Subclinical hyperthyroidism and the risk of developing cardiovascular disease - a systematic review.

Introduction: It is debated whether the presence of subclinical hyperthyroidism (SH) constitutes an increased risk of cardiovascular disease. This review presents a summary of the literature examining the association between SH and atrial fibrillation (AF), heart failure (HF), myocardial infarction (MI) and cardiovascular mortality.

Methods: A systematic literature search of the PubMed database was performed. Studies were included if they were of observational design, about SH in humans, and had AF, HF, MI and/or cardiovascular mortality as outcome, were published in either Danish or English language and included euthyroid controls.

Results: A total of 33 papers were suitable for inclusion. Thus, 13 papers on AF and five papers on HF were included for review and supported an association between SH and AF and HF, respectively. In all, 14 papers on MI and 15 papers on cardiovascular mortality were included for review; but, overall, they did not support an association between SH and MI or cardiovascular mortality.

Conclusions: Based on our review, current literature supports an association between SH and AF and HF, respectively; but not between SH and MI or cardiovascular mortality.