Heart Beat: May 2018
Common Antibiotic Increases Risk of Death in People with Heart Disease
The bacterium Chlamydia pneumonia is known to be present in atherosclerotic plaques, and macrolide antibiotics will eradicate C. pneumoniae from atherosclerosis. Two studies have shown this improves the cardiovascular health of patients with coronary artery disease (CAD), likely by reducing inflammation. But a randomized, placebo-controlled clinical trial designed to determine the effects of a 14-day course of the macrolide clarithromycin (Biaxin) on patients with stable CAD reached a disturbing conclusion. Although researchers expected treatment to lower cardiovascular risk, they found an increase in deaths starting a year later. Because the reason for these deaths could not be explained, in February 2018 the U.S. Food & Drug Administration issued an advisory suggesting physicians avoid prescribing clarithromycin to patients with CAD. Clarithromycin is commonly used to treat bacterial infections of the skin, ears and sinuses, as well as Mycobacterium avium complex (MAC), a lung infection affecting people with the human immunodeficiency virus (HIV).
Two Diet Strategies Found to Be Equally Effective for Weight Loss
If your doctor advises you to lose weight in order to improve your heart health, would a low-fat diet or a low-carbohydrate diet be more effective? Researchers in the Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) study decided to investigate the issue by randomizing 609 overweight adults without diabetes to these options (Journal of the American Medical Association, Feb. 20, 2018). The low-fat diet limited oils, fatty meats, whole-fat dairy products and nuts. The low-carbohydrate diet restricted cereals, grains, rice, starchy vegetables and legumes. Because preliminary trials had suggested that genotypes and insulin secretion rates would determine which diet would be more effective for an individual, these factors were also measured. After 12 months, study participants on the low-fat diet lost an average of 5.3 kilograms (11.6 pounds), and those on the low-carbohydrate diet lost 6 kg (13.2 lbs)—not a significant difference. Neither genotype nor insulin secretion rate was useful in predicting which diet would be better for whom. The takeaway? Choose the diet you are most likely to stick with.
Where Women Carry Extra Pounds Matters to Their Heart
Being overweight is a risk factor for heart disease, but where your body stores extra fat appears to influence a woman’s risk of heart attack. Doctors use body-mass index (BMI) to determine whether someone is overweight, and if so, by how much. However, researchers in the U.K. found waist-to-hip ratio was nearly 20 percent more effective than BMI at predicting a heart attack in women, but only 6 percent more effective in men (Journal of the American Heart Association, online Feb. 28, 2018). It is important to note that this study was performed on 266,000 women and 213,600 men ages 40 to 69. This age range encompasses the years most women go through menopause and start gaining weight, most commonly in the waist and abdomen. The study confirms that this type of weight gain, although normal, is not benign.
In the Future, Will Your Heart Risk Be Predicted Through Your Eyes?
Google, the company that puts answers to almost any question as close as your fingertips, is training computers to predict risk of cardiovascular disease (CVD) by looking at photos of the back of the eye (retina). Using retinal photos and data from 284,000 patients, Google researchers taught computers to zero in on particular structures and form algorithms to predict increased CVD risk. To determine blood pressure, smoking and age, certain models concentrated on vasculature. Those trained to evaluate blood sugar (HbA1c) looked at the tissue surrounding the blood vessels. Models trained to determine the patient’s sex looked at the optic disc, blood vessels and macula. An algorithm was then able to correctly predict systolic and diastolic blood pressure, body-mass index and HbA1c and closely predict age. The same researchers then created a model that predicted the onset of major cardiovascular events within five years (Nature Biomedical Engineering, online Feb. 19, 2018).