The present study evaluates skin microvascular reactivity and coronary physiology in the same coronary artery disease (CAD) patients.

This study is expected to find associations between systemic microvascular reactivity, measured non-invasively at the skin surface, and coronary reserve evaluated by the invasive angiographic method.

Introduction: Microvascular reactivity (MR) evaluated in the skin has been proposed as representative of systemic endothelial function, including coronary circulation. There is a lack of studies investigating the association between skin MR and invasive evaluation of coronary reserve. Objective: To evaluate skin MR and coronary physiology in the same coronary artery disease (CAD) patients. Methods: Transversal study, recruiting adult patients with indication for elective coronary angiographic study for the evaluation of CAD by an independent medical team. The evaluation of microvascular cutaneous blood flow of the forearm will use laser speckle contrast imaging (LSCI) coupled with acetylcholine iontophoresis. Coronary physiology will be evaluated in the same patients and in the same day with coronary angiography with lesion assessment by fractional flow reserve (FFR, after intracoronary adenosine administration) and contrast fractional flow reserve (cFFR, after intracoronary contrast media administration), with measurements of hyperemic intravascular pressures. FFR and cFFR will be performed in vessels with intermediate lesions, as evaluated in quantitative angiography. Expected results: This study is expected to find associations between systemic MR, measured non-invasively at the skin surface, and coronary reserve evaluated by the invasive angiographic method.

Inclusion Criteria:

• Patients with intermediate obstructive coronary artery disease (40-80% lumen obstruction of epicardial vessels or 30-60% obstruction of left main coronary artery).

Exclusion Criteria:

• ST elevation myocardial infarction in the first 72 hours of evolution.
• Allergy to contrast media or adenosine
• Asthma or chronic obstructive pulmonary artery disease diagnosis
• Ongoing acute coronary syndrome
• Systolic blood pressure under 90mmHg
• Baseline arrhythmias or advanced atrioventricular blockade
• Advanced arterial calcification
• Renal failure (defined as serum creatinine above 1.5mg/dl)
• Saphenous graft or mammary artery graft anastomosis stenosis
• Severe left ventricular systolic dysfunction.