Novel measures of left ventricular electromechanical discoordination predict clinical outcomes in children with pulmonary arterial hypertension

Abstract

Adverse ventricle-ventricle interaction and resultant left ventricular (LV) dysfunction are a recognized pathophysiological component of disease progression in pulmonary arterial hypertension (PAH) and can be associated with electrical and mechanical dyssynchrony. The purpose of this study was to investigate the clinical and mechanistic implications of LV electromechanical dyssynchrony in children with PAH by using novel systolic stretch and diastolic relaxation discoordination indexes derived noninvasively from cardiac MRI (CMR). In children with PAH referred for CMR ( n = 64) and healthy controls ( n = 20), we calculated two novel markers of ventricular discoordination, systolic stretch fraction (SSF) and diastolic relaxation fraction (DRF). SSF and DRF were evaluated with respect to 1) electrical dyssynchrony, 2) functional status, and 3) composite clinical outcomes. SSF was increased in patients with PAH compared with controls ( P = 0.004). There was no difference in DRF between PAH and control groups. There were no differences between groups in standard mechanical dyssynchrony and LV global circumferential strain. Increased SSF was associated with greater electrical dyssynchrony (QRS duration) as well as worse WHO functional class. SSF, DRF, mechanical dyssynchrony, and right ventricular (RV) volumes were prognostic for worse clinical outcomes. LV dyssynchrony indexes are altered in pediatric patients with PAH compared with controls in proportion with greater degrees of RV dilation. Patients with PAH with greater dyssynchrony have worse clinical outcomes. RV-induced increased LV electromechanical dyssynchrony therefore may be an important link in the causal pathway from PAH to clinically significant LV dysfunction. Since dyssynchrony could precede overt LV dysfunction, addition of ventricular synchrony analysis to CMR postprocessing protocols may be of clinical benefit. NEW & NOTEWORTHY We demonstrate that left ventricular discoordination indexes are altered in pediatric patients with pulmonary arterial hypertension compared with controls and pediatric patients with pulmonary arterial hypertension with greater dyssynchrony have worse clinical outcomes. Furthermore, there is evidence for the mechanism of right ventricular-induced left ventricular discoordination to include a combination of delayed early systolic electromechanical activation, late-systolic septal shift, and prolonged, postsystolic septal thickening.

Cardiac Magnetic Resonance Imaging in Pulmonary Arterial Hypertension: Ready for Clinical Practice and Guidelines?

“…The improved strain values correlate with improvements in known prognostic markers of PAH such as 6-min walk test, pro-BNP, and mean pulmonary arterial pressure (MPAP) [ 21 ••]. Furthermore, an interventricular dyssynchronous contraction has been documented with a left-to-right delay assessed by strain in adult and paediatric patients with PAH [ 33 – 36 ].…”

Echocardiographic Changes and Long-Term Clinical Outcomes in Pediatric Patients With Pulmonary Arterial Hypertension Treated With Bosentan for 72 Weeks: A Post-hoc Analysis From the FUTURE 3 Study

“…LV dysfunction is of increasing interest in pediatric PAH, since its prognostic relevance has become more apparent (20), and it may reflect LV compression as a result of RV enlargement (21). Burkett et al demonstrated the strongest correlations for maximal eccentricity index, a new and highly reproducible measure (19).…”

“…In that study, Burkett et al demonstrated that eccentricity index and right-to-left ventricular ratio correlated with invasive simultaneous hemodynamic measurements, PH-related hospitalizations, BNP/NT-proBNP levels, and WHO FC ( 19 ). LV dysfunction is of increasing interest in pediatric PAH, since its prognostic relevance has become more apparent ( 20 ), and it may reflect LV compression as a result of RV enlargement ( 21 ). Burkett et al demonstrated the strongest correlations for maximal eccentricity index, a new and highly reproducible measure ( 19 ).…”

Role of cardiovascular magnetic resonance in pediatric pulmonary hypertension—novel concepts and imaging biomarkers

“…As a result of an altered position of the interventricular septum, impaired LV diastolic filling (74,75) and reduced LV torsion have been reported in PH patients (76). Progressive electrical dyssynchrony occurring with RV dilatation and dysfunction further contributes to systolic LV dysfunction and a discoordinate contraction pattern that, in turn, is of prognostic relevance (31,32). Accompanied by adverse interactions on the ventricular level, increased stiffness of the ascending aorta seems to be present and is directly related to MPA distension.…”