Dr Antonis Pantazis, consultant cardiologist, discusses the need for family screening in all types of cardiomyopathy and practice adopted at the Heart Hospital in London
Cardiomyopathies are conditions that are commonly secondary to genetic defects and can therefore be transmitted from one generation to the next.
Because of this, they may affect several members of the same family.
The knowledge about specific patterns of inheritance has grown rapidly over the last few years but it was not long ago when it was believed that these conditions were entirely acquired and influenced by environmental factors or were incidental.
Another very common and complicating feature of the cardiomyopathies is that they have a very variable so-called "phenotype", which means that within the same cardiomyopathy the clinical expression differs significantly.
Genetic studies have helped the understanding of the pathology and it is now well documented that even people with the same genetic defect may have a very different heart condition at a different age and with a different clinical course.
In reality, the range extends between no disease and severe disease. Fortunately only a minority of people affected by cardiomyopathy find themselves at the severe end and suffer from persisting symptoms and complications.
It is generally accepted in medicine nowadays that the earlier a condition is diagnosed, the more efficient the management. In fact, many side effects of the cardiomyopathies can be prevented when the diagnosis is early and this offers a better quality of life to patients.
The risk of arrhythmias (irregular heart beats) causing death is another major concern for quite a few people who suffer from these conditions, althought the overall incidence of these adverse events is very low. This risk can also be successfully managed in the great majority of those who are exposed to it and this again relies on timely diagnosis and follow up.
Screening of relatives
It is easy to understand from the above that in families where cardiomyopathy has been diagnosed in one of the relatives, screening of other members is indicated. This should start independently of symptoms as these are not always present when the disease first develops.
The likelihood of presenting with changes in the heart is thought to be greater in young people. So the clinical screening should start from a young age.
Nevertheless, because cases in childhood are rather infrequent, it is usually recommended that young children see the cardiologist less frequently than teenagers.
It is also now known that for most of the cardiomyopathies there is no age beyond which the disease can be safely ruled out without clinical evaluation. Infrequent screening is therefore advised for adult relatives too.
The precise time intervals between visits to the cardiologist may have to be decided individually for each family or relative because other factors than blood relationship may also play a role.
Obviously, for people of any age who complain of symptoms such as breathlessness, chest pain, palpitations or fainting in the context of familial disease, it is wise to organise an earlier clinical assessment, even when those symptoms are not entirely typical for heart disease.
New symptons of any kind are also an alarming sign and should initiate some action. In any case, discussing and taking advice from an experienced in-the-field cardiologist usually puts the individual person and the GP on the safe side.
The extent of clinical screening in a family has to be decided individually again and generally the risk of carrying the same genetic information as the affected person declines with distance on the family tree.
Screening at the Heart Hospital in London is performed in a more intense fashion than it might be generally recommended or afforded because is is a national and international referral centre for these conditions with several dedicated clinics.
We tend to see children a few times before their teens and then we follow adolescents at least annually depnding on the condition and individual characteristics.
In adulthood, people who have not developed features of the familial condition are usually seen every five years unless there is a reason for this plan to be amended.
It is understandable that this may not be applicable in district general hospitals.
But fortunately the safety for patients does not appear to be problematic if looser screening plans are followed, provided that the clinic visits are according to a regular pattern and people's new symptoms are taken immediately into consideration.
Screening of the general population
It would be ideal if doctors were in a position to identify every person with cardiomyopathy immediately after the first changes in the heart. Unfortunately though, this is not feasible. Although not uncommon, the cardiomyopathies are not frequent diseases in the general population. Even less frequent, in fact rare, is the rate of severe complication secondary to these conditions in the unselected population.
This is one of the reasons why screening people who have no previous personal or familial background and targeting the prevention of severe adverse events would be a really difficult and low yield operation.
Some features of the cardiomyopathies identified during the clinical evaluation of people suffering from early disease are non-specific or subtle but they gain a lot of significance when put in the context of the family history by the experts performing the evaluation.
The interpretation of the subtle findings can be difficult in the general population and the risk of false positive results increases substantially with possible medical and social ramifications.
Conclusion
It is therefore important to understand the familial pattern of the cardiomyopathies and intensify efforts to recognise and manage the people who are at risk of having or later developing these conditions. The increased awareness among families and medical professionals is a cornerstone for that.
Dedicated to Damian McLoughlin, who died age 20 of cardiomyopathy. This site is supported by Damian's family and friends.
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