Warning Signs of Heart Failure

Common symptoms of the potentially deadly condition can often be mistaken for other health conditions, even aging

Liz Szabo,

AARP

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Published September 30, 2025

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Bill Miller felt like he had been kicked in the chest by a horse.

When Miller’s internal defibrillator detected an irregular heartbeat — the kind that can lead to sudden cardiac arrest — it sent a series of powerful shocks to jump-start his heart. Because Miller’s heart was severely out of rhythm — the cardiac equivalent of an electrical storm — the device fired 22 times.

The first shock knocked Miller out of his chair at a restaurant. The pain was so intense that Miller, then 56, began screaming for someone to turn the defibrillator off. In spite of the pain it caused, Miller, 62, says, “the defibrillator saved my life.… It was a wake-up call.”

Miller had been diagnosed with heart failure three years before his near-death experience. Heart failure is a serious condition in which the heart muscle becomes too weak to pump blood to the rest of the body, which can deprive vital organs and tissues of oxygen.

And while Miller took the medication his doctors prescribed, he says he didn’t pay enough attention to his doctors’ warnings and continued working long hours at a stressful job in banking.

Deaths from heart failure are on the rise

One in four Americans develop heart failure, which contributes to the deaths of about 425,000 people in the U.S. each year. It’s estimated that 6.7 million people are living with heart failure.

Deaths from heart attacks have fallen sharply in recent decades, thanks to medical innovations and lower smoking rates, according to a study published in June in the Journal of the American Heart Association. But up to 40 percent of Americans who survive heart attacks develop heart failure, which has contributed to the 146 percent increase in heart failure mortality from 1970 to 2022.

When Miller was first diagnosed with heart failure, the only warning signs were a cough that refused to go away, as well as fatigue, which Miller attributed to chronic sleep apnea. When he finally saw a cardiologist, tests showed Miller’s heart was pumping out only a fraction of the blood his body needed.

After a few months on medication, Miller’s doctor told him that he remained at very high risk of a heart attack and suggested the implantable defibrillator. After a while, Miller says, he almost forgot about the device in his chest.

“To be perfectly honest,” says Miller, of Pearl River, New York, “I was not taking it seriously enough.… You’ve got to pay attention to your doctors and pay attention to your health and what you’re eating, and I didn’t.”

Miller’s brush with death terrified him, he says. The experience left him with post-traumatic stress disorder (PTSD), as well as a determination to lead a healthier life.

“I got into the best physical condition of my life over the next 18 months,” says Miller, who received treatment for PTSD. He weighed 283 pounds when his heart stopped, after which he joined a weight-loss program and lost 87 pounds. He says he realized he had no choice but to change his habits.

What are the warning signs of heart failure?

The nagging cough that led Miller to seek medical care is a classic symptom of heart failure, says Dr. Biykem Bozkurt, a professor of medicine-cardiology at Baylor College of Medicine.

When the heart doesn’t pump effectively, fluid can build up in the lungs, causing a lingering cough. Other common warning signs include fatigue; swelling in the feet, ankles, legs, fingers and stomach; and shortness of breath, especially when active, Bozkurt says.

Some people with heart failure feel so short of breath when lying on their backs that they begin propping themselves up with pillows in bed, says Dr. Gregg Fonarow, a spokesperson for the American Heart Association, director of the Ahmanson-UCLA Cardiomyopathy Center and co-director of UCLA’s Preventive Cardiology Program.

Other people become breathless when bending over to tie their shoes. In some cases, heart failure can lead to loss of appetite or nausea, a racing heart rate, sudden weight loss and temporary mental confusion or memory loss.

Symptoms of heart failure can be confused with other conditions, Fonarow says. Coughing or shortness of breath is sometimes attributed to asthma, while swelling in the legs is sometimes blamed on varicose veins. Persistent fatigue can be misinterpreted as a sign of aging.

The warning signs of heart failure can mimic those of a serious condition called chronic obstructive pulmonary disease, or COPD, which occurs when the airways of the lung become swollen and irritated by smoking or other causes.

Even primary care physicians can make the wrong diagnosis, leading to delays in receiving effective therapy, Fonarow says.

By the time some patients are diagnosed with heart failure, “you look back and there were months or even years of symptoms,” Fonarow says. “There were many opportunities” to intervene.

Diagnosing heart failure often requires a number of tests, including a physical exam; blood tests; chest X-rays; an electrocardiogram, or EKG, which measures heart rhythm; an echocardiogram, which uses sound waves and can reveal whether the heart wall has become thicker; exercise stress tests, which can be performed on a treadmill or stationary bike; an X-ray, which takes a picture of the heart; and other scans.

Treating heart failure

In recent years, doctors have made great strides in treating heart failure, Bozkurt says. Medications can relieve symptoms and reduce the need for hospitalization for patients with any type of heart disease.

“The earlier we start therapy, the more effective treatment can be,” Fonarow says.

Doctors classify heart failure into two major types, depending on whether the heart can pump out all the blood required. In one type of heart failure, known as heart failure with reduced ejection fraction, the heart is so weak that it only pumps out a fraction of the blood needed. In the second type of heart failure, known as heart failure with preserved ejection fraction, the heart pumps normally but is too stiff to fill properly.

For younger patients with a type of heart failure in which the heart only expels a fraction of blood every time it beats, prescribing a drug combination called quadruple therapy can reduce the risk of dying by 75 percent, Fonarow says.

Although heart failure medications are available as cheaper generics and usually covered by insurance, most people with heart failure with reduced ejection fraction only receive one or two of them, rather than all four, Fonarow says. “There’s a lot of work to be done to improve care,” he says. “If patients aren’t on four drugs, they should ask their doctor, ‘Why not?’ ”

Recent research suggests that people with heart failure with preserved ejection fraction who take GLP-1 drugs, such as semaglutide (Ozempic), are less likely to die or be hospitalized for heart failure.

Most people with heart failure do not need a defibrillator, the device that Miller received. In the most serious cases, people with heart failure may need a heart transplant.

Preventing heart failure

Lifestyle change plays an important role in preventing heart failure, as well as treating it, Fonarow says. About 80 percent of heart failure that’s attributed to hypertension can be prevented through healthier living and avoiding risk factors such as smoking and alcohol, he adds.

Lowering systolic blood pressure — the top number in a blood pressure reading — can be lifesaving, Fonarow says. In a large randomized controlled trial of people with hypertension, people who took medications to get their systolic blood pressure below 120 mm Hg were 38 percent less likely to develop heart failure than those whose systolic blood pressure was below 140.

People can also reduce their risk by maintaining a healthy weight and getting treatment for chronic conditions, such as thyroid disorders and coronary artery disease, in which the arteries of the heart become blocked. Both thyroid disorders and coronary artery disease can be treated with medication.

People may also be able to lower the risk of heart failure by receiving all recommended vaccinations, including those that protect against pneumonia, influenza, RSV and COVID-19, Bozkurt says. In a study published in July in the Journal of the American Geriatrics Society, researchers found that at least 1 in 10 people hospitalized for RSV later developed heart failure.

Vaccines also benefit people with heart failure. A study published in The Lancet in September found that people hospitalized with acute heart failure were 17 percent less likely to die for any reason over the next year if they were vaccinated against flu while in the hospital.

Doctors can lower the risk of heart failure among people being treated for cancer by administering certain medications that protect the heart during chemotherapy, Fonarow says.

A second chance

Heart failure remains a serious threat to Miller’s life. He has regained some of the weight he lost and continues to struggle with anxiety.

In 2023, during a particularly stressful period, Miller suffered a cardiac arrest while at work. His defibrillator delivered a single shock to his heart, restoring its normal rhythm. This time, Miller says, he was unconscious when his heart was shocked.

“If you’ve got something like heart failure, you’ve got to manage the stress level,” says Miller, who performs deep breathing exercises to reduce stress. He also enjoys walking with his dog, Shea.

“Even though she’s never been trained as a therapy dog, she was very, very important in my mental recovery,” Miller says.

He now uses a combination pacemaker/defibrillator. He also has undergone a thoracic sympathectomy, a surgery designed to help normalize heart rhythms.

“I’m blessed,” Miller says, “that I’ve got a second chance.”

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