High recurrence of atrial fibrillation in patients with high tissue atrial natriuretic peptide and amyloid levels after concomitant maze and mitral valve surgery.

BACKGROUND: Hemodynamic burden is thought to play a role in valvular atrial fibrillation (AF), but the detailed pathophysiology is unclear. We hypothesized that atrial natriuretic peptide (ANP) tissue levels and amyloid deposits in the left atrial appendage (LAA) were associated with the pre-operative hemodynamic status and post-operative rhythm outcome in patients undergoing a concomitant mitral valve and maze surgery.

METHODS: We quantified the fibrosis, atrial amyloid deposits, ANP tissue levels, and multiple biomarker proteins (Western blot) in LAA tissues taken from 26 patients (53.8% male, 58.4±9.7 years) who underwent concomitant maze and mitral valve surgery. The histologic and biochemical results were compared with the pre-operative pulmonary artery pressure (PAP) and post-operative rhythm outcome.

RESULTS: The ANP tissue level was positively correlated with the atrial amyloid deposit areas (R=0.880, p<0.001), but not with the degree of fibrosis. The pre-operative systolic PAP negatively correlated with both the ANP tissue expression level (R=-0.467, p=0.019) and atrial amyloid deposit area (R=-0.589, p=0.008). The angiotensin II tissue expression level was significantly higher in tissues without ANP expression than in those with expression (p=0.003). AF recurrence after the maze operation was significantly lower in patients without than in those with ANP expression (log rank p=0.031, HR 3.779, 95% CI 1.163-12.277, p=0.027).

CONCLUSIONS: A lower ANP atrial tissue expression and amyloid deposits were correlated with a high pre-operative hemodynamic loading, and those patients had a paradoxically lower AF recurrence after relief of the hemodynamic burden by concomitant maze and mitral valve surgery.