UBC Theses and Dissertations
Cardiovascular function in HER2-postivie breast cancer survivors Bonsignore, Lynne Alis Jean
Background: Trastuzumab, a HER2 antagonist, has been shown to improve rates of overall survival in patients with HER2-positive breast cancer. However, cardiotoxic effects associated with treatment limits these benefits. Due to an increase in survival years, women with a history of HER2-positive breast cancer might be at increased risk of developing cardiotoxicity (i.e., LVEF < 55% with or without accompanying symptoms of heart failure) during survivorship. Exercise (“stress”) conditions is an established method to examine comprehensively impairments in cardiovascular function that may go undetected during resting conditions providing insight into the risk for future cardiac events. Purpose: We sought to assess cardiac and vascular function of HER2-positive breast cancer survivors at rest and under exercise conditions. Hypothesis: 1) At rest, vascular dysfunction would be evident in breast cancer survivors. 2) Exercise would reveal cardiac dysfunction in HER2-positive breast cancer survivors, which was not apparent under resting conditions. Methods: Eight HER2-positive breast cancer survivors and eight age-matched healthy controls underwent the following measures: 1) resting vascular function (Applanation tonometry, pulse wave velocity and baroreceptor sensitivity) and cardiac function (2D-echocardiography), 2) exercise haemodynamics (heart rate, stroke volume, cardiac output) during an incremental exercise test, and 3) ventricular-vascular coupling (left ventricular elastance and arterial elastance) at rest and during incremental exercise. Results: At rest, there were no differences between groups in any echocardiographic measures. No differences were detected in vascular function, although baroreceptor sensitivity was reduced in the breast cancer group. Resting ventricular-vascular coupling was also similar between groups. With exercise, there was evidence of reduced left ventricular performance with a blunted response to increase left ventricular elastance. No differences were observed in arterial elastance or ventricular-vascular coupling. All haemodynamic responses were similar between groups. Conclusion: In HER2-positive breast cancer survivors there are indicators of impairments in cardiac function during exercise conditions, but limited differences during resting conditions. Exercise echocardiography may be clinically relevant for detecting impairments in left ventricular function in HER2-positive breast cancer survivors that appear to have normal cardiac function at rest.
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