Women are nearly nine times as likely as men to suffer stress-induced cardiomyopathy, and older women are at the highest risk, a new study of a large US national database has found.
Comparing the 1998 incidence of the syndrome, called Takotsubo cardiomyopathy, to the US national census of the same year, researchers determined that for every 100 000 people, 5.2 women and 0.6 men are hospitalised.
How the study was done
"The rates we found were similar to those found in other smaller studies. However, we were able to show the same gender difference from 6 837 hospitalisations - the largest study to date across the United States," Dr Abhishek Deshmukh from the University of Arkansas for Medical Sciences in Little Rock, who led the study, told Reuters Health by email.
Dr Deshmukh and his colleagues published their results online in the American Heart Journal. They described Takotsubo syndrome as characterised "by transient systolic dysfunction of the apical and or midsegments of the left ventricle that mimics acute myocardial infarction but with no obstructive coronary artery disease."
The researchers examined records from the Nationwide Inpatient Sample and included all adult patients diagnosed with the condition who underwent coronary angiography but not revascularisation therapy. Of the total hospitalised cohort, 6 177 patients (90.4%) were women and 660 (9.6%) were men, giving women an odds ratio of 8.8.
Increased higher in women
Age appeared to increase women's risk, but not men's, the study found. Women older than age 55 years were 4.8 times more likely to develop the condition as women age 55 and younger. Compared to men of the same age, women older than age 55 had 10 times the risk, while women younger than 55 years were about twice a likely to develop the condition.
Other risk factors included hyperlipidemia, smoking, alcohol, anxiety and stress, which were all significantly linked to the condition after adjusting for confounders. Also, hospitalizations were more common in the summer months, with the highest number of cases in July and the lowest in January.
The finding that hyperlipidemia, smoking, alcohol, and summer months were risk factors came as a surprise to Dr Junyo Ako, a cardiovascular expert at Jichi Medical University in Saitama-city, Japan who was not involved in the research. "These associations may warrant further investigation," Dr Ako said.
Findings of study
This study's findings on the prevalence of the condition seem to fit with what is known about Takotsubo cardiomyopathy, Dr Ako added. "In fact, this study included patients with 'primary' diagnosis of TTC (Takotsubo cardiomyopathy). However, TTC can complicate the clinical course of various diseases including cancer, infection, etc. Therefore, I would say that actual prevalence of TTC could be even more."
Possible causes for the gender and age differences are beyond this study's scope, but the researchers had a theory. "Evolutionary evidence suggests that men were exposed to more physical stress than women and, thus, might have developed several mechanisms to cope with the negative effects of stressors," they wrote in the paper.
For example, men have a higher density of adrenergic receptors in the membrane of cardiomyocytes, which may protect against a severe catecholamine storm. Saturation of adrenoreceptors takes longer in men than in women, the researchers write. Future research would need to address that hypothesis.
(Reuters Health, Rob Goodier, August 2012)
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