Coronary flow velocity reserve during pharmacologic stress echocardiography with normal contractility adds important prognostic value in diabetic and nondiabetic patients.
Coronary flow velocity reserve (CFVR) increases the diagnostic sensitivity of stress echocardiography. The aim of this study was to evaluate the prognostic value of CFVR in patients without new wall motion abnormalities during pharmacologic stress echocardiography. The outcomes of 651 patients with normal wall motion response during stress echocardiography with dobutamine up to 50 μg/kg/min (n = 351) or dipyridamole up to 0.84 mg/kg over 4 min (n = 300) were evaluated. CFVR was calculated simultaneously in the distal territory of the left anterior descending coronary artery. CFVR ≥ 2 was defined as normal. Major events considered during follow-up were cardiovascular death, myocardial infarction, and late myocardial revascularization. Normal CFVR was recorded in 523 patients and reduced CFVR in 128. During a mean follow-up period of 34.6 ± 18 months, 48 major events occurred, in 25 patients (4.8%) with normal and 23 patients (18%) with reduced CFVR; event-free survival was significantly different between patients with normal versus abnormal CFVR (P < .0001). Diabetes increased risk only in patients with abnormal CFVR (P = .05). In the multivariate analysis, CFVR and history of smoking were the only independent predictors of combined morbidity and mortality. Abnormal CFVR was associated with a higher event rate, independently of the pharmacologic stress technique used. The event hazard ratio was inversely proportional to CFVR. CFVR was an independent predictor of mortality after pharmacologic stress echocardiography with normal wall motion, and the degree of decrease was associated with increased risk. Diabetes worsened prognosis only with abnormal CFVR.