Past studies have found upswings in heart-related deaths after a stressful mass event -- from natural disasters like earthquakes, to sports disasters like a home team losing the Super Bowl.

But in the new study, researchers found no evidence that the October 2008 crash led to a spike in deaths -- from heart problems or otherwise -- in LA.

“It was surprising, given what other studies have found," said lead researcher Dr. Bryan Glen Schwartz, of the Heart Institute at Good Samaritan Hospital in LA.

But what the findings suggest, he told Reuters Health, is that while the stock market crash was stressful, it may not have been an intense, personal emotional trigger for most Angelenos.

There is plenty of research suggesting that for people with heart disease risk factors -- like high blood pressure or diabetes -- acute stress can temporarily raise the odds of a cardiac “event," such as a heart attack.

Acute stress can be physical, like sudden, heavy exertion, or it can be emotional, Schwartz said. And this study doesn't negate the importance of acute stress in people's heart risks, he added.

But the stress surrounding the 2008 crash may not have been enough to cause a “population shift" in heart disease deaths, explained Dr. Robert A. Kloner, the senior researcher on the study.

The findings, published in the American Journal of Cardiology, are based on LA county death certificate data and daily stock market figures for 2005 through the end of 2008.

The researchers found no evidence that the October market crash affected death rates, overall or from heart complications specifically. After the crash, deaths remained at or below the seasonal average.

For 2008 overall, the death rate from heart disease in LA was 0.12 percent -- slightly lower than the 2005 rate of 0.14 percent.

The findings stand in contrast to a study in Shanghai, China, where the stock market woes of 2008 were tied to a spike in deaths. Published last year by Chinese researchers, that study found that every 100-point change in the Shanghai stock market index during 2007 and 2008 was linked to a five percent rise in heart-related deaths.

But the apparent link may be due to population differences in Shanghai and LA, Schwartz and Kloner said.

In Shanghai, many new investors in China's boom years of 2006 and 2007 were elderly, and already at increased risk of heart disease. And unlike LA investors, who typically leave their money in the hands of professionals, Shanghai investors were generally watching the market themselves, monitoring it daily.

They were more personally and emotionally involved in it," Schwartz said. Because of that, he speculated, market volatility may have been a bigger risk for Shanghai investors' hearts compared to their LA counterparts.

It's thought, Kloner explained, that emotional stress can contribute to heart attacks or cardiac arrest via the fight-or-flight" response -- a spike in nervous system activity and stress hormones that leads to higher heart rate, changes in blood vessel dilation and other physiologic shifts.

So the stressful event would have to be intense and personal enough to trigger that kind of response. And it would have to be coupled with chronic heart risk factors like high blood pressure, high cholesterol or diabetes.

In contrast to the stock market findings, the researchers did find another apparent risk factor for heart deaths: winter.

Overall, cardiac death rates have been steadily dropping since the 1980s, the study confirmed, but they peak fairly consistently in late December and early January.

The finding is in line with seasonal variations seen in other studies, the researchers say.

Holiday stress is often blamed for the effect.

Even during mild LA winters, there are a number of other potential explanations for the pattern, as well as some common sense" ways to lessen the risk, Kloner said.

One is to get a flu shot," he said.

Older adults and people with established heart disease are particularly encouraged to get a yearly flu shot, because they are at increased risk of flu complications -- which include pneumonia, heart attack and death.

Kloner also advised maintaining a healthy diet and regular exercise during the winter, when those habits tend to fall away. And stay bundled up against the cold, he said, since low temperatures can have potentially risky effects on the cardiovascular system, like making the blood more prone to clotting.

SOURCE: bit.ly/wCMwLE American Journal of Cardiology, online March 1, 2012.

• A Permanent Economic Emergency