Furthermore, the pooled results for the American region still show no significant association between them (SMD = 0.20, 95% CI: −0.21 to 0.61, P = .33), even though Shaikh et al[25] showed that circulating BNP levels were independently associated with late AF recurrence after pulmonary vein isolation. The gene discussed is NPPB; the disease is atrial fibrillation.