OBJECTIVES:The goal of this study was to compare echocardiographic measurements of global longitudinal strain (GLS) (using 3 apical views) with single-view longitudinal strain (LS, 4- or 2-chamber [4CV_LS and 2CV_LS, respectively]) for detection of cancer-therapy related cardiotoxicity. BACKGROUND:GLS is useful for the detection of cardiotoxicity, but the need for repeated measurements poses a significant burden on busy echocardiography laboratories. A single-view LS measurement, possibly at point of care, could improve efficiency. METHODS:Seventeen international centers prospectively recruited 108 patients (mean age 54 ± 13 years) at high risk for cardiotoxicity as part of the ongoing SUCCOUR (Strain Surveillance for Improving Cardiovascular Outcomes During Chemotherapy) randomized controlled trial. Echocardiography performed at baseline and follow-up were analyzed in a core laboratory setting blinded to clinical information. Peak systolic GLS and LS were measured from raw data. Cardiotoxicity was defined by reduction in left ventricular ejection fraction >0.10 to <0.55 or a relative drop in GLS by ≥12%. RESULTS:Cardiotoxicity developed in 46 patients by either criteria. Baseline and follow-up 2-dimensional left ventricular ejection fraction were 61 ± 4% and 58 ± 5%, respectively (p < 0.001). The baseline GLS (-20.9 ± 2.4%) was not different from 4CV_LS (-20.7 ± 2.5%; p = 0.09) or 2CV_LS (-21.1 ± 3.1%; p = 0.25). The follow-up GLS (-19.5 ± 2.4%) was also similar to 4CV_LS (-19.5 ± 2.6%; p = 0.80) and 2CV_LS (-19.7 ± 3.1%; p = 0.19). There was good correlation between GLS and 4CV_LS at baseline (r = 0.86; p < 0.001) and follow-up (r = 0.89; p < 0.001) and with 2CV_LS at baseline (r = 0.87; p < 0.001) and follow-up (r = 0.88; p < 0.001). However, there was 15% to 22% disagreement between GLS and 4CV_LS or 2CV_LS for the detection of cardiotoxicity. The interobserver and intraobserver reproducibility was higher for GLS (intraclass correlation: 0.93 to 0.95; coefficient of variance: 2.9% to 3.7%) compared with either single-chamber-based LS measurement (intraclass correlation: 0.85 to 0.91; coefficient of variance: 4.1% to 4.8%). CONCLUSIONS:Although there was good correlation between GLS and single-view LS measurements, single-view LS measurement led to disagreement in the diagnosis of cardiotoxicity in up to 22% of patients. GLS measurements were more reproducible than single-view LS. GLS based on 3 apical views should remain the preferred technique for detection of cardiotoxicity. (Strain Surveillance for Improving Cardiovascular Outcomes During Chemotherapy [SUCCOUR]; ACTRN12614000341628).