Heart disease risk — it’s not as simple as just looking at your cholesterol levels!
Cardiovascular disease remains the major killer around the globe being associated with around 17 million deaths annually. In Australia alone, one person dies every 12 minutes from this condition. Typically, when you consider the causes of heart disease, high cholesterol and, to a lesser extent, high blood pressure are felt to be the major factors in this disease.
But, over the past few decades, our knowledge in this area has burgeoned. The commonest cause of cardiovascular disease is atherosclerosis, the progressive build-up of fat, inflammatory cells and calcification in the walls of our arteries for decades occurring before the plaques rupture to cause acute vascular syndromes such as heart attack and stroke. The vast majority of people living in the modern world develop some degree of atherosclerosis as they age and clinically this takes decades to develop with most people with clinical heart disease manifesting over the age of 50.
Firstly, let me make the point that severe atherosclerosis is all genetic but as I have said repeatedly, it is your genes that loads the gun and your environment that pulls the trigger. Two recent interesting studies have highlighted the importance of environmental factors as precipitants for heart disease with a number of other studies showing that there are a number of factors from pre-cradle to grave that influence this condition.
The first study I would like to review presented data from the German Health Interview and Examination survey for Children and Adolescents (KIGGS cohort). This was a national survey including 4,716 participants age between ages 3 to 17 examining BP, height and weight. There was a follow-up 11 years later in the 14 to 28 year-olds (at that stage), when they had ultrasounds measuring the thickness of the walls of the carotid arteries which supply blood to the brain. This arterial thickness has been used for many years as a marker for atherosclerosis.
High blood pressure at the initial assessment was associated with a 33% higher risk for thickened arteries 11 years later but if the BP was high at both assessments this became a 63% increased risk and obesity at both examinations led to a 53% greater risk. Firstly, BP is hardly checked in childhood and I’m not sure (as a practising adult cardiologist who does not see children as patients) how often weight is measured in young children and addressed by their treating doctors.
It is disturbing to think that poor eating habits and lack of exercise, contributing to obesity and hypertension in children is already impacting on their arteries. This is a salient warning that we should be focusing on good life habits and health, probably prior to conception. Educating the public as to the vital importance of healthy lifestyle practices throughout their entire lives is probably the most crucial step. It is also somewhat disturbing to realise that the examples you show to your children may also impact on their lifetime health.
Another unrelated but very interesting study has just been published from the University of Queensland looking at the link between hot flushing, night sweats and cardiovascular risk. Hot flushing and night sweats are known as vasomotor symptoms or VMS. This study showed that women who suffer significant VMS have an increased risk for cardiovascular disease by around 70%. For those women who are experiencing these symptoms but have not progressed through menopause the risk increases 40%.
Interestingly the risk is more related to the severity of the hot flushing rather than the frequency or duration. In the women who reported severe VMS the risk doubled for non-fatal cardiovascular events, such as a heart attack, compared with women who experienced no significant hot flushing. The study looked at 24,000 women in Australia, the US and the UK and with follow up between age 40 up to age 60.
There was no good explanation given for this link but there is clearly an hormonal connection. Oestrogen is one of the main vasodilator (artery opening) hormones and one of the explanations given as to why the risk for cardiovascular disease in pre-menopausal women is relatively low. Men and women experience heart disease in equal proportions but women tend to experience heart disease 10 years after men, felt to be because of protection from hormones.
Some experts in the area believe it is the variation between oestrogen and progesterone levels that leads to vascular instability and it may be that this variation promotes higher rates of VMS. An interesting study, which has not been performed as yet, could examine the link between hormone replacement therapy and heart attack risk, performed around the time of menopause.
Over 20 years ago, many of the observational trials clearly suggested that women who took hormone replacement therapy were at much lower risk for cardiovascular disease. But, a large, randomised trial known as the Women’s Health Initiative suggested that hormone replacement therapy increased cardiovascular risk. The obvious problem with this trial was a number of women involved were treated with hormone replacement therapy, sometimes as long as 15 years after the end of menopause, which, in my view, is physiologic nonsense as the trial should have only been performed in women around the time of menopausal onset.
I believe it would be sensible to have a trial involving women with significant VMS and randomise those women to hormone replacement therapy over at least five years, and preferably 10, to determine whether there is any vascular benefit and, of course, harm from other co-morbid conditions.
The problem with all aspects of life is that one size never fits all and as science becomes more sophisticated, it is my opinion we are moving rapidly towards the era of personalised medicine where we will be able to assess an individual’s genome to determine what therapies are appropriate for that particular person. The prevention and management of cardiovascular disease over the past few decades has become incredibly effective and sophisticated but, watch this space, as I believe the next decade will see the management of all conditions being taken to the next level.