A systematic review of 10 trials of Mineralocorticoid Receptor Antagonists [MRA] (e.g. spironolactone in NZ) found a 23% reduction in the risk of AF.1
Five trials involved spironolactone in doses from 20 mg/day to 45 mg/day. The other five trials were in MRAs not routinely used in NZ. There was a range of baseline prevalences from 1.8% to 80.49%, reflecting different populations.
The strength of this review is that they are all randomised controlled trials. The risk of bias was assessed as low.
In Europe, MRA is the 4th line antihypertensive, but remember caution when renal function is poor and regular monitoring of potassium is essential.