Introduction: There is paucity of data on effective screening tools and risk predictors of cardiovascular dysfunction to aid early disease intervention in breast patients post radiation therapy. We aimed to assess the use of coronary artery calcium (CAC) and myocardial global longitudinal strain (GLS) by speckle tracking transthoracic echocardiography (echo) as screening tools for early identification of cardiovascular disease in breast cancer patients post radiation therapy.
Methods: Using records from the RUMC cancer registry, we identified women aged 18-79 years diagnosed with left sided breast cancer between 1999-2003, post prior treatment with radiation therapy. Seventeen enrolled subjects completed a detailed questionnaire on breast cancer and cardiac disease history and underwent cardiac computed tomography to quantify CAC by Agatston score; and echo to assess subclinical LV dysfunction by GLS. Logistic regression was used to compare subjects’ CAC scores with historical controls using age and race matched MESA CAC calculator [derived from The Multi-Ethnic Study of Atherosclerosis cohort of participants; free of cardiovascular disease at baseline (2000-2002)]; and GLS with historical controls from prior meta-analysis with defined normal GLS.
Results: There was no significant asymmetry in the distribution of the CAC recorded values around the corresponding MESA reported median values (Nonparametric Wilcoxon test p-value=0.13). However, there were more cases with CAC present (non-zero CAC) than what is predicted by MESA, reported probabilities (p-value < 0.02 based on a goodness-of-fit test). The average GLS for 14 subjects whom were tested was -20.6%, with a range of -18% to -22.3%. The average GLS was found to be significantly different (p=0.03) from that reported in the meta-analysis, mean GLS of -19.7% (95% CI, -20.4% to -18.9%).
Conclusion: Despite the small number of subjects, radiation therapy was associated with presence of CAC 12-16 years later, compared with age and sex matched historical controls from MESA. There is need for further large scale investigation on the use of CAC with or without GLS as screening tools for moderate risk cardiovascular dysfunction following treatment with left sided chest wall radiation.