Abstract 3708: Impact of Impaired Coronary Flow Reserve Evaluated by Transthoracic Doppler Echocardiography on Long-term Outcome in Patients With Coronary Risk Factors and Normal Coronary Artery
Background. Coronary flow reserve (CFR) is dependent on microvascular blood flow which reflects the combined effects of the epicardial coronary stenosis and microvascular dysfunction. Therefore, various coronary risk factors cause impaired CFR, even in the absence of coronary artery stenosis. However, its prognostic importance has not been fully discussed.
Purpose. To investigate whether impaired CFR without coronary stenosis is predictive of event-free survival in patients with various coronary risk factors.
Methods. In 101 patients without significant left anterior descending artery (LAD) stenosis, CFR was measured by transthoracic Doppler echocardiography (TTDE). The mean length of follow-up period was 61±18 months. Late cardiovascular events included cardiovascular death, myocardial infarction, stroke, and unstable/recurrent angina.
Results. Twenty-eight patients (28%) had cardiovascular events during follow-up period. Patients with cardiovascular events had lower CFR (2.9±0.6 vs 3.3±0.8) and higher prevalence of hypertension (79% vs 59%) than those without cardiovascular events (both p=0.04). Multivariate analysis revealed that CFR was the independent factor of cardiovascular events (p=0.04). The ROC curve provided CFR <3.0 as the best cut-off value predicting late cardiovascular events.
Conclusion. This study demonstrated that impaired CFR evaluated by TTDE was associated with late cardiovascular events in patients with various coronary risk factors and normal coronary artery. Close follow-up and strict control of coronary risk factors may be required in patients with CFR <3.0, in the presence of normal coronary artery.