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Prognostic Value of PET-Derived Myocardial Flow Reserve in Patients With Very High Coronary Artery Calcium Score
Mahmoud Al Rifai1, Maria Alwan1, Ahmed Ibrahim Ahmed1,2
1Houston Methodist DeBakey Heart and Vascular Center, TX (M.A.R., M.A., A.I.A., T.A., M.H.A.-M.).
Insights
Patients with very high coronary artery calcium (CAC) scores benefit from assessing myocardial flow reserve (MFR). Higher MFR (≥2) is linked to reduced risk of death and heart attack in this high-risk group.
Area of Science:
- Cardiology
- Medical Imaging
- Preventive Cardiology
Background:
- Coronary artery calcium (CAC) is a key cardiovascular risk predictor.
- Extremely high CAC (≥1000) signifies a distinct high-risk population.
- Myocardial flow reserve (MFR) is an emerging prognostic marker.
Purpose of the Study:
- To assess the prognostic value of MFR in patients with very high CAC (≥400).
- To determine if MFR can further stratify risk in patients with elevated CAC scores.
Main Methods:
- Prospective study of 3091 patients undergoing positron emission tomography.
- Utilized multivariable-adjusted Cox proportional hazards models.
- Assessed association between MFR and incident cardiovascular events (death, myocardial infarction) in patients with CAC ≥400.
Main Results:
- A total of 278 events occurred during follow-up.
- MFR ≥2 was inversely associated with lower event risk.
- Hazard ratios for MFR ≥2 were 0.65 (CAC 400-999) and 0.44 (CAC ≥1000).
Conclusions:
- Positron emission tomography-derived MFR ≥2 is inversely associated with adverse outcomes in patients with CAC ≥400.
- MFR provides prognostic information in patients with very high CAC.
- MFR may aid in risk stratification for secondary prevention populations.
Background:
Coronary artery calcium (CAC) is a strong predictor of cardiovascular outcomes, with patients having high CAC experiencing event rates similar to those in secondary prevention populations. Emerging evidence suggests that patients with extremely high CAC (≥1000) represent a distinct high-risk group. Therefore, this study aims to evaluate the prognostic value of myocardial flow reserve (MFR) in patients with very high CAC.
Methods:
Consecutive patients who had a clinically indicated positron emission tomography were enrolled and followed prospectively for incident outcomes (all-cause death and myocardial infarction). Multivariable-adjusted Cox proportional hazards models were used to study the association between MFR and incident events (composite of all-cause death and myocardial infarction) among those with CAC ≥400.
Results:
The study population consisted of 3091 patients; mean (SD) age 69.6 (10.1) years, 36.8% female, 64.5% White, 46.0% with a CAC score of 400 to 999, and 54.0% with a CAC score of ≥1000. The median (interquartile range) MFR was 1.9 (1.45-2.35). Over a median (interquartile range) follow-up time of 1.36 (0.45-2.50) years, there were 278 incident events (81 myocardial infarctions and 217 deaths). In adjusted analyses, an MFR ≥2 was inversely associated with a lower risk of incident events; hazard ratio, 0.65 (95% CI, 0.38-1.12) for a CAC score of 400 to 999 and hazard ratio, 0.44 (95% CI, 0.28-0.69) for a CAC score of ≥ 1000. There was no significant interaction between MFR and CAC score; P=0.53.
Conclusions:
Among patients with CAC ≥400, positron emission tomography-derived MFR ≥2 is inversely associated with a lower risk of all-cause death and myocardial infarction.
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