Left Atrial Expansion Index for Noninvasive Estimation of Pulmonary Capillary Wedge Pressure: A Cardiac Catheterization Validation Study

Mortality Associated With Proportionality of Secondary Mitral Regurgitation After Transcatheter Mitral Valve Repair: North American Mitraclip for Functional Mitral Regurgitation Registry

The association, if any, between the effective regurgitant orifice area (EROA) to left ventricular end-diastolic volume (LVEDV) ratio and 1-year mortality is controversial in patients who undergo mitral transcatheter edge-to-edge repair (m-TEER) with the MitraClip system (Abbott Vascular, Santa Clara, CA). This study's objective was to determine the association between EROA/LVEDV and 1-year mortality in patients who undergo m-TEER with MitraClip. In patients with severe secondary (functional) mitral regurgitation (MR), we analyzed registry data from 11 centers using generalized linear models with the generalized estimating equations approach. We studied 525 patients with secondary MR who underwent m-TEER. Most patients were male (63%) and were New York Heart Association class III (61%) or IV (21%). Mitral regurgitation was caused by ischemic cardiomyopathy in 51% of patients. EROA/LVEDV values varied widely, with median = 0.19 mm2/ml, interquartile range [0.12,0.28] mm2/ml, and 187 patients (36%) had values <0.15 mm2/ml. Postprocedural mitral regurgitation severity was substantially alleviated, being 1+ or less in 74%, 2+ in 20%, 3+ in 4%, and 4+ in 2%; 1-year mortality was 22%. After adjustment for confounders, the logarithmic transformation (Ln) of EROA/LVEDV was associated with 1-year mortality (odds ratio 0.600, 95% confidence interval 0.386 to 0.933, p = 0.023). A higher Society of Thoracic Surgeons risk score was also associated with increased mortality. In conclusion, lower values of Ln(EROA/LVEDV) were associated with increased 1-year mortality in this multicenter registry. The slope of the association is steep at low values but gradually flattens as Ln(EROA/LVEDV) increases.

Left atrial expansion index measured with cardiovascular magnetic resonance estimates pulmonary capillary wedge pressure in dilated cardiomyopathy

BACKGROUND

Pulmonary capillary wedge pressure (PCWP) assessment is fundamental for managing dilated cardiomyopathy (DCM) patients. Although cardiovascular magnetic resonance (CMR) has become the gold-standard imaging technique for evaluating cardiac chamber volume and function, PCWP is not routinely assessed with CMR. Therefore, this study aimed to validate the left atrial expansion index (LAEI), a LA reservoir function parameter able to estimate filling pressure with echocardiography, as a novel CMR-measured parameter for non-invasive PCWP estimation in DCM patients.

METHODS

We performed a retrospective, single-center, cross-sectional study. We included electively admitted DCM patients referred to our tertiary center for further diagnostic evaluation that underwent a clinically indicated right heart catheterization (RHC) and CMR within 24 h. PCWP invasively measured during RHC was used as the reference. LAEI was calculated from CMR-measured LA maximal and minimal volumes as LAEI =  ( (LAVmax-LAVmin)/LAVmin) × 100.

RESULTS

We enrolled 126 patients (47 ± 14 years; 68% male; PCWP = 17 ± 9.3 mmHg) randomly divided into derivation (n = 92) and validation (n = 34) cohorts with comparable characteristics. In the derivation cohort, the log-transformed (ln) LAEI showed a strong linear correlation with PCWP (r = 0.81, p < 0.001) and remained a strong independent PCWP determinant over clinical and conventional CMR parameters. Moreover, lnLAEI accurately identified PCWP ≥ 15 mmHg (AUC = 0.939, p < 0.001), and the optimal cut-off identified (lnLAEI ≤ 3.85) in the derivation cohort discriminated PCWP ≥ 15 mmHg with 82.4% sensitivity, 88.2% specificity, and 85.3% accuracy in the validation cohort. Finally, the equation PCWP = 52.33- (9.17xlnLAEI) obtained from the derivation cohort predicted PCWP (-0.1 ± 5.7 mmHg) in the validation cohort.

CONCLUSIONS

In this cohort of DCM patients, CMR-measured LAEI resulted in a novel and useful parameter for non-invasive PCWP evaluation.

Asymmetric remodeling between the left and right atria in patients with advanced interatrial block and atrial fibrillation

BACKGROUND

Advanced interatrial block (A-IAB) on electrocardiography (ECG) represents the conduction delay between the left and right atria. We investigated the association of A-IAB with left and right atrial (LA/RA) remodeling in patients with atrial fibrillation (AF).

METHODS

We enrolled 74 patients who underwent ECG, cardiac computed tomography (CCT), and echocardiography during sinus rhythm before catheter ablation of AF. A-IAB was defined as P-wave duration ≥120 ms with a biphasic morphology in leads III and aVF or notched morphology in lead II. We compared the maximum and minimum LA/RA volume indices (max and min LAV/RAVI), LA/RA expansion index (LAEI/RAEI), and total, passive, and active LA/RA emptying fraction (LAEF/RAEF) between patients with and without A-IAB.

RESULTS

Of the 74 patients (mean age, 64.3 ± 9.6 years), 35 (47%) showed A-IAB. Patients with A-IAB had a significantly higher likelihood of hypertension and left ventricular diastolic dysfunction than those without. Patients with A-IAB had significantly larger max (69.2 [60.7-79.7]mL/m2 vs. 60.9 [50.4-68.3]mL/m2, P < 0.01) and min (44.0 [37.2-52.1]mL/m2 vs. 34.1 [29.2-43.5]mL/m2, P < 0.01) LAVI than those without. The max and min RAVI were not significantly different between groups. LAEI (55.1 [48.2-78.5]% vs. 72.1 [57.8-84.8]%, P < 0.05), total LAEF (35.5 [32.5-44.0]% vs. 41.9 [36.6-45.9]%, P < 0.05), and passive LAEF (12.2 [10.0-14.4]% vs. 15.5 [11.2-19.6]%, P < 0.05) were significantly lower in patients with A-IAB than without.

CONCLUSIONS

A-IAB was associated with LA, but not RA enlargement, in patients with AF. A-IAB may indicate LA functional remodeling in the reservoir and conduit phases.

Early predicting improvement of severe systolic heart failure by left atrial volume

Left atrium (LA) modulates left ventricle (LV) filling and cardiac performance. We aimed to assess the effect of heart failure (HF) therapy on LA and LV function, and the relationship between LA/LV improvement and clinical outcome in acute HF with reduced LV ejection fraction (LVEF). Totally, 224 hospitalized patients with acute HF and LVEF < 35% were enrolled and underwent echocardiography. They all received maximal tolerable doses of evidence-based medications. Patients received echocardiographic measurements at each visit including stroke volume, LVEF, LA minimal/maximal volume (LAV_min/LAV_max), LA expansion index, and tissue Doppler parameters. The threshold of LV functional improvement was LVEF > 45% ever occurred before study end. During the mean follow-up of 6.3 years, 62 cases improved well, mean LVEF 49 ± 5% at study end. The reduction of LV filling pressure occurring as early as 2 weeks later, LV systolic function improvement took longer (> 1 month). The reductions in LAV_min and LAV_max between initial stabilization and 2 weeks after HF treatment (Initial-2 W) and the increase of LA expansion index (Initial-2 W) were associated independently with LVEF improvement (p 0.002, 0.006, and 0.007, respectively). The best predictor of LVEF improvement was LAV_min reduction (Initial-2 W) > 5 ml with 77% sensitivity, 76% specificity. Cox proportional hazard regression analyses for cardiovascular events revealed LVEF improvement reduced 74% of events (hazard ratio 0.264, 95% CI 0.192-0.607, p < 0.0001); and LA expansion index (per 1% increase) reduced 14% of events (hazard ratio 0.862, 95% CI 0.771-0.959, p < 0.0001). The early reduction of LAV (Initial-2 W), especially LAV_min, is a powerful early predictor of LVEF improvement. Its occurrence reduces cardiovascular events significantly. ClinicalTrials.gov number: NCT01307722.

Non-invasive evaluation of pulmonary capillary wedge pressure using the left atrial expansion index in mitral valve stenosis, prosthesis and repair

Pulmonary capillary wedge pressure (PCWP) non-invasive evaluation is limited in patients with mitral valve (MV) stenosis, prosthesis, and surgical repair. This study aimed to assess the left atrial expansion index (LAEI) measured through transthoracic echocardiography (TTE) as a novel parameter for estimating PCWP in these challenging cardiac conditions. We performed a retrospective, cross-sectional study, including chronic cardiac patients receiving within 24 h a clinically indicated right heart catheterization (RHC) and transthoracic echocardiographic (TTE) exam. PCWP measured during RHC was used as the reference. TTE measurements were performed offline, blinded to RHC results. LAEI was calculated as LAEI = [(LAmaxVolume-LAminVolume)/LAminVolume] × 100. We included 167 patients (age = 73 ± 11.5 years; PCWP = 18 ± 7.7 mmHg) with rheumatic mitral valve (MV) stenosis (16.2%), degenerative MV stenosis (51.2%), MV prosthesis (18.0%), and MV surgical repair (13.8%). LAEI correlated logarithmically with PCWP, and the log-transformed LAEI (lnLAEI) showed a good linear association with PCWP (r = - 0.616; p < 0.001). lnLAEI was an independent PCWP determinant, providing added predictive value over conventional clinical (age, atrial fibrillation, heart rate, MV subgroups) and echocardiographic variables (LVEF, MV effective orifice area, MV mean gradient, net atrioventricular compliance, and pulmonary arterial systolic pressure). lnLAEI identified PCWP > 12 mmHg with AUC = 0.870, p < 0.001; and PCWP > 15 mmHg with AUC = 0.797, p < 0.001, with an optimal cut-off of lnLAEI < 3.69. The derived equation PCWP = 36.8-5.5xlnLAEI estimated the invasively measured PCWP ± 6.1 mmHg. In this cohort of patients with MV stenosis, prosthesis, and surgical repair, lnLAEI resulted in a helpful echocardiographic parameter for PCWP estimation.

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.

Cardiac Imaging for the Assessment of Left Atrial Mechanics Across Heart Failure Stages

The left atrium (LA) is emerging as a key element in the pathophysiology of several cardiac diseases due to having an active role in contrasting heart failure (HF) progression. Its morphological and functional remodeling occurs progressively according to pressure or volume overload generated by the underlying disease, and its ability of adaptation contributes to avoid pulmonary circulation congestion and to postpone HF symptoms. Moreover, early signs of LA dysfunction can anticipate and predict the clinical course of HF diseases before the symptom onset which, particularly, also applies to patients with increased risk of HF with still normal cardiac structure (stage A HF). The study of LA mechanics (chamber morphology and function) is moving from a research interest to a clinical application thanks to a great clinical, prognostic, and pathophysiological significance. This process is promoted by the technological progress of cardiac imaging which increases the availability of easy-to-use tools for clinicians and HF specialists. Two-dimensional (2D) speckle tracking echocardiography and feature tracking cardiac magnetic resonance are becoming essential for daily practice. In this context, a deep understanding of LA mechanics, its prognostic significance, and the available approaches are essential to improve clinical practice. The present review will focus on LA mechanics, discussing atrial physiology and pathophysiology of main cardiac diseases across the HF stages with specific attention to the prognostic significance. Imaging techniques for LA mechanics assessment will be discussed with an overlook on the dynamic (under stress) evaluation of the chamber.