title: Impaired adaptation to left atrial pressure increase in patients with atrial fibrillation.
abstract: OBJECTIVE
  Episodes of left atrial (LA) pressure increase predispose to atrial fibrillation (AF). The adaptation of LA mechanical function and electrophysiology to pressure elevation in healthy adults, and in patients with AF, is largely unknown.
  
  
  METHODS
  Eleven patients with left-sided accessory pathway (controls) and 16 patients with paroxysmal AF undergoing catheter ablation were studied. LA pressure (LAP) was recorded through transseptal catheterization, while speckle tracking-derived peak LA longitudinal strain (PALS) was measured using transthoracic echocardiography. Stiffness index (SI) was calculated as mean LAP/PALS. Effective refractory period (ERP) of the LA was determined during simultaneous atrioventricular (AV) pacing and during atrial pacing.
  
  
  RESULTS
  At baseline, AF patients had higher LA pressure (mean LAP 8.3 ± 4.7 vs. 5.1 ± 3.1 mmHg, p = 0.048), reduced LA mechanical function (PALS 15.1 ± 5.1 vs. 21.6 ± 6.2 %, p = 0.006, SI 0.69 ± 0.75 vs. 0.28 ± 0.22, p = 0.015), and longer LA ERP (242.3 ± 33.4 vs. 211.7 ± 15.6 ms, p = 0.017). Mean LAP was increased to the same extent by AV pacing in controls and AF patients (mean change 12.6 ± 7.4 vs. 12.6 ± 7.5 mmHg, p = 0.980). At the same time PALS decreased (from 15.1 ± 5.1 to 11.6 ± 3.3 %, p = 0.008), SI increased (from 0.69 ± 0.75 to 1.29 ± 1.17, p < 0.001) and ERP shortened (from 242.3 ± 33.4 to 215.9 ± 26.3 ms, p = 0.003) in AF patients, while they remained unchanged in controls.
  
  
  CONCLUSIONS
  The stiffened LA in patients with AF responds to acute pressure elevation with an exaggerated increase in wall tension and decrease in ERP, which is not seen in the normal LA. This may underlie the propensity for AF during episodes of atrial stretch in these patients.
authors.affiliation: 2nd Department of Medicine and Cardiology Centre, University of Szeged, Semmelweis str. 6., 6725, Szeged, Hungary.
authors.forename: Gergely
authors.initials: G
authors.lastname: Ágoston
authors.affiliation: 2nd Department of Medicine and Cardiology Centre, University of Szeged, Semmelweis str. 6., 6725, Szeged, Hungary.
authors.forename: Judit
authors.initials: J
authors.lastname: Szilágyi
authors.affiliation: 2nd Department of Medicine and Cardiology Centre, University of Szeged, Semmelweis str. 6., 6725, Szeged, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Bencsik
authors.affiliation: 2nd Department of Medicine and Cardiology Centre, University of Szeged, Semmelweis str. 6., 6725, Szeged, Hungary.
authors.forename: Cristina
authors.initials: C
authors.lastname: Tutuianu
authors.affiliation: 2nd Department of Medicine and Cardiology Centre, University of Szeged, Semmelweis str. 6., 6725, Szeged, Hungary.
authors.forename: Gergely
authors.initials: G
authors.lastname: Klausz
authors.affiliation: 2nd Department of Medicine and Cardiology Centre, University of Szeged, Semmelweis str. 6., 6725, Szeged, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Sághy
authors.affiliation: 2nd Department of Medicine and Cardiology Centre, University of Szeged, Semmelweis str. 6., 6725, Szeged, Hungary.
authors.forename: Albert
authors.initials: A
authors.lastname: Varga
authors.affiliation: 2nd Department of Medicine and Cardiology Centre, University of Szeged, Semmelweis str. 6., 6725, Szeged, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Forster
authors.affiliation: 2nd Department of Medicine and Cardiology Centre, University of Szeged, Semmelweis str. 6., 6725, Szeged, Hungary. pap.paprobert@gmail.com.
authors.forename: Róbert
authors.initials: R
authors.lastname: Pap
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D001281:Atrial Fibrillation / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000601:surgery*; D001794:Blood Pressure; D017115:Catheter Ablation; D005260:Female; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D014463:Ultrasonography
keywords: Atrial fibrillation; Left atrial pressure; Left atrial strain; Mechanoelectric feedback