Risk factors for cardiac dysfunction in children on treatment for cancer at Kenyatta National Hospital

Abstract

Introduction: Management of paediatric malignancies requires a multimodal approach to treatment. Modalities include combination of various antineoplastic drugs and radiotherapy. This multimodal approach puts patients at risk of multi-organ toxicity especially the heart. Knowledge of the local risk factors for cardiac dysfunction in paediatric oncology patients on treatment may facilitate strategies that reduce morbidity and mortality. Objective: To assess the risk factors for cardiac dysfunction In paediatric oncology patients on chemotherapy at Kenyatta National Hospital (KNH). Design: Descriptive cross-sectional study with a nested case control study. Setting: The Kenyatta National HospitaJ General ~aediatric Wards, including Paediatric Oncology Ward & Paediatric Opthalmolgy Ward. Subjects: Paediatric patients admitted to Kenyatta National Hospital with established diagnosis of cancer and who have started chemotherapy. Procedure: The subjects underwent 12 lead Electrocardiography (ECG) and Echocardiography (ECHO). Children were classified as having cardiac disease if the ejection fraction and fractional shortening was < 55% and < 29% respectively. Study Duration: February 2006 - April 2006 Results: A total of III patients were enrolled of whom 32 had abnonnaI cardiac function and therefore were classified as cases and 79 with normal cardiac function who were classified as controls. The point prevalence for cardiac dysfunction in paediatric oncology patients on chemotherapy was 29% (95%CI21.2-37.9%). Cumulative anthracycline dose was also an important risk factor with Odd's ratio 1.005 (95% CI 1.001-1.009), P value= 0.02. Associated echocardiographic abnormalities included

diastolic dysfunction 26(23 %), pericardial effusion 21(19%), valvular abnormalities 1O(C;}%a)nd tumour infiltrates 7(6%) of the total study population. Conclusion: This study showed that about a third (point prevalence 29%) of paediatric cancer patients on chemotherapy at KNH have cardiac dysfunction as exemplified by left ventricular dysfunction. Cumulative anthracycline dose is a risk factor for cardiac dysfunction in paediatric oncology patients on chemotherapy at KNH. Above the cumulative dose of 200mg/m2 the attributable risk percentage of cardiac dysfunction is 77%. Recommendation: Serial echocardiography should be done on oncology patients undergoing chemotherapy where anthracyclines are part of the treatment 'Protocol. With an attributable risk percentage of 77% above cumulative anthracycline dose of 200mg/m2 , alternative nonanthracycline based treatment protocols are recommended above this level. Lastly, a meta-analysis of published studies and randomised clinical trials should be done to further establish the safety of anthracyclines and to further assess the other risk factors in our population.