Sinoatrial conduction abnormalities – an underestimated cardiac complication in women with systemic sclerosis

Introduction
It has been claimed that patients with systemic sclerosis (SSc) have an increased risk of developing cardiac arrhythmias and atrioventricular conduction disorders, but it is unknown whether SSc may be a cause of sinoatrial conduction abnormalities.

Aim
To establish the incidence of sinoatrial conduction abnormalities in patients with SSc and verify the relationship of these disorders with various clinical descriptors of SSc.

Material and methods
Forty women with systemic sclerosis of varying duration and severity underwent 24-hour ambulatory ECG monitoring. The occurrence of type I second-degree sinoatrial block (SA-block) and calculation of sinoatrial conduction time (SACT) were evaluated to establish the incidence of sinoatrial conduction abnormalities. The measurements of SACT were obtained using spontaneous atrial premature beats. The effect of various clinical descriptors on sinoatrial conduction abnormalities was assessed.

Results
The mean ± SD SACT for the 40 patients was 150 ±15 ms. Prolonged (> 150 ms) SACT was found in 20 patients. In 14 (35%) patients SA-block occurred during ambulatory ECG monitoring. The discriminant analysis identified the severity of SSc cutaneous manifestation as an independent marker for developing SA-block (p < 0.005) and SACT prolongation (p < 0.0002).

Conclusions
Patients with SSc are at an increased risk of developing type I second-degree sinoatrial block and prolonged sinoatrial conduction time. The occurrence of these abnormalities is related to the severity of skin involvement. Therefore, cardiological diagnosis using 24-hour ambulatory ECG in this group of patients should be focused also on this type of disorders. Prospective, controlled studies are needed to assess their prognostic role.