Cardiovascular responses to dynamic submaximal exercise in children previously treated with anthracycline

Area of Science:

• Cardiology
• Pediatric Oncology
• Exercise Physiology

Background:

• Anthracycline chemotherapy is vital for treating pediatric cancers but can cause long-term cardiotoxicity.
• Assessing the functional cardiovascular impact of low-dose anthracyclines in childhood cancer survivors is crucial for understanding long-term outcomes.

Purpose of the Study:

• To evaluate the long-term (5-year) effects of pediatric low-dose anthracycline therapy on the circulatory response to moderate exercise.
• To determine if cancer survivors exhibit impaired cardiac function during exercise intensities comparable to daily activities.

Main Methods:

• A cohort of 13 pediatric cancer survivors (13 +/- 4 years) and 15 age-matched controls underwent maximal cycle ergometry.
• Cardiac index and stroke index were measured using carbon dioxide rebreathing during submaximal exercise tests (33% and 66% of maximal oxygen uptake).

Main Results:

• Cancer survivors had significantly lower maximal oxygen uptake (V(O2)max) compared to controls.
• Patients demonstrated smaller relative increases in cardiac index and stroke index during submaximal exercise.
• Despite normal resting systolic function, survivors exhibited a reduced stroke index and higher heart rate for a given oxygen uptake.

Conclusions:

• Pediatric cancer survivors treated with low-dose anthracyclines exhibit impaired stroke index during moderate exercise, indicating a limited inotropic reserve.
• This exercise-induced cardiac dysfunction may affect the ability to perform routine physical activities and play.
• Long-term cardiovascular monitoring is essential for childhood cancer survivors to detect and manage potential exercise-related circulatory impairments.