Abstract 12216: The Etiology of Right Ventricular Dysfunction in Systemic Sclerosis Associated Pulmonary Arterial Hypertension
Introduction: Systemic sclerosis with pulmonary artery hypertension (SScPAH) has a worse prognosis compared to idiopathic pulmonary arterial hypertension (IPAH), with a median 3-year survival after diagnosis. Some studies report right ventricular (RV) function is more depressed with SScPAH, but this could be due to greater pulmonary vascular load (particularly vessel stiffening with reduced compliance) and/or a primary decline in right ventricular contractile function.
Methods: To test these influences, we analyzed pulmonary artery pressures and mean flow in 76 SScPAH and 131 IPAH patients, and performed RV pressure-volume loop analysis in a second subset of patients (n=5-6/group). Loops at rest and during Valsalva (to vary preload) were determined and combined to derive end systolic elastance normalized to end-diastolic volume (Eesnorm), preload recruitable stroke work (Msw), pulmonary vascular afterload (effective arterial elastance, Ea), and ventricular-arterial coupling (Eesnorm/Ea).
Results: Pulmonary vascular afterload was similar in SScPAH (pulmonary vascular resistance (PVR) = 7.2± 3.1 Wood units; Ea = 1.0 ± 0.3 mmHg/mL; compliance (C) = 1.8 ± 0.7 mL/mmHg) and IPAH groups (PVR = 7.5 ± 4.3, 1.3 ± 0.3; 1.3 ± 0.5, respectively, p = 0.9; p = 0.2; p = 0.3). Plotting PVR versus C (log/log plot, Fig. 1A) showed C was very similar for a given PVR in each group, though there was a statistically significant but slight shift in SScPAH towards less compliance (p<0.002). More strikingly, SScPAH had reduced Eesnorm (1.2±0.5 vs 3.3±1.6, Figure 1B) and Msw (21.5± 11.5 vs 42.8±12.6, both p<0.05), and a trend towards lower coupling ratio (1.1±0.5 vs 2.5±1.6, p=0.15).
Conclusion: The greater degree of RV dysfunction in SScPAH compared to IPAH is due largely to intrinsic impaired myocardial contractility. Pulmonary vascular load, including pulsatile as well as resistive components, only slightly differs, and is unlikely to explain the disparate clinical outcome.
- © 2011 by American Heart Association, Inc.