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Ask the doctor

Q. After a year of taking a statin, my LDL cholesterol measurement is 50 mg/dL, which seems awfully low. Is there any downside to a very low LDL?

A. Based on what we currently know, a low-density lipoprotein (LDL) level of 50 mg/dL appears to be reasonably safe, especially when attained naturally. Studies of people who've already had a heart attack suggest that lowering LDL to about 50 mg/dL provides further protection against recurrent cardiovascular events versus reaching a level of around 70 mg/dL. In studies lasting up to seven years or so, these lower LDL levels appeared to be well tolerated.

But if you are healthy, deciding if these commonly prescribed drugs are right for you is a personal choice.

Exercise and lifestyle changes can thwart heart failure down the road.

Targeted screening and improved repair techniques may minimize the danger of this uncommon condition.

With a diameter roughly the size of a garden hose, the aorta is the body's largest artery. It curves out of the heart through the chest, passing straight down the center of the body before dividing into the arteries that serve the legs (see illustration).

NSAID users: Take the lowest effective dose for the shortest possible time.

If you have heart disease, national guidelines recommend that you take a low-dose (81-mg) aspirin every day. It's an inexpensive and effective way to lower your risk of a heart attack or stroke. According to a report in the July 17 Morbidity and Mortality Weekly Report, about seven in 10 adults with heart disease follow this advice.

The study relied on telephone surveys done by the CDC about health behaviors. It included data from more than 17,900 adults from 20 states and the District of Columbia.

Boosting your fitness level may help decrease the symptoms of the most common heart rhythm disorder, according to a study published online June 22 by the Journal of the American College of Cardiology. The disorder—atrial fibrillation, or afib—causes an irregular, rapid heartbeat that can lead to shortness of breath, dizziness, and fainting.

The study included 308 people with afib who were also overweight or obese, a condition that raises the risk of afib. The participants answered questions about their afib symptoms and underwent tests to determine their fitness levels, which were described in metabolic equivalents, or METs. (METs measure your level of exertion and are based on how much oxy-gen your body uses during activities; sitting still is 1 MET, and brisk walking is 3.)

It helps build cardiovascular fitness with shorter workouts.

Have you heard about interval training but aren't sure how it works and whether it's right for you? Interval training simply means alternating between short bursts of intense exercise and brief periods of rest (or a different, less-intense activity). The payoff is improved cardiovascular fitness.

Changing lifelong habits is hard, but these practical tips can help.

When blood pressure persists above healthy limits, men are faced with a decision: take a medication now, or try to lower it with nutrition, exercise, and other lifestyle changes. Many men are reluctant to start taking a new pill every day—possibly for life. Although changing deeply ingrained habits can be hard, it really works.

Training the public how to do CPR saves the lives of people struck by cardiac arrest outside of a hospital, according to a study in The New England Journal of Medicine. The survival boost was markedly higher for men who experienced cardiac arrest outside the home.

In the United States, 420,000 people per year experience cardiac arrest outside of hospitals. It seems like a no-brainer that cardiopulmonary resuscitation (CPR) saves lives, but hard evidence has been lacking on exactly how many lives are saved. To help clarify the issue, researchers in Sweden analyzed more than 30,000 out-of-hospital cardiac arrests that occurred from 1990 to 2011. It's a good country to test CPR's power, since a third of the Swedish population knows how to do it.