Repolarization in systemic sclerosis: a meta-analysis

Systemic sclerosis (SSc) is a rare connective tissue disease characterized by immune dysregulation, vascular damage, and increased deposition of extracellular matrix. In SSc, cardiac manifestations are common and account for 14% of deaths. Numerous studies have examined electrocardiographic findings in SSc patients yielding conflicting reports regarding QTc duration. We conducted a systematic review and meta-analysis of existing studies to investigate whether QTc duration may aid in diagnosis and risk stratification of SSc patients.

Two electronic databases (PubMed and Embase) were searched for case-control and cohort studies assessing QTc duration in SSc patients published before March 1, 2021. A random-effects model was used to meta-analyze the results, and included studies were tested for heterogeneity. Linear regression was performed to determine correlations between comorbidities, and QTc duration.

Ninety-six studies, abstracts, and posters were identified. After abstract review and duplicate removal, 23 manuscripts remained. After application of the inclusion and exclusion criteria, 10 studies remained which were quantitatively analyzed. The weighted mean QTc was found to be 422.21 ms for SSc patients and 411.43 ms for control subjects. A significant increase in QTc duration among SSc patients was found, with a standardized mean difference of 0.59 (p < 0.01, 95% CI 0.27-0.92). No significant correlation was found between underlying traits and QTc values. Substantial heterogeneity was found between the studies (I² = 83%, p < 0.01).

A significant increase in QTc duration is observed in SSc patients, though the absolute prolongation is not extreme. Therefore, the clinical utility of this finding is unclear and merits large prospective observations. Key Points • A statistically significant prolongation of the QTc interval exists in patients with systemic sclerosis. • Absolute QTc differences between healthy controls and scleroderma patients are not extreme, and, as such, may be of limited clinical utility. • When assessing the underlying traits of systemic sclerosis patients, no statistically significant correlations were found between underlying parameters and QTc duration.