Systematic review of biological therapies for atrial fibrillation.

Biological therapies that increase or suppress the expression of transcripts underlying atrial fibrillation (AF) progression are increasingly being explored to create novel treatment paradigms beyond simply suppressing or destroying tissue. To date, there has been no systematic overview of the preclinical evidence exploring manipulation of fundamental biological principles in the treatment of AF. As such, the objective of this study was to establish the effect of biological approaches used in the treatment of AF within large and small animals. We performed a systematic search using predefined terms, which yielded 25 studies. We determined the effect of biological approaches on primary efficacy outcomes and assessed the quality of included studies or possible bias in the treatment of AF. Compared with non-transduced or transduced controls, biological therapies reduced AF inducibility (85% less AF; odds ratio 0.15; 95% confidence interval [CI] 0.07-0.35; P < .01) and atrial scar burden (6.7% smaller scars; 95% CI 4.2-9.2; P < .01) or increased number of days in sinus rhythm (6.4 more days in sinus rhythm; 95% CI 5.83-6.97; P < .01). Similar effects were seen in both large and small animals, while a minor tendency to higher risk of bias was observed in small animal studies. In conclusion, treatment with any biological therapy significantly improved AF in preclinical animal models compared with controls. Although biological therapies target markedly different fundamental mechanisms, we observed a consistent difference in their effect on AF outcomes. [ABSTRACT FROM AUTHOR]