Age‐related changes in the coronary microcirculation influencing the diagnostic performance of invasive pressure‐based indices and long‐term patient prognosis

OBJECTIVES: Investigate age-related changes in coronary microvascular function, its effect on hyperemic and non-hyperemic indices of stenosis relevance, and its prognostic implications. BACKGROUND: Evidence assessing the effect of age on fractional flow reserve (FFR), resting mean distal intracoronary pressure/mean aortic pressure (Pd/Pa), and microcirculatory function remains scarce. METHODS: This is a post hoc study of a large prospective international registry (NCT03690713) including 1134 patients (1326 vessels) with coronary stenoses interrogated with pressure and flow guidewires. Age-dependent correlations with functional indices were analyzed. Prevalences of FFR, resting Pd/Pa, and coronary flow reserve (CFR) classification agreement were assessed. At 5 years follow-up, the relation between resting Pd/Pa, CFR, and their age-dependent implications on FFR-guided percutaneous coronary intervention (PCI) deferral (deferred if FFR > 0.80) were investigated using vessel-oriented composite outcomes (VOCO) composed of death, myocardial infarction, and repeated revascularization. RESULTS: Age correlated positively with FFR (r = 0.08, 95% confidence interval CI: 0.03 to 0.13, p = 0.005), but not with resting Pd/Pa (r = -0.03, 95% CI:-0.09 to 0.02, p = 0.242). CFR correlated negatively with age (r = -0.15, 95% CI: -0.21 to -0.10, p 0.80, CFR and resting Pd/Pa have an incremental value in predicting future vessel-oriented patient outcomes.