But cardiologists thrive on the dramatic saving of lives, said Dr. Michael Bristow, a cardiologist at the University of Colorado Denver. They devote their professional lives to rescuing patients having heart attacks and bringing them back from the brink.

End-of-life care is not typically their focus; neither do they spend much time pondering what some of their patients may experience in the future. “Those who go into cardiology are not necessarily ones who want to deal with death and dying,” Dr. Bristow said.

The very nature of end-stage heart failure makes it all the more difficult to prepare.

“Very few patients understand the trajectory of the disease,” said Dr. Lynne Warner Stevenson, a heart failure specialist at Vanderbilt University. The path has peaks and valleys, but as the patient declines, each peak is a little lower than the one before.

And often doctors do not tell patients what to expect.

“Unfortunately, when you have patients with a chronic illness like heart failure, everyone thinks someone else will talk about it,” Dr. Stevenson said. “Too often, no one takes ownership of the last stage of the journey with the patient.”

Dr. Ellen Hummel of the University of Michigan, one of a small number of doctors specializing in cardiology palliative care, said the typical patient with cancer will usually experience a “fairly predictable” decline.

“They will be less able to take care of themselves,” she said. “They will be more symptomatic and come back to the hospital more frequently. And once this starts, it will probably continue until they die. Most people can see the end coming.”

But patients with end-stage heart failure are more likely to have wild swings, Dr. Hummel said, veering from feeling better to being terribly ill.