atherothrombosis, coronary artery disease per se
without plaque disruption does not exclude type
2 MI. 1 Indeed, the mismatch between oxygen
supply and demand that defines type 2 MI often
occurs on the basis of underlying coronary artery
disease. 1 Potential causes of MI type 2 are acute
stressors including severe arrhythmias, severe
anaemia, severe hypertension or hypotension,
and respiratory failure. 1 Such stressors might
induce myocardial ischaemia in patients with
and without coronary artery disease, whereas
individual ischaemic thresholds differ depending
on the presence and severity of the underlying
coronary artery disease. 1 Besides the described
mechanistic stressors causing oxygen supply and
demand mismatch, coronary pathologies beyond
atherothrombosis, such as coronary artery
dissection, coronary spasm or coronary embolism,
might result in type 2 MI. 1
Type 3 MI
MI type 3 denotes the clinical scenario of cardiac
death with symptoms suggestive of myocardial
ischaemia and concomitant presumed new
ischaemic ECG changes or ventricular fibrillation,
but occurrence of death before blood samples for
cardiac biomarkers can be obtained. 1 Cardiac
death with proven MI by autopsy is also referred
to as type 3 MI. 1
Type 4 and 5 MI
Infarctions in the context of coronary procedures,
either percutaneous coronary intervention (PCI)
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or coronary artery bypass grafting (CABG), are
defined as type 4 or type 5 MI, respectively. 1
Type 4 MI refers to PCI-related infarcts,
whereas three subtypes (4a, 4b and 4c) have been
suggested in the Fourth Universal Definition of
MI. 1 Type 4a MI is defined as peri-procedural MI
directly related to the index PCI (≤48h after the
procedure). 1 The criteria of PCI-related MI are
arbitrarily defined as elevation of cTn values
>5-times the 99th percentile URL in cases of
normal baseline values, or increase of >20% in
cases of chronically elevated pre-procedural cTn
concentrations. 1 To allow for definite diagnosis
of 4a MI, objective parameters of myocardial
ischaemia are required in addition to cTn
dynamics. 1 Such clinical criteria of myocardial
ischaemia are new ischaemic ECG changes and
pathological Q waves, imaging evidence of new
loss of viable myocardium or new regional wall
motion abnormality as well as angiographic
findings of procedural flow-limiting complications
including coronary dissection, occlusion of an
epicardial artery, disruption of collateral flow
and distal embolisation. 1 Other subtypes of
MI associated with PCI are stent or scaffold
thrombosis (type 4b MI) and restenosis following
PCI (type 4c MI). 1 MI type 4b is defined as stent/
scaffold thrombosis as detected by angiography or
autopsy applying the same formal criteria as used
for MI type 1. 1 According to the timing of
thrombosis occurrence after the index PCI, it
should be distinguished between acute (0 to 24 h),
subacute (>24 h to 30 days), late (>30 days to 1