People who develop blood clots in their legs—a condition called venous thromboembolism—must take warfarin (Coumadin) for several months or longer to prevent another clot from forming and possibly traveling to the lungs, with deadly results. Yet warfarin can cause unwanted bleeding and requires regular blood testing. As a result, no one wants to be on this treatment forever. The question is, what else might they do to reduce their risk for another blood clot if they stop taking warfarin?

Now the combined results of two compatible studies have determined that a low dose of aspirin (100 mg per day) may be an effective substitute for long-term use of warfarin. Both studies examined people who had developed a clot in the legs for unknown reasons. In both studies, the clots were dissolved with heparin, and treatment with warfarin followed for up to three months. Then warfarin was discontinued, and the study participants were given either daily low-dose aspirin or placebo (sugar pill). Compared with placebo, aspirin reduced the rate of recurrent clots by one-third, and helped prevent strokes, heart attacks, and other undesirable consequences, with a very low risk of bleeding. The researchers concluded that low-dose aspirin would be a reasonable option for long-term clot prevention in people who suffer a first clot for unknown reasons.

Q. I have atrial fibrillation and have been taking warfarin to prevent blood clots for 10 years. It has not given me any problems. However, I do hate going to my doctor's office to get my INR blood test every month. I'm wondering whether I should switch to one of the newer blood thinners that don't require blood testing.

A. If you have been successfully taking warfarin for this long, and do not have problems with wide, unpredictable variations in your INR levels, I would recommend that you stay on warfarin. The newer drugs, which include dabigatran (Pradaxa) and rivaroxaban (Xarelto), are wonderful innovations, but they have undergone less testing than warfarin.

Their value immediately after surgery is being questioned.

Drugs known as angiotensin-converting enzyme (ACE) inhibitors can make all the difference in the world to length and quality of life for some people with heart disease and high blood pressure, one of the risk factors for heart disease. ACE inhibitors work by blocking hormones that regulate blood vessel constriction. This can reduce damage to the heart and kidneys in many ways—for example, by slowing deterioration of the heart muscle that occurs over time following a heart attack or deterioration of the kidneys in people with diabetes and kidney disease. The first ACE inhibitor, captopril (Capoten), was approved by the FDA in 1981 to lower blood pressure. Nine more are available today (see box).

In the early 1990s, the ability of ACE inhibitors to prolong survival in people with heart failure was discovered, along with their ability to lower the risk of having a heart attack. Soon thereafter, Harvard researchers led by Dr. Marc Pfeffer found that people taking ACE inhibitors were less likely to die from their heart attacks. These unique benefits secured the place of ACE inhibitors mong the most significant drugs for the treatment of heart disease.

Ask the doctor

Do I really need a statin?

Q. I am 71 years old, have chronic kidney failure, and am on dialysis.  I know my overall outlook is not good, and I wonder whether it is worth it to take a statin to control my cholesterol.

A. It's a good question. We have a tendency in medicine to prescribe statins whenever we see elevated cholesterol levels—even in people who might have conditions that make it less likely they will benefit from cholesterol reduction. That being said, the risk of cardiovascular complications is very high in people with kidney disease, and there are pretty good data that lowering cholesterol can reduce cardiac deaths and complications from atherosclerosis by about 20%. Side effect rates are so low that I think this medication is probably worthwhile for you.

Q. I need surgery for a gastrointestinal problem, and my question is how to handle my antiplatelet therapy, which I have been taking for two years since I had angioplasty. I take aspirin and clopidogrel, which were started after I had a heart attack and a stent was placed to keep the narrowed artery open. Things have been going just fine. But I know the surgeon wants to stop the clopidogrel during the period around surgery, and that worries me.

A. Your cardiologist will most likely ask your surgeon to let you continue taking the aspirin through the surgical period. However, you should stop clopidogrel at least a couple of weeks before surgery, if there is time, and you and your cardiologist should discuss whether it should be restarted at all afterward. The evidence that clopidogrel is helpful for more than six to 12 months after stent placement is slim. Without clopidogrel, you will be able to go through life with fewer bruises

Drugs may not be enough to lower stubborn high blood pressure.

Approximately half of the 67 million Americans with high blood pressure are unable to bring their blood pressure down to desired levels with medications. When taking the maximum-tolerated doses of at least three medications—one of which is a diuretic—fails to work, these people are said to have resistant hypertension. It's a huge concern.

People with heart disease can save thousands of dollars by passing up brand-name products in favor of their generic equivalents. But many people still wonder whether generic medications are safe. Rumors abound: they aren't the same as brand-name medications; they are manufactured with cheaper ingredients; or even that people have died from taking generics.

Dr. Thomas Lee, co–Editor in Chief of the Harvard Heart Letter, says these statements aren't true.

High LDL cholesterol levels are known to increase the risk of heart attack, and lowering LDL levels has been proven to help protect against heart attack.

Many therapies can be effective, but care must be individualized.

Modern treatments for heart disease have saved many people. Some of them, however, now live with heart failure—a heart that does not function well. Blood from the body is constantly returning to the heart and then being pumped out to the body. A "failing" heart either resists the inflow of blood, struggles to pump it out, or both.

If you take daily aspirin, make sure you know why and understand the small but real bleeding risk.

Are you taking an aspirin a day to keep the cardiologist away? If so, you are among millions of Americans taking a daily dose of the cheap, widely available anti-inflammatory drug for "primary prevention" of cardiovascular disease. Primary prevention means you don't have cardiovascular disease, and hope that aspirin will help prevent it.