Various ECG abnormalities ranging from ST-T wave changes, conduction defects, and voltage changes indicative of left ventricular hypertrophy were seen in the remaining 24 subjects.
The aim of the study was to identify, in addition to conduction defects, possible predictors of cardiac events and death in patients with myotonic dystrophy (DM1).
In 2 litters, all Scn5a+/− mice had mild conduction defects (2 and 3 mice, respectively).
Correspondingly, symptomatic SCN5A mutated Brugada patients had more severe conduction defects than asymptomatic patients.
In 2 others, all Scn5a+/− mice had, in contrast, severe conduction defects (3 mice in each).
As shown in Figure 2B, the ajmaline-induced QRS prolongation in aged patients was more pronounced in those with severe conduction defects under baseline conditions (+55±7 ms) than in those with mild conduction defects (+34±5 ms; p<0.05).
Loss-of-function mutations in SCN5A, the gene encoding Nav1.5 Na+ channel, are associated with inherited cardiac conduction defects and Brugada syndrome, which both exhibit variable phenotypic penetrance of conduction defects.
DM1 is a multisystemic disorder characterized by skeletal muscle wasting and myotonia, cardiac conduction defects, insulin resistance and cataracts.
The presence of conduction defects is also one striking feature of BrS SCN5A-mutation carriers [6], [7].
In our cohort, symptomatic SCN5A-related BrS patients were characterized by more pronounced ventricular conduction defects than asymptomatic patients.
