By Michael H. Crawford, MD, Editor
Synopsis: A study of patients undergoing catheter ablation for atrial fibrillation with periprocedural echocardiograms and directly measured left atrial pressure (LAP) has shown that mean LAP can be estimated with a high degree of accuracy by a hierarchical algorithm using three Doppler echocardiographic parameters.
Source: Seo J, Yu HT, Kim IS, et al. Novel algorithm for non-invasive estimation of left atrial pressure in patients with atrial fibrillation. Eur Heart J Cardiovasc Imaging. 2024; Dec 3. doi: 10.1093/ehjci/jeae311. [Online ahead of print].
Estimating mean left atrial pressure (mLAP) by echocardiography in patients with atrial fibrillation (AF) is challenging because the typical algorithms for this purpose do not apply to AF. Also, AF-specific algorithms have only been validated in small studies against pulmonary capillary wedge pressure or left ventricular (LV) end-diastolic pressure. Thus, these investigators from South Korea recruited 200 patients undergoing catheter ablation of AF between 2020 and 2022 at two tertiary hospitals who had Doppler echocardiograms performed immediately before or during the procedure. mLAP was measured immediately after interatrial septal puncture and averaged over 10 beats. Elevated mLAP was defined as ≥ 15 mmHg. After excluding those with significant mitral regurgitation, stenosis or with a prosthetic valve, and those with constrictive physiology or an LV ejection fraction < 50%, 176 patients (mean age 64 years, 84% men) were available for analysis.
Pulsed Doppler parameters associated with LA function were averaged over 20 beats. mLAP > 15 mmHg was present in 36% of the patients, and these patients had more hypertension, LA enlargement, and elevated N-terminal pro-B natriuretic peptide (NT-proBNP). The strongest single parameter correlated with mLAP was septal E/e’ ≥ 11 (r = 0.35; P < 0.001; area under the curve [AUC], 0.70; sensitivity 65%; specificity 73%; accuracy 70%). A hierarchical algorithm using three parameters (septal E/e’, LA reservoir strain, and LA volume index [Vi]) increased specificity and accuracy (sensitivity 61%, specificity 91%, positive predictive value [PV] 80%, negative PV 79%, and accuracy 80%).
The authors concluded that the septal E/e’ ratio was the best single parameter for detecting elevated mLAP in patients with AF and a hierarchical algorithm incorporating septal E/e’, LA reservoir strain, and LAVi improves the accuracy of elevated mLAP identification.
Commentary
Increased LAP frequently is found in patients with AF and heart failure with preserved ejection fraction. Reducing LAP often is a treatment goal for both of these conditions. Thus, the ability to estimate LAP noninvasively is desirable.
Several echocardiographic methods for doing so exist but cannot be used in patients with AF. A few methods for estimating LAP in patients with AF have been promulgated, but they were validated using pulmonary capillary wedge pressure (PCWP) or left ventricular end-diastolic pressure (LVEDP) rather than LAP. Some guidelines recommend using peak tricuspid regurgitation velocity > 2.8 m/s as an indicator of increased LAP. However, in the Korean study, few had tricuspid regurgitation velocities > 2.8 m/s and, among those, 30% had mLAP < 15 mmHg. Previous studies with a smaller number of patients have failed to find a single parameter that accurately predicted mLAP in AF patients. One study developed an algorithm with six parameters that predicted either PCWP, mLAP, or LVEDP.
In the more robust Korean study, a three-measurement hierarchical algorithm proved to be quite accurate for determining elevated mLAP. The researchers found that, in addition to septal E/e,’ which was the best single predictor, LAVi provided good negative predictive value and LARS provided good positive predictive value, despite the fact that neither of the latter two measurements was a strong predictor alone.
Use of the algorithm is quite simple:
- If septal E/e’ is < 11, mLAP is < 15 mmHg.
- If septal E/e’ is ≥ 11 and LAVi is < 38 mL/m², mLAP is < 15 mmHg.
- If septal E/e’ is < 11 and LAVi is ≥ 38 mL/m2 and LARS is < 10, mLAP is < 15 mmHg.
- If septal E/e’ is ≥ 11, LAVi is ≥ 38 mL/m2 and LARS is < 10, then mLAP is ≥ 15 mmHg.
The strengths of the Korean study include the simultaneous measurement of Doppler echocardiographic measures and LAP. Also, many of their patients were at risk of heart failure because more than one-third had elevated mLAP, mean NT-proBNP was 554, the majority had a diagnosis of hypertension, and about one-half were obese. In addition, all Doppler echo measurements were the average of 20 beats and the LAP measurements were the average of 10 beats.
Weaknesses include the relatively small number of patients, all of whom were Korean and most of whom were men. Also, all the patients were referred for AF catheter ablation and may be different than other patients referred for heart failure evaluation to measure LAP. In addition, elevated mLAP was defined as > 15 mmHg, since most had an mLAP > 12 mmHg.
Michael H. Crawford, MD, is Professor of Medicine and Consulting Cardiologist, University of California Health, San Francisco.
A study of patients undergoing catheter ablation for atrial fibrillation with periprocedural echocardiograms and directly measured left atrial pressure (LAP) has shown that mean LAP can be estimated with a high degree of accuracy by a hierarchical algorithm using three Doppler echocardiographic parameters.
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