Data_Sheet_1_A Machine Learning Aided Systematic Review and Meta-Analysis of the Relative Risk of Atrial Fibrillation in Patients With Diabetes Mellitus.PDF

<p>Background: Meta-analysis is a widely used tool in which weighted information from multiple similar studies is aggregated to increase statistical power. However, the exponential growth of publications in key areas of medical science has rendered manual identification of relevant studies increasingly time-consuming. The aim of this work was to develop a machine learning technique capable of robust automatic study selection for meta-analysis. We have validated this approach with an up-to-date meta-analysis to investigate the association between diabetes mellitus (DM) and new-onset atrial fibrillation (AF).</p><p>Methods: The PubMed online database was searched from 1960 to September 2017 where 4,177 publications that mentioned both DM and AF were identified. Relevant studies were selected as follows. First, publications were clustered based on common text features using an unsupervised K-means algorithm. Clusters that best matched the selected set of potentially relevant studies (a “training” set of 139 articles) were then identified by using maximum entropy classification. The 139 articles selected automatically on this basis were screened manually to identify potentially relevant studies. To determine the validity of the automated process, a parallel set of studies was also assembled by manually screening all initially searched publications. Finally, detailed manual selection was performed on the full texts of the studies in both sets using standard criteria. Quality assessment, meta-regression random-effects models, sensitivity analysis and publication bias assessment were then conducted.</p><p>Results: Machine learning-assisted screening identified the same 29 studies for meta-analysis as those identified by using manual screening alone. Machine learning enabled more robust and efficient study selection, reducing the number of studies needed for manual screening from 4,177 to 556 articles. A pooled analysis using the most conservative estimates indicated that patients with DM had ~49% greater risk of developing AF compared with individuals without DM. After adjusting for three additional risk factors i.e., hypertension, obesity and heart disease, the relative risk was 23%. Using multivariate adjusted models, the risk for developing AF in patients with DM was similar for all DM subtypes. Women with DM were 24% more likely to develop AF than men with DM. The risk for new-onset AF in patients with DM has also increased over the years.</p><p>Conclusions: We have developed a novel machine learning method to identify publications suitable for inclusion in meta-analysis.This approach has the capacity to provide for a more efficient and more objective study selection process for future such studies. We have used it to demonstrate that DM is a strong, independent risk factor for AF, particularly for women.</p

Reduced RyR2 protein expression in heterozygous RyR2 Ex3-del mutant hearts.

<p>(A) Whole heart homogenates were prepared from wild type (WT) (n = 4) and RyR2 Ex3-del^−/− mutant (n = 4) mice (2–3 months) and used for immunoblotting analysis using antibodies against RyR2 or β-actin. (B) The expression of RyR2 in the Ex3-del hearts was significantly reduced (58±3%) as compared to that in WT hearts (*<i>P</i><0.001).</p

Cardiac-specific, conditional knockout of the WT RyR2 allele in heterozygous RyR2 Ex3-del mutant mice results in early death.

<p>iRyR2^flox/flox (n = 13, black circles) and iRyR2^flox/Ex3-del (n = 11, white circles) mice were injected with tamoxifen (75 mg/kg/day) for 3 consecutive days. The percentage of live mice (survival rate) on day 6–14 post tamoxifen treatment is shown.</p

Deletion of exon-3 in the RyR2 mRNA from heterozygous RyR2 Ex3-del mice.

<p>A fragment of the mouse RyR2 mRNA covering exon-3 was converted to cDNA and amplified using RT-PCR from total RNAs isolated from wild type (WT) and heterozygous RyR2 Ex3-del (Het) mutant mice (A). The RT-PCR products were isolated and sequenced. The sequence of the RyR2 Ex3-del cDNA was shown (B). Note that the exon-2 sequence is directly followed by the exon-4 sequence, i.e. the exon-3 sequence has been deleted.</p

Heterozygous RyR2 Ex3-del mutant mice with cardiac specific, conditional KO of the WT RyR2 allele exhibit bradycardia, but no CPVT.

<p>iRyR2^flox/flox (n = 11) and iRyR2^flox/Ex3-del (n = 8) mice were treated with tamoxifen. ECG recording was performed 12 days post tamoxifen treatment to determine their basal heart rates (before epinephrine/caffeine challenge) (A) and their susceptibility to CPVT (B, C). Representative ECG recordings of the tamoxifen-treated iRyR2^flox/flox mice (B) and the tamoxifen-treated iRyR2^flox/Ex3-del mice (C) before (top panel) and after (bottom panel) the injection of epinephrine (1.6 mg/kg) and caffeine (120 mg/kg). Note that no VTs were detected in either the tamoxifen-treated iRyR2^flox/flox mice (B) or the tamoxifen-treated iRyR2^flox/Ex3-del mice during the 30-min period of ECG recording after the injection of the triggers (*P<0.05).</p

Depolarization-induced Ca²⁺ transients in WT and heterozygous RyR2 Ex3-del mutant cardiomyocytes.

<p>Ventricular myocytes isolated from RyR2 WT and Ex3-del<b>^+/</b>⁻ mutant hearts were loaded with Rhod-2-AM and perfused with 2 mM extracellular Ca²⁺ in KRH solution and paced at 3Hz. Ca²⁺ transients were monitored by line-scan confocal Ca²⁺ imaging. Representative images/traces of WT (A) and Ex3-del<b>^+/</b>⁻ mutant (B) cardiomyocytes, and average data of the amplitude (C), time to peak (D), and time to 50% decay (E) of Ca²⁺ transients in WT and Ex3-del<b>^+/</b>⁻ mutant cells are shown. Data shown are mean ± SEM from 35 WT and 58 mutant cells (**P<0.001; *P<0.05).</p

Cardiac specific, conditional knockout of the WT RyR2 allele results in markedly reduced RyR2 expression.

<p>Whole heart homogenates were prepared from iRyR2^flox/flox (A) and iRyR2^flox/Ex3-del (B) mice before and after tamoxifen treatment, and used for immunoblotting analysis using antibodies against RyR2 or β-actin. Note that the expression of RyR2 in iRyR2^flox/flox hearts (n = 6) or iRyR2^flox/Ex3-del hearts (n = 6) was significantly reduced 12 days post tamoxifen treatment (*<i>P</i><0.001).</p