Myocardial strain imaging by cardiac magnetic resonance for detection of subclinical myocardial dysfunction in breast cancer patients receiving trastuzumab and chemotherapy.

BACKGROUND: Our objectives were to evaluate the temporal changes in CMR-based strain imaging, and examine their relationship with left ventricular ejection fraction (LVEF), in patients treated with trastuzumab. PATIENTS AND METHODS: In this prospective longitudinal observational study, 41 women with HER2+ breast cancer treated with chemotherapy underwent serial CMR (baseline, 6, 12, and 18 months) after initiation of trastuzumab (treatment duration 12 months). LVEF and LV strain (global longitudinal[GLS] and circumferential[GCS]) measurements were independently measured by 2 blinded readers. RESULTS: Of the 41 patients, 56% received anthracycline-based chemotherapy. Compared to baseline (60.4%, 95%CI 59.2-61.7%), there was a small but significant reduction in LVEF at 6 months (58.4%, 95%CI 56.7-60.0%, p = 0.034) and 12 months (57.9%, 95%CI 56.4-59.7%, p = 0.012), but not at 18 months (60.2%, 95%CI 58.2-62.2%, p = 0.93). Similarly, compared to baseline, GLS and GCS decreased significantly at 6 months (p = 0.024 and < 0.001, respectively) and 12 months (p = 0.002 and < 0.001, respectively) with an increase in LV end-diastolic volume, but not at 18 months. There were significant correlations between the temporal (6 month-baseline) changes in LVEF, and all global strain measurements (Pearson's r = -0.60 and r = -0.75 for GLS and GCS, respectively, all p < 0.001). CONCLUSION: There was a significant reduction in LV strain during trastuzumab treatment, which correlated with a concurrent subtle decline in LVEF and was associated with an increase in LV end-diastolic volume. LV strain assessment by CMR may be a promising method to monitor for subclinical myocardial dysfunction in breast cancer patients receiving chemotherapy. Future studies are needed to determine its prognostic and therapeutic implications.