Study Design

WIFI II was a predefined prospective, observational, investigator-initiated Dan-NICAD substudy with paired assessment of QFR and pressure wire–based FFR. Patients with suspected coronary artery disease and indication for coronary computed tomographic angiography (CTA) evaluation were enrolled at 2 referring centers (Department of Cardiology, Hospitalsenheden Midt, Silkeborg, Denmark; and Department of Cardiology, Hospitalsenheden Vest, Herning, Denmark) between September 11, 2014, and March 31, 2016.¹⁴ Patients with stenosis identified by coronary CTA were referred for invasive coronary angiography (ICA) and formed the study population of WIFI II. Lesions with diameter stenosis (DS) of 30% to 90% in vessels with a reference diameter >2.0 mm by visual estimate entered the analyzed population. Angiographic and procedural exclusion criteria were (1) <2 projections with visible stenosis; (2) stenosis in the ostium of the right coronary artery or the left main coronary artery; (3) no administration of intracoronary nitrates; and (4) pressure wire position not documented angiographically. All patients provided informed written consent. The Danish Data Protection Agency and The Central Denmark Region Committees on Health Research Ethics approved the study. At least 2 authors (J.W. and N.R.H.) had access to all data presented. All authors are responsible for the data integrity. The study material will not be made available to other researchers for competitive reasons.