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Updated: May 28, 2026
Evaluation of Coronary Flow Reserve After Myocardial Ischemia Reperfusion in Rats
Published on: June 28, 2019
Improved cardiac risk assessment with noninvasive measures of coronary flow reserve
Venkatesh L Murthy1, Masanao Naya, Courtney R Foster
1Division of Cardiovascular Medicine, Department of Medicine, Brigham & Women's Hospital, Boston, MA 02115, USA.
Insights
Noninvasive coronary vasodilator function assessment using positron emission tomography significantly predicts cardiac death risk. This method offers improved risk stratification for patients with coronary artery disease.
Area of Science:
- Cardiology
- Nuclear Medicine
- Diagnostic Imaging
Background:
- Impaired vasodilator function is an early sign of coronary artery disease (CAD), potentially preceding detectable stenosis.
- The prognostic value of noninvasively assessed coronary vasodilator function in patients with suspected or known CAD was previously unknown.
Purpose of the Study:
- To determine if noninvasive assessment of coronary vasodilator function provides incremental prognostic significance in patients with suspected or known CAD.
Main Methods:
- 2783 patients undergoing rest/stress positron emission tomography (PET) were followed for a median of 1.4 years.
- Coronary flow reserve (CFR) was calculated from rest and stress myocardial blood flow.
- Cardiac death was the primary endpoint, with risk assessed using Cox proportional hazards models and reclassification metrics.
Main Results:
- Low coronary flow reserve (<1.5) was linked to a 5.6-fold increased risk of cardiac death.
- Incorporating CFR into risk models improved predictive accuracy (c-index increased from 0.82 to 0.84, P=0.02).
- CFR correctly reclassified 34.8% of intermediate-risk patients, significantly improving risk assessment.
Conclusions:
- Quantitative, noninvasive assessment of coronary vasodilator function via PET is a potent, independent predictor of cardiac mortality.
- This PET-derived measure offers meaningful incremental risk stratification beyond clinical factors and myocardial perfusion imaging.
Background:
Impaired vasodilator function is an early manifestation of coronary artery disease and may precede angiographic stenosis. It is unknown whether noninvasive assessment of coronary vasodilator function in patients with suspected or known coronary artery disease carries incremental prognostic significance.
Methods And Results:
A total of 2783 consecutive patients referred for rest/stress positron emission tomography were followed up for a median of 1.4 years (interquartile range, 0.7-3.2 years). The extent and severity of perfusion abnormalities were quantified by visual evaluation of myocardial perfusion images. Rest and stress myocardial blood flows were calculated with factor analysis and a 2-compartment kinetic model and were used to compute coronary flow reserve (coronary flow reserve equals stress divided by rest myocardial blood flow). The primary end point was cardiac death. Overall 3-year cardiac mortality was 8.0%. The lowest tertile of coronary flow reserve (<1.5) was associated with a 5.6-fold increase in the risk of cardiac death (95% confidence interval, 2.5-12.4; P<0.0001) compared with the highest tertile. Incorporation of coronary flow reserve into cardiac death risk assessment models resulted in an increase in the c index from 0.82 (95% confidence interval, 0.78-0.86) to 0.84 (95% confidence interval, 0.80-0.87; P=0.02) and in a net reclassification improvement of 0.098 (95% confidence interval, 0.025-0.180). Addition of coronary flow reserve resulted in correct reclassification of 34.8% of intermediate-risk patients (net reclassification improvement=0.487; 95% confidence interval, 0.262-0.731). Corresponding improvements in risk assessment for mortality from any cause were also demonstrated.
Conclusion:
Noninvasive quantitative assessment of coronary vasodilator function with positron emission tomography is a powerful, independent predictor of cardiac mortality in patients with known or suspected coronary artery disease and provides meaningful incremental risk stratification over clinical and gated myocardial perfusion imaging variables.
