The prognostic significance of coronary flow reserve in the risk stratification of patients with chronic total occlusion of the right coronary artery and the intermediary stenosis of the left coronary artery

Introduction: Coronary Flow Reserve (CFR) is a clinically useful, non-invasive diagnostic method for assessing the functional ability of coronary arteries and it is important for their long-term follow-up in patients. However, CFR has not always been sufficiently investigated in previous studies. Objective: To examine the prognostic significance of CFR in the risk stratification of patients with chronic total occlusion of the right coronary artery (RCA) and the intermediary stenosis of the left coronary artery (LAD). Material and Methods: Number of 71 patients, mean age 64 ± 7 years, (84%) patients male, having LAD stenosis, diameter 50-70%, and CTO of RCA, were referred for noninvasive estimation of functional significance of LAD stenosis. Transthoracic Doppler echocardiography was used to obtain coronary flow velocities in the distal segment of LAD. Patients were followed for the mean period of 18.3 ± 7.1 months for the occurrence of composite end point including cardiovascular death, myocardial infarction, bypass surgery and PCI. Results: During the follow-up period, there were a total of 23 adverse events (4 deaths, 2 myocardial infarction, 7 bypass surgeries and 10 PCI). Patients with CFR < 2 had significantly more adverse events (n = 9; 56.3% vs. n = 14; 25.5%; p = 0.021), they were significantly older (68 ± 9 vs. 62 ± 6; p = 0.011), with a higher incidence of a positive family history (14; 87.5% vs. 26; 47.3%; p = 0.039), as well as a significantly higher frequency of three-dose coronary disease (14; 87.5% vs. 30; 54.5%; p = 0.017). Using Kaplan-Meier estimator, we obtained that patients with CFR < 2 have a significantly shorter average period without unwanted event (15.4 ± 2.8 months vs 23.5 ± 1.1 months, Log Rank 7.407; p = 0.008). Conclusion: CFR plays an important role in stratifying the risk of patients with CTO of RCA and the intermediary stenosis of LAD.