Echocardiographic estimation of left atrial pressure - validation of an old standard

Evaluation of left atrial pressure (LAP) is essential for effective management of cardiovascular disease. Current techniques do not provide an easy method of LAP measurement. Pulmonary capillary wedge pressure (PCWP) is used as a surrogate for LAP despite its limitations. Nagueh et. al. have demonstrated that the diastolic ratio of early mitral inflow velocity (E) and early lateral mitral annular tissue Doppler velocity (El) is related to PCWP by the equation PCWP = 1.24(E/El) + 1.9. Current guidelines recommend averaging the septal and lateral mitral annular velocities to use in this formula. The relationship between E/El and the gold standard of directly measured invasive LAP has not been well studied.

We aim to assess the validity of the Nagueh formula in predicting invasive LAP.

A retrospective analysis was conducted on data recorded prospectively during percutaneous closure of patent foramen ovale (PFO) and atrial septal defects (ASD). Standard echocardiographic evaluation of diastolic indices was performed by transoesophageal echocardiography and simultaneous invasive LAP measurement was achieved by a 6 French multipurpose catheter placed in the left atrium prior to device deployment. Patients with significant mitral valvular pathology or atrial fibrillation were excluded from analysis. The relationship between invasive LAP and diastolic ratio was analysed by Pearson’s correlation. Agreement between Nagueh formula estimated LAP and invasive LAP was assessed by intraclass correlation (ICC) based on average measures, absolute agreement and a two-way mixed effects model. The ratios of E velocity with tissue Doppler derived mitral annular septal velocity (Es), average of septal and lateral velocities (Esl) and a global average of anterior, posterior, septal, and lateral mitral annular velocities (Eg) were also substituted for E/El in the Nagueh formula to determine which provided the strongest correlation and agreement with invasive LAP.

A 106 patients were included in the analysis. Mean age was 45 (SD 13) years; 48% (n=51) were female; 33% (n=35) had an ASD. The most common indication for PFO closure was ischemic stroke (61.3%). Median LAP was 10 mmHg (IQR 9-12). Invasive LAP had the best correlation with E/Eg (r=0.65, p<.001), followed by E/Esl (r=0.59, p<.001), E/El (r=0.57, p<.001) and E/Es (r=0.52, p<.001). LAP by Nagueh formula had a stronger agreement with invasive LAP when E/Eg was used in the estimation (ICC=0.77, 95% CI 0.65-0.85, p<.001), as compared to E/Esl (ICC=0.74, 95% CI 0.62-0.82, p<.001) or E/El(ICC=0.71, 95% CI 0.56-0.8, p<.001).

The diastolic ratio remains a simple and accurate echocardiographic parameter for non-invasive estimation of true LAP. When used in the Nagueh formula, E/Eg provides the closest approximation of invasive LAP.