Diagnostic and prognostic value of Doppler echocardiographic coronary flow reserve in the left anterior descending artery

Background Vasodilator stress echocardiography allows dual imaging of regional wall motion and coronary flow reserve (CFR) on left anterior descending (LAD) artery. Hypertension may affect CFR independently of obstructive coronary artery disease (CAD) through coronary microcirculatory damage. Aims The authors sought to determine the best value of Doppler-echocardiography-derived coronary flow reserve (CFR) for detecting ≥75% stenosis of the left anterior descending artery (LAD) and assessing the risk in patients with and without hypertension. Participants The study group was formed by 2089 patients (1411 hypertensive patients and 678 normotensive patients) with known or suspected coronary artery disease who underwent dipyridamole (up to 0.84 mg/kg over 6 min) stress echo with CFR assessment of LAD by Doppler and coronary angiography. Results Mean CFR was 2.20±0.62 in hypertensive patients and 2.36±0.70 in normotensive patients (p<0.0001). A significant LAD stenosis was present in 376 (18%) cases. With a receiver operating characteristic analysis, a CFR ≤1.91 was the best value for diagnosing LAD stenosis in both hypertensive patients (area under curve 0.86 (95% CI 0.84 to 0.88), sensitivity 87% (95% CI 82% to 91%), specificity 76% (95% CI 73% to 78%)) and normotensive patients (area under curve 0.90 (95% CI 0.88 to 0.92), sensitivity 89% (95% CI 81% to 95%), specificity 80% (95% CI 77% to 83%)). During a median follow-up of 15 months, there were 348 events (58 deaths, 79 ST elevation myocardial infarctions and 211 non-ST elevation myocardial infarctions). Multivariable prognostic indicators were age (HR=1.0; 95% CI 1.0 to 1.04), test positivity for wall motion criteria (HR=5.9; 95% CI 3.6 to 9.6) and CFR on LAD ≤1.91 (HR=3.4; CI 95% 2.0 to 5.6) in normotensive patients and previous myocardial infarction (HR=1.3; 95% CI 1.0 to 1.7), test positivity for wall motion criteria (HR=5.0; 95% CI 3.8 to 6.6) and CFR on LAD ≤1.91 (HR=3.1; CI 95% 2.4 to 4.1) in hypertensive patients. Conclusions CFR on LAD provides useful information for vessel stenosis and prognostic assessment in both hypertensive and normotensive patients. However, diagnostic specificity is reduced in hypertensive.