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Rapid Fire Abstracts

Rapid Fire 06- Valvular Heart Disease II

Increased Pulmonary Transit Time Is An Early Marker of Cardiac Decompensation In Aortic Stenosis and Aortic Regurgitation (RF_FR_356)

Friday, January 31, 2025
11:10 AM – 11:20 AM East Coast USA Time
Location: Blue Room PreFunction
Background:

Pulmonary transit time (PTT) is a quantitative biomarker of cardiopulmonary status encompassing biventricular function, left atrial volume and left ventricular (LV) filling pressures. PTT and pulmonary blood volume (PBV) are surrogates of pulmonary congestion, which precedes onset of symptoms in heart failure and may add value in the assessment of patients with valve disease and unclear symptoms (1,2). PTT and PBV can be measured by perfusion cardiovascular magnetic resonance (CMR)(3).  This study aims to assess the association between PTT and left ventricular structure and function in aortic stenosis (AS) and regurgitation (AR).



Methods: Multicenter prospective observational cohort study of patients with severe AS or severe AR listed for aortic valve replacement and healthy controls (HCs). Participants underwent perfusion CMR with automated sampling of the right ventricular (RV) and left ventricular (LV) arterial input function (2). PTT was estimated with the centroid approach (Figure 1) and was normalized to the RR interval (PTTn). PBV was calculated as the product of PTT and right ventricular cardiac output, indexed for body surface area (PBVi). Associations of PTTn in AS and AR were assessed by multivariable regression.

Results: 262 participants were included; 72 AR (81% male), 163 AS (71% male), and 27 HCs (48% male). Median rest PTTn for HCs was 8.6s [6.9-9.3s], AS 9.4s [IQR: 8.3-10.9s], and AR 11.7s [IQR: 9.6-14.8s];  median rest PBVi for HCs was 480ml/m2 [405-526 ml/m2], AS 472ml/m2 [194-577 ml/m2], and AR 881ml/m2 [665-1122ml].
 
There was a significant difference in PTTn and PBVi across groups. By pairwise comparison the PTTn was higher in AR vs AS (P< 0.001), AR vs HCs (P< 0.001) and AS vs HCs (P=0.007). This relationship persisted when patients with LVEF< 55% were excluded. Pairwise comparison demonstrated higher PBVi in AR vs AS (P< 0.001), and AR vs HCs (P< 0.001) however no statistically significant difference between AS and HCs (P=0.943)(Figure 2).
 
In multivariable analysis, associations of PTTn in AS were male sex (β =0.160, P=0.036), AF (β =0.187, P=0.013), LVEF (β =-0.372, P< 0.001), and log-NTproBNP (β =0.220, P=0.047). In AR, associations of PTTn were LVEF (β =-0.016, P=0.012) and AR regurgitation volume (β =0.350, P=0.035) (Table 1).

Conclusion: Pulmonary transit time and pulmonary blood volume is prolonged in AR compared to AS and healthy controls. In AR, PTT is worse with left ventricular function and regurgitant volume and in AS, PTT is associated with left ventricular function and NT-proBNP.