(Health.com) -- December 26 is historically one of the most dangerous days of the year for people vulnerable to cardiac problems, including heart attacks, arrhythmias, and heart failure.

And many of these so-called Merry Christmas coronaries will hit people who didn't even realize they were at risk when they unwrapped their gifts the day before.

But the holiday season isn't good for heart health to begin with. A 2004 study by researchers at the University of California, San Diego and Tufts University found that heart-related deaths increase by nearly 5% during the holidays, perhaps because patients delay seeking treatment for heart problems or because hospital staffing patterns change.

But anecdotally, doctors say that their ERs stay quiet on Christmas Day itself. Then, come December 26, they see a surge of cardiac traffic. A 2008 study found that daily visits to hospitals for heart failure increased by 33% during the four days after Christmas.

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"This time of year is notorious for heart attacks, heart failures, and arrhythmias," says Samin Sharma, MD, director of interventional cardiology at Mount Sinai Medical Center in New York. Here's how to steer clear of the hospital.

Keep your ticker ticking It's easy to knock back several glasses of wine when you're sitting around the holiday table for long stretches of time, especially if you tell yourself that wine is good for your heart.

But more than one alcoholic drink can have consequences: Excessive drinking can trigger atrial fibrillation, a form of irregular heartbeat. If it persists, atrial fibrillation ups your odds of suffering a stroke.

"There are huge campaigns not to drink and drive during the holidays, but no one talks about the heart dangers," says Dr. Sharma.

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Extra money woes coupled with an already stressful holiday season can also be a setup for overindulgence.

"People don't have as much money, but they still need to spend," says Gerald Fletcher, MD, a cardiologist at the Mayo Clinic in Rochester, Minn. "They're cutting back, but they're worried about the credit card bill on the way. With all this in mind, people might be drinking more than ever."

Normally, a holiday heart arrhythmia isn't fatal, and in fact it usually fades on its own. Some of the symptoms are the same as a hangover -- nausea, weakness, and a pale face -- and your heart should be back to normal in 24 hours. But if it isn't, you may need to see a doctor for medication or electrical cardioversion, which will stabilize your heart beat.

How to avoid a holiday heart attack

Every year, cardiologists see a spike in heart attacks once the weather starts to turn. When temperatures drop, blood vessels tend to constrict, raising blood pressure. You may want to think twice before you decide to shovel your stoop or take a postprandial hike in bitter weather, as strenuous physical activity can leave you clutching your chest.

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But cold weather isn't the only culprit. Come Christmas Day, many people confuse the signs of a heart attack -- like shortness of breath or chest pains -- with indigestion from a big dinner. And while you may be apt to play it safe on any other day, hauling yourself down to the hospital may seem like too much of a hassle on a big holiday.

Instead, many people ignore the telltale signs of a heart attack until they wake up on the 26th, still feeling that discomfort. But by then it may be too late.

"If you're having a heart attack, studies show that you can't wait longer than 12 hours to be treated," says Dr. Sharma.

So if you wait until December 26, you may be playing with your fate.

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Listen to your body over the long holiday haul and don't dismiss any discomfort as a by-product of overindulgence. Keep an eye on any friends or family members who have had a heart attack in the past.

Breaking diet rules and heart failure

Patients with heart failure who are following a low-sodium diet need to exercise extra caution this Christmas. Experts say that these people may choose not to live within their everyday rules, opting to partake in holiday overindulgences instead. Heavy meals, too much salt, and excess alcohol can all exacerbate heart failure.

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"Doctors need to make a point of telling their patients not to overindulge," says Dr. Sharma. "Ultimately, though, it's the patients who are going to decide what to do."

But everyone, not just heart patients, can benefit from watching what they eat.

"We need to try to stay healthy through the holidays, not wait until January 1," says Dr. Fletcher. "You can't keep your resolution if you don't live through the holidays."

Copyright Health Magazine 2011