Inherited disorders associated with arrhythmias and increased risk of death is a challenge for all physicians, related not only to difficulties in making a correct diagnosis but also to the problem of identifying patients at risk of sudden death.
The use of gene-specific electrocardiograms for risk stratification can be useful in clinical decision making. Major risk factors identifiable on the ECG in LQTS patients were reported to be a QTc time above or equal to 500 ms, T wave alternans and low heart rate related to conduction block. The risk for an event was 70% in patients
with a QT time equal to or above 499 milliseconds, versus 18 % in those with a QT time equal to or less than 446 milliseconds, during a 40 year follow up period.
The predictive value of invasive electrophysiological investigation (EP study) with programmed stimulation for the induction of ventricular arrhythmias in asymptomatic patients with typical ECG pattern type 1, indicating Brugada syndrome, was still debated probably related to divergent results obtained from different patient populations. While some advocated EP study in asymptomatic patients with the Brugada syndrome and spontaneous type 1 ECG pattern, others questioned the value of such an approach for risk stratification. Consensus was that patients with a spontaneous ECG pattern type 1, syncope and male gender were at high risk of death.
The difficulties of identifying relatives at risk for sudden death in families with hypertrophic cardiomyopathy were emphasised and explained by the variable expressions and incomplete penetrance in the families. There is therefore a need for DNA based tests since non-penetrant mutation carriers can still be at risk of sudden death.