Microvascular Resistance Reserve (MRR) derived from continuous thermodilution is a more accurate, specific, and reproducible index for detecting coronary microvascular dysfunction in ANOCA patients than traditional indices.
MRR is a novel, specific physiological index derived from continuous thermodilution that improves the diagnostic assessment of coronary microvascular dysfunction in patients with ANOCA.
In recent years, there have been numerous developments in the field of coronary physiology with the addition of new indices for the evaluation of the coronary microcirculation, such as invasive measurement of absolute coronary blood flow and microvascular resistance. This has resulted in more accurate diagnostic tools for patients with angina and no obstructive coronary artery disease (ANOCA), with the possibility to distinguish different endotypes of coronary microvascular dysfunction (CMD). Because of the growing recognition of ANOCA and, along with that, the increasing application of coronary function testing due to the latest guideline recommendations, it is timely and important to further explain the concept of absolute coronary flow, microvascular resistance, and the latest addition to the field: Microvascular Resistance Reserve (MRR). Differentiation between specific endotypes of CMD will help to develop tailored therapy for ANOCA patients.
Vos et al. (Thu,) conducted a review in Patients with angina and no obstructive coronary artery disease (ANOCA) undergoing coronary function testing for microvascular dysfunction assessment. Microvascular Resistance Reserve (MRR) assessed by continuous thermodilution measurements of absolute coronary blood flow and microvascular resistance vs. Coronary Flow Reserve (CFR) and Index of Microvascular Resistance (IMR) assessed by bolus thermodilution or Doppler methods was evaluated on Accuracy and specificity of Microvascular Resistance Reserve (MRR) for diagnosing coronary microvascular dysfunction. Microvascular Resistance Reserve (MRR) derived from continuous thermodilution is a more accurate, specific, and reproducible index for detecting coronary microvascular dysfunction in ANOCA patients than traditional indices.