Abstract 11278: The Value of Core Lab Stress Echocardiography Interpretations: Observations From the ISCHEMIA Trial
PURPOSE: Stress echocardiography (SE) is dependent on subjective interpretations. As a prelude to the I nternational S tudy of C omparative H ealth E ffectiveness with M edical and I nvasive A pproaches (ISCHEMIA) Trial, potential sites were required to submit two SE, one with moderate or more left ventricular (LV) myocardial ischemia and one with mild ischemia. We evaluated the concordance of site and core lab interpretations.
METHOD AND MATERIALS: 81 exercise and pharmacologic SE were submitted from 41 international sites (30 exercise, 48 pharmacologic, 3 unknown). Regional LV wall motion abnormalities (WMA) were evaluated in 16 segments. Ischemia was classified by the number of new or worsening segmental WMA: none, mild (1 or 2) or moderate or more (3 or more). Core lab determination of image quality was based on adequacy of LV border definition.
RESULTS: Core lab classified 6 SE as no ischemia, 35 mild and 40 moderate or greater. There was agreement between the site and core in 66 of 81 total cases (81%, weighted kappa coefficient (K) =0.635). Agreement was similar for 1) geographic location of site - 19 of 24 North America cases (79%, K=0.571) vs. 47 of 57 non-North America cases (82%, K=0.662) and 2) SE type - 24 of 30 exercise (80 %, K=0.571) vs. 40 of 48 pharmacologic (83%, K=0.680). For image quality, the agreement between poor or fair image quality cases (27 of 36 cases, 75%, K=0.492) was not as good as for the good or excellent image quality cases (39 of 45 cases, 87%, K=0.755). Significant differences in concordance were noted for degree of ischemia with the majority of discordant interpretations in patients with no or mild ischemia (TABLE).
CONCLUSION: While site SE interpretations are comparable in most cases, this appears dependent on image quality and the extent of WMA. Agreement increases as the extent of stress induced WMA increases. Thus core lab interpretations remain important in clinical trials where consistency of interpretation across a range of cases is critical.
- © 2013 by American Heart Association, Inc.