Heart Beat: April 2019
Genetic Sex Differences May Influence Heart Disease
Our biological clock (circadian system) governs many physiological processes, including blood pressure. Blood pressure normally dips at night. People who do not experience this temporary drop (called "non-dippers") are at increased risk for developing heart disease. Researchers discovered that one of four main genes comprising the circadian system act differently in men and women. They found that male mice missing this gene (PER1) become non-dippers and have a higher risk of heart and kidney disease. In contrast, female mice missing the PER1 gene continue to show normal dips in blood pressure at night (American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, January 2019 ahead of print). This phenomenon may explain in part why premenopausal women, who are less likely to be non-dippers than men of the same age, have a lower risk of heart disease. After menopause, their risk climbs due to other factors and quickly erases this biological benefit.
Certain Antibiotics Increase Risk of Aortic Rupture
Fluoroquinolones are a class of antibiotics highly valued for the treatmentof bacterial infections. The class includes ciprofloxacin (Cipro®), moxifloxacin (Avelox®) and other drugs ending in "floxacin." A recent study by the U.S. Food & Drug Administration (FDA) found that fluoroquinolones can increase the occurrence of ruptures or tears in the aorta (see"What You Need to Know About Thoracic Aortic Aneurysms" from this issue). On Dec. 20, 2018, the FDA issued an advisory recommending anyone at increased risk for aortic disease not take fluoroquinolones unless absolutely necessary. These include patients with peripheral arterial or vascular disease, hypertension, genetic conditions such as Ehlers-Danlos or Marfan syndrome and the elderly. The FDA also advises anyone who experiences the symptoms of aortic rupture or tear-a sudden, severe, constant pain in the stomach, chest or back-to call 911, particularly if they are taking fluoroquinolones.
Statins May Help Protect Against Ovarian Cancer
Statins have many beneficial effects in addition to lowering cholesterol levels. One of the latest findings is their ability to lower the risk of ovarian cancer. Researchers examined women who had taken statins for at least six consecutive months and found the risk of ovarian cancer was 37percent lower in women who began using statins between the ages of 50 and 59. In those who started at age 60 and after, the risk was 59 percent lower. Statin users who were obese (a body-mass index of 30 or higher) or had type 1 or type 2 diabetes were exempted from this protection. No association between statin use and ovarian cancer was seen in women who took the medication before age 50. As reported in the International Journal of Cancer in 2018, the reduction in ovarian cancer risk was the most apparent in women who took statins for two to 4.9 years. These findings complement earlier research verifying that statin use significantly reduces the risk of esophageal and colorectal cancers. The researchers speculate that statins' beneficial effect comes from two pathways: reducing the amount of estrogen created in fat, and lowering inflammation and angiogenesis (development of new blood vessels that feed tumors) by reducing cholesterol levels.
Factor Xa Antidote Now Available Nationwide
Factor Xa (pronounced "10-A") inhibitors are a newer class of blood thinners used in the treatment and prevention of deep-vein thrombosis, pulmonary embolism and non-valve atrial fibrillation. Until this year, the only antidote to two of these drugs-rivaroxaban (Xarelto®) and apixaban (Eliquis®)-was available only in 40 U.S. hospitals. Then in January, the FDA released the antidote, called Andexxa®, for use nationwide. This gives all users of rivaroxaban and apixaban access to a method of reversing life-threatening bleeding. No antidote is yet available for edoxaban (Savaysa ) or fondaparinux (Arixtra®).