The main objective is to prospectively validate the capacity of continuous thermodilution coronary flow reserve (CFRflow) as a predictor of the presence of angina measured by SAQ7 in patients with INOCA at 3 months. Secondary objectives include identifying hemodynamic factors related to the persistence of angina at 3 and 12 months, identifying clinical factors associated with the persistence of angina, establishing the prevalence of patients with coronary microvascular dysfunction within the cohort of INOCA patients, identifying predictors of major cardiovascular events at 12 months, validating the pathological value of MMR and establishing the pathological value of AF measured in ml/min. The study also aims to evaluate the concordance between measures of the coronary microvascular function obtained by continuous thermodilution and bolus thermodilution, as well as their concordance with clinical characteristics.

Invasive study of microvascular function has become highly relevant for the diagnosis of alterations in coronary physiology for diagnostic, prognostic, and therapeutic purposes. Currently, the microvascular resistance index (IMR) is considered the gold standard for invasive diagnosis of coronary microvascular function, with a recommendation of 2A in the current clinical practice guidelines of the European Society of Cardiology. In recent years, technical innovation has allowed for the measurement of absolute coronary flow (AF) and minimal microvascular resistance (MMR) using continuous thermodilution, enabling the determination of quantitative flow and resistance units. However, the main limitation is the absence of reference values.

Objectives:

The main objective is to prospectively validate the capacity of CFRflow as a predictor of the presence of angina measured by SAQ7 in patients with INOCA at 3 months. Secondary objectives include identifying hemodynamic factors related to the persistence of angina at 3 and 12 months, identifying clinical factors related to the persistence of angina, establishing the prevalence of patients with coronary microvascular dysfunction within the cohort of INOCA patients, identifying predictors of major cardiovascular events at 12 months, validating the pathological value of MMR and establishing the pathological value of AF measured in ml/min. The study also aims to evaluate the concordance between measures of the coronary microvascular function obtained by continuous thermodilution and bolus thermodilution, as well as their concordance with clinical characteristics.

Inclusion Criteria:

• Over 18 years of age, and
• Clinical indication for coronary angiography and in whom the use of microvascular function diagnosis by pressure guide is considered clinically necessary.
• Clinical diagnosis of typical or atypical angina.
• Coronary arteries without lesions or with epicardial lesions <50% by visual estimation or fractional flow reserve (FFR)>0.80.
• Absence of clinical or anatomical contraindications for the study of microvascular function.

Consent for participation in the study prior to information and consent form signature.

Exclusion Criteria:

• Decompensated heart failure or cardiogenic shock.
• Admission due to Acute Coronary Syndrome with an elevation of markers in the month prior to inclusion.
• Indication for coronary angioplasty.
• Severe pulmonary hypertension.
• Obstructive hypertrophic cardiomyopathy.
• Severe valvular disease.
• Previous allergy or intolerance to adenosine or adenosine triphosphate.

Consecutive patients with a clinical indication for diagnostic study of coronary microvascular function due to angina without obstructive coronary lesions.