Classification of angina by pathophysiology
Angina with obstructive CAD | ||
Obstructive CAD | Flow limiting epicardial coronary artery disease* |
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Symptoms and/or signs of ischaemia but no obstructive CAD (INOCA) | ||
Microvascular angina†17 | 1. Symptoms of myocardial ischaemia |
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2. Absence of obstructive CAD* |
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3. Objective evidence of myocardial ischaemia |
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4. Coronary microvascular dysfunction |
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Vasospastic angina‡42 | Nitrate-responsive angina | At least one of:
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Ischaemic ECG changes |
During spontaneous episode, any one of the following in at least two contiguous leads:
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Coronary artery spasm |
Either spontaneously or in response to provocation (eg, acetylcholine):
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*The finding of obstructive epicardial disease does not exclude other important contributors to ischaemia (microvascular dysfunction and/or vasospasm). The physiological ischaemic lesion thresholds are drawn from 2018 ESC guidelines for myocardial revascularisation and randomised trials; however, the authors acknowledge that majority of lesions with grey-zone physiology values (eg, FFR 0.75–0.82) are not associated with downstream myocardial ischaemia (NCT02425969—Dr B Hennigan, Personal Correspondence).
†Definitive MVA is only diagnosed if all four criteria are present. Suspected MVA is diagnosed if criteria 1 and 2 are met but only one of the final two criteria are met (either objective evidence of ischaemia (criterion 3) or evidence of coronary microvascular dysfunction (criterion 4).
‡'Definitive vasospastic angina’ is diagnosed if nitrate-responsive angina is evident during spontaneous episodes and either the transient ischaemic ECG changes during the spontaneous episodes or coronary artery spasm criteria are fulfilled. ‘Suspected vasospastic angina’ is diagnosed if nitrate-responsive angina is evident during spontaneous episodes but transient ischaemic ECG changes are equivocal or unavailable and coronary artery spasm criteria are equivocal. NHPR (eg, iwFR, dPR).
CAD, coronary artery disease; CFR, coronary flow reserve; CFR, coronary flow reserve; dPR, diastolic pressure ratio; FFR, fractional flow reserve; HMR, hyperaemic microvascular resistance; IMR, index of microcirculatory resistance; MVA, microvascular angina; NHPR, non-hyperaemic pressure ratio.