Microvascular Resistance Reserve vs Coronary Flow Reserve to Assess Age-Related Trends in Coronary Microvascular Dysfunction

Structural CMD increases with age regardless of obstructive CAD, while functional CMD prevalence increases only in nonobstructive CAD. CFR may overestimate CMD in epicardial disease, whereas MRR provides a more consistent assessment regardless of obstructive CAD, underscoring the need for prospective studies on their clinical relevance.