The RFR-FFR gradient: A novel predictor of preprocedural microvascular dysfunction and mortality

Area of Science:

• Cardiology
• Interventional Cardiology
• Vascular Physiology

Background:

• Fractional flow reserve (FFR) is the gold standard for assessing coronary artery stenosis.
• Non-hyperemic pressure ratios (NHPRs), like resting full-cycle ratio (RFR), offer less invasive alternatives.
• NHPR-guided percutaneous coronary intervention (PCI) has been linked to inferior outcomes, prompting investigation into novel metrics.

Purpose of the Study:

• To investigate the clinical significance of the difference between RFR and FFR (RFR-FFR).
• To determine if RFR-FFR can predict long-term outcomes in patients undergoing elective PCI for chronic coronary syndrome.

Main Methods:

• Retrospective analysis of 460 patients with chronic coronary syndrome undergoing FFR-guided elective PCI.
• Functional assessment of the left anterior descending artery using both RFR and FFR.
• Stratification of patients into tertiles based on RFR-FFR values, with all-cause death as the primary endpoint.

Main Results:

• Patients in the lowest RFR-FFR tertile had a higher-risk profile, including older age, female sex, and greater comorbidity burden.
• Evidence of microvascular dysfunction was more prevalent in the lowest RFR-FFR tertile.
• A lower RFR-FFR value independently predicted a higher rate of all-cause death during a median follow-up of 5.2 years.

Conclusions:

• A lower RFR-FFR value serves as a marker for increased comorbidities and microvascular dysfunction.
• This metric correlates with poorer long-term clinical outcomes in patients with chronic coronary artery disease.
• The RFR-FFR metric shows potential for risk stratification and personalized treatment strategies in LAD PCI.