A new study published in JAMA claims to have found evidence to support a causal association between high levels of “bad” cholesterol and aortic valve stenosis – a form of aortic valve disease in which the valve is narrowed, restricting blood flow from the heart.
According to the research team, including Dr. George Thanassoulis of McGill University in Canada, aortic valve disease is the most common form of heart valve disease in North America and Europe. It is also the most common reason for patients to require an aortic valve replacement.
Past studies have associated elevated low-density lipoprotein (LDL) cholesterol – known as the “bad” cholesterol – with development of aortic valve stenosis.
But Dr. Thanassoulis and colleagues note that researchers observing the effects of cholesterol-lowering drugs in patients who already have aortic valve disease have failed to show reduced disease progression.
“Nonetheless,” the researchers add, “if LDL cholesterol plays a causal role in the earlier stages of aortic valve disease, this could have important implications for prevention.”
With the aim of establishing a better understanding of the link between LDL cholesterol and aortic valve disease, the researchers used an approach called “Mendelian randomization.”
The method allows researchers to use genetic variation to distinguish biomarkers that cause disease from those that do not. “This approach has been successfully applied to assess for causality of several biomarkers with various clinical end points,” the researchers note.
In this study, the researchers analyzed the relationship between participants’ genetic risk score – a measure of genetic predisposition to high lipid levels in the blood – and aortic valve disease.
They looked at this association among more than 35,000 individuals who were part of studies in the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE): the Framingham Heart Study, the Multi-Ethnic Study of Atherosclerosis, the Age/Gene Environment Study and the Malmö Diet and Cancer Study.
The researchers analyzed calcium levels in the aortic valves of participants using computed tomography (CT) scans. A calcium build-up in the valve – known as aortic valve calcification – is a known cause for aortic valve stenosis.
The researchers found that the presence of aortic valve calcium was more prominent in participants who were genetically predisposed to elevated levels of LDL cholesterol.
Participants genetically predisposed to high LDL cholesterol levels in the Malmö Diet and Cancer Study were more likely to have a new diagnosis of aortic valve stenosis. Furthermore, in a subgroup of this study who had their lipid fractions measured, elevated LDL cholesterol at baseline was linked to new diagnoses of aortic valve stenosis.
Commenting on these findings, the study authors say:
“Our findings link a genetically mediated increase in plasma LDL cholesterol with early subclinical valve disease, as measured by aortic valve calcium and incident clinical aortic stenosis, providing supportive evidence for a causal role of LDL cholesterol in the development of aortic stenosis.
These data suggest that, in addition to the established risks for myocardial infarction and other vascular diseases, increases in LDL cholesterol are also associated with increased risk for aortic stenosis.”
The researchers conclude that further research is warranted to determine whether early intervention strategies to reduce LDL cholesterol levels could prevent aortic valve disease.
Earlier this year, Medical News Today reported on a study revealing how surgeons in France performed the world’s first completely endoscopic aortic valve replacement.