Evaluation of Right Intraventricular Dyssynchrony by Two-Dimensional Strain Echocardiography in Patients With Pulmonary Arterial Hypertension

Background: Right ventricular (RV) function has major prognostic implications for patients with pulmonary arterial hypertension (PAH). Intraventricular dyssynchrony might play an important role in RV dysfunction in these patients. Methods: Thirty-six patients with PAH without right bundle branch block (mean age 44 ± 14 yr, 24 women) and 39 controls (mean age 43 ± 18 yr, 26 women) were evaluated. Global and segmental RV longitudinal deformation parameters were recorded by 2-dimensional strain echocardiography from apical 4-chamber views using a 6-segment RV model. The standard deviation of the heart rate-corrected intervals from QRS onset to peak strain for the 6 segments (RV-SD₆) was used to quantify right intraventricular dyssynchrony. Results: RV-SD₆ was significantly higher in patients with PAH compared with controls (63 ± 21 vs 25 ± 15ms, P < .001). Dyssynchrony in patients with PAH was found to derive mainly from delayed contraction of the basal and mid RV free wall. In patients with PAH, RV-SD₆ was strongly correlated with RV fractional area change (β = -.519, P = .002), RV myocardial performance index (β = .427, P = .009), and RV global strain (β = .512, P = .002); in models controlling for RV systolic pressure, RV size, and QRS duration, RV-SD₆ was still an independent predictor of RV fractional area change (β = -.426, P = .005) and RV global strain (β = .358, P = .031). RV function was significantly worse in the subgroup of patients with PAH (n = 25) with RV-SD₆ > 55 ms (the upper 95% limit in controls). Conclusion: Right intraventricular dyssynchrony, as quantified by 2-dimensional strain echocardiography, is prevalent in PAH and is associated with more pronounced RV dysfunction. The clinical implications of these findings remain to be determined in follow-up studies.