Relation between Duke treadmill score and coronary flow reserve using transesophageal Doppler echocardiography in patients with microvascular angina

Objectives: The link between coronary flow reserve (CFR) and Duke treadmill score (DTS) in patients with microvascular angina remains elusive. Methods: We studied 108 subjects (M/F=48:60, mean age 54±9 years) with chest pain and normal coronary angiogram. ETT was performed by Bruce's protocol and the equation for calculating DTS was DTS=exercise duration−(5× ST deviation)−(4× exercise angina), with 0=none, 1=nonlimiting, 2=exercise limiting. The coronary flow velocity at diastole (PDV) using transesophageal Doppler echocardiography (TEE) was obtained from the proximal left anterior descending coronary artery and CFR was calculated as the ratio of hyperemic PDV after the intravenous infusion of dipyridamole (0.56 mg/kg) to baseline PDV. Results: CFR was 3.04±0.45 in group with negative ETT and 2.19±0.62 in group with positive ETT (P<0.001) and was 1.51±0.31 in high risk group with a score of ≤−11, 2.39±0.63 in moderate risk group with scores between −11 and + 5, and 3.04±0.43 in low risk group with a score of ≥+5 on DTS (P<0.001 versus low risk group, respectively). DTS has significant correlation with CFR (r=0.704, P<0.001). Conclusions: DTS is a composite index that reflects CFR and helps clinicians determine the severity of ischemia in patients with microvascular angina.