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NEW YORK (Reuters Health) - Following the massive earthquake and tsunami of March, 2011, which devastated parts of eastern Japan, the number of heart failure cases spiked in Miyagi Prefecture and remained elevated for six weeks, according to a new study.
The number of people diagnosed with cardiac arrest and other heart problems also jumped immediately following the earthquake, but tapered back to earlier levels within three weeks.
Dr. Hiroaki Shimokawa, one of the authors of the study and a professor at Tohoku University Graduate School of Medicine, told Reuters Health that factors such as drug discontinuation, cold temperatures in the short term, excessive salt intake from preserved food, and mental and physical stresses over a long period likely contributed to the sustained increase in heart failure cases.
The quake, in Japan often called the Great Earthquake of East Japan, registered at a formidable 9.0 on the Richter scale, and resulted in more than 15,000 deaths.
Shimokawa and his colleagues wrote in the European Heart Journal that Miyagi Prefecture was the closest to the epicenter, and more than 9,500 people died there.
In an email, the researcher said that earlier studies have linked earthquakes to short-term increases in cardiovascular problems.
And a previous study found that months following the 2011 earthquake, workers at nuclear power plants in the region suffered from high rates of stress and depression. (see Reuters Health report of August 14, 2012).
Shimokawa and his colleagues wanted to look at longer-term effects on heart health, and they gathered the medical records of all people brought by ambulance to one of Miyagi Prefecture's 57 hospitals in the month preceding the earthquake and the four months following.
They compared the number of stroke, heart failure, cardiac arrest and pneumonia diagnoses during this time period in 2011 to the same time period in 2008, 2009 and 2010.
The number of people diagnosed with cardiac arrest jumped immediately on the day of the earthquake. For instance, there were 17 cases on March 11, 2011, compared to five the day before and between two and four on March 11 in each of the three years prior.
The reason for the swift jump in cardiac arrest cases appears to be that the heart is "sensitive to sudden onset of stresses," said Shimokawa.
Heart failure numbers, on the other hand, remained normal for several days following the earthquake, but then increased by March 15.
The cardiac arrest rate returned to levels seen in previous years two weeks after the earthquake, whereas the heart failure rate remained elevated.
The study could not pinpoint the causes of the increase in heart problems.
"I'm not really sure whether indeed it's the increase of cardiovascular disease by stress (from the earthquake) that's counted here, or whether it's simply the consequence of the catastrophe they've been in - that is, the trauma, the breakdown of lifelines, water, food, etc.," said Dr. Gerhard Steinbeck, a professor at the University of Munich in Germany, who was not involved in the Japanese study.
In an editorial, Steinbeck and a colleague wrote that there could be some inaccuracies in the ways heart failure and cardiac arrest were counted.
For one, the definition of heart failure and how it was diagnosed was not given. Steinbeck said making such a diagnosis is time-consuming and difficult, especially in the midst of a catastrophe.
Additionally, the causes of cardiac arrest are not detailed, and they could reflect cases of people who drowned.
Therefore, he said, it's not clear whether the numbers reflect a prolonged exacerbation of heart disease caused by the earthquake itself or the negative health effects caused by the aftermath of the disaster.
"Whatever the mechanisms... the data clearly show that it's a real challenge to any healthcare system," Steinbeck told Reuters Health.
Steinbeck said the study is useful in helping healthcare systems prepare for the extended needs after natural disasters.
"It's not a matter of hours or days thereafter, but any healthcare system has to deal with increased emergencies and cardiovascular disease not for days, but months," he added.
SOURCE: bit.ly/PDvk1M European Heart Journal, online August 28, 2012.