Utility of left atrial strain to volume relationship during passive leg lift to identify elevated left ventricular filling pressure - a proof-of-concept study

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Abstract Background Assessment of left ventricular (LV) filling pressure in heart failure (HF) poses a diagnostic challenge, particularly when patients display normal LV filling pressures at rest but elevated LV filling pressures during exercise. Rapid preload increase during passive leg lift (PLL) has displayed promise to unmask HF in such challenging scenarios. Novel echocardiographic variables that identify patients with elevated LV filling pressures during PLL are of important clinical value. We explored the dynamic interplay between left atrial (LA) function and volume using LA strain/volume loops during PLL and compared their diagnostic performance to detect elevated LV filling pressure with conventional echocardiographic surrogates. Methods We retrospectively reviewed 39 patients with a clinical HF that underwent simultaneous echocardiography and right heart catheterization before and immediately after PLL. Patients with atrial fibrillation (n=4) were excluded. LA-strain volume dynamics at rest and at PLL were also evaluated in 20 age-matched, healthy controls. LA reservoir strain (LASr) was analyzed using speckle-tracking echocardiography. LA strain-volume loops were generated including the best-fit linear regression line employing simultaneous LASr and LA volume. Results LA strain-volume slope was lower for HF patients when compared with controls (0.71 vs. 1.22 %/mL, p<0.001). During PLL, LA strain-volume slope displayed a moderately strong negative correlation with invasive pulmonary arterial wedge pressure (PAWP) (r = -0.71, p<0.001) (Fig. 1). At a 0.74 %/mL cut-off, LA strain-volume slope displayed 88% sensitivity and 86% specificity to identify elevated PAWP (AUC 0.89 [0.76–1.00]). In comparison, LASr displayed strong but numerically lower diagnostic performance (AUC 0.83 [0.67–1.00]) and mitral E/e’ demonstrated poor performance (AUC 0.68 [0.40–0.96]) to identify elevated PAWP either at rest or at PLL (Fig 2). Conclusions In this proof-of-concept study, LA strain-volume characteristics display potential to provide incremental diagnostic value compared to conventional echocardiographic measures at rest in identification of elevated LV filling pressure. Our preliminary findings need validation in larger cohorts. Figure 1 Figure 2