Diabetes was detected in 12% of cases where episodic hypoglycaemia may have contributed to the development of paroxysmal atrial fibrillation. Forty per cent of young patients with non-valvular atrial fibrillation were in heart failure with raised N-terminal pro-brain natriuretic peptide (NT-proBNP) (> 125 pg/ml). This evidence concerns the gene NPPB and heart failure.