When it is impossible to cure an elderly person's chronic disease, many doctors might assume that the patient would choose to improve the quality of his or her remaining life rather than to extend it. Those doctors would be mistaken most of the time, according to a new study.

Swiss researchers, who surveyed more than 500 elderly heart failure patients, found that three quarters wouldn't trade a longer life with symptoms for a shorter life without them, and the severity of symptoms was not a good predictor of who would pick a measure of relief over more time.

I was quite surprised by the results, said lead author Dr. Hans-Peter Brunner-La Rocca, of University Hospital Basel in Switzerland. Often we think we know what is best for a patient, but this is often wrong, he told Reuters Health in an email.

When patients get to an age where the chance of dying in the near future becomes more evident, pure survival may be more important, said Brunner-La Rocca, who is also affiliated to the Cardiovascular Research Institute at Maastricht University Medical Center in the Netherlands.

Heart failure is a chronic and incurable condition, in which the heart is too weak to pump enough blood to meet the body's needs. It affects around six million people in the U.S., according to the Centers for Disease Control and Prevention.

Symptoms include shortness of breath, fatigue, weakness and swelling in the legs and feet, reducing a person's ability to walk or exercise. Heart disease, high blood pressure or diabetes can weaken the heart muscle over time, which can lead to heart failure.

The researchers surveyed 555 heart failure patients, most in their seventies and eighties, asking a series of questions about end-of-life preferences. Then they repeated the survey after 12 months, and again after another six months.

At the start of the study, 74 percent of the respondents said they would not choose to live one more year in excellent health over living two more years in their current state. After a year had elapsed, 80 percent were unwilling to trade more time for symptom relief.

At 18 months, few had changed their minds. When asked about whether they wanted CPR in a crisis, about a third said they didn't want to be resuscitated.

Even among people with do not resuscitate orders in their medical files, about a third said they in fact did want CPR. Dr. Eugene Storozynsky, who studies cardiology at the University of Rochester Medical Center, noted that the study participants represented a broad range of people with heart failure -- from those with a just a few symptoms to those with many more severe problems.

Those with milder disease might not consider it bad enough to trade-off their remaining time. For these patients, it seems oral medications are still adequate enough to relieve their symptoms so they don't need to be frequently hospitalized, said Storozynsky, who was not part of the study.

Patients with end-stage heart failure require multiple hospitalizations in a short period of time due to their symptoms, he pointed out.

Life expectancy may be six months or less without advanced therapies, he told Reuters Health. Patients in this study were less bothered by their symptoms, so I would define them as less sick than those with end-stage heart failure, he added.

Participants in the study who were willing to trade more time for symptom relief were older, often female and had more heart failure symptoms, suggesting people may change how they manage their disease over time.

We couldn't find particular patterns to predict what individuals would want, Brunner-La Rocca told Reuters Health. So it's crucial to individually discuss these issues with the patient.

Storozynsky also thinks doctors should be upfront with patients. We should discuss all stages of heart failure to make them aware that at its end stage, their life will likely shorten, he said, adding, Not to scare them, but inform them and tailor our treatment to their wishes.