Aortic stenosis is the most common form of heart valve disease in developed countries and is thought to affect 2-7% of those over the age of 65. The disease is characterised by restricted blood flow through the valve, with affected individuals commonly experiencing symptoms such as chest pain, shortness of breath, heart palpitations and, in more severe cases, collapse and loss of consciousness.
The study team used a state-of-the-art method called Mendelian randomization to determine this causal effect. At fertilisation (the union of a human egg and sperm cell), we are all randomly allocated genes that are known to be associated with health-related characteristics in later life; in this case either normal or high cholesterol levels. Researchers were therefore able to categorise the study population by genetically-determined cholesterol level and then directly compare outcomes in terms of onset of aortic stenosis.