Researchers now know that fat in the stomach— called abdominal obesity — increases the risk of a first heart attack. Yet new research finds that having excess fat often increases the risk of subsequent heart attacks in this particular area.
“The reason abdominal obesity is very common in people with a first heart attack is that it is closely linked to conditions that worsen the atherosclerosis clogging of arteries,” explains study author Dr. Hanieh Mohammadi of the Karolinska Institute in Stockholm, Sweden.
“These conditions include increased blood pressure, high blood sugar and insulin resistance (diabetes) as well as increased blood lipid levels.”
However, Dr. Mohammadi says the team’s results “suggest that other abdominal obesity-related mechanisms may exist that are independent of these risk factors and remain unrecognized.”
Though a newly known region, the relation between stomach fat and repeated heart attacks was so distinct that the authors of the study conclude that healthcare professionals should use waist circumference to classify patients at risk.
The biggest study
The research, published in the European Journal of Preventive Cardiology, looked not only at recurrent heart attacks, but also at ischemic strokes and death from coronary heart disease that followed an initial heart attack.
The study has involved more than 22,000 participants aged 35–77, making it, to date, the largest study on the subject. The Swedish team has recruited people from the SWEDEHEART cardiac registry in the region. Nearly 17,000 were men.
After their heart attack, the researchers followed each participant for some 4 years. The team used the data from the initial hospital visits and further inspections of the participants.
The researchers identified cardiovascular risk factors during those visits through a standardized survey.
The researchers measured the waist circumferences of the participants along with weight, height, blood pressure, rhythm of the electrocardiogram (ECG), blood lipid levels and glucose levels.
By measuring the stomach between the last rib and the iliac crest, which is the most prominent part of the pelvic, they measured waist circumference— the main focus of the study.
A link to remember
Independent researchers linked abdominal obesity to both fatal and non-fatal heart attacks and strokes, even when taking into account other cardiovascular risk factors such as smoking and blood pressure.
The team actually concluded that stomach fat is a more vital indicator of recurring heart attacks than general obesity.
Most participants in the study exhibited abdominal obesity (78% of men and 90% of females). In this area, the researchers defined obesity as a 94 cm or more circumference for males, and 80 cm or more for females.
Secondary preventive treatments also had no impact on the relationship between stomach fat and repeated cardiovascular incidents; a result which, according to Dr Mohammadi, was “previously unknown.”
Dr Mohammadi says that doctors typically give patients secondary prevention treatments “after their first attack to avoid second events.” Such treatments work “by lowering heart attack and stroke-related risk factors, such as high blood sugar, lipids and blood pressure.”
“In our study,” continues Dr. Mohammadi, “patients with increasing levels of abdominal obesity still had an increased risk of repeated events despite having therapies that reduce typical risk factors associated with abdominal obesity— such as anti-hypertensive medication, diabetes medication, and lipid-lowering medication.”
Notable gender differences
As well as being the first study to find that, if abdominal obesity is present, secondary prevention treatment has no effect on recurrent risk, the research is also the first to analyze by sex.
The males and females demonstrated certain differences when examined separately. For example, in men the relationship between waist circumference and subsequent heart attacks was stronger.
However, the lowest risk in females did not mean having the smallest circumference of waists. Rather it was the mid-range circumference that reduced the risk of recurring events for a female.
Dr. Mohammadi has a theory: “Many studies have suggested that abdominal obesity may be correlated more specifically with the evil visceral fat (fat that lies around the organs) in men than in women.
” In women, a larger portion of abdominal fat is thought to be formed by subcutaneous fat, which is relatively harmless.
“Furthermore, these variations need further analysis because” there were three times as many men in the sample as women, leading to less statistical power in the female group.
“Nevertheless, the conclusion is still clear , notes Dr. Mohammadi.
“Maintaining a healthy circumference of the waist is important to prevent potential heart attacks and strokes regardless of how many medications you can take or how safe your blood tests may be.”