Echocardiographic diagnosis of atrial cardiomyopathy allows outcome prediction following pulmonary vein isolation

Abstract

Background: Relevant atrial cardiomyopathy (ACM), defined as a left atrial (LA) low-voltage area ≥ 2 cm² at 0.5 mV threshold on endocardial contact mapping, is associated with new-onset atrial fibrillation (AF), higher arrhythmia recurrence rates after pulmonary vein isolation (PVI), and an increased risk of stroke. The current study aimed to assess two non-invasive echocardiographic parameters, LA emptying fraction (EF) and LA longitudinal strain (LAS, during reservoir (LASr), conduit (LAScd) and contraction phase (LASct)) for the diagnosis of ACM and prediction of arrhythmia outcome after PVI.

Methods: We prospectively enrolled 60 consecutive, ablation-naive patients (age 66 ± 9 years, 80% males) with persistent AF. In 30 patients (derivation cohort), LA-EF and LAS cut-off values for the presence of relevant ACM (high-density endocardial contact mapping in sinus rhythm prior to PVI at 3000 ± 1249 sites) were established in sinus rhythm and tested in a validation cohort (n = 30). Arrhythmia recurrence within 12 months was documented using 72-h Holter electrocardiograms.

Results: An LA-EF of < 34% predicted ACM with an area under the curve (AUC) of 0.846 (sensitivity 69.2%, specificity 76.5%) similar to a LASr < 23.5% (AUC 0.878, sensitivity 92.3%, specificity 82.4%). In the validation cohort, these cut-offs established the correct diagnosis of ACM in 76% of patients (positive predictive values 87%/93% and negative predictive values 73%/75%, respectively). Arrhythmia recurrence in the entire cohort was significantly more frequent in patients with LA-EF < 34% and LASr < 23.5% (56% vs. 29% and 55% vs. 26%, both p < 0.05).

Conclusion: The echocardiographic parameters LA-EF and LAS allow accurate, non-invasive diagnosis of ACM and prediction of arrhythmia recurrence after PVI.

Keywords: Arrhythmia recurrence; Atrial cardiomyopathy; Atrial fibrillation; Atrial strain; Echocardiography; Pulmonary vein isolation.

Fig. 1

Illustration of two representative patients without and with relevant atrial cardiomyopathy. Invasive endocardial voltage map of the left atrium (a) and the corresponding left atrial strain (LAS) curves (b) are shown. Region of interest including endocardial borders was automatically determined by the speckle tracking software. On the left side, a patient without relevant atrial cardiomyopathy (ACM) with a left atrial low-voltage substrate (LA-LVS) of 0.3 cm² and normal strain values (LAS in reservoir phase (LASr): 36.5%, LAS in conduit phase (LAScd): 16.2% and LAS in contraction phase (LASct): 20.3%) is shown. On the right side, a patient with relevant ACM with 54.8 cm² LA-LVS and reduced strain values (LASr: 9.95%, LAScd: 6.15% and LASct: 3.8%) is depicted

Fig. 2

Diagnosis of relevant atrial cardiomyopathy based on echocardiographic parameters. Receiver-operating curves within the derivation cohort determined a left atrial emptying fraction (LA-EF) cut-off of < 34% as predictor for relevant atrial cardiomyopathy (ACM) diagnosis with a sensitivity of 69.2% and a specificity of 76.5%, a left atrial strain in reservoir phase (LASr) < 23.5% (sensitivity of 92.3% and specificity of 82.4%), in conduit phase (LAScd) < 13.4% (sensitivity of 84.6% and specificity of 82.4%) and in contraction phase (LASct) < 5.4% (sensitivity of 61.5% and specificity of 88.2%) (a). Application of these cut-offs to the validation cohort showed a significantly increased left atrial low-voltage substrate (LA-LVS) extent in patients with pathological echocardiography criteria (b) and allowed accurate differentiation between patients with and without relevant ACM (c). Whiskers depict median with 25% and 75% interquartile range. Dashed line marks border between absence (< 2 cm² LA-LVS at < 0.5 mV) and presence of relevant ACM

Fig. 3

Correlations between echocardiographic parameters and ACM extent. Echocardiographic parameters from both standard left atrial emptying fraction (LA-EF, a, left box) and left atrial strain (LAS) parameters (b–d, right box) correlated significantly with left atrial low-voltage substrate (LA-LVS). Of all echocardiographic parameters, LAS in reservoir phase (LASr) showed the best correlation with LA-LVS (b). Green dashed line marks border between absence (< 2 cm² LA-LVS extent at < 0.5 mV) and presence of relevant atrial cardiomyopathy (ACM). Linear regression (black line) and 95% confidence bands (black dashed lines) are illustrated. In patients with relevant ACM, LA-EF and LAS parameters were significantly reduced in all phases: 41.5% versus 28.0% for LA-EF, 29.8% versus 15.4% for LASr, 16.7% versus 10.8% for LAScd and 11.7% versus 3.9% for LASct (p < 0.0001 for all, e)

Fig. 4

Arrhythmia recurrence after pulmonary vein isolation. Kaplan–Meier curves for arrhythmia recurrences in patients with values above the calculated cut-off values for relevant atrial cardiomyopathy (ACM) (green curves) compared to patients with values below the cut-off values (red curves) are shown in a–d. With exception of left atrial strain in conduit phase (LAScd), all echocardiographic cut-offs were able to predict ablation outcome