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Drouin JS1, Kennedy K1, Sheehan S1, Schummer A1, Krawczyk M1, Murley M1, Marks C2
1Oakland University, Physical Therapy, Rochester, Michigan, United States, 2Oakland University, Exercise Science, Rochester, Michigan, United States
Background: Women in breast cancer survivorship (BCS) are at increased risk for cardiovascular disease (CVD). Heart Rate Variability (HRV) is a non-invasive measure of cardiac autonomic dysfunction that predicts CVD risk; however, few studies used HRV to assess CVD risk among women in long term BCS.
Purpose: Therefore, this study determined CVD risk from HRV measures among women in BCS. The study also examined trends in HRV related to age, treatment type, and exercise participation.
Methods: Following institutional review board approval, data was collected from seven females [60.9 (8.1) years] who completed cancer treatments between two to 16 years prior to the study. Participants' mean BMI was 29.2 (4.8) kg/m2 and cancer stages were between 0 (DCIS) and 2B. Cancer treatment regimens were surgery alone (two subjects), surgery and chemotherapy (one subject), and surgery with radiation and chemotherapy (4 subjects). The HRV measure was the 5-minute Standard Deviation (SDNN) of Peak-to-Peak heart rate intervals using a metabolic cart, an electrocardiogram and Biopac MP-150 software (ICC reliability > .96). Two HRV measures were taken in the morning following an overnight fast and exercise abstention the prior day. Subjects rested for 10 minutes prior to testing in a quiet, dimly lit laboratory and breathing rates were standardized using a metronome. The two HRV measures were repeated again within 10 days and the four measures were averaged for the analysis. Differences between HRV measures and predicted norms were assessed using paired samples t-tests with significance set at p .05. Clinical relevance was determined according to Hillebrand (2013) with the mean millisecond (ms.) difference from the predicted norm being equal to the percent increase or reduction in CVD risk.
Results: Data from six subjects was used to calculate the outcomes, as one subject's data was determined to be an extreme outlier. The mean HRV measure of 39.5 (12.0) ms. was significantly lower (t=2.78; df=5; p=.039) compared to the mean predicted HRV of 52.1 (3.3) ms. Clinically, this represents an average 12.6% increase in CVD risk among these subjects. Secondary analyses, found that HRV reductions were not consistently associated with age; however, reductions were associated with radiation and/or chemotherapy compared to surgery alone. HRV also improved with exercise participation.
Conclusion(s): This study found that HRV measures were significantly lower than predicted norms and differences represented an increased risk in CVD in this population. A limitation of this study is the small sample size, the 5- minute measurement period, and self-reported exercise participation.
Implications: Women in long-term breast cancer survivorship have reduced HRV responses that are associated with higher risk for CVD. Study results support the need for cardiovascular screening and healthy lifestyle interventions to reduce CVD risks in this population.
Keywords: Breast Cancer, Heart Rate Variability, Cardiovascular Disease Risk
Funding acknowledgements: N/A
Purpose: Therefore, this study determined CVD risk from HRV measures among women in BCS. The study also examined trends in HRV related to age, treatment type, and exercise participation.
Methods: Following institutional review board approval, data was collected from seven females [60.9 (8.1) years] who completed cancer treatments between two to 16 years prior to the study. Participants' mean BMI was 29.2 (4.8) kg/m2 and cancer stages were between 0 (DCIS) and 2B. Cancer treatment regimens were surgery alone (two subjects), surgery and chemotherapy (one subject), and surgery with radiation and chemotherapy (4 subjects). The HRV measure was the 5-minute Standard Deviation (SDNN) of Peak-to-Peak heart rate intervals using a metabolic cart, an electrocardiogram and Biopac MP-150 software (ICC reliability > .96). Two HRV measures were taken in the morning following an overnight fast and exercise abstention the prior day. Subjects rested for 10 minutes prior to testing in a quiet, dimly lit laboratory and breathing rates were standardized using a metronome. The two HRV measures were repeated again within 10 days and the four measures were averaged for the analysis. Differences between HRV measures and predicted norms were assessed using paired samples t-tests with significance set at p .05. Clinical relevance was determined according to Hillebrand (2013) with the mean millisecond (ms.) difference from the predicted norm being equal to the percent increase or reduction in CVD risk.
Results: Data from six subjects was used to calculate the outcomes, as one subject's data was determined to be an extreme outlier. The mean HRV measure of 39.5 (12.0) ms. was significantly lower (t=2.78; df=5; p=.039) compared to the mean predicted HRV of 52.1 (3.3) ms. Clinically, this represents an average 12.6% increase in CVD risk among these subjects. Secondary analyses, found that HRV reductions were not consistently associated with age; however, reductions were associated with radiation and/or chemotherapy compared to surgery alone. HRV also improved with exercise participation.
Conclusion(s): This study found that HRV measures were significantly lower than predicted norms and differences represented an increased risk in CVD in this population. A limitation of this study is the small sample size, the 5- minute measurement period, and self-reported exercise participation.
Implications: Women in long-term breast cancer survivorship have reduced HRV responses that are associated with higher risk for CVD. Study results support the need for cardiovascular screening and healthy lifestyle interventions to reduce CVD risks in this population.
Keywords: Breast Cancer, Heart Rate Variability, Cardiovascular Disease Risk
Funding acknowledgements: N/A
Topic: Oncology, HIV & palliative care; Cardiorespiratory; Health promotion & wellbeing/healthy ageing
Ethics approval required: Yes
Institution: Oakland University Rochester, Michigan USA
Ethics committee: Oakland University Institutional Review Board
Ethics number: 809476-4
All authors, affiliations and abstracts have been published as submitted.
