64 The prevalence of late anthracycline induced cardiotoxicity in survivors of childhood malignancy in northern ireland

Background Cardiotoxicity is a recognised complication of anthracycline based chemotherapy. Although early toxicity is often reversible, late toxicity involves a cascade of injury that is significantly more difficult to treat. Subclinical myocardial cell injury is followed by asymptomatic and symptomatic heart failure and can potentially lead to an irreversible cardiomyopathy. Periodic screening for cardiotoxicity is fundamental to early initiation of treatment during the reversible phase of this process. There are however several barriers to screening programmes. Current epidemiologic knowledge is based on retrospective studies from the 1990s, whereas newer imaging and biomarker techniques have since been developed which allow identification of at-risk patients at a subclinical stage. Notably, global longitudinal strain (GLS) of >-19% was identified as an independent marker of future left ventricular systolic impairment. We reviewed data from 73 survivors of childhood cancer who were treated with anthracycline based chemotherapy in Northern Ireland. Methods Clinic letters, laboratory results and echocardiographic reports were collated from 73 survivors of childhood cancer who were invited to cardiology clinics between November 2015 to April 2019. Results 55 patients attended adult cardiology clinic for review. Patients were aged between 17 and 38 years old. The mean age at therapy completion was 8.59 years (range 1–17, median 8.6 years). The average time from therapy completion to this latest clinic review was 12.8 years (range 1–31, median 12 years). 14 patients had concomitant chest radiotherapy. Only three patients received the cardioprotective agent dexrazoxane. Nt-proBNP levels were abnormal (>125pg/ml) in 11 patients, (mean 377pg/ml). 68 patients had echo imaging carried out. Left ventricular systolic function (Simpson’s Biplane) was impaired in 8 patients (5 mild, 2 moderate, 1 severe). Furthermore 7 patients had a borderline function at 55%. GLS was impaired in 42/52 patients. 5/11 patients with elevated BNP had reduced GLS. 38 patients had received high-risk anthracycline doses of >250 mg/m2. 6/38 of this high-risk group had a raised NT-proBNP. 11/38 had no GLS record. Of the remaining 27 high-risk patients who had GLS measured 20/27 had a reduced GLS value. Conclusion Screening compliance was lower than anticipated for such a high-risk cohort with only 75% of invited patients (55/73) attending for review. A significant number of patients had already reached the stage of systolic dysfunction 15/68. Furthermore subclinical dysfunction was highly prevalent with 42/52 patients displaying evidence of impaired global strain. This highlights the importance of encouraging patient compliance with screening in this population. Further research is required to establish if treatment with standard heart failure therapies can provide long-term benefit in this subclinical population.