Update From the Medical Journals: January 2010 - What Your Doctor Is Reading - Harvard Commentaries

What's the latest news in the medical journals this month? Find out what your doctor is reading.

Less Salt Means Better Heart Health and Lower Health Care Costs
Ablation Procedure for Atrial Fibrillation Seems Effective, With Some Risks
More News in Brief: Exercise Can Improve Mild Memory Loss; New Blood Thinner Beats Plavix in Tests; Obesity Surgery Leads to Longer Survival for the Very Obese

The New England Journal of Medicine released a report online on January 20 making it clear that Americans can improve their health and reduce health-care costs if they are willing to eat a less salty diet. The report comes from epidemiologists at Johns Hopkins University.

The researchers used a computer simulation to predict the health benefits nationwide, if adults 35 years and older reduced average salt intake by 3 grams per day. (This equals 1,200 milligrams of sodium per day). The computer simulator used predictable relationships between salt and blood pressure, and between blood pressure and heart or stroke events. According to predictions, during the first decade after Americans cut back, there would be from 54,000 to 99,000 fewer heart attacks per year, 32,000 to 66,000 fewer strokes per year, and 44,000 to 92,000 fewer deaths per year from any cause. Roughly one-fourth of all people who currently need medication to treat high blood pressure would be able to stop taking their medications.

Most Americans eat a total of about two teaspoons of salt in a day — men take in 10.4 grams of salt per day on average, and women consume 7.3 grams per day. Cutting salt by 3 grams is an ambitious change. But even if we reduce salt intake by an average of 1 gram per day — even if it's over the next decade — we would save somewhere between $19 billion and $32 billion in health care costs over the next ten years. If we cut out 3 grams of salt per day on average, Americans as a nation could save between $57 billion and $97 billion health care dollars over the next ten years.

Most of the salt we eat — 75% to 80% — comes from processed foods. With our health and health dollars at stake, some experts are making a case that it may be appropriate for the U.S. Food and Drug Administration to regulate the amount of salt that can be allowed in processed food products.

A study in the January 27 issue of JAMA compared two different ways to prevent episodes of atrial fibrillation, a common irregular heart rhythm. The study evaluated people in whom the irregular rhythm only occurs intermittently (also called paroxysmal) and who did not respond to treatment with a rhythm-control drug. The study suggests that a procedure called ablation causes better rhythm control and slightly fewer serious complications than treatment with additional drugs that are meant to prevent the arrhythmia.

An ablation procedure for atrial fibrillation involves placing a catheter in an artery and threading the catheter into the heart. Instruments at the tip of the catheter are used to map out the flow of electricity in the heart and to cauterize (burn) a small area of heart muscle where the pulmonary veins empty into the heart. For most patients who have intermittent atrial fibrillation, this treatment appears to eliminate the trigger for the rhythm change.

In the study, 167 patients were randomized to receive either ablation or additional drug treatment. About two-thirds of the patients got the ablation procedure. Sixty-six percent of them stayed symptom-free during the subsequent nine months. Only 19% of people in the drug-treatment group had the same success. About 5% of individuals treated with ablation had serious complications, which compared well to the drug-treatment group. Complications of ablation can include other rhythm problems, such as atrial flutter, inflammation of the sac that surrounds the heart (pericarditis) and slow emptying of the stomach caused by damage to nerves that are near the heart.

This study is helpful because it gives us information about a procedure that is new, but becoming more popular. For the time being, this procedure is not for people whose usual or "chronic" rhythm is atrial fibrillation. In addition, except for people who have bothersome symptoms, preventing episodes of the arrhythmia (known as rhythm control) may be a less safe or helpful strategy than simply controlling the heart rate during episodes when they occur (rate control). The blood-thinning medicine warfarin (Coumadin) is recommended for most people with atrial fibrillation as a way to prevent strokes. (Strokes are a complication of atrial fibrillation.) This is true whether or not the rhythm problem has been treated with ablation.

Longer follow-up from this study will eventually give us a better idea about the value of ablation for treating intermittent (paroxysmal) atrial fibrillation. If its benefits last long-term, this procedure may become more widely recommended.

Exercise Can Improve Mild Memory Loss. "Mild cognitive impairment" is the medical term for memory loss that cannot be attributed to normal aging, but is not severe enough to interfere with daily activities. Mild cognitive impairment does not always progress noticeably. However, within a year, 10% to 15% of people who notice mild cognitive impairment will see their symptoms worsen and be diagnosed with dementia. Previous studies have shown that people who exercise regularly are less likely to develop dementia. But can exercise make a difference once memory loss has started? A study published in the January issue of the Archives of Neurology showed that aerobic exercise appears to improve mild cognitive impairment. This was a small study of 33 adults. The average age was 70. All of the adults had mild cognitive impairment. Twenty-three people were randomly assigned to do aerobic exercise while supervised by a trainer for 45 to 60 minutes per day, four days per week. The other 10 people did gentle stretching exercises with supervision for the same duration of exercise time, but they kept their heart rate low. The exercise programs lasted for six months. The people in the aerobic exercise program had measurable improvement on memory recall tests and tests of word-finding skill (fluency). The benefit was more noticeable in women than in men. The group who did the gentle stretching did not improve their scores when they were retested.

New Blood Thinner Beats Plavix in Tests. Tests of a new drug called ticagrelor (brand name, Brilinta) show that in heart emergencies, it is superior to the widely-used blood thinner clopidogrel (Plavix). The promising study was published online January 13 in The Lancet. When chest pain is treated as an emergency, doctors can expand a narrowed coronary artery with a balloon (angioplasty) with or without placement of a stent. Following this procedure, blood thinners are used to prevent a clot from forming inside the artery as it heals. Typically, clopidogrel (Plavix) and aspirin are used in combination to thin the blood during the first six to twelve months after angioplasty. Plavix and aspirin together reduce the risk of further heart attacks, stroke and death. When the new drug ticagrelor was substituted for Plavix, the risk for having one of these events was lowered by 16% in the year after angioplasty, relative to what was seen for Plavix. The rates of bleeding complications were similar for the old and new drug. Ticagrelor is likely to become the new first choice for treatment after angioplasty. Ticagrelor is more expensive than Plavix, and it must be taken twice a day instead of once. For people who would have difficulty affording the new drug or remembering to take the second daily dose, Plavix still may be the better choice.

Obesity Surgery Leads to Longer Survival for the Very Obese. The January issue of Archives of Surgery contains a summary of risks and benefits of obesity surgery for people who have a body mass index (BMI) of 40 or more and are considered morbidly obese. The study authors collected data from more than 23,000 patients who underwent gastric bypass surgery, and from nearly 400,000 people who were morbidly obese but did not have surgery. Overall, surgery had more benefits than risks for young morbidly obese people. A person who is in his or her early 40s and who has a BMI of 45 could add between 2 ½ and three years to life expectancy by having surgery, the researchers concluded. For older patients, the benefit was smaller. Women appeared to have more survival gain than men.

Mary Pickett, M.D. is an Associate professor at Oregon Health & Science University where she is a primary care doctor for adults. She supervises and educates residents in the field of Internal Medicine, for outpatient and hospital care. She is a Lecturer for Harvard Medical School and a Senior Medical Editor for Harvard Health Publications.