The additional prognostic value of coronary flow reserve on left anterior descending artery in patients with negative stress echo by wall motion criteria. A Transthoracic Vasodilator Stress Echocardiography Study

Background Vasodilator stress echocardiography allows imaging of left anterior descending (LAD) coronary flow reserve (CFR), which may provide additional prognostic information over regional wall motion. Aim To assess the prognostic value of CFR in patients with known or suspected coronary artery disease (CAD) and negative stress echo. Methods We studied 329 consecutive patients (193 men, age 61 ± 13 years) with known (n = 101) or suspected (n = 228) CAD and negative stress echo by standard wall motion criteria. All patients underwent dipyridamole (up to 0.84 mg/kg in 10 minutes) stress echo with CFR evaluation of LAD by Doppler. Results During follow-up (28 ± 10 months), 22 events occurred: 1 cardiac death, 6 nonfatal myocardial infarctions, 5 unstable anginas, and 10 late (>6 months) coronary revascularizations. Moreover, 9 patients underwent early (<6 months) revascularization and were censored. Using a receiver operating characteristic analysis, CFR ≤1.92 was the best predictor of future events (area under the curve = 0.80, sensitivity = 77%, specificity = 85%) and was taken as criterion for reduced CFR accordingly. Sixty-three (19%) patients had reduced and 266 (81%) had normal CFR on LAD. The 36-month event-free survival was higher in patients with normal and lower in patients with reduced CFR (98% vs 64%, P < .0001). At Cox analysis, CFR of LAD (hazard ratio [HR] 16.52, 95% CI 5.76-47.40, P < .0001), left ventricular mass index (HR 1.03 per unit increment, 95% CI 1.00-1.05, P = .01), and smoking habit (HR 3.00, 95% CI 1.24-7.23, P = .01) were independent prognostic indicators. Using an interactive stepwise procedure, CFR on LAD provided additional prognostic information to clinical, resting echo, and angiographic findings. Conclusions In patients with known or suspected CAD and negative stress echocardiography by wall motion criteria, CFR provides independent information for prognostic stratification, and a reduced CFR is associated with a less benign long-term outcome.