MINOCA and INOCA: Twin Aspects of a Cardio Conundrum

MINOCA and INOCA: Twin Aspects of a Cardio Conundrum

The National Institutes of Health (NIH) recently reported MINOCA (myocardial infarction with non-obstructive coronary arteries) and INOCA (ischemia with non-obstructive coronary arteries) as non-conventional presentations of coronary syndromes that are increasingly recognized in the clinical arena, particularly with the availability of new cardiovascular imaging techniques. Both are related to heart failure (HF). MINOCA is not associated with benign outcomes, and HF is among the most prevalent events.

Regarding INOCA, microvascular dysfunction has also been found to be associated with HF, particularly with preserved ejection fraction (HFpEF).

The new Oct. 1 code set includes codes for the general condition of “CMD-Coronary Microvascular Dysfunction” and the symptoms and other conditions it can cause. This may be new to you, or you may have already seen this terminology in your facility.

Coronary microvascular dysfunction (or CMD) refers to the “microvasculature” (tiniest blood vessels) of the heart, which supply blood flow to the heart. CMD restricts the blood flow to the myocardium and increases the resistance in the microvasculature. The microvasculature can be as small as a human hair, and cannot be assessed with a cardiac catheterization. This tiny network of vessels is downstream from the epicardial vessels, which are larger and well-known, such as the left anterior descending artery and right coronary artery (which can be seen with a cardiac catheterization).

When a patient presents with symptoms with diagnostic evidence of angina, ischemia, or myocardial infarction, and a cardiac catheterization is performed that shows no blockages in the larger epicardial vessels, it may be that the blockage or other problem is in the microscopic vessels that cannot be seen during the cardiac catheterization.

INOCA is defined as patients with angiographic evidence of ischemia, but no obstructive coronary artery disease (CAD) at coronary angiography. The prevalence of INOCA has increased over the past decade and is estimated to affect 3-4 million individuals, with a female predominance. This condition has been associated with increased adverse clinical outcomes, recurrent hospitalization, additional procedures, decline in quality of life, and mortality, as compared to healthy individuals.

MINOCA is increasingly being recognized as a leading cause of ischemic heart disease (IHD). Notwithstanding the increasing interest, MINOCA remains a puzzling clinical entity that can be classified by distinguishing different underlying mechanisms, which can be divided into atherosclerotic and non-atherosclerotic categories. In particular, coronary microvascular dysfunction (CMD), classifiable in non-atherosclerotic mechanisms, is a leading factor with MINOCA.

Genetic susceptibility may have a role in CMD. However, few results have been obtained for understanding the genetic mechanisms underlying CMD. Future studies are essential to find a deeper understanding of the role of multiple genetic variants in the genesis of microcirculation dysfunction.

The major difference between MINOCA and INOCA is that the former requires evidence of acute myocardial infarction, and at the same time, angiographic proof of non-occlusive coronary disease. With new codes for 2024, we will be contributing to the data available to monitor this condition and support further research of innovative treatment modalities.

Look for documentation to indicate CMD as the cause of any of these conditions.

The new coding for CMD and the related conditions include:

  • New code-I20.81- Angina pectoris with coronary microvascular dysfunction
INOCA-Ischemia with non-obstructive coronary arteries
  • New code-I24.81-Acute coronary microvascular dysfunction 
  • New code-I25.85-Chronic coronary microvascular dysfunction
DOCUMENTATION GUIDANCE-Educate physicians to document acute or chronic.
  • Code I24.8-Other forms of acute ischemic heart disease were expanded to I24.89 to accommodate the addition of a fifth character to Category I24.8             
MINOCA-Myocardial infarction with non-obstructive coronary arteries
  • New code I21.B- Myocardial infarction with coronary microvascular dysfunction (Myocardial Infarct with non-obstructed Coronary Arteries-MINOCA)

Remember that there is other documented evidence that a patient had a myocardial infarction, such as chest pain, high-sensitivity troponin elevation trend, and EKG evidence when the cardiac catheterization is not conclusive for the myocardial infarction by a blockage in the larger vessels.

For visual images, this URL may be of interest:https://medicaldialogues.in/cardiology-ctvs/news/tmt-has-limited-sensitivity-to-detect-coronary-microvascular-disease-finds-study-83073 Go to images.

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