Prolongation of the corrected QT interval in adult patients with anti-Ro/SSA-positive connective tissue diseases.

Objective: Newborns of mothers positive for anti-Ro/SSA autoantibodies may develop a series of electrocardiographic (EKG) disturbances. Prolongation of the corrected QT (QTc) interval was recently reported in a significant proportion of children with maternally acquired anti-Ro/SSA antibodies, with a concomitant disappearance of EKG abnormalities and acquired maternal autoantibodies during the first year, suggesting a direct, reversible electrophysiologic effect of anti-Ro/SSA antibodies on the ventricular repolarization. On this basis, we investigated whether these antibodies may also affect cardiac repolarization in anti-Ro/SSA-positive adult patients with connective tissue diseases.

Methods: Fifty-seven patients with connective tissue diseases were selected: 31 had anti-Ro/SSA antibodies and 26 did not (controls). In all subjects, we analyzed the QTc interval, heart rate variability, and signal-averaged high-resolution EKG recording.

Results: Anti-Ro/SSA-positive patients showed a significant prolongation of the mean QTc interval compared with the controls (mean +/- SD 445 +/- 21 versus 419 +/- 17 msec; P = 0.000005). Eighteen of the 31 anti-Ro/SSA-positive patients (58%) and none of the 26 anti-Ro/SSA-negative patients had QTc values above the upper limit of normal (440 msec). Both groups had a reduction in heart rate variability, with a prevalence for the sympathetic nervous system and a high incidence of ventricular late potentials; these values were not significantly different between the 2 groups.

Conclusion: Adult patients with anti-Ro/SSA-positive connective tissue diseases showed a high prevalence of QTc interval prolongation. This feature, with the concomitant abnormalities in the autonomic tone and ventricular late excitability observed in all patients studied, suggests that anti-Ro/SSA-positive patients may have a particularly high risk of developing life-threatening arrhythmias.