Heart Disease: Assessing Your Risk Based on Family History
So you have a family member with heart disease. Don't panic! Medcan's director of cardiology on what that means for you.
So you have a family member with heart disease. Maybe it was a parent, grandparent or even a sibling. It’s hard not to stay awake at night worrying whether your days are numbered. The fact is, most patients are deeply concerned about their family history of heart problems and the implications for their own health. But having a relative with a heart problem doesn’t necessarily mean that you need to shore up your will. It may surprise you to know that for most of the patients I deal with, family history is of negligible if any concern. Even though a positive family history of coronary artery disease (CAD) may increase your chances of suffering a heart attack, the existence of a heart problem in a family member does not necessarily qualify as a bell-ringing, alarm-sounding worry.
The importance of family history depends on how much information the patient knows and how good the doctor is at getting that information. Firstly, what type of heart problems are we talking about? A history of an arrhythmia, murmur or chest pain in a family member is meaningless more than 99.9 per cent of the time. When assessing the importance of family heart history, the main concern are premature heart attacks, angioplasty and cardiac bypass surgery.
There are exceptions. For example, a family history of sudden and unexpected death must be critically evaluated for rare genetic causes such as congenital long QT syndrome (LQTS) or arrhythmogenic right ventricular dysplasia (ARVD) to name a couple. Another rare heart disease, hypertrophic cardiomyopathy (HOCM), may have a 50 per cent chance of being passed down to a child. All children and siblings of patients with HOCM must be assessed.
Coronary artery disease is not a single gene disorder, like cystic fibrosis or sickle cell anemia. In CAD, the genetic contribution to risk is far more complex. Genetics interact with more modifiable problems like smoking, high blood pressure, diabetes, obesity and lack of exercise. Together they raise the risk of heart attacks. Only in very rare circumstances can a family’s history of severe premature coronary artery disease be traced to a single gene mutation. I have seen one such case in twenty years of practice.
So what defines a relevant family history of coronary artery disease? When does the heart attack in your relative matter? Firstly, it depends which member of your family was affected. The further away the relative, the less it matters to you. A second cousin or uncle simply doesn’t share enough bad genes to make his or her heart attack matter to you and this will not significantly increase your risk of a heart attack. Keep in mind that more than a third of all deaths in Canada are from some form of cardiovascular disease, so it won’t be difficult to find an affected relative. The only family members that matter are brothers, sisters, mother or father. These define our first degree relatives.
How do we know that a family history of premature coronary artery disease increases the risk of a heart attack? The connection has been demonstrated in numerous trials including a Swedish study of twins. There are two types of twins, identical (called monozygotic) and fraternal (called dizygotic, basically siblings born on the same day). In this study several thousand twins born between 1886 and 1925 were looked at. The study showed that a person’s risk of dying from CAD was much higher if he or she lost a twin to CAD before age 55 for men and 65 for women. The risk was particularly high if the twins were monozygotic, though still significant if they were dizygotic. The older the twin was when he or she died of CAD, the less the risk to the surviving twin.
Disease in a first degree relative is not only significantly more important than disease in an uncle, cousin or grandparent, but the more first degree relatives affected the greater the risk. Most of my patients have long outlived any negative impact of what is often a vague story of heart disease in a relative. By the time you reach your late 60’s and beyond, your very existence becomes a testament to good genetics. A premature history of coronary artery disease is exactly that, premature. The death of a mother, father, brother or sister at an older age is more reality than risk.
Undoubtedly, it seems that each year a new trial on cholesterol further lowers the threshold for treatment with cholesterol lowering pills (typically statins). Though many patients leap to diet as the main culprit for high cholesterol and LDL levels, the ability of a diet to lower cholesterol is heavily over stated and should not be the sole strategy to lower LDL. An aggressive dietary strategy, though important in health maintenance, will reduce total and LDL cholesterol by 5-10 per cent, enough to make only a very small difference. This is because cholesterol levels are dominantly determined by genetics.
Guidelines are in a seemingly constant state of flux, with more and more people needing lower and lower cholesterol. A family history of (true) premature CAD has been poorly integrated into guidelines. When a patient tells me of a verifiable history of premature coronary artery disease in a first degree relative at a young age in the absence of smoking, I almost always advise a statin such as Crestor. Crestor is tolerated by 98 per cent of patients with mild and reversible side effects in nearly all of the remaining 2 per cent. Prescribing this medication in this scenario, despite the fact this practice has not been proposed in guidelines, is in my view a sensible response to an improving scientific knowledge.
In conclusion, not all family history of heart disease is relevant. The devil is in the details, and the only details that matter are those related to a mother or sister before age 65 and a father or brother before age 55.
Want to talk to a Medcan doctor about your family history and heart disease? Call (416) 350-5900 or email firstname.lastname@example.org.