Bedside assessment of left atrial pressure in critical care: a multifaceted gem.

Evaluating left atrial pressure (LAP) solely from the left ventricular preload perspective is a restrained approach. Accurate assessment of LAP is particularly relevant when pulmonary congestion and/or right heart dysfunction are present since it is the pressure most closely related to pulmonary venous pressure and thus pulmonary haemodynamic load. Amalgamation of LAP measurement into assessment of the 'transpulmonary circuit' may have a particular role in differentiating cardiac failure phenotypes in critical care. Most of the literature in this area involves cardiology patients, and gaps of knowledge in application to the bedside of the critically ill patient remain significant. Explored in this review is an overview of left atrial physiology, invasive and non-invasive methods of LAP measurement and their potential clinical application.

Transesophageal Echocardiography For The Assessment of Left Atrial Pressure After Trans-Septal Mitral Valve Interventions.

The measure of left atrial pressure (LAP) is an ideal marker for the clinical efficacy of transcatheter mitral valve intervention. Currently, only the invasive measurement of LAP (i-LAP) is available and no echocardiographic methods are reliable in the setting of transcatheter mitral valve intervention. This study sought to validate a new echocardiographic method for the estimation of LAP (e-LAP) by comparing it with i-LAP. During percutaneous edge-to-edge procedure with MitraClip, the i-LAP was routinely monitored. Across the iatrogenic interatrial septum defect, the flow was sampled with continuous-wave Doppler echocardiography for deriving the mean pressure gradient between the left atrium and the right atrium, and the central venous pressure was added to obtain the e-LAP. The correlation between the measures derived from these 2 methods was explored. A total of 34 consecutive patients were included. Intraclass correlation coefficient between e-LAP and i-LAP was high (intraclass correlation coefficient [95% confidence interval] 0.809 [0.625 to 0.902], R Pearson 0.6, p <0.001); a bias of -1.3 mm Hg for e-LAP versus i-LAP was found (p = 0.32). The median follow-up was 108 days (interquartile range 40 to 264). No death occurred and 6 patients were rehospitalized for heart failure. Postimplant e-LAP was correlated with rehospitalization at follow-up (hazard ratio 1.46, 95% confidence interval 1.022 to 2.1, p = 0.038). A cut-off value of 9.5 mm Hg for the e-LAP was identified as predictor of rehospitalization for heart failure. The evaluation of e-LAP has optimal reliability compared with i-LAP; a value more than 9.5 mm Hg was found to be related to higher risk of events at short follow-up.

Assessment of Right-Sided Heart Failure in Patients with Dilated Cardiomyopathy using Magnetic Resonance Relaxometry of the Liver.

In non-ischemic dilated cardiomyopathy (DC) patients at risk of developing right heart failure (RHF), early depiction of congestive heart failure (CHF) is pivotal to inform about the hemodynamic status and tailor medical therapy. We hypothesized increased liver relaxation times measured at routine cardiovascular magnetic resonance (CMR), reflecting passive hepatic congestion, may be a valuable imaging biomarker to depict congestive heart failure. The study cohort consisted of DC patients with LV dysfunction (i.e., ejection fraction <35%) with (n = 48) and without (n = 46) right ventricular dysfunction (RVD), defined as a right ventricular ejection fraction <35%, and >45%, respectively, and a control group (n = 40). Native T1, T2, and extracellular volume (ECV) liver values were measured on routinely acquired cardiac maps. DC+RVD patients had higher C-reactive protein, troponin I and NT-pro BNP values, and worse LV functional parameters than DC-RVD patients (all p <0.001). T1, T2 and ECV Liver values were significantly higher in DC+RVD compared to DC-RVD patients and controls, that is, T1: 675 ± 88 ms verses 538 ± 39 ms and 540 ± 34 ms; T2: 54± 8 ms versus 45 ± 5 ms and 46 ± 4 ms; ECV: 36 ± 7% versus 29 ± 4% and 30 ± 3% (all p <0.001). Gamma-glutamyltranspeptidase (GGT) correlated moderately but significantly with native T1 (r2 = 0.34), T2 (r2 = 0.27), and ECV liver (r2 = 0.23) (all p <0.001). Using right atrial (RA) pressure, as surrogate measure of RHF (i.e., RA pressure >5 mm Hg), native T1 liver yielded at ROC analysis the highest area under the curve (0.906), significantly higher than ECV liver (0.813), GGT (0.806), T2 liver (0.797), total bilirubin (0.737) and alkaline phosphatase (0.561)(p = 0.04). A T1 value of 617 ms yielded a sensitivity of 79.5% and specificity of 91.0% to depict RHF. Excellent intra-/inter-observer agreement was found for assessment of native T1/T2/ECV liver values. In conclusion, in DC patients, assessment of liver relaxation times acquired on a cardiovascular magnetic resonance exam, may provide valuable information with regard to the presence of RHF.

Application of Guideline-Based Echocardiographic Assessment of Left Atrial Pressure to Heart Failure with Preserved Ejection Fraction.

BACKGROUND: Early, noninvasive identification of patients with heart failure with preserved ejection fraction (HFpEF) with congestion may allow timely tailoring of decongestive therapies. The 2016 American Society of Echocardiography and European Association of Cardiovascular Imaging guidelines provide an algorithm to assess for elevated left atrial pressure (LAP); the associations of echocardiographic LAP with clinical status and disease progression in patients with HFpEF are unclear. METHODS: Participants in the Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in HFpEF trial were categorized into one of four prespecified guideline-based echocardiographic LAP categories: (1) normal, (2) elevated, (3) atrial fibrillation (AF) at the time of echocardiography, or (4) indeterminate. Associations of echocardiographic LAP categories with baseline exercise capacity, change in exercise capacity, and change in N-terminal pro-B-type natriuretic peptide over 24 weeks were evaluated. RESULTS: Of 216 participants, 199 underwent mitral inflow Doppler echocardiography for LAP categorization. Participants with elevated echocardiographic LAP (n = 81) or AF (n = 57) were older and had a higher prevalence of kidney dysfunction. Compared with the normal echocardiographic LAP group (n = 28), elevated echocardiographic LAP and AF were each independently associated with a greater reduction in peak oxygen consumption over 24 weeks after adjusting for baseline values and clinical covariates (ß for elevated echocardiographic LAP = -1.55 [95% CI, -2.59 to -0.51], P = .004; ß for AF = -1.33 [95% CI, -2.49 to -0.17], P = .03). Indeterminate echocardiographic LAP (n = 33) was also independently associated with a reduction in exercise capacity at 24 weeks compared with normal echocardiographic LAP (ß = -1.35; 95% CI, -2.51 to -0.19; P = .02). Finally, elevated echocardiographic LAP and AF were significantly associated with increases in N-terminal pro-B-type natriuretic peptide over 24 weeks compared with normal echocardiographic LAP. CONCLUSIONS: In patients with chronic HFpEF, elevated echocardiographic LAP and indeterminate echocardiographic LAP, as defined by contemporary guidelines, and AF were each independently associated with a reduction in exercise capacity compared with normal echocardiographic LAP. These findings suggest the potential utility of noninvasive LAP assessment in patients with HFpEF for tailoring treatments that decrease congestion.

Imaging, biomarker and invasive assessment of diffuse left ventricular myocardial fibrosis in atrial fibrillation.

BACKGROUND: Using cardiovascular magnetic resonance imaging (CMR), it is possible to detect diffuse fibrosis of the left ventricle (LV) in patients with atrial fibrillation (AF), which may be independently associated with recurrence of AF after ablation. By conducting CMR, clinical, electrophysiology and biomarker assessment we planned to investigate LV myocardial fibrosis in patients undergoing AF ablation. METHODS: LV fibrosis was assessed by T1 mapping in 31 patients undergoing percutaneous ablation for AF. Galectin-3, coronary sinus type I collagen C terminal telopeptide (ICTP), and type III procollagen N terminal peptide were measured with ELISA. Comparison was made between groups above and below the median for LV extracellular volume fraction (ECV), followed by regression analysis. RESULTS: On linear regression analysis LV ECV had significant associations with invasive left atrial pressure (Beta 0.49, P = 0.008) and coronary sinus ICTP (Beta 0.75, P < 0.001), which remained significant on multivariable regression. CONCLUSION: LV fibrosis in patients with AF is associated with left atrial pressure and invasively measured levels of ICTP turnover biomarker.

Prevention of serious air embolism during cryoballoon ablation; risk assessment of air intrusion into the sheath by catheter selection and change in intrathoracic pressure: An ex vivo study.

INTRODUCTION: One cause of cerebral infarction during cryoballoon ablation is the entry of air into a sheath due to the use of inappropriate catheters. It is known that the left atrial pressure of patients with obstructive sleep apnea syndrome can be negative. However, the effects of catheter selection and negative pressure changes in the sheath on air intrusion are not yet well understood. The aim of this study was to evaluate how catheter selection and negative pressure changes affect air intrusion and to perform countermeasures for air intrusion. METHODS AND RESULTS: This experiment used siphon principle to create negative pressure in the sheath. Noncryoablation catheters (not designed exclusively for cryoballoon ablation) and cryoballoon catheters were investigated. Catheters were inserted into the sheath and then removed. Thereafter, the amount of air in the sheath was measured. For catheters producing significantly larger amounts of air intrusion, the catheters were inserted via a long sheath in the sheath (sheath-in-sheath technique) and the same procedures were repeated. We found that the amount of air intrusion through most of the noncryoablation catheters was significantly larger than that through cryoablation catheters. An increase in the magnitude of negative pressure in the sheath resulted in a proportional increase in air intrusion, but the sheath-in-sheath technique significantly reduced air intrusion. CONCLUSION: The amount of air intrusion increased when using catheters with complicated tip shapes and thin outer diameters and when the magnitude of negative pressure in the sheath increased. The sheath-in-sheath technique may be an effective countermeasure.

Noninvasive Assessment of Hemodynamic Status in HeartWare Left Ventricular Assist Device Patients: Validation of an Echocardiographic Approach.

OBJECTIVES: The aim of this prospective study was to validate an echocardiographic protocol derived from 5 HeartWare left ventricular assist device (HVAD) patients for the noninvasive evaluation of right atrial pressure (RAP) and left atrial pressure (LAP) in HVAD patients. BACKGROUND: Echocardiography is an invaluable tool to optimize medical treatment and pump settings and also for troubleshooting residual heart failure. Little is known about the echocardiographic evaluation of hemodynamic status in HVAD patients. METHODS: Right heart catheterization and Doppler echocardiography were performed in 35 HVAD patients. Echocardiography-estimated RAP (eRAP) was assessed using inferior vena cava diameter, hepatic venous flow analysis, and tricuspid E/e' ratio. Echocardiography-estimated LAP was assessed using E/A ratio, mitral E/e' ratio, and deceleration time. RESULTS: eRAP and estimated LAP significantly correlated with invasive RAP and LAP (respectively, r = 0.839, p < 0.001, and r = 0.889, p < 0.001) and accurately detected high RAP and high LAP (respectively, area under the curve 0.94, p < 0.001, and area under the curve 0.91, p < 0.001). High eRAP was associated with high LAP (area under the curve 0.92, p < 0.001) and correlated with death or hospitalization at 180 days (odds ratio: 8.2; 95% confidence interval: 1.1 to 21.0; p = 0.04). According to estimated LAP and eRAP, patients were categorized into 4 hemodynamic profiles. Fifteen patients (43%) showed the optimal unloading profile (normal eRAP and normal wedge pressure). This profile showed a trend toward a lower risk for adverse cardiac events at follow-up (odds ratio: 0.2; 95% confidence interval: 0.1 to 1.0; p = 0.05) compared with other hemodynamic profiles. CONCLUSIONS: Doppler echocardiography accurately estimated hemodynamic status in HVAD patients. This algorithm reliably detected high RAP and LAP. Notably, high RAP was associated with high wedge pressure and adverse outcome. The benefit of noninvasive estimation of hemodynamic status in the clinical management of patients with left ventricular assist devices needs further evaluation.

Echocardiographic and hemodynamic assessment for predicting early clinical events in severe acute mitral regurgitation.

The diagnostic role of echocardiographic and hemodynamic assessment in acute mitral regurgitation (AMR) remains unclear. The central question of this study was to determine if echocardiographic and hemodynamic parameters can predict early clinical events in AMR. AMR was induced by percutaneously severing the mitral valve chordae tendineae in 39 Yorkshire pigs. Immediately after AMR induction, echocardiographic and hemodynamic exams were performed, and compared between those who died and those who survived within 30-days of the procedure. Echocardiographic indices of MR severity as well as the left atrial pressure showed significant differences between survivors and non-survivors in univariate analysis. Multi-variate logistic regression analysis revealed that echocardiography-derived regurgitant fraction and vena contracta as well as mean left atrial pressure could be used to segment the cohort into survivors and non-survivors. Our study demonstrated, for the first time, that echocardiographic and hemodynamic assessment of AMR provides predictive information on early clinical events in a clinically relevant animal model of AMR.

Significant Drop in Right Atrial Pressure Does Not Influence Fractional Flow Reserve Coronary Assessment.

The effect of a highly elevated level of right atrial filling pressure on fractional flow reserve (FFR) measurement remains unclear. Transcatheter tricuspid valve intervention, a recently introduced option for inoperable or high-risk patients, represents a unique model of in-vivo physiology to investigate the eventual influence of central venous pressure on coronary FFR measurements. The case is reported of a patient with a degenerated tricuspid surgical bioprosthesis who underwent transcatheter tricuspid valve-in-valve replacement and concomitant coronary functional assessment with FFR. In an experimental model, the significant fall in right atrial pressure did not influence FFR measurements in the presence of angiographically proven mild coronary artery disease.

Risk assessment, prognosis and guideline implementation in pulmonary arterial hypertension.

Current European guidelines recommend periodic risk assessment for patients with pulmonary arterial hypertension (PAH). The aim of our study was to determine the association between the number of low-risk criteria achieved within 1 year of diagnosis and long-term prognosis.Incident patients with idiopathic, heritable and drug-induced PAH between 2006 and 2016 were analysed. The number of low-risk criteria present at diagnosis and at first re-evaluation were assessed: World Health Organization (WHO)/New York Heart Association (NYHA) functional class I or II, 6-min walking distance (6MWD) >440 m, right atrial pressure <8 mmHg and cardiac index ≥2.5 L·min-1·m-21017 patients were included (mean age 57 years, 59% female, 75% idiopathic PAH). After a median follow-up of 34 months, 238 (23%) patients had died. Each of the four low-risk criteria independently predicted transplant-free survival at first re-evaluation. The number of low-risk criteria present at diagnosis (p<0.001) and at first re-evaluation (p<0.001) discriminated the risk of death or lung transplantation. In addition, in a subgroup of 603 patients with brain natriuretic peptide (BNP) or N-terminal pro-brain natriuretic peptide (NT-proBNP) measurements, the number of three noninvasive criteria (WHO/NYHA functional class, 6MWD and BNP/NT-proBNP) present at first re-evaluation discriminated prognostic groups (p<0.001).A simplified risk assessment tool that quantifies the number of low-risk criteria present accurately predicted transplant-free survival in PAH.

Quantification of mitral regurgitation during percutaneous mitral valve repair: added value of simultaneous hemodynamic and 3D echocardiographic assessment.

The objective of this study was to investigate the usefulness of intraprocedural hemodynamic monitoring for MR evaluation during pMRV. Assessment of mitral regurgitation (MR) during percutaneous mitral valve repair (pMVR) procedure is challenging. 3D color Doppler allows exact quantification of MR, but is technically demanding. Sixty patients with moderate to severe MR (14 with structural and 46 functional MR) were included in the study. Intraprocedural pressure curves were continuously obtained in the left atrium (LA) and left ventricle (LV). Transesophageal echocardiography was performed using 3D color Doppler derived mean vena contracta area (VCAmean) and mitral regurgitation volume (RegVol) to quantify MR severity before and after each clip implantation. In the entire patient group, strongest correlations were observed firstly between VCA and the raise of the ascending limb of the left atrial V pressure wave (Vascend; r = 0.58, p < 0.001) and secondly between the difference of peak V wave pressure and mean LA pressure divided by systolic LV pressure [(Vpeak - LAmean) - LVsystole; r = 0.53, p < 0.001]. In patients with structural MR, the highest area under the ROC curve for prediction of mild MR (VCAmean < 0.2 cm² and RegVol < 30 ml) after clip implantation was found for Vascend (AUC 0.89, p < 0.001) whereas in functional MR calculation of (Vpeak - LAmean) - LVsystole showed the highest predictive value (AUC 0.69, p = 0.003). Invasive pressure monitoring can give a direct feedback with regard to the success of clip placement during pMVR.

Serial semi-invasive hemodynamic assessment following pericardiectomy for chronic constrictive pericarditis.

OBJECTIVES: This study was designed to prospectively investigate the effects of pericardiectomy via median sternotomy on intra- and postoperative hemodynamics by a new semi-invasive device (Flotrac/VigileoTM monitor) using arterial pressure waveform analysis. PATIENTS AND METHODS: Thirty consecutive patients aged 15 to 55 years (mean+SD, 31.73 + 13.53 years), who had undergone total pericardiectomy via median sternotomy underwent serial hemodynamic evaluation. FlotracTM Sensor - derived stroke volume, stroke volume variation, systemic vascular resistance index (SVRI), cardiac index and right atrial pressure were measured just before and after pericardiectomy, at 12 hours, 24 hours, 48 hours, 72 hours and at discharge postoperatively. RESULTS: Majority of patients (73.33%) exhibited statistically significant reduction of right atrial pressure and SVRI along with improvement in cardiac index and oxygen delivery in the immediate and late postoperative period. However, the stroke volume and stroke volume variation did not increase proportionately on completion of surgery. Patients with low cardiac output syndrome exhibited persistently high central venous pressure with reduced cardiac index and echocardiographically abnormal diastolic filling characteristics. CONCLUSIONS: We conclude that there is early normalization of hemodynamics following pericardiectomy via median sternotomy and the adequacy of pericardiectomy can be accurately assessed by the new semi-invasive arterial pressure waveform analysis device. Stroke volume variation is a non-predictor of fluid requirement during and after pericardiectomy.

Intraprocedural assessment of mitral regurgitation during the mitraclip procedure: Impact of continuous left atrial pressure monitoring.

INTRODUCTION: Intraprocedural assessment of mitral regurgitation (MR) is a challenging issue during the MitraClip procedure, which might influence not only the position but also the number of MitraClips implanted. Though transesophageal echocardiography (TEE) is the predominant tool used during the MitraClip procedure, MR assessment might be facilitated by a multimodality approach including continuous and simultaneous determination of left atrial and left ventricular (LV) pressure. METHODS: 86 consecutive patients (76.5 ± 8 years) who qualified for the MitraClip procedure were included into the study. In all patients, the multimodal assessment of MR (TEE, LV angiogram, TEE bubble evaluation, left atrial (LA) pressure => MitraScore) was performed after introducing the MitraClip guide catheter. In the first 42 patients (group A, no CAP), left atrial (LA) pressure (peak pressure of V-wave) was determined only before and after MitraClip implantation, whereas, in the subsequent 44 patients (group B, with CAP), continuous left atrial pressure monitoring (CAP) was performed. RESULTS: Patients with CAP (group B) had similar total procedural durations and no increase in the complication rate. MitraScore decreased from 10.5 to 3.5 in group A compared to 10.7 to *2.8 in group B (*P = 0.021 vs. group B). Whether the significant improvement of intraprocedural MR in group B translated into superior MR reduction in the conscious patient, was analyzed by transthoracic echocardiography (TTE) in a blinded fashion. Again MR reduction was significantly greater (P = 0.03) in group B (MR grade 2.8 to 0.9) as compared to group A (MR grade 2.8 to 1.3) and 2D vena contracta decreased from 0.54 ± 0.15 cm to 0.17 ± 0.10 in group B compared to group A (0.56 ± 0.19 cm to *0.23 ± 0.12; *P = 0.01 vs. group B). CONCLUSIONS: Multimodality assessment of intraprocedural MR supported by continuous left atrial pressure monitoring was associated with superior intraprocedural results translating into improved MR reduction also at the end of the hospital stay. © 2016 Wiley Periodicals, Inc.

Echocardiographic Assessment of Right Atrial Pressure in a Pediatric and Young Adult Population.

Right atrial pressure (RAP) reflects right-sided cardiac hemodynamics and is useful in management of patients with cardiac and systemic disease. Studies in older adults demonstrated that inferior vena cava (IVC) diameter, IVC collapsibility index, hepatic vein systolic filling fraction (SFF), and right atrial volume (RAV) correlated with mean RAP at catheterization. This study aimed to assess the utility of echocardiographic parameters for assessment of RAP in children and young adults. Patients with pulmonary hypertension or heart transplantation undergoing right heart catheterization were recruited for this prospective observational pilot study. Transthoracic echocardiographic assessment of RAP was performed simultaneously with catheterization. For each parameter, three consecutive cardiac cycles were recorded. Long- and short-axis images of the IVC were obtained. RAV was assessed by area-length and biplane methods. IVC diameters and RAV were indexed to body surface area (BSA)(0.5) and (BSA)(1.4), respectively. Relationships between echocardiographic parameters and mean RAP were correlated using "Pearson's r." Fifty subjects aged 0.3-23 years (median 13, mean 12.3 ± 7 years) were enrolled. Mean RAP correlated modestly with RAV (r = 0.51, p < 0.001). Long-axis IVCmax (r = 0.30, p < 0.05) and tricuspid E wave velocity (r = 0.36, p < 0.01) also correlated with mean RAP. RV free wall tissue Doppler velocities, IVC collapsibility index, and hepatic vein SFF had no relation to mean RAP. In a pediatric and young adult population with pulmonary hypertension or heart transplantation, echocardiographic assessment of RAV and long-axis IVCmax provided a reasonable estimate of mean RAP. IVC collapsibility index and hepatic vein SFF demonstrated no association with mean RAP.

Assessment of left sided filling dynamics in diastolic dysfunction using cardiac computed tomography.

BACKGROUND: Left ventricular (LV) diastolic dysfunction (DD) often accompanies coronary artery disease but is difficult to assess since it involves a complex interaction between LV filling and left atrial (LA) emptying. OBJECTIVE: To characterize simultaneous changes in LA and LV volumes using cardiac computed tomography (CT) in a group of patients with various grades of DD based on echocardiography. METHODS: We identified 35 patients with DD by echocardiography, who had also undergone cardiac CT, and 35 age-matched normal controls. LV and LA volumes were measured every 10% of the RR interval, using semi-automatic software. From these, - systolic, early-diastolic and late-diastolic volume changes were calculated, and additional parameters of diastolic filling derived. Conduit volume was defined as the difference between the LV and LA early-diastolic volume change. RESULTS: Patients with DD had significantly larger LV mass, and LA volumes, reduced early emptying volumes and increased conduit volume as percent of early LV filling (All p<0.001). LA function, manifesting as total emptying fraction (LATEF), decreased proportionately with worsening grades of DD (p<0.001). LA contractile function was maintained until advanced grade-3 DD. By receiver operating characteristic analysis, LATEF had an AUC of 0.88 to separate between normals and DD. At a threshold of <42.5%, LATEF has 97% sensitivity and 69% specificity to detect DD. CONCLUSIONS: DD is characterized by reduced LA function and an alteration in the relative contributions of the atrial emptying and conduit volume components of early LV filling. In patients undergoing cardiac CT, it is possible to identify the presence and severity of DD.

Echocardiography in the Assessment of Left Atrial Pressure After Pediatric Heart Surgery: A Comparison Study With Measurements Obtained From Left Atrial Catheter.

BACKGROUND: Correlation between ventricular end-diastolic pressure and pulsed Doppler and tissue Doppler-derived E/e' ratio has been widely reported in adults but scarcely studied in children with congenital heart diseases. This ratio is defined as the relationship between diastolic transmitral flow velocity (cm/s; E) and myocardial diastolic relaxation velocity (cm/s; e') in the lateral aspect of the mitral annulus. Our main objective was to ascertain whether a correlation existed between direct measurement of left atrial pressure and echocardiographic E/e' ratio in children after heart surgery. METHODS: Prospective study including 27 consecutive children after pediatric heart surgery. Data were analyzed according to whether they were obtained within the first 72 hours following surgery or later on. Sensitivity, specificity, positive and negative predictive values, and areas under the receiver-operating characteristics curve of E/e' ratio in detection of left atrial pressure values ≥13 mm Hg were evaluated. RESULTS: Forty-eight studies were conducted in 27 patients. Thirty-two studies were performed during the first 72 hours after heart surgery and 16 beyond the third day. Median patient age was 0.82 years (5 days-16 years). Median left atrial pressure values and E/e' measurements of the whole cohort (N = 48) were 12.0 and 10.2, respectively. Intraclass correlation index between left atrial pressure values and echocardiographic E/e' ratio was 0.35, 0.25 for studies performed within 72 hours, but 0.78 (P < .01) for those performed later. There was also a high positive predictive value, since in 13 (87%) of 15 studies with an E/e' ratio ≥13, the left atrial pressure was ≥13 mm Hg. CONCLUSION: While echocardiographic E/e' ratio did not show a good correlation with left atrial pressure in the immediate postoperative period, the positive predictive value may suffice to aid clinicians in predicting elevated pressures.