Acute coronary obstruction in ST-segment elevation myocardial infarction (STEMI) is not necessarily atherothrombotic: intraplaque haemorrhage and the resulting intra-adventitial haematoma may also be implicated, spreading longitudinally along the coronary artery, dissecting the tunicae, especially if the adjacent arterial segments are normal. Such dissecting haematoma may appear on the angiogram with or without associated intimal tearing. When there is no intimal tear, angiographic diagnosis is difficult, although the length, filiform and tubular aspect of the obstruction with long abrupt change in arterial diameter may be suggestive, notably in women less than 50 years of age. Signs specific to this STEMI aetiology, however, can be detected on intravascular ultrasound (IVUS) or optical coherence tomography (OCT), on which the aspect is characteristic and pathognomic.
In case of positive diagnosis, any intervention, especially with primary stenting, is to be delayed for as long as the mechanism and segment length involved preclude a good angiographic and functional result. Sometimes, angioplasty is performed using only a small balloon at low pressure (4 bars), maintained (3 min) to redistribute the haematoma until Thrombolysis In Myocardial Infarction (TIMI) flow grade 3 is achieved. The haematoma should be allowed to achieve spontaneous resorption by reducing antiplatelets and stopping anticoagulants, with control coronary angiography at D3–5 to allow discharge at a subsequent control at 2 months to check the final evolution and correct any residual obstruction.
We report two cases of STEMI, illustrating the process of diagnosing dissecting haematoma, with and without intimal tear, and their evolutions ( Figs. 1 and 2 ). Both forms were induced by the same haemorrhagic mechanism: haematoma, lacerating the coronary arterial wall, complicating nascent atherosclerosis. When such a mechanism is detected, as it should be on IVUS or OCT, the appropriate approach should not be systematic stenting but rather to allow spontaneous resorption by reducing antiplatelets and stopping anticoagulants, with invasive check-up at 2 months.
