Additional Developments in One of Med-Tech's Key Sectors

Keeping you up to date in recent developments in cardiology

Research links breast cancer and heart disease risks . . . Women who are at risk for breast cancer may also be at greater risk for heart disease, new research has found. The majority of women with hereditary breast and ovarian cancer have a mutated form of the BRCA1 or BRCA2 genes, which normally suppress the growth of breast and ovarian tumors. Subodh Verma, a cardiac surgeon at St. Michael's Hospital (Toronto), said his research team was surprised to discover the genes also regulate heart function. Following a heart attack, mice with the mutated BRCA1 gene had a three-to-five times higher rate of death. This was largely due to the development of profound heart failure, possibly because their heart attacks were twice as severe as those in mice who did not have the mutated gene. A similar two-fold increase in heart failure was observed when mice with a mutated BRCA1 or BRAC2 gene were treated with doxorubicin, one of the most common chemotherapy drugs for patients with breast cancer. In addition to studies in mice, the authors also verified this observation in human tissues. The researchers believe that the mutated BRCA1/2 prevents DNA repair in muscle cells that is essential to recovery after a heart attack. Their findings were published in the journals Nature Communications and Journal of Biological Chemistry. “Our findings suggest that individuals who are at risk of breast cancer may also be at a previously unrecognized risk of heart disease,“ Verma said. “More importantly, we now understand that breast cancer and heart disease - the two leading causes of death for Canadian women - have a common biological basis, a common soil.“

Increase in resting heart rate over 10-year period linked with increased risk of death . . . In a study that enrolled nearly 30,000 apparently healthy men and women, those who had an increase in their resting heart rate over a 10-year period had an increased risk of death from all causes and from ischemic heart disease, according to a study in the Dec. 21 issue of the Journal of the American Medical Association. Some evidence indicates that a high resting heart rate (RHR) is associated with increased cardiovascular disease and death in the general population, independent of conventional risk factors. However, whether changes in RHR over time influence the risk of death from ischemic heart disease (IHD) is not known, according to background information in the article. Javaid Nauman, PhD, of the Norwegian University of Science and Technology (Trondheim, Norway), and colleagues conducted a study to examine the association of changes in RHR with the risk of death from IHD in a population-based group consisting of 13,499 men and 15,826 women without known cardiovascular disease. Resting heart rate was measured on two occasions around 10 years apart, with the second RHR measurement taking place between August 1995 and June 1997. There was follow-up until December 2008. A total of 60 participants were lost to follow-up due to emigration from Norway. During an average of 12 years of follow-up, a total of 3,038 people died. Among all deaths, 975 were caused by cardiovascular disease and 388 were due to IHD. The researchers found that compared with participants with a RHR of less than 70 beats/min at both measurements, participants with a RHR of less than 70 beats/min at the first measurement but greater than 85 beats/min at the second measurement had a 90% increased risk of death from IHD. Participants with RHRs between 70 and 85 beats/min at the first measurement and greater than 85 beats/min at the second measurement had an 80% increased risk. The researchers also found that the association of changes in RHR with all causes of death were similar to those observed for IHD mortality, but the estimates of effect were generally weaker. Analysis also suggested that a decrease in RHR showed no general benefit in relation to IHD mortality.

Surgeon volume affects mortality outcomes for AAA repair . . . Researchers from Southwestern Texas University's Division of Vascular and Endovascular Surgery and the Veterans Medical Center (both in Dallas), have reported that composite surgeon (overall) volume rather than operation-specific (annual) surgeon volume is a key determinant of in-hospital mortality for elective open abdominal aortic aneurysm surgery (AAA). Their research was published in the December issue of the Journal of Vascular Surgery. According to study co-author J. Gregory Modrall, MD, who now is a professor of surgery and a vascular surgeon at the University of Arkansas for Medical Sciences (Little Rock), prior studies only reported improved clinical outcomes with higher surgeon volume, which was assumed to be a product of the surgeon's experience with the index operation. “We analyzed approximately 111,533 records of patients who had elective open AAA surgery performed by 6,857 surgeons between 2000 and 2008,“ Modrall said. “The surgeons were stratified into deciles based on operation-specific volume and composite volume. Composite volume was defined by the total number of several open vascular operations: carotid endarterectomy, aortobifemoral bypass, femoral-popliteal bypass, and femoraltibial bypass. Multiple logistic regression analyses were used to examine the relationship between surgeon volume and in-hospital mortality for open AAA repair, adjusting for patient and hospital characteristics.“ The crude in-hospital mortality rate over the study period was 6.1% (95% CI, 5.6% to 6.5%). The mean number of open AAA repairs performed annually was 2.4 operations per surgeon. The mean composite volume was 5.3 operations annually. As expected, in-hospital mortality for open AAA repair decreased with increasing volume of open AAA repairs performed by a surgeon. Mortality rates for the lowest and highest deciles of surgeon volume were 10.2% and 4.5%, respectively. A similar pattern was observed for composite surgeon volume, as the mortality rates for the lowest and highest deciles of composite volume were 9.8% and 4.8%, respectively. After adjusting for patient and hospital characteristics, increasing composite surgeon volume remained a significant predictor of lower in-hospital mortality for open AAA repair (odds ratio, 0.994; 95%, confidence interval, .992-.996), whereas increasing volume of AAA repairs per surgeon did not predict in-hospital deaths. “These data suggest that composite case numbers may be a more valid criterion than operation-specific case numbers,“ Modrall said. “Whether this finding may be generalized to other open and endovascular procedures should be clarified and be considered for future credentialing of surgeons.“

Middle-age blood pressure changes affect lifetime heart disease, stroke risk . . . An increase or decrease in your blood pressure during middle age can significantly impact your lifetime risk for cardiovascular disease (CVD), according to research in Circulation. Researchers found people who maintained or reduced their blood pressure to normal levels by age 55 had the lowest lifetime risk for CVD (between 22% to 41% risk). In contrast, those who had already developed high blood pressure by age 55 had a higher lifetime risk (between 42% to 69% risk). Using data from 61,585 participants in the Cardiovascular Lifetime Risk Pooling Project, researchers examined how changes in blood pressure during middle age affected lifetime CVD risk. Previous studies had considered a single measurement at a given age. In this study, age 55 was considered a mid-point for middle age. Starting with baseline blood pressure readings from an average of 14 years prior, researchers tracked blood pressure changes until age 55, then continued to follow the patients until the occurrence of a first cardiovascular event (including heart attack or stroke), death or age 95. “Taking blood pressure changes into account can provide more accurate estimates for lifetime risk of cardiovascular disease, and it can help us predict individualized risk, and thus, individualized prevention strategies,“ said Norrina Allen, PhD, lead author of the study and assistant professor in the Department of Preventive Medicine at the Northwestern University Feinberg School of Medicine (Chicago). “Both avoiding hypertension during middle age or delaying the onset of the development of hypertension appear to have a significant impact on an individual's remaining lifetime risk for CVD.“

– Compiled by Amanda Pedersen, MDD