Pediatric Track Session
SCMR 22nd Annual Scientific Sessions
Background: Subclinical cardiotoxicity is highly prevalent among childhood cancer survivors after anthracycline (AC) therapy with CMR derived decrease in mid-wall peak circumferential strain magnitude (ecc) and mid-wall peak longitudinal strain magnitude (ell) present in a high percentage of patients.1 Previous studies in adults demonstrate that transmural infarct segments have lower ecc (−10.7±6.3) than sub endocardial infarcts (−15.4±7.0) and normal myocardium (-17.8±5.41).2 Preliminary data in adult post chemotherapy patients has demonstrated that segmental strain dysfunction [# of segments with ecc>-10% (non-viable myocardium) and # of segments with ecc>-17% (at risk myocardium)] may be a more sensitive parameter to identify patients at risk of heart failure (HF).3,4 This study sought to identify the prevalence of myocardial segments at risk and non-viable myocardial segments in a cross-sectional cohort of childhood cancer survivors, and compare those segments to clinical HF stage as determined by echocardiography-derived EF< 55% and ell >-17% and clinical symptoms as per current guidelines.
Methods: Eighty-seven subjects, 21.5±5.7 (10.2-42.2) years of age, with cumulative AC doses 277.8±115 (78-622) mg/m2, were studied by CMR and echocardiography 10.1±6.4 (2.0-26.8) years after chemotherapy. Subjects were classified clinically in HF stages (A-D). Tagged cine CMR was acquired in the 4-chamber and 3 short-axis planes (basal, mid-cavity, and apical). Tagged images were analyzed with the HARmonic Phase (Diagnosoft, Palo Alto, CA) technique for calculation of global ecc, ell, and segmental ecc from the 3 short axis planes. Subjects were subdivided into low risk and high risk (2+ segments>-10% or 9+ segments>-17%).
Results: Fifty (57.5%) subjects demonstrated decreased ecc >-17% and 22 (25.3%) subjects demonstrated ell > -17% by CMR. The number of segments with ecc >-17% ranged from 0-13 while the number of segments with ecc >-10% ranged from 0-6. Six or more segments with ecc >-17% and ≥2 with ecc >-10% resulted in abnormal global ecc >-17% (Figure 1). The basal anterior, septal and inferior segments were predominantly affected (Figure 2). Nineteen (24.7%) subjects met high risk definition and 58 (75.3%) met low risk definition. Four (21.1%) subjects in the high risk group were misclassified in Stage A, while 15 (75.4%) subjects in the high risk group were correctly identified in stage B-D based on clinical and echocardiographic parameters. Three dimensional EF < 55% was the best echocardiographic predictor to identify high risk patients (p=0.001).
Conclusion: Segmental strain dysfunction is a novel CMR imaging biomarker that may allow early identification of patients at risk for developing HF. Future longitudinal studies are needed to confirm the utility of segmental strain dysfunction to predict HF.