Coronary microvascular dysfunction endotypes: IMR tips and tricks.

Coronary microvascular dysfunction (CMD) is an important clinical disease spectrum which has gained widespread attention due to chronic anginal symptoms, and worse clinical outcomes, with or without obstructive coronary artery disease (CAD). Coronary microcirculatory dysfunction is due to a wide array of mechanisms such as inflammation, platelet aggregation, vessel wall collagen deposition, imbalance of nitric oxide, free radicals, and sympathetic/parasympathetic simulation. As noted in this supplement, CMD can occur as a primary disease or co-exist with multi-array of diverse cardiac conditions such as CAD (old infarct), hypertrophic cardiomyopathy, Takotsubo cardiomyopathy, hypertension, or infiltrative diseases. CMD, which is often under diagnosed, leads to increase in medical expenses, decrease in quality of life, exacerbation of underlying conditions such as heart failure and even increased mortality. CMD presents a challenge for patients as well as physicians to manage. Here, we review CMD and focus on its endotypes, techniques for microcirculatory assessment, associated tips and tricks and available treatment options.