Long QT affects more people than estimated

THE prevalence of the genetic arrhythmogenic disorder, long QT syndrome (LQTS), may be significantly higher than previously thought.

Italian researchers who conducted the first large-scale population-based study of its prevalence say it may be present in as many as one in every 2500 people, far more than previous estimates. 

They conducted ECG-guided molecular screens in 44,596 infants aged 15-25 days old.

In total, 17 of 43,000 white infants were affected by LQTS. Approximately 515 family members of genotype-positive infants were found to carry disease-causing mutations.  

“ECG-guided molecular screening can identify most infants affected by LQTS and unmask affected relatives, thus allowing effective preventative measures,” the authors said.

They said a neonatal ECG screening program in infants aged 2-6 months to identify LQTS would be highly cost-effective in Europe.

Associate Professor Mark McGuire, senior staff cardiologist at Royal Prince Alfred Hospital in Sydney, said LQTS rates would be similar in Australia, and the true prevalence of the condition would likely be even higher because no test detected all cases. 

Professor McGuire, also a clinical associate professor at the University of Sydney, agreed with the authors’ view that routine ECG screening of infants would detect families with LQTS, but said its cost-effectiveness was undetermined in Australia.

Circulation 2009; 120:1761-67