Is circulating Gla-rich protein linked with coronary calcium and cardiovascular pathology in patients with atrial fibrillation or heart failure? A pilot study

Introduction: Nowadays Gla-rich protein (GRP) is recognized as a novel biomarker playing a pivotal role in the crosstalk between chronic inflammation and vascular calcification. Aim: The aim of this article is to study the link between circulating GRP, cardiovascular pathology, and the degree of arterial calcification evaluated by the coronary arterial calcium score (CACS) in a Bulgarian population sample. Materials and Methods: Adult participants (n = 81) of both genders were divided into: controls (n = 41)—subjects with estimated moderate-to-high risk without known cardiovascular diseases (CVDs) and a combined CVD group (n = 40)—patients with paroxysmal or persistent atrial fibrillation in sinus rhythm, and heart failure subjects with preserved ejection fraction. A structured interview was carried out for evaluation of the classical CVD risk factors. CACS was determined by multislice computed tomography. Routine laboratory parameters were extracted from medical records. Serum levels of total GRP, matrix Gla protein, and osteocalcin were estimated by commercial ELISA kits. Standard statistical methods (descriptive statistics, Student’s t-test and Spearman’s correlation) were applied. Statistical significance was considered at p<0.05. Results: Significantly lower GRP levels were established in patients with coronary calcium compared to those without calcium deposits. Clear tendency for decreased levels of GRP was observed in the combined CVD group vs controls. Circulating GRP significantly correlates with uncarboxylated matrix Gla protein. An association between serum GRP, CRP, and low-density lipoproteins (LDLs) was demonstrated. Conclusion: This study adds new information regarding the role of circulating GRP as a new player in calcification inhibition. Our findings illuminate the link between total circulating GRP, CVD pathology, and the degree of coronary calcification.