# The value of phenylalanine in predicting atrial fibrillation risk in chronic heart failure

## TL;DR

High phenylalanine levels in heart failure patients are linked to a higher risk of atrial fibrillation and worse outcomes.

## Contribution

This study identifies phenylalanine as a novel predictor of atrial fibrillation risk in chronic heart failure patients.

## Key findings

- Phenylalanine levels increase progressively in heart failure patients with atrial fibrillation.
- Higher phenylalanine levels are independently associated with increased atrial fibrillation risk in heart failure.
- Elevated phenylalanine correlates with poor outcomes in heart failure patients with atrial fibrillation.

## Abstract

Atrial fibrillation (AF) is a common complication of chronic heart failure (HF). Serum phenylalanine (Phe) levels are related to inflammation disorder. It is meaningful to study the circulating Phe with AF occurrence in HF.

The cross-sectional study recruited 300 patients (78.0% male; mean age, 65 ± 13 years) with HF (left ventricular ejection fraction of ≤50%, containing 70 AF patients) and 100 normal controls. Serum Phe value was measured by liquid chromatography–tandem mass spectrometry. Logistic regression analysis was conducted to measure the association between Phe and AF risk in HF. The association between Phe and high-sensitivity C-reactive protein (hsCRP) was assessed by simple correlation analysis. In the prospective study, the 274 HF subjects (76.6% male; mean age, 65 ± 13 years) were followed up for a mean year (10.99 ± 3.00 months).

Serum Phe levels increased across the control, the HF without AF, and the HF with AF groups (77.60 ± 8.67 umol/L vs. 95.24 ± 28.58 umol/L vs. 102.90 ± 30.43 umol/L, ANOVA P < 0.001). Serum Phe value was the independent risk factor for predicting AF in HF [odds ratio (OR), 1.640; 95% CI: 1.150–2.339; P = 0.006]. Phe levels were correlated positively with hsCRP value in HF patients with AF (r = 0.577, P < 0.001). The elevated Phe levels were associated with a higher risk of HF endpoint events in HF patients with AF (log-rank P = 0.005).

In HF with AF subjects, elevated Phe value confers an increased risk for prediction AF and was more related to poor HF endpoint events. Phe can be a valuable index of AF in HF.