Abstract Body (Do not enter title and authors here): Background: Transthoracic echocardiographic (TTE) surveillance for left ventricular dysfunction following cardiotoxic chemotherapy, particularly anthracyclines, is a key component of cardio-oncology care. The 2017 American Society of Clinical Oncology (ASCO) guidelines recommend routine TTE screening in older adults after anthracycline-based chemotherapy, but it remains uncertain if these guidelines had an effect on physician TTE ordering frequency.

Methods: The Surveillance, Epidemiology, and End Results (SEER) Medicare dataset was used to identify older adults (>65 years) with HER2-negative breast cancer, lymphoma, or soft tissue sarcoma who received anthracyclines for a first cancer diagnosis from 2010-2020. Monthly TTE surveillance rates (TTEs per eligible patient-month) in the first year following chemotherapy initiation were compared before and after the ASCO guideline release in January 2017 using an interrupted time series approach.

Results: Of 15,045 individuals included (mean age 74.1 ± 5.9 years, 64.9% female, 84.9% White), 9,611 (63.9%) had lymphoma, 5,106 (33.9%) breast cancer, and 328 (2.2%) sarcoma. An average of 43.6% ± 1.3% of individuals received a surveillance TTE during the first year after chemotherapy (mean 7.2 ± 0.9% per month). The monthly TTE surveillance frequency remained constant prior to 2017 (-0.003%/month, 95% CI -0.01% to +0.007%, p = 0.58) and after 2017 (+0.18%/month, 95% CI -0.57% to +0.92%, p = 0.65), with no significant change following the ASCO guideline release (+0.03%/month, 95% CI -0.005% to +0.06, p = 0.11) (Figure).

Conclusion: TTE surveillance rates did not significantly change following the release of the 2017 ASCO guidelines among older Medicare beneficiaries receiving anthracycline chemotherapy for non-HER2+ malignancies. More than half of older anthracycline treated patients did not receive a post-anthracycline TTE in the year after their cancer treatment.