Association between multiple sclerosis and heart diseases: Systematic review and meta-analysis of observational studies

•MS was associated with higher incidence of heart failure and myocardial infarction.•The associations were stronger in women and in younger persons.•A lower incidence of atrial fibrillation among pwMS might be caused by confounding.•No associations were found between multiple sclerosis and other heart diseases.•Included studies yielded high risk of bias and the certainty of evidence was low.