Assessing anthracycline-treated childhood cancer survivors with advanced stress echocardiography

Surveillance for anthracycline cardiotoxicity in cancer survivors typically utilizes resting M-mode and two-dimensional echocardiography, which are insensitive to detection of subtle myocardial changes. We examined childhood cancer survivors treated with anthracyclines during exercise using various echocardiography techniques to investigate if these tools can better detect subclinical cardiac dysfunction.

We recruited asymptomatic survivors at least five years post treatment. Echocardiography was performed at rest and at termination of exercise utilizing tissue Doppler techniques and strain rate imaging.

Eighty participants were characterized by cardiotoxicity risk status (high [12], moderate [23], low [24], no risk [21]) as defined by the Children's Oncology Group Long Term Follow-Up Guidelines v3.0. The high-risk group had a higher resting heart rate than controls (100 vs. 88 bpm [P for trend = 0.049]). Peak aerobic capacity in all groups was similar. Compared to controls at rest, the high-risk group had evidence of diastolic dysfunction with lower E/A ratios (1.4 vs. 2.0, P = 0.008) and higher septal early diastolic velocities (E/E') of 11.7 versus 9.9 (P = 0.165). With exercise, this difference resolved and myocardial contractile reserve was preserved.

Asymptomatic, pediatric cancer survivors at high-risk for anthracycline cardiotoxicity have some evidence of diastolic filling abnormalities at rest. With exercise, they augment their systolic and diastolic function to achieve normal maximal aerobic capacity suggesting they are able to compensate for mild cardiac dysfunction in the early years after exposure. Additionally, findings suggest that routine exercise echocardiography may not be a useful surveillance tool to assess anthracycline cardiotoxicity.