Hypertrophic Cardiomyopathy (HCM), is a monogenetic autosomal dominant disease with an estimated prevalence of about 0.2% in the Western world. In about 50% of cases a mutation is found in one of 10 major genes with a predominance in myosin binding protein C, beta-myosin and troponin T-genes.
In the other 50% of cases no mutation is found, but it could still be unrecognised in one of the ten genes or be present in yet unrecognised genes. There is no proof as to why the myocardium hypertrophies in the disease and much effort has been put into discovering the relation between the genotype and phenotype. Certain mutations have been said to be more prone to malignant arrythmias, but the picture is not clear.
It is, however, pretty obvious that extreme hypertrophy, no matter what underlying mutation, is more likely to develop malignant arrhythmias. Philippe Charron addressed this important question and finalised his talk by stating that the relationship between genotype and phenotype will be better envisaged after completion of large trials like The Eurogene Heart Failure trial, sponsored by the Leducq Foundation. In the first presentation today E. Aliot from France showed that sudden death is distributed in all age groups and that the risk for SD can be stratified according to certain defined risk factors. This problem has become even more important in sports medicine where physiologic cardiac hypertrophy has to be differentiated from HCM. Where is the line between healthy adaptive growth and malignant hypertrophy?
Age of presentation of the disease is another interesting question, the mechanism of which is by no means understood. Is an early debut a sign of malignancy and late onset related to a more benign course? Spirito presented interesting information on the distribution of mutated genes in the elderly, which is different from that seen in the young. Only with a thorough knowledge of the different aspects of disease may a relevant treatment strategy be outlined. This was therefore done by one of the investigators in the field, Prof McKenna who again addressed the question of risk factor stratification. What should be done with high risk and low risk patients might be simple. But it is more complicated to give good advice to patients with an intermediate risk profile. The clinical problem was demonstrated by a number of informative clinical case presentations.