Impact of Electrical Dyssynchrony on Biventricular Size and Function in Children with Pulmonary Arterial Hypertension

Objectives: Pulmonary arterial hypertension (PAH) is a progressive disease of the pulmonary vasculature that eventually leads to right ventricular failure. We hypothesized that electrical dyssynchrony may have an impact on right ventricular (RV) and left ventricular (LV) size and function. The purpose of this study was the evaluation of biventricular function by cardiac magnetic resonance (CMR) imaging with emphasis on LV strain mechanics in pediatric PAH patients with and without electrical dyssynchrony.

Methods: Sixty PAH patients (mean age: 13.1 ± 4.9 years) were prospectively assessed by CMR. The protocol consisted of standard cine long-axis, short-axis, and 4-chamber axis using steady-state free precession during end-expiratory breath holds. Myocardial strain/strain rate was measured using feature tracking technique. LV mechanical intraventricular dyssynchrony was analyzed by computing standard deviation of strain time to peak generated for six separate LV segments. Electrical dyssynchrony was assessed by 12-lead electrocardiograms defined as QRS duration z-score ≥2.

Result: Fifteen of 60 patients (25%) showed electrical dyssynchrony which was associated with significantly lower RV ejection fraction (38.5 vs. 48.3%; p = 0.008) and lower global LV circumferential strain (−16.4 vs. −19.0%; p = 0.017). Furthermore, patients with electrical dyssynchrony had significantly greater end-diastolic (161.7 vs. 115.4 mL/m²; p = 0.015) and end-systolic (113.1 vs. 62.4 mL/m²; p = 0.006) RV volumes. Patients with electrical dyssynchrony showed significantly more severe global LV mechanical intraventricular dyssynchrony (21.1 vs. 15.9 ms; p = 0.022). Patients with World Health Organization (WHO) functional class III/IV showed higher QRS z-scores associated with more pronounced electrical dyssynchrony than patients in WHO class I/II (QRS z-score 1.73 vs. 0.74; p = 0.048).

Conclusion: In children with PAH, electrical dyssynchrony is associated with larger RV size, reduced biventricular function, more severe global LV mechanical intraventricular dyssynchrony, and worse clinical status, and may therefore reflect to be a marker of advanced disease.

Publication History

Article published online:
21 February 2021