In recent years, thanks to the appearance of new endocoronary imaging techniques and new intracoronary measurements, abnormalities of the coronary microcirculation have been described, explaining symptoms hitherto of unknown cause reported by many patients.
Minoca, acute illness
The Minocas, for Myocardial infarction with non-obstructive coronary artery disease, are myocardial infarctions – i.e. acute situations, with pain, elevation of troponin, abnormal ECG – without any abnormality found on coronary angiography. This entity was identified around ten years ago, in 2013, using two types of imaging techniques: cardiac MRI, and endocoronary imaging (optical coherence tomography [OCT] Or intravascular ultrasound [IVUS]), which make it possible to observe phenomena of millimeter or micrometer size, invisible to coronary angiography. More precisely, four main etiologies of Minoca have been discovered:
– The most common (38 to 40% of patients with Minoca) concerns the rupture, erosion or fissure of an atherosclerotic plaque: a thrombus in formation, of extremely small size and visible only on endocoronary imaging, can migrate distally , in the coronary microvascularization, and cause microinfarctions.
– Other Minoca can be caused by spontaneous coronary dissection, itself due to the presence of a hematoma between the intima and the media of the artery, leading to a reduction in coronary flow and an infarction visible only on imaging coronary.
– Cases of Minoca may have the origin of vasospastic angina – with areas of focal necrosis visible on cardiac MRI after provocation test with acetylcholine or Merthergin.
– Finally, microvascular dysfunction may be involved.
In total, 5 to 10% of patients with heart attacks – mainly young and female – are affected. Until recently, these individuals could not benefit from a precise diagnosis and were often treated empirically. And this even though the annual mortality rate among subjects affected by Minoca reaches 2%, not counting the morbidity linked to a high risk of recurrence of heart attack, stroke, or the development of heart failure. Today, the diagnosis of Minoca and its etiology makes it possible to guide prevention (interventionist), and treatment – exclusively medicinal (double antiplatelet aggregation, statin, more or less an angiotensin II receptor antagonist), without angioplasty or stent implantation.
Inoca and Anoca, chronic diseases
More recently, over the past four to five years, two other new entities relating to chronic situations have emerged: the Inoca, for Ischemia with non-obstructive coronary artery disease and the Anoca, for Angina with non-obstructive coronary artery diseasewhich concern patients presenting symptoms of ischemic heart disease or angina, often atypical, with sometimes only blockpnea, asthenia or shoulder pain on exercise but, again, without any abnormality on coronary angiography.
These new diseases are still the subject of research using PET scan, cardiac MRI or even myocardial scintigraphy, but more invasive techniques – coronary angiography with microcirculation tests – have become routine to help diagnosis.
In fact, these invasive techniques make it possible to highlight two main types of microcirculation abnormalities: a lack of structural remodeling (with a reduction in the density of capillaries and their conductance), and a spasm of the microcirculation (linked to a arterial hypersensitivity, aggravated by cardiovascular risk factors such as smoking, diabetes, cannabis or cocaine consumption, etc.). Three main patient profiles can be found: those mainly having a structural remodeling defect, those mainly having microcirculation spasms, and a mixed profile.
In total, 40% of patients with angina could in fact be affected by Anoca. Here again, these are often young patients, often presenting cardiomyopathies – hypertrophic or dilated, associated with cardiovascular risk factors – who until now remained in diagnostic wandering, with a very impaired quality of life.
Difficulty accessing imagery
Treatment is based on management of risk factors (diabetes, hypertension, dyslipidemia), the introduction of low-dose aspirin and vasodilators – beta-blockers and calcium channel blockers in the case of microvascular angina, and calcium channel blockers alone. in case of microcirculatory spasm. Furthermore, cardiovascular rehabilitation appears fundamental.
Finally, if all these entities, and in particular the Minoca, seem to be better and better known, the diagnosis remains limited by the accessibility of examinations. For example, the delays in accessing a cardiac MRI are long, and endocoronary imaging, which is very expensive, is not reimbursed. Regardless, science is progressing, opening up prospects for improving these techniques in the years to come. And the search for new treatments is not left out, giving hope for progress in the management of symptoms and prognosis.
According to an interview with Dr Clément Servoz, interventional cardiologist at Toulouse University Hospital
