Echo-derived hemodynamic categorization for risk stratification in transthyretin cardiac amyloidosis

Abstract

Abstract Background Transthyretin cardiac amyloidosis (TTR-CA) is a rare disease characterized by the deposition of abnormal proteins in the heart, which can lead to heart failure (HF) and death. Echocardiography provides valuable diagnostic and prognostic information in CA, but indices of left ventricular performance alone cannot thoroughly characterise patients with restrictive cardiomyopathy. Evaluating the hemodynamic profile by studying the forward flow and left ventricular filling pressure (LVFP) already proved its value in stratifying disease severity in patients with heart failure (HF). Purpose This study evaluated the prognostic relevance of a non-invasive hemodynamic categorization of TTR-CA patients based on the estimation of stroke volume index (SVi) and systolic pulmonary artery pressure (PAPs). Methods Baseline clinical, transthoracic echocardiogram and laboratory data were collected prospectively in patients with diagnosed TTR-CA. Patients were classified into four groups based on forward flow (SVi < or ≥30 ml/m2) and systolic pulmonary artery pressure (PAPs ≥ or <40 mmHg). The four profiles obtained were Profile-A, normal-flow, normal-pressure; Profile-B, low-flow, normal-pressure; Profile-C, normal-flow, high-pressure; Profile-D, low-flow, high-pressure. We assessed the incidence of the composite endpoint of cardiovascular death and HF hospitalization accordingly to the hemodynamic profile. We performed univariate and multivariate Cox regression using profile A as a reference for HR estimation (profile A corresponding to HR=1). Results Fifty-nine patients were enrolled in the analysis (Table). Over a mean follow-up of 35.9 months (IQR 11.7 - 51.2 months) 23 patients met the composite endpoint (10%, 23%, 43%, 60% for Profile A, B, C and D respectively). Compared to Profile A, Profile D showed the greatest risk of CV mortality and HF hospitalization (HR 10.17), followed by Profile C (HR 6.77) and B (HR 3.45), with P-value=0.015. The C-statistic for the model was 0.72. Kaplan-Meier curves confirmed that patients with PAPs >40 mmHg and SVi< 30 ml/m2 presented the highest risk of the composite endpoint (Log-rank P = 0.010) (Figure). Hemodynamic profiling remained an independent predictor of outcome even after adjusting for the NAC stage (Profile B, HR 2.26; Profile C, HR 6.96; Profile D, HR 17.13; P-value=0.0012). Conclusions The proposed echocardiographically-derived hemodynamic classification based on forward-flow and LVFP estimation is useful for TTR-CA patients risk stratification. Patients with low SVi and high PAPs have the greatest risk of CV death and HF hospitalization, even after adjustment for NAC stage. These findings highlight the importance of early detection and monitoring of hemodynamic changes in TTR-CA patients for tailored management and to improve outcomes.Table.Figure.