Anti-Ro/SSA-associated corrected QT interval prolongation in adults: the role of antibody level and specificity

Objective Recent evidence suggests that anti-Ro/SSA antibodies, strongly associated with the development of congenital heart block, may also be arrhythmogenic for the adult heart. In fact, anti-Ro/SSA–positive patients with connective tissue disease (CTD) frequently display corrected QT (QTc) prolongation associated with an increase in ventricular arrhythmias. However, QTc prolongation prevalence markedly differs throughout the studies (10–60%), but the reason why is not yet clear. The aim of this study was to evaluate whether anti-Ro/SSA–associated QTc prolongation in adult patients with CTD is related to antibody level and specificity. Methods Forty-nine adult patients with CTD underwent a resting 12-lead electrocardiogram recording to measure QTc interval, and a venous withdrawal to determine anti-Ro/SSA antibody level and specificity (anti–Ro/SSA 52 kd and anti–Ro/SSA 60 kd) by immunoenzymatic methods and Western blotting. Results In our population, a direct correlation was demonstrated between anti–Ro/SSA 52-kd level and QTc duration (r = 0.38, P = 0.007), patients with a prolonged QTc had higher levels of anti–Ro/SSA 52 kd with respect to those with a normal QTc (P = 0.003), and patients with a moderate to high level (≥50 units/ml) of anti–Ro/SSA 52 kd showed a longer QTc interval (P = 0.008) and a higher QTc prolongation prevalence (P = 0.008) than those with a low positive/negative level (