Correlation between the extracellular volume fraction and hemodynamic parameters in light-chain cardiac amyloidosis...

Light-chain cardiac amyloidosis (AL-CA) is a severe disease marked by amyloid protein deposits in cardiac tissues. This study aimed to explore the correlation between extracellular volume fraction (ECV) assessed via cardiac magnetic resonance (CMR) and invasive hemodynamic measurements in AL-CA patients.

This was a cross-sectional study. All AL-CA patients underwent right heart catheterization to measure hemodynamic parameters and CMR at baseline. Pearson correlation analysis and quantile regression were employed to explore the relationship between the ECV and hemodynamic parameters. Patients were categorized into two groups based on hemodynamic status using hierarchical clustering. The two groups were analyzed as binary outcomes using logistic regression to evaluate the effects of ECV and other variables on hemodynamic status. The receiver operating characteristic (ROC) curve was employed to identify the ECV threshold distinguishing the two groups.

The study enrolled 40 AL-CA patients, predominantly male (n=28), with an average age of 58 years. Some 32.5% of patients were classified as Mayo 2004 stage IIIb. The mean ECV was 0.52±0.08. Regarding hemodynamics, the cardiac index (CI) of all patients was 2.2±0.6 L/min/m², pulmonary artery wedge pressure (PAWP) was 17±8 mmHg, and mean pulmonary artery pressure (mPAP) was 27±11 mmHg. Pearson correlation analysis demonstrated a significant correlation between ECV and composite hemodynamic parameters, such as the mPAP to CI ratio (mPAP/CI, R =0.609, P<0.001), PAWP to CI ratio (PAWP/CI, R =0.621, P<0.001), and the (mPAP + PAWP)/CI ratio (R =0.626, P<0.001). Quantile regression indicated that the worse the hemodynamic status, the stronger the correlation with ECV. Hierarchical clustering based on mPAP, PAWP, and CI classified the 40 patients into group 1 (n=18) and group 2 (n=22). Patients in group 2 exhibited a significantly reduced CI (P=0.024) and significantly elevated PAWP and mPAP (both P<0.001). Additionally, ECV in group 2 patients was significantly higher than that in group 1 (P=0.003). The univariate logistic regression analysis identified ECV as a predictor of deteriorated hemodynamic status {odds ratio (OR), 1.204 [95% confidence interval (CI), 1.065-1.428]; P=0.011}. The ROC curve indicated that ECV had good diagnostic performance in identifying patients with worse hemodynamic status [the area under the curve (AUC) was 0.758], with an ECV cut-off value of 0.52.

Our research indicated a strong correlation between ECV, a quantitative measure of amyloid deposition, and composite hemodynamic parameters that represent systolic and diastolic function in AL-CA patients. Additionally, ECV can be used as a predictor of worse hemodynamic status.