Brugada syndrome patients with an SCN5A mutation had significantly longer baseline PQ and HV intervals compared to non-carriers, with PQ ≥210 ms and HV ≥60 ms predictive of mutation presence.
Observational (n=77)
Yes
Does the presence of an SCN5A mutation in Brugada syndrome patients correlate with specific clinical or electrocardiographic features compared to non-carriers?
Brugada syndrome patients with an SCN5A mutation exhibit significantly longer conduction intervals on baseline ECG and after sodium channel blockade, allowing for phenotypic differentiation from non-carriers.
OBJECTIVES We have tested whether a genotype-phenotype relationship exists in Brugada syndrome (BS) by trying to distinguish BS patients with (carriers) and those without (non-carriers) a mutation in the gene encoding the cardiac sodium channel (SCN5A) using clinical parameters. BACKGROUND Brugada syndrome is an inherited cardiac disease characterized by a varying degree of ST-segment elevation in the right precordial leads and (non)specific conduction disorders. In a minority of patients, SCN5A mutations can be found. Genetic heterogeneity has been demonstrated, but other causally related genes await identification. If a genotype-phenotype relationship exists, this might facilitate screening. METHODS In a multi-center study, we have collected data on demographics, clinical history, family history, electrocardiogram (ECG) parameters, His to ventricle interval (HV), and ECG parameters after pharmacologic challenge with I(Na) blocking drugs for BS patients with (n = 23), or those without (n = 54), an identified SCN5A mutation. RESULTS No differences were found in demographics, clinical history, or family history. Carriers had a significantly longer PQ interval on the baseline ECG and a significantly longer HV time. A PQ interval of > or =210 ms and an HV interval > or =60 ms seem to be predictive for the presence of an SCN5A mutation. After I(Na) blocking drugs, carriers had significantly longer PQ and QRS intervals and more increase in QRS duration. CONCLUSIONS We observed significantly longer conduction intervals on baseline ECG in patients with established SCN5A mutations (PQ and HV interval and, upon class I drugs, more QRS increase). These results concur with the observed loss of function of mutated BS-related sodium channels. Brugada syndrome patients with, and those without, an SCN5A mutation can be differentiated by phenotypical differences.
SMITS et al. (2002) conducted an observational in Brugada syndrome (n=77). SCN5A mutation (carriers) vs. No SCN5A mutation (non-carriers) was evaluated on Electrocardiographic parameters including PQ interval and HV time. Brugada syndrome patients with an SCN5A mutation had significantly longer baseline PQ and HV intervals compared to non-carriers, with PQ ≥210 ms and HV ≥60 ms predictive of mutation presence.