Hyperemic stenosis resistance index for evaluation of functional coronary lesion severity

Area of Science:

• Cardiovascular physiology
• Interventional cardiology
• Diagnostic imaging

Background:

• Coronary blood flow velocity reserve (CFVR) and fractional flow reserve (FFR) assess coronary lesion severity.
• Discordant results between CFVR and FFR occur in 25-30% of intermediate lesions.
• A combined pressure and flow velocity index may enhance functional assessment.

Purpose of the Study:

• To evaluate the hyperemic stenosis resistance index (h-SRv) for assessing functional coronary lesion severity.
• To compare the predictive value of h-SRv against CFVR and FFR for reversible perfusion defects.

Main Methods:

• 151 angina patients underwent SPECT before cardiac catheterization.
• Coronary pressure and flow velocity were measured in 181 lesions (mean stenosis 56%).
• Hyperemia induced by adenosine; CFVR, FFR, and h-SRv calculated. h-SRv defined as (Aorta Pressure - Distal Pressure) / Peak Flow Velocity.

Main Results:

• Area under the curve (AUC) for h-SRv (0.90±0.03) was significantly higher than for CFVR (0.80±0.04) and FFR (0.82±0.03).
• Agreement with SPECT was higher for h-SRv (73%) compared to CFVR (49%) and FFR (51%) in discordant cases.
• h-SRv demonstrated superior predictive value for reversible perfusion defects.

Conclusions:

• The hyperemic stenosis resistance index (h-SRv) is a more powerful predictor of reversible perfusion defects than CFVR or FFR.
• h-SRv offers improved assessment of functional coronary lesion severity, particularly in cases with discordant CFVR/FFR results.