Relative coronary flow velocity reserve improves correlation with stress myocardial perfusion imaging in assessment of coronary artery stenoses.

Abstract

STUDY OBJECTIVE: To evaluate the angiographic and coronary flow velocity parameters that best correlate with the results of stress myocardial perfusion imaging. DESIGN: Criterion standard. SETTING: Tertiary care center. PATIENTS: Forty-eight patients undergoing diagnostic coronary angiography for angina or silent ischemia. INTERVENTIONS: We performed angiographic and coronary flow velocity measurements at rest and during hyperemia at the post-stenotic segment and in the adjacent angiographically normal branch of the left coronary artery. Relative coronary flow velocity reserve (RCFVR) was calculated as the ratio of post-stenotic to reference vessel coronary flow velocity reserve (CFVR). The best cutoff points for reversible perfusion defects were calculated using receiver operating characteristic curves. MEASUREMENTS AND RESULTS: Post-stenotic CFVR showed fairly good correlations with minimal lumen diameter and percentage of diameter stenosis (r = 0.57 and r = 0.55, respectively; p < 0.001). RCFVR showed stronger correlations with these angiographic indexes of stenosis severity (r = 0.66 and r = 0.68, respectively; p < 0.0001). Based on receiver operating characteristic cutoff values (1.67 for post-stenotic CFVR and 0.64 for RCFVR), RCFVR had better agreement with myocardial perfusion imaging results, compared to post-stenotic CFVR (92% vs 75%, respectively). This agreement was more meaningful in patients with moderate coronary artery stenoses (50 to 75%). The area under the curve was 0.65 (not significant) for post-stenotic CFVR and 0.88 (p < 0.01) for RCFVR. CONCLUSIONS: RCFVR describes better than post-stenotic CFVR the functional significance of coronary artery stenoses.