The three-fold increase had first been observed two years after the August 2005 hurricane and, much to the surprise of researchers collecting the data, it has persisted.

"We expected a down-trend after four years," said lead researcher Dr. Anand Irimpen, who continues to collect heart attack statistics as the six-year anniversary approaches. "But it appears to be more far reaching than expected."

The data was based on patients admitted with heart attacks to Tulane University Hospital two years prior to Katrina, and compared with heart attack rates four years after the storm.

In the four years after the storm, 2.2 percent of hospital admissions were due to confirmed heart attacks. Prior to the storm, the rate was 0.7 percent of admissions.

Irimpen said continuing high levels of stress and psychiatric illnesses that did not appear to be a factor at the two-year mark were playing a significant role longer term.

"There might be a lag phase between the onset of psychiatric illness and it's manifestation in the form of a heart attack," he suggested.

"Many of the patients we see are not yet back to their pre-Katrina residences, have not regained employment and are less likely to comply with treatment plans that can help prevent heart attacks. The emphasis is not on health but on getting back to your home," Irimpen said.

The heart health findings could have long-term implications for Japan, which is still reeling from the immediate devastation of a massive earthquake and tsunami that struck on March 11.

Irimpen had a message for physicians in Japan and other areas hit by large-scale disasters: "It's important to let people know that they should give health a priority, concentrate on diet and exercise, be compliant with their medications and make an appointment with their doctors."

He expects the situation in Japan will be further exasperated by long-term fears of radiation from the badly damaged Fukushima nuclear facility.

"It appears that these psychiatric illnesses from post-disaster trauma — such as anxiety and depression — all seem to be contributing to cardiac illnesses," he warned.