PURPOSE: Pulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling and right heart failure. As the right (RV) and left ventricles (LV) share a common pericardial sac and septum, they demonstrate interdependence. A delayed relaxation mitral inflow pattern associates with poor outcome and has been suggested to indicate impaired LV filling. We sought to evaluate the prognostic significance of LV mechanics in PAH.
METHODS: 2D, Doppler and speckle tracking strain transthoracic echocardiography and hemodynamic catheterization was performed in 82 consecutive adults with World Health Organization (WHO) Group 1 PAH. Survival was assessed over two years.
RESULTS: Patients had elevated mean pulmonary artery pressure (49±10 mmHg), dilated right-sided chambers (RA volume index 44±19 mL/m2; RV end-diastolic area 34±9 cm2), and reduced RV systolic function (RV fractional area change 28±12%; Tei index 0.66±0.23; RV free wall systolic strain -15±3%). A delayed relaxation mitral inflow predicted worse outcome (2-year survival 45% [95% CI 26, 66] versus 83% [71,91]; p<0.0001). Despite similar pulmonary capillary wedge pressures (8±3 versus 10±4 mmHg; p=0.2), LV ejection fraction (64±10% vs 65±6%; p=0.6), LV diastolic dimension (41±6 versus 43±6 mm; p=0.2) and left atrial size (26±10 versus 29±11 cc/m2; p=0.3), patients with a delayed relaxation pattern had evidence of reduced LV contractility (LV free wall longitudinal peak systolic strain -12±3% vs -16±3, p<0.0001). For each 5% absolute decline in LV longitudinal systolic strain the two-year mortality rate was 2.4-fold higher (unadjusted hazard ratio [HR] 2.40, 1.22-4.68, 95% CI) and adjusted for age, sex, WHO functional class, and PAH subgroup, the HR was 3.11 (1.38-7.20).
CONCLUSIONS: Pressure overload in PAH results in geometric alterations and functional decline of the RV. LV free wall systolic strain is suppressed and predicts early mortality, highlighting the importance of ventricular interdependence in PAH.
CLINICAL IMPLICATIONS: While PAH primarily affects the RV, these results demonstrate the significance of ventricular interdependence and highlight the utility of LV systolic strain by echocardiography in the prediction of early outcomes in PAH.
DISCLOSURE: The following authors have nothing to disclose: Evan Hardegree, Arun Sachdev, Hector Villarraga, Naser Ammash, Robert Frantz, Michael McGoon, Robert McCully, Fletcher Miller, Patricia Pellikka, Jae Oh, Garvan Kane
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