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← Section VI · Miscellaneous Topics (Role of Echo)
VI.E

Atrial Fibrillation

5 cards

Notes

Echo assessment in AF

  • LA volume index - chronically elevated in AF; LAVI > 34 mL/m² common; > 48 mL/m² severely enlarged.
  • LAA emptying velocity on TEE - < 20 cm/s → high thrombus risk.
  • SEC (spontaneous echo contrast) - swirling smoke-like echoes; marker of stasis and embolic risk.
  • Loss of atrial contraction - no A wave on mitral inflow.

Cardioversion decision

  • AF duration > 48 hr (or unknown) → need therapeutic anticoagulation for 3 weeks OR pre-cardioversion TEE to rule out LAA thrombus.
  • After cardioversion, continue anticoagulation for at least 4 weeks (atrial stunning window even after rhythm restored).

Diastolic assessment in AF

  • Cannot use E/A ratio (no A wave).
  • Alternative markers of elevated LAP:
    • Deceleration time (DT) < 160 ms with reduced EF.
    • E acceleration rate > 1900 cm/s².
    • IVRT ≤ 65 ms.
    • E/e′ ≥ 11.
    • TR peak velocity.
  • Average across 5+ beats for accuracy.

LAA closure devices

  • Watchman, Amulet - implanted via TEE guidance.
  • Post-procedure follow-up TEE at 45 days and 1 year to confirm complete seal.
  • Peri-device leak > 5 mm considered significant.

MAZE / PVI-associated echo findings

  • Post-ablation LA stunning: attenuated A wave despite return of electrical p-wave.
  • Rare complication: PV stenosis, atrio-esophageal fistula.

AF-related cardiomyopathy

  • Tachycardia-mediated CM: reversible LV dysfunction from persistent rapid rates.
  • Rate control (< 110) or rhythm control can reverse it.

Cards

  • basicVI.E-001
    When is a pre-cardioversion TEE indicated for atrial fibrillation?
    → AF duration > 48 hours (or unknown) without therapeutic anticoagulation for at least 3 weeks. TEE rules out LA/LAA thrombus, allowing safe cardioversion.
  • basicVI.E-002
    Why should anticoagulation be continued for ≥ 4 weeks after cardioversion even if sinus rhythm is restored?
    → Atrial mechanical stunning persists for several weeks after electrical restoration of sinus rhythm — the atrium remains a thrombogenic environment.
  • basicVI.E-003
    State four echo parameters used to assess elevated LV filling pressure in patients with AF.
    → 1) DT < 160 ms with reduced EF. 2) E acceleration rate > 1900 cm/s². 3) IVRT ≤ 65 ms. 4) E/e′ ≥ 11. Also TR peak velocity, LAVI. Cannot use E/A (no A wave).
  • basicVI.E-004
    Post-Watchman LAAC device: what perileak size is considered clinically significant?
    → A peri-device leak > 5 mm is considered significant and typically warrants continuation of anticoagulation.
  • basicVI.E-005
    What is atrial stunning after cardioversion or PVI?
    → Transient reduction in mechanical atrial contraction despite return of electrical sinus rhythm. Manifests as an attenuated or absent A wave and represents a period of ongoing thromboembolic risk (4+ weeks post-conversion).