Abstract
BackgroundMitochondria are energy-producing structure of the cell and help to maintain redox environment. In cardiovascular disease, the number of mitochondrial DNA (mtDNA) will changes accordingly compare to normal condition. Some investigators ask whether it has a clear association between mtDNA and cardiovascular disease with its adverse events. Thus, we conduct the meta-analysis to assess the role of circulating mtDNA in evaluating cardiovascular disease.MethodsThe meta-analysis was conducted in accordance with a predetermined protocol following the recommendations of Cochrane Handbook of Systematic Reviews. We searched the Pubmed, Embase, the Cochrane Central Register of Controlled Trials and World Health Organization clinical trials registry center to identify relevant studies up to the end of October 2017. Data were analyzed using STATA. Besides, publication bias and meta-regression analysis were also conducted.ResultsWe collected results from 5 articles for further analyses with 8,252 cases and 20,904 control. The normalized mtDNA copy number level is lower in cardiovascular disease (CVD) than the control groups with a pooled standard mean difference (SMD) of -0.36(95%CI,-0.65 to -0.08); The pooled odds ratio (OR) for CVD proportion associated with a 1-SD (standard deviation) decrease in mtDNA copy number level is 1.23 (95% CI,1.06–1.42); The OR for CVD patients with mtDNA copy number lower than median level is 1.88(95% CI,1.65–2.13); The OR for CVD patients with mtDNA copy number located in the lowest quartile part is 2.15(95% CI, 1.46–3.18); the OR between mtDNA copy number and the risk of sudden cardiac death (SCD) is 1.83(95% CI, 1.22–2.74).ConclusionAlthough inter-study variability, the overall performance test of mtDNA for evaluating CVD and SCD revealed that the mtDNA copy number presented the potential to be a biomarker for CVD and SCD prediction. Given that, the fewer copies of mtDNA, the higher the risk of CVD.
Highlights
Cardiovascular diseases (CVDs), especially coronary vascular disease, ischemic heart failure, and cardiomyopathy, are major causes of clinical mortality and lead to a significant health and economic burden worldwide[1]
Inter-study variability, the overall performance test of Mitochondrial DNA (mtDNA) for evaluating CVD and sudden cardiac death (SCD) revealed that the mtDNA copy number presented the potential to be a biomarker for CVD and SCD prediction
8 articles were excluded after reading the whole article; in four of these, useful data was unable to be extracted for the meta-analysis, 2 articles were not focused on the relationship between CVD and the mtDNA copy number, and 2 articles used the mtDNA copy number to differentiate types of CVD without a sufficient control population or cohort
Summary
Cardiovascular diseases (CVDs), especially coronary vascular disease, ischemic heart failure, and cardiomyopathy, are major causes of clinical mortality and lead to a significant health and economic burden worldwide[1]. Decades have passed since researchers started to identify diagnostic biomarkers for CVDs to predict the disease prognosis. Mitochondria are double-membrane structures that exist in all cells. Once mtDNA damage occurs, the copy number level of mtDNA is altered, resulting in mitochondrial dysfunction that is considered to be an important pathogenesis of CVDs [7]. The mtDNA copy number could reflect the level of mtDNA damage; it is thought to be an indicator of mitochondrial function [8]. Some researchers hypothesize that we can predict the risk and prognosis of CVDs by measuring the copy numbers of mtDNA. We performed a meta-analysis to determine whether changes in the mtDNA copy number are related to the severity of CVDs and their prognoses. The number of mitochondrial DNA (mtDNA) will changes compare to normal condition. We conduct the meta-analysis to assess the role of circulating mtDNA in evaluating cardiovascular disease.
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