Abstract
Background
Coronary flow velocity reserve (CFVR) of left anterior descending artery is useful for risk stratification during stress echocardiography (SE) as an add-on to regional wall motion abnormalities (RWMA), but the age-and sex-dependence of prognostic cutoff values remains unclear.
Purpose
To provide sex and age-specific prognostic cut-off values which may be needed to account for the physiologic decline of CFVR with age, and sex-related differences in resting flow.
Methods
In an observational, prospective, multicenter, registry study design, we enrolled from August 2003 to August 2017 in 4 Italian cardiology referral centers with accredited, quality-controlled stress echo laboratory a consecutive sample of 5,577 patients (of them, 2,284 women and 110 aged ≥85 years) referred to the SE lab for known or suspected coronary artery disease, after exclusion of patients with inadequate acoustic window (n=295), premature test interruption (n=105), and lost to follow-up (n=173).All underwent dual imaging (RWMA and CFVR) dipyridamole SE (0.84 mg/kg over 6') and were followed-up. All-cause death and non-fatal myocardial infarction were the main outcome measures. Median follow-up of 20 months (1st quartile 8, 3rd quartile 43 months),
Results
There were 649 hard events (236 deaths and 413 non-fatal myocardial infarctions), 288 of which occurred in women and 38 in patients ≥85 years. With a ROC analysis, the best prognostic cut-off value for CFVR was almost the same for men (2.03) and women (2.02) and consistent across all age strata (<45 years: 2.03; 45–54 years: 2.04; 45–64 years: 2.03; 65–74 and 75–84 years: 2.0) except for the very elderly (>85 years) who showed an optimal value of 1.90. Independent prognostic indicators were RWMA (HR=5.42, 95% CI=2.42–12.15; p<0.0001) and reduced CFVR (HR=3.26, 95% CI 2.27–3.90; p<0.0001) in patients aged <85 years, and RWMA (HR=5.42, 95% CI=2.42–12.15; p<0.0001) in patients aged >85 years.
Best prognostic cut-off value of CFVR
Conclusion
A sex-independent cut-off value of CFVR ≤2.0 provides the optimal risk stratification across all age groups, except those >85 years in whom a lower cut-off <1.90 is needed. Risk stratification is more effective for all age groups when CFVR is combined with RWMA.
Prognostic value of heart rate reserve is additive to coronary flow velocity reserve during dipyridamole stress echocardiography
