BRCA1 Reflects Myocardial Adverse Remodeling in Idiopathic Dilated Cardiomyopathy

Left ventricular global longitudinal strain is worse in BRCA mutation positive breast cancer patients prior to cancer treatment and premature menopause

PURPOSE

Breast cancer patients with mutations in human tumor suppressor genes BRCA1 and BRCA2 are at higher risk of cardiovascular disease (CVD) than the general population, as they are frequently exposed to cardiotoxic chemotherapy, anti-estrogen therapy, radiation, and/or oophorectomy for cancer-related treatment and prophylaxis. Animal and cell culture models suggest that BRCA mutations may play an independent role in heart failure. We sought to evaluate cardiac structure and function in female BRCA1 and BRCA2 mutation carriers with breast cancer compared to BRCA wildtype women with breast cancer.

METHODS

We performed a 1:2 age- and hypertension-matched retrospective cohort study comparing BRCA1 and BRCA2 mutation carriers (n = 38) versus BRCA wildtype controls (n = 76) with a new diagnosis of breast cancer. Echocardiographic data were obtained within 6 months of breast cancer diagnosis and prior to chemotherapy, anti-estrogen therapy, radiation, or oophorectomy. Left ventricular global longitudinal strain (LV-GLS), a highly sensitive marker of LV function, was measured using QLab 15 (Philips Healthcare).

RESULTS

In the total cohort of 114 patients with a new diagnosis of breast cancer, the median age was 45 ± 11 years and the prevalence of hypertension was 8%. There were no differences in traditional cardiovascular disease risk factors between cases and controls. BRCA carriers had lower LV-GLS (- 18.1% ± 4.7% vs. - 20.1% ± 3.8%, p = 0.02) and greater right atrial area (12.9 cm2 ± 2.7 cm2 vs. 11.8 cm2 ± 2.0 cm2, p = 0.04) compared to controls; however, both LV-GLS and right atrial area were within the normal range. Compared to controls, BRCA carriers had a trend toward worse LV posterior wall thickness (0.89 cm ± 0.15 cm vs. 0.83 cm ± 0.16 cm, p = 0.06) although not statistically significant.

CONCLUSION

In women with newly diagnosed breast cancer and prior to treatment, LV-GLS was worse in BRCA1 and BRCA2 mutation carriers compared to those with BRCA wildtype. These findings suggest that BRCA mutations may be associated with subtle changes in cardiac function. Whether differences in GLS translate to increased cardiovascular risk in women with BRCA mutations needs to be further characterized.

Effects of Breast Cancer Genes 1 and 2 on Cardiovascular Diseases

Carriers of mutations of breast cancer gene 1 and/or 2 (BRCA1/2) have a higher risk of developing breast and ovarian cancers at a relatively young age. Recently, a causative role for BRCA1/2 in cardiovascular diseases has been emerging. In this review, we summarize currently available evidence obtained from studies on animal models and human BRCA1/2 mutation carriers that shows a correlation of BRCA1/2 deficiency with various cardiovascular diseases, including ischemic heart disease, atherosclerosis, and chemotherapy-linked cardiac muscle disorders. We also discuss one of the major mechanisms by which BRCA1/2 protects the heart against oxidative stress, ie mediating the activity of Nrf2 and its downstream targets that govern antioxidant signaling. More research is needed to elucidate whether the carriers of the BRCA1/2 mutations with ovarian and breast cancers have increased susceptibility to chemotherapy-induced cardiac functional impairment.

An Exploratory Study to Determine Whether BRCA1 and BRCA2 Mutation Carriers Have Higher Risk of Cardiac Toxicity

Anthracycline-based cardiotoxicity is concerning for women with breast cancer and portends a dose-dependent risk of developing left ventricular dysfunction. Overall, the prevalence of heart failure (HF) is ≈2% of the total US population; however, BRCA-deficient mice have shown increased HF. We evaluated for the inherent risk of HF in women with BRCA mutations to determine whether treatment with anthracycline-based therapy increased this risk. We obtained results on BRCA mutation carriers regarding cancer treatment and HF, identified through the BRCA patient advocacy organization Facing Our Risk for Cancer Empowered (FORCE) and the Moffittbased Inherited Cancer Registry. In our patient group (232 BRCA1 and 159 BRCA2 patients; 10 with both mutations), 7.7% reported HF, with similar proportions in BRCA1 versus BRCA2 carriers (7.4% and 8.2%, respectively). These proportions are significantly higher than published rates (p < 0.001). There was no statistically significant difference in HF rates comparing anthracycline-treated versus anthracycline-naïve patients however (7.1% vs. 8.3%; p = 0.67). In addition, 9.1% of BRCA1 carriers and 8.2% of BRCA2 carriers reported arrhythmias. BRCA mutation carriers showed increased risk of cardiotoxicity versus the general population and an overall increased risk of cardiotoxicity from anthracycline-based therapy. Our study supports data that BRCA carriers have increased noncancer mortality from cardiotoxicity. A prospective trial to determine HF and conduction abnormalities in this population is warranted.