Some people thus have pockets of fat hidden in the muscles and these same people face a higher risk of hospitalization and death of cardiovascular causes. This is worth whatever their body mass index (BMI). The main author, Dr. Viviany Taqueti, professor at the Harvard Medical School, adds: “Obesity is today one of the largest threats to cardiovascular health, but the body mass index – our principal Indicator to define obesity and intervention thresholds – remains a controversial and erroneous marker of the cardiovascular prognosis. This is particularly true in women, in whom a high BMI can reflect more “mild” fat types.
This “intermuscular” fat has so far been little studied,
Even if in humans, it is the equivalent of animal fat (saturated fatty acids) popular in the rib steak, but not recommended for health, underline the authors. However, in humans, you know its impact on health. Intermuscular fat can be found in most body muscles, but the amount of fat can vary considerably from person to person.
It is indeed the first research to examine the effects of different fatty muscles and different types of fat in terms of heart risk, to understand how body composition can influence small blood vessels or “microcirculation” of the heart, as well as The future risk of heart failure, heart attack and death.
The study Followed for 6 years 669 patients, aged on average of 63 years, at 70 % of women, followed in BWh for chest pain and/or shortness of breath, having a priori no sign of obstructive coronary disease (when the arteries that feed The heart are obstructed). Participants all passed a cardiac Petscan in order to assess the functioning of the heart and tscanners to assess the body composition, the quantities and the location of fat and muscles in a part of the torso. The researchers finally calculated the relationship between intermuscular fat and the total muscles plus fat: this measure was called
“Grasse muscle fraction”.
Data analysis during follow -up reveals that:
-- Participants with higher quantities of fat stored in their muscles have an increased risk of lesions of blood micro-vessels which serve the heart (coronary microvascular dysfunction);
- incur increased risk of hospitalization and death of heart;
- For each 1 % increase in muscle fat, the risk of coronary microvascular microvascular dysfunction increases by 2 % and the risk of serious 7 % serious heart disease;
- These associations are still worth taking into account possible confusion factors and BMI;
- high levels of intermuscular fat and signs of coronary microvascular dysfunction are associated with a particularly high risk of death, heart attack and heart failure;
- On the other hand, higher amounts of lean muscle are associated with a lower risk;
- The analysis also confirms that fat stored under the skin (subcutaneous fat) does not increase these risks.
“Compared to subcutaneous fat, intramuscular fat can contribute to inflammation and alteration of glucose metabolism, lead to resistance to insulin and metabolic syndrome. These chronic conditions damage blood vessels, including those who feed the heart, and the heart muscle itself ”explain the authors.
It is now a question of studying, with this new perspective, the effects on the intramuscular fat of the therapies based on incretins – which modify the fat and the muscles – and the new class ofGLP-1 agonists.
“What we do not yet know is how we can reduce the risk for people with fatty muscles”, but this new discovery proves, in any case, that existing measures, such as those that target the index Body mass or the waist, are not sufficient to accurately control the risk of heart disease “.
