Scientists
already know that stomach fat — known as abdominal obesity — increases the risk
of having a first heart attack. But new research finds that having excessive
fat in this specific area also increases risk of subsequent heart attacks.
“The reason abdominal obesity is very common
in people with a first heart attack is that it is closely linked with
conditions that accelerate the clogging of arteries through atherosclerosis,”
explains study author Dr. Hanieh Mohammadi, from the Karolinska Institute in
Stockholm, Sweden.
“These
conditions include increased blood pressure, high blood sugar, and insulin
resistance (diabetes) as well as raised blood lipid levels.”
However,
Dr. Mohammadi says the team’s results “suggest that there may be other
mechanisms associated with abdominal obesity that are independent of these risk
factors and remain unrecognized.”
Although
a relatively understudied area, the link between stomach fat and recurring
heart attacks was so distinct that the study’s authors believe that healthcare
professionals should use waist circumference to identify at-risk patients.
The largest study
The
research, published in the European Journal of Preventive Cardiology, did not just
look at recurrent heart attacks, but also at ischemic strokes and coronary
heart disease death that occurred after an initial heart attack.
The
study involved more than 22,000 participants aged 35–77, making it the largest
study on the topic, to date. The Swedish team enlisted people from the
country’s SWEDEHEART cardiac
registry. Almost 17,000 were male.
The
researchers followed each participant for around 4 years after their heart
attack. The team used the data from the participants’ initial hospital visits
and further check-ups.
The
first follow-up visit took place between 4 and 10 weeks after the person had a
heart attack, and the second took place between 12 and 14 months after the
cardiovascular incident.
During
these visits, the researchers identified cardiovascular risk factors via a
standardized survey.
The
researchers measured the participants’ waist circumferences along with weight,
height, blood pressure, electrocardiogram (ECG) rhythm, and levels of blood
lipids and glucose.
They
calculated waist circumference — the main focus of the research — by measuring
the stomach between the last rib and the iliac crest, which is the most
prominent part of the pelvis.
A link to remember
Independent
researchers associated abdominal obesity with both fatal and non-fatal heart
attacks and strokes, even when they took other cardiovascular risk factors,
such as smoking and blood pressure, into account.
In
fact, the team concluded that stomach fat was a more vital indicator of
recurrent heart attacks than general obesity.
The
majority of the study’s participants exhibited abdominal obesity (78% of men
and 90% of women). The researchers defined obesity in this area as a
circumference of 94 cm or more for males and 80 cm or more for females.
Secondary
prevention treatments also had no effect on the relationship between stomach
fat and recurrent cardiovascular incidents; a finding that was “previously
unknown,” according to Dr. Mohammadi.
Doctors
typically give secondary prevention treatments to patients “after their first
attack to prevent second events,” Dr. Mohammadi says. These treatments work “by
reducing risk factors associated with heart attack and stroke, such as high
blood sugar, lipids, and blood pressure.”
“In
our study,” Dr. Mohammadi continues, “patients with increasing levels of
abdominal obesity still had a raised risk for recurrent events despite being on
therapies that lower traditional risk factors connected with abdominal obesity
— such as anti-hypertensives, diabetes medication, and lipid lowering drugs.”
Notable gender differences
As
well as being the first study to find that secondary prevention treatment has
no effect on recurrent risk if abdominal obesity is present, the research is
also the first to analyze by sex.
When
examined separately, males and females demonstrated certain differences. The
link between waist circumference and subsequent heart attacks was stronger in
men, for example.
But,
in females, the lowest risk did not mean having the smallest waist
circumference. Instead, it was the mid-range circumference that decreased a
female’s risk of recurrent events.
Dr.
Mohammadi has a theory: “Some studies have suggested that abdominal obesity may
be more directly associated with the evil visceral fat (fat that sits around
your organs) in men compared to women.
“In
women, it is thought that a greater portion of the abdominal fat is constituted
by subcutaneous fat, which is relatively harmless.”
These
differences, however, need further examination as “there were three times as
many men in the study compared to women, contributing to less statistical power
in the female group.”
Source:
Medical News Today
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