METHODS
Search Strategy
We followed the recommendation of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.13 We queried the electronic databases Medline, Cochrane databases, CINAHL using the following search keywords: ‘Echocardiography’, ‘Speckle tracking’, and ‘Sarcoidosis’. We only compiled articles published in English language.
Study Selection and Data Extraction
We included all studies reporting LVGLS and/or GCS, comparing patients with confirmed extra-cardiac sarcoidosis versus a control group of healthy patients. Studies that exclusively included patients with probable or definite CS were excluded. We also collected studies that reported LVGLS in sarcoidosis patient’s experiencing major cardiac events (MCEs) which was defined as composite outcomes of all cause death, arrhythmia, heart failure hospitalization, cardiac device implantation, or appropriate firing of defibrillator. We excluded case reports, review articles, editorials, and correspondences to the editor. Data was extracted by two independent investigators (K.B., M.C). into a predefined collection sheet. All disagreements were resolved in consensus with a third reviewer (D.R.). Extracted data included baseline characteristics, echocardiographic parameters, LVGLS and LVGCS.
Statistical Analysis
Continuous data (e.g., LVGLS and GCS) were pooled as a standard mean difference (SMD) between the sarcoidosis group and the control group. Random effect model was adopted in all analyses. We used inverse variance method with Restricted Maximum-Likelihood estimator of Tau2, for random effect analysis. We assessed between-study heterogeneity using Q and I2 statistics. AI2 statistic <25% indicates a low amount of heterogeneity and >50% indicates a high heterogeneity. Analyses were conducted using STATA 16 (State Corp LLC, College Station, Texas). P-value <0.05 was considered statistically significant.
Quality Assessment
Quality of included studies was assessed using the Newcastle-Ottawa Scale (NOS).14 This included a checklist for representativeness of included cohort, ascertainment of exposure, comparability and adequacy of follow-up as per the NOS. A maximum of 9 stars were awarded to each study. Studies awarded ≥6 stars were considered moderate-to-high quality studies.14