A recent study published in the European Heart Journal raises alarming concerns about intermuscular fat—fat stored within muscle tissue—and its association with increased risks of mortality and hospitalization linked to heart-related issues.
This research underscores the shortcomings of traditional metrics like body mass index (BMI) in assessing heart disease risk.
It turns out that individuals can be at risk for heart problems regardless of what their BMI suggests.
Study Overview
The study, spearheaded by Professor Viviany Taqueti, who holds the position of Director of the Cardiac Stress Laboratory at Brigham and Women’s Hospital and is a faculty member at Harvard Medical School, delves into the importance of fatty tissues contained in muscles.
Professor Taqueti emphasizes that obesity poses a major threat to cardiovascular health worldwide.
Yet, the continued use of BMI as the main indicator of obesity draws critique, especially since it often fails to reflect true cardiovascular risk in women, where a higher BMI may indicate less harmful fat types.
Every individual has a different amount of intermuscular fat, and the researchers sought to determine how the composition of muscle—including the fatty muscle fraction, which is essentially the ratio of intermuscular fat to overall muscle and fat—affects small blood vessels in the heart, as well as risks for conditions like heart failure and heart attacks.
Findings and Implications
The study involved a cohort of 669 participants, mostly women (70%), with an average age of 63, who were assessed for symptoms like chest pain or breathlessness at Brigham and Women’s Hospital.
Significantly, none of these individuals showed signs of obstructive coronary artery disease.
Each participant underwent cardiac PET/CT scans to evaluate cardiac function, as well as CT scans to analyze body composition, particularly focusing on the distribution and amount of fat and muscle in the torso.
During a follow-up that lasted about six years, researchers monitored the participants for hospitalizations due to heart-related issues and mortality rates.
The findings revealed that those with higher levels of intermuscular fat had a substantially increased likelihood of experiencing coronary microvascular dysfunction, which in turn raised their risks for severe heart disease.
Specifically, every 1% rise in the fatty muscle fraction resulted in a 2% increase in the risk of CMD and a 7% escalation in the odds of developing severe cardiovascular issues, regardless of other known risk factors, including BMI.
This study highlighted that individuals with both elevated intermuscular fat and signs of CMD faced significantly higher risks of fatal outcomes and serious cardiac events.
On the flip side, participants with more lean muscle mass demonstrated lower risk profiles.
Interestingly, subcutaneous fat—fat that lies beneath the skin—did not show a link to increased cardiovascular risks.
Future Research Directions
According to Professor Taqueti’s research, intermuscular fat may play a role in initiating inflammation and disrupting glucose metabolism, leading to insulin resistance and metabolic syndrome.
Such conditions could harm blood vessels and heart tissue.
Identifying intermuscular fat as a potential risk factor for heart disease opens new doors for recognizing individuals who may be at elevated risk, independent of their BMI.
This discovery suggests possible implications for assessing the cardiovascular impacts of new treatments aimed at altering fat and muscle composition, particularly the emerging class of glucagon-like peptide-1 receptor agonists.
However, questions remain about how to effectively reduce the risks associated with fatty muscle.
The effects of new weight-loss therapies on muscle fat, relative to fat in other areas, lean tissue, and heart health, are still unclear.
To advance this understanding, Professor Taqueti and her research team are currently exploring how various treatment approaches—such as exercise, dietary changes, and weight-loss medications or procedures—affect body composition and the progression of metabolic heart disease.
Source: ScienceDaily