ivabradine 1
• Aspirin 75-325 mg daily for atherosclerotic risk reduction 1
• Statin therapy based on ASCVD risk (moderate-to-high intensity) 1
• ACE inhibitor or ARB may improve microvascular function 1, 2
• Risk factor modification: Aggressive blood pressure control (<130/80 mmHg), smoking cessation, diabetes management (HbA1c <7%) 1

ANOCA Treatment

• Exclude cardiac ischemia as primary cause before attributing symptoms to non-cardiac etiology 1
• If microvascular dysfunction suspected despite negative stress test, consider empiric trial of antianginal therapy (beta-blocker or calcium channel blocker) 1
• Address cardiovascular risk factors with lifestyle modification and appropriate pharmacotherapy 1
• Consider referral for further evaluation if symptoms persist or worsen 1

Common Pitfalls to Avoid

• Do not assume benign prognosis: All three conditions carry increased cardiovascular risk compared to asymptomatic individuals, with MINOCA having similar long-term mortality to obstructive MI 1
• Do not withhold evidence-based therapies: Patients with MINOCA and INOCA benefit from guideline-directed medical therapy including antiplatelet agents, statins, and ACE inhibitors/ARBs 1
• Do not skip invasive coronary function testing in INOCA: Without CFR measurement and vasospasm provocation, the underlying mechanism remains unclear and treatment is empiric 1
• Do not dismiss ANOCA as "non-cardiac": These patients warrant thorough evaluation and may have undetected microvascular dysfunction 1

Prognostic Implications

• MINOCA: 1-year mortality approximately 3-5%, with recurrent MI risk of 5-10% 1
• INOCA: Increased risk of major adverse cardiovascular events (MACE) with 5-year event rate of 10-20% 1
• ANOCA: Prognosis depends on underlying etiology; cardiovascular risk intermediate between INOCA and general population 1