Torsion and dyssynchrony differences between chronically paced and non-paced heart failure patients

Background: Chronic right ventricular pacing may lead to left ventricular dyssynchrony, systolic dysfunction, remodeling, and heart failure. Cardiac mechanics may differ between paced and nonpaced heart failure patients, and their optimal treatment may also differ. Methods and Results: Echocardiograms were analyzed using tissue Doppler imaging and speckle tracking echocardiography in 20 patients with chronic right ventricular pacing for complete heart block (RVP group), 29 nonpaced patients with different heart failure etiologies but ejection fractions similar to the RVP group (HF group), and 25 control subjects without pacemakers or heart failure (control group). Left ventricle volumes were smaller in RVP than HF (end-diastolic volume = 93.6 ± 25.1 mL vs. 112.1 ± 22.8 mL), but intraventricular longitudinal and radial dyssynchrony were similar. Dyssynchrony within the septum was greater (number of segments lengthening during systole = 1.9 ± 1.7 vs. 0.9 ± 1.8), systolic torsion was lower (6.2 ± 7.3° vs. 10.6 ± 4.2°), untwisting was delayed (time from peak torsion to peak untwist rate = 188 ± 141 ms vs. 102 ± 73 ms), and apical rotation was reversed in more subjects (35% vs 0%) in RVP than HF groups (P < .05 for all). Conclusions: Intraventricular dyssynchrony was similar between RVP and HF groups with similar ejection fraction. However, RVP subjects had smaller ventricles, greater dyssynchrony within the septum, lower torsion, altered apical rotation, and delayed untwisting.