Reduced Left Atrial Reservoir Strain Is Associated with Histopathologically Confirmed Atrial Natriuretic Peptide-Amyloid Deposition.

BACKGROUND

Isolated atrial amyloidosis is characterized by atrial natriuretic peptide- (ANP-) amyloid deposition confined to the atria and has been primarily linked to atrial fibrillation. However, its relationship with atrial mechanical function remains unclear. We investigated the association between left atrial reservoir strain (LASr) and histopathologically confirmed ANP-amyloid deposition. We also explored the potential clinical implications.

METHODS

We retrospectively analyzed the available left atrial appendage tissue of 166 consecutive patients who underwent cardiac surgery. Atrial natriuretic peptide-amyloid deposition was semiquantitatively graded (0-3+) and categorized as negative (0-1+) or positive (2+ to 3+). Echocardiographic parameters were analyzed across grades. Multivariable logistic regression and sensitivity analyses were performed. The primary endpoint was a composite outcome comprising all-cause death, stroke or systemic embolism, and heart failure hospitalization. Perioperative and longitudinal clinical outcomes were assessed.

RESULTS

Atrial natriuretic peptide-amyloid deposition was present in 51.2% of patients. Left atrial reservoir strain declined progressively across increasing amyloid grades, which indicated a graded inverse relationship (P for trend <.001). Multivariable analysis showed that lower LASr remained significantly associated with ANP-amyloid positivity (adjusted odds ratio 0.75 per 1% increase; 95% CI, 0.65-0.87; P < .001). Sensitivity analyses showed consistent results. Perioperative outcomes did not differ significantly between groups. During follow-up, ANP-amyloid positivity was associated with a higher incidence of the composite endpoint. This association was primarily driven by an increased risk of heart failure hospitalization, whereas all-cause mortality and thromboembolic events did not differ significantly between groups.

CONCLUSIONS

In this surgical cohort, reduced LASr was associated with higher ANP-amyloid deposition as confirmed through histopathology. These findings support an association between atrial mechanical dysfunction and histopathologically confirmed localized atrial amyloid involvement. Atrial natriuretic peptide-amyloid deposition was associated with a higher incidence of composite clinical events, predominantly driven by heart failure hospitalization, warranting further investigation.