Left Atrial Hypertension, Electrical Conduction Slowing, and Mechanical Dysfunction – The Pathophysiological Triad in Atrial Fibrillation-Associated Atrial Cardiomyopathy

Figures

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  FIGURE 1. Comparison between left atrial pressure (LAP), left atrial electrical and left atrial mechanical parameters in patients with and without atrial cardiomyopathy (ACM). In patients with ACM (red boxes and whiskers), LAP (A) and left atrial electrical parameters [invasive atrial activation time (IAAT), amplified p-wave duration (aPWD), (B)] were significantly increased. In contrast, left atrial mechanical parameters [left atrial emptying fraction (LA-EF), left atrial strain during reservoir phase (LASr), conduit phase (LAScd), and contraction phase (LASct), (C) were significantly reduced in ACM compared to patients without ACM (green boxes and whiskers). Boxes include data between lower and upper quartiles and whiskers mark 10th and 90th percentiles.

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  FIGURE 2. Correlations between atrial cardiomyopathy (ACM) extent and left atrial pressure (LAP), electrical parameters and mechanical parameters. LAP (A), left atrial electrical parameters [invasive atrial activation time (IAAT), amplified p-wave duration (aPWD), (B)] and left atrial mechanical parameters [left atrial emptying fraction (LA-EF), left atrial strain during reservoir phase (LASr), conduit phase (LAScd), and contraction phase (LASct), (C)] correlated significantly with ACM extent [assessed as left atrial area displaying low-voltage substrate (LA-LVS) <0.5 mV]. The dashed line marks the border between absence (<2 cm2 LA-LVS extent at 0.5 mV threshold) and presence of relevant ACM.

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  FIGURE 3. Diagnosis of relevant atrial cardiomyopathy (ACM) based on left atrial pressure (LAP), left atrial electrical and mechanical parameters. Receiver-operating curve analysis determined a LAP ≥12.4 mmHg as predictor for relevant ACM with a sensitivity of 72% and a specificity of 60% (A). The corresponding values for the left atrial electrical parameters (B) were ≥143 ms (sensitivity 84% and specificity 80%) for the invasive atrial activation time (IAAT) and ≥153 ms (sensitivity 80% and specificity 79%) for the amplified p-wave duration (aPWD). The values for the left atrial mechanical parameters (C) were ≤33% for LA-EF (sensitivity 84% and specificity 72%), ≤23% for LASr (sensitivity 84% and specificity 84%), ≤13.4% for LAScd (sensitivity 88% and specificity 80%), and ≤6.8% for LASct (sensitivity 80% and specificity 64%).

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  FIGURE 4. Association of pathological cut-off values for left atrial function and atrial cardiomyopathy (ACM) extent. ACM extent for patients with calculated cut-off values for presence of ACM (red boxes and whiskers) compared to cut-off values for absence of ACM (green boxes and whiskers) are depicted. With the exception of left atrial pressure [LAP, (A)], all left atrial electrical [invasive atrial activation time (IAAT), amplified p-wave duration (aPWD), (B)] and left atrial mechanical parameters [left atrial emptying fraction (LA-EF), left atrial strain during reservoir phase (LASr), conduit phase (LAScd), and contraction phase (LASct), (C)] allowed significant differentiation between high and low ACM extent: 4.3 (0.7–20.6) cm2 versus 1.1 (0.2–12.2) cm2 for LAP, 13.1 (3.2–27.6) cm2 versus 0.5 (0–1.2) cm2 for IAAT, 14.7 (4.0–26.9) cm2 versus 0.8 (0.2–1.8) cm2 for aPWD, 9.6 (3.8–26.6) cm2 versus 0.7 (0–2.8) cm2 for LA-EF, 17.7 (4.1–29.1) cm2 versus 0.5 (0.1–1.5) cm2 for LASr, 14.6 (3.5–29.4) cm2 versus 0.6 (0.1–1.9) cm2 for LAScd, and 11.5 (3.0–25.0) cm2 versus 0.7 (0.2–3.7) cm2 for LASct. Boxes include data between lower and upper quartiles and whiskers mark 10th and 90th percentiles.

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  FIGURE 5. Arrhythmia recurrence after pulmonary vein isolation (PVI). Kaplan–Meier curves illustrate arrhythmia recurrence after PVI in patients with relevant atrial cardiomyopathy [ACM defined as ≥2 cm2 left atrial low-voltage substrate (LA-LVS) extent at 0.5 mV threshold, red curve in A], prolonged left atrial electrical conduction parameters [invasive atrial activation time (IAAT), red curve in B] and impaired left atrial mechanical parameters [left atrial emptying fraction (LA-EF) and left atrial strain during contraction phase (LASct), red curves in C] compared to patients with normal cut-offs (green curves).

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  FIGURE 6. Pathophysiology of atrial cardiomyopathy (ACM). This illustration summarizes the pathophysiology of ACM and the diagnostic possibilities to detect the different pathophysiological mechanisms. The representative patient illustrated has a relevant ACM with a left atrial low-voltage substrate (LA-LVS) at 0.5 mV threshold of 25 cm2, a hypertensive left atrial pressure (LAP) of 23 mmHg, an impaired left atrial emptying fraction (LA-EF) of 9%, an impaired left atrial strain during reservoir phase (LASr) of 7.8%, during conduit phase (LAScd) of 5.7%, and during contraction phase (LASct) of 2.1% as well as a prolonged amplified p-wave duration (aPWD) of 181 ms.