The evaluation of left ventricular function in childhood cancer survivors by pharmacological stress echocardiography

Late cardiotoxicity after anthracycline chemotherapy for childhood cancer is well recognized sequelae. Many long-term survivors may have subclinical cardiac dysfunction undetectable at a baseline evaluation. Various tests have been utilized for the diagnosis of left ventricular impairment. Recently, low-dose dobutamine stress echocardiography has been proposed as a more sensitive screening test. We have applied low-dose dobutamine stress echocardiography (5-10 microg/kg/min) in 36 asymptomatic survivors (20 male/16 female aged 14.6+/-4.7 years) treated with a cumulative dose of 226+/-106 mg/m2 of doxorubicin. The median follow-up was 5 years. Control group consisted of 20 sex and age matched volunteers (12 male/8 female aged 12.6+/-4.9 years). We found significant differences in mean velocity of circumferential fibre shortening, myocardial performance index (Tei index), left ventricular posterior wall thickening and endsystolic wall stress at a baseline. The stress response was significantly blunted only in a patient group in the following parameters: endsystolic wall stress, isovolumic relaxation time and myocardial performance index. The threshold response was abnormal (0-5% improvement of a variable only) in 45% of subjects from a control group in one or two parameters. On the contrary, 63% of subjects from a patient group responded pathologically (the worsening of a variable) in one or more parameters. We have not found a good correlation between risk factors of late cardiotoxicity and stress changes of left ventricular function parameters. Low-dose dobutamine stress echocardiography is safe and feasible diagnostic tool in children and adolescents. Dobutamine significantly increases the differences in cardiac variables between healthy population and asymptomatic survivors for childhood cancer. In comparison to the controls, most asymptomatic patients revealed subclinical myocardial damage at test. The predictive value for the development of clinical symptoms and cardiac complications need to be assessed in a large prospective study.