title: Effects of right ventricular pacing on intra-left ventricular electromechanical activation in patients with native narrow QRS.
abstract: Some patients with right ventricular (RV) apical pacing show contractile asynchrony of the left ventricle. Whether the asynchrony is due to RV pacing or was a preexistimg condition remains unknown. The aim of this study was to evaluate how much pacing from the RV apex affects left ventricular (LV) electromechanical activation and to assess whether the extent of LV asynchrony during RV pacing can be predicted by clinical, electrocardiographic, or echocardiographic findings obtained during spontaneous rhythm. We evaluated 56 patients with narrow QRS and preserved atrioventricular conduction who received permanent backup RV pacing. Intra-LV electromechanical activation was assessed during spontaneous rhythm and during pacing using tissue Doppler echocardiography. An abnormal intra-LV electromechanical delay (EMD) (defined as a >41-ms difference between the faster and slower activated LV wall) was found in 15 patients (27%) during spontaneous rhythm and 28 patients (50%) during RV pacing (p<0.001). Of the 9 baseline variables (age, gender, history of heart failure, QRS duration in spontaneous rhythm and during pacing, LV end-diastolic and end-systolic diameters, LV ejection fraction, and intra-LV EMD in spontaneous rhythm), an abnormal baseline intra-LV EMD and QRS duration of >85 ms were independent predictors of an abnormal intra-LV delay during RV pacing. RV apical pacing induces asynchrony of LV contractions in a substantial percentage of patients but not in all. Although normal baseline intra-LV electromechanical activation cannot exclude the development of significant asynchrony during RV pacing, the presence of preimplant LV asynchrony predicts for a worsening of this detrimental effect.
authors.affiliation: Department of Cardiology, Ospedali del Tigullio, Lavagna, Italy, and Department of Cardiology, University Hospital of Crete, Herakleion, Greece.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Lupi
authors.forename: Biagio
authors.initials: B
authors.lastname: Sassone
authors.forename: Luigi
authors.initials: L
authors.lastname: Badano
authors.forename: Carlo
authors.initials: C
authors.lastname: Peraldo
authors.forename: Oscar
authors.initials: O
authors.lastname: Gaddi
authors.forename: Marta
authors.initials: M
authors.lastname: Sitges
authors.forename: Fragiskos
authors.initials: F
authors.lastname: Parthenakis
authors.forename: Santo
authors.initials: S
authors.lastname: Molteni
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Pagliuca
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Grovale
authors.forename: Carlo
authors.initials: C
authors.lastname: Menozzi
authors.forename: Michele
authors.initials: M
authors.lastname: Brignole
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017180:Tachycardia, Ventricular / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology*