Echocardiographic assessment alone is inadequate for determining elevated left sided filling pressures in patients with cardiogenic shock

Abstract

Abstract Background Left atrial (LA) filling pressure assessment is of paramount importance in tailoring treatments for patients with cardiogenic shock (CS). ESC guidelines advocate for the use of mitral inflow Doppler and mitral annulus tissue Doppler measurements to predict elevated left atrial pressure in clinical practice. Echocardiographic measurement of LA pressures could reduce the need for invasive monitoring in CS patients, but its utility remains unproven in this population. Purpose We assessed the validity of mitral inflow velocity and mitral annulus velocity indices to determine LA pressures, correlating them with invasive measurement of pulmonary capillary wedge pressure (PCWP) in CS patients admitted to the cardiac intensive care unit (CICU). Methods We prospectively evaluated consecutive patients who underwent pulmonary artery catheter insertion in the CICU, measuring their haemodynamic parameters, including PCWP. This was immediately followed by a transthoracic echocardiography (TTE) performed by a critical care cardiologist, blinded to the invasive measurements. The early (E) and late (A) mitral inflow velocities were measured using mitral inflow Doppler and septal and lateral mitral annulus velocities (e') were measured using tissue Doppler, all in the apical 4-chamber view. TTE images were later reported by a second cardiologist, blinded to the invasive measurements and the patient. Correlations between E; E/A ratio; E/e' ratio and PCWP were evaluated using Pearson's correlation. Results Sixty patients were recruited into the study, aged 58±14 years, 27% female, with 96 assessments undertaken. The majority (55%) of patients were SCAI stage C, with 14% having had a cardiac arrest prior to CICU admission and 27% required mechanical ventilation at the time of assessment. Mean PCWP was 16.0±6.5 mmHg. Full mitral valve Doppler and tissue Doppler profiles were measured in 67 (70%) assessments, limited due to E/A fusion, atrial fibrillation and limited acoustic windows. There was only weak correlation between PCWP and E/A ratio (R=0.33, p=0.01), with no correlation between PCWP and the other measured values (Table 1), including E/e'. The AUC for identifying patients with elevated PCWP (≥15 mmHg) using E/A ratio was 0.67 (p=0.02), although there was no suitable value to use as a cut off with adequate sensitivity and specificity (Figure 1). Conclusion Echocardiographic non-invasive assessment of left sided cardiac filling pressures is technically challenging in patients with CS. Even when possible, there is weak correlation between echocardiographic and invasive measurements, suggesting limited value in this technique. Alternative non-invasive modalities, such as lung ultrasound, should be investigated in this population to assist clinical assessment. Funding Acknowledgement Type of funding sources: None.